DE1466043A1 - Synchronized wireless communication system - Google Patents

Description

Control Data Corporation, South. Minneapolis, Minnesota / USA

Synchronized wireless communication system

The invention "relates to radio communication systems and in particular on a system by which several stations provide information on their mutual distance, their mutual azimuth and their altitude in order to be able to use for air traffic control, to contribute to the avoidance of collisions and to the control of air traffic.

I. Introduction ■ - "., _

One object of the invention is a system for synchronizing the transmission times or pulses of different stations to create that can be both fixed and movable without the need for a superordinate main station (master station) will.

These broadcasts or transmissions can be used to. Distance and altitude information of a station in relation to to identify another.

According to the invention, preferably all stations in a Göbiet (network area) of several stations synchronize the generation of their signals, that is, those of a main oscillator with those of all other stations. The main oscillator in each station generates several first signals, while an "interrogation ^{signal 1} * is sent in a certain temporal relationship to a first signal, normally synchronously therewith. Each station also receives the interrogation signals of the other stations in the Gobiüts and sends a" response signal " in response to receiving an interrogation signal.

009820/0296

In the inventive system, all stations in existing "Send l Liebig en times interrogation signals. Within a certain period of time, one or more pairs of stations measure the time difference between the generation of their first signals when their respective interrogation signals are transmitted and the receipt of the interrogation and response signals from the other station in the pair. The generation of the first signals, and therefore the transmission time of the next interrogation signal from both stations of the pair, is corrected in the direction of synchronism based on the measured time difference by reducing the phase shift (or time difference) of the main oscillators of both stations by half in the direction towards each other, that is, it is moved forward in one station and backward in the other. By continuously synchronizing any two stations with one another in this way, all the stations are gradually synchronized with one another without using a main station for synchronizing. Finally, the first signals from a station that is newly added to a network area can also be roughly synchronized with the station in the area that is in the next area.

If all stations are then synchronized with each other, each station can send position data signals, e.g. regarding the height, send and with the help of the sent signals the xJitf ernung measure up to all other stations.

The invention will now be described in detail with reference to the accompanying drawings, all of which are taken from the description and FIG the details or features of the drawings Can contribute to the solution of the problem within the meaning of the invention

ÖÖ9S2Ö / 0296

BATH ORIGINAL

and bit the will for patenting included in the application became·

fig · '1 is a timing diagram of various transmissions or transmission pulses fixed ground radio stations and mobile stations}

fig · 2 is a timing diagram of transmitted and received pulses two stations in a synchronized state}

fig · 3 is a timing diagram of transmitted and received pulses two stations in non-synchronized (out of sync) state}

fig 4 is a schematic block diagram of a circuit type for phase correction of an oscillator up to synchronism}

Fig. 5 iet a graphical representation of the number of comparisons required for synchronization as a function of the Number of stations on a logarithmic scale}

Figure 6 is a timing diagram illustrating the use of start pulses (B) shows the rough synchronization of the stations}

Figures 7A, 7B and 70 show the effect of coarse synchronization at three stations}

Fig. 8 is a timing diagram illustrating certain effects. Principles of the invention}

9 is a simplified block diagram of the system of FIG ο of the invention} ·

ο Fig. 1o is a more typical detailed block diagram Q assemblies that are used in the system according to the invention}

cd ■

. 11A, 11B and 110 are schematic block diagrams of FIG Sharing the system according to the invention}

Hg, ¹ schematiaches 12A is a block diagram of the height of the rear derailleur;

Pig * 12B is a timing chart to illustrate the operation des Honensohaltwerkej

Figures 13A and 13B are time representations of a synchronization correction using a pulse counting technique;

Eg. 14 is a blookshield of a device in one Station to carry out the synchronization with the help of a pulse counting;

Pig, 15A and 150 are block diagrams of different types of reversible counters, while Pig · 15B is a binary counting method represents;

Pig, 16 is a block diagram of a circuit for generating the "cut-off voltage";

Pig. 17 is a block diagram of a circuit for selecting the transmission times for the pulses B _Q , A _Q and GL;

Pig. 18 is a block diagram of a circuit for selecting the. Sending times for the I ₀ pulses;

Pig. 19 is a block diagram of a circuit for performing coarse synchronization of the start pulses;

_o Pig. 2o is a frequency control circuit of the main clock oscillator .Jg by Pig. 14;

- ^. Pig. 21 is a block diagram of a circuit for selecting the transmission times for the pulses A _Q ;

Pig. 22 is a block diagram of a circuit by which the Generation of information pulses is prevented if the station is not synchronized;

BATH ORIGINAL

Pig. 25 and 24 are block diagrams each of a pulse encoder and pulse decoders;

Fig. 25 is a block diagram of a receiver-transmitter which is used in this system »

II, system signal transmissions

To explain the mode of operation of the system according to the invention, the following abbreviations have been used for the various transmission pulses chosen:

H = response pulses
I = interrogation pulses
B = start impulses

G = interrogation pulses from a ground station
A = interrogation pulses from an aircraft

0 = index to identify a transmission signal from the own station

Throughout the description, the term "ground station" is used for a station that is stationary relative to moving stations. The ground station can, for example, be a fixed land radio station or a relatively stationary radio beacon on the water. The term "mobile station" is used for single stations that move relative to the ground stations and / or to each other. These can be, for example, planes, helicopters or other types of stations that move in the air, on land or on water. As a result, it should be noted that other stations also fall under the term "land" or "mobile" according to the definition above,
to

is> To explain the mode of operation of the system, reference is made to FIG. 1

- ^ Reference which shows some of the signals that ° are sent during each operating interval that is * ° purification was accepted with one second.

The 1-second interval is for illustration in 548 transmission positions or times that are split every 1/548 of a second

appear. At time t = O, in transmission time No. 1, the transmission interval begins with a start pulse B, which is transmitted by every station in operation. Positions No, 2 "to No, 2oo are transmission positions with even-numbered position numbers, No, 2, No, 4 · '··· No, 2oo, which are assigned to special ground stations for the transmission of ground station information pulses G, while the odd-numbered position numbers, starting with No * 3 to No, 199, are assigned to the mobile stations of, air station information pulses A corresponding to the elevation layer in which the respective air stations are located « ¹

For example, ground station X is position No. 2 for the transmission of an information pulse G, the ground station Y the position No ₀ 4 for ^{the transmission of an information pulse B β 1} , « ¹ and the ground station ZZ assigned the position No ₉ 2oo for the transmission of the information pulse G. Since a certain "ground station only sends an information pulse at the time of transmission assigned to it in relation to the start pulse B, a ground station can thus be identified at its time of transmission. It should be noted that the same transmission positions can be used for two different stations, provided that that the two ground stations are far enough apart so that the transmission pulses from one ground station cannot be received by a mobile station which was operating in the area of the other station

In the illustrative embodiment of FIG

Invention are the odd positions No. 3 o ·· »No“ 199 co
ο for sending aircraft interrogation pulses several at intervals

J ₀ assigned to successive altitude layers of 100 m ',' Thus those aircraft that are at an altitude of 0 to 10Om

"^ interrogation pulses A fly at the point in time No * 3, those of flight
»S> witnesses that fly at altitudes of 100 to 200 m, impulses A im

^ Time No, 5 etc. It should be said that several in one - And aircraft flying in the same altitude range send their respective altitude information pulses only at the appropriate point in time.

The height of the height range can be determined according to the requirements of the overall system, including the Operating heights of the various plug-in tools include »It must it can be said that the individual heights are not always must have the same height, so can the height of the individual Ei ehe, / for example increase with increasing height, if you want to take into account the fact that the accuracy of the aircraft altimeter decreases with increasing altitude In this case, the upper height areas would have a greater height than the lower height areas. For example the lower areas would be 100 m high and the upper areas 300 to 500 m high »·

The send positions Ho 2o1 to Ko 548 of Pig, 1 are both from ground stations as well as from mobile stations for the transmission of interrogation pulses I for the purpose of synchronization and maintaining the synchronism of all stations with each other is used. The synchronization is therefore necessary with it the different stations send the information at the appropriate times and identify all times can to get information from the other stations. According to the invention, no station transmits, be it fixed or movable, information impulses G or A in the times Ho 2 to No 200, before it is not synchronized «Whether synchronism is automatically generated by each station of zero or minimum fault signals in the station fault determination circuits and how synchronism is achieved will be described.

If the individual stations are synchronized with each other, you can determine the distance and height of the other stations within determine their transmission and reception area. In the synchronized state, for example, ^ knows every moving station the time of transmission of the information pulse G of a special Ground station, and the measurement of the time between the transmission exit point and the reception of the information pulse G gives the distance or the distance of the moving stations from the

BADOm ₀₁ NAL 809820/0296

Ground station. A ground station can have distance and altitude of an airplane by measuring the time between an odd Determine the point in time and the receipt of an information pulse A from the aircraft. In the same way can each aircraft determine the distance and altitude of every other aircraft.

Although the system is described in terms of 548 transmission positions, of which 199 are used as information pulses and 248 for synchronization purposes, other numbers of transmission times, either higher or lower, can also be used. If you want, you can also design the relationship between the information and synchronization times differently. The choice of suitable proportions depends on ■ several factors. This includes the station density (number of stations per area), the desired operating distance between the stations, the performance of the system, etc.

The following is a comprehensive overview of the various Send impulses given by the system. At the beginning of each transmission interval, each station, whether fixed or movable, transmits a start pulse B at time No 1j the information pulses G and A are respectively from the ground stations and the Movable stations are sent at the even-numbered and odd-numbered times No 2 to Ho 200 assigned to them in each case; and the interrogation pulses I are from both the fixed and also from the moving stations for synchronization purposes sent in the times No 2o1 bia No 548.

to During intended to synchronize time (times No 2o1 to No 548) (not shown in FIG. 1) sends each station except for the above-erwähn Jj ^ th pulses a response pulse R ο under certain conditions. The response pulse is ο of a station in the time interval between the time of transmission, in which the station transmits ^ their eiganen interrogation pulse, and sent to the next transmission time point ^m. One station only sends. after receiving the first interrogation pulse from another station, a response pulse, ■ which is then sent from the other station to the syn-

chronization is used.

Thus, every station sends during the synchronization provided time their own impulses I and receives impulses I from other stations. Each station also sends R-pulses in response to "certain received I-pulses and." receives R-pulses from other stations in response be sent on the first-mentioned I-impulses of its own station «As will be described below, each uses Station their own interrogation pulses I and those received from other stations in response to their own interrogation pulses I. Response pulses R for synchronization.

III »Synchronization of two stations

To explain how several stations in a Yerbund area (i.e. all those fixed or moving stations that work together for mutual synchronization) Synchronized will be on Pig. 2 referred to. In this figο the position in time of the transmission pulses of two synchronized stations in a Yerbund area is shown. The phrase "synchronized" may be understood as follows: On the assumption that there is an impulse from every station at the moment is sent when an oscillator in the station, which is the pulse generating device controls, has a certain phase angle, e.g. at the time of a positive zero crossing of a Sinusoidal oscillation, are 2 stations or, respectively, their respective oscillators considered synchronized if the pulses sent by each station at a given point in time are in the middle between the two stations can be observed at the same time. This requirement applies to the synchronization of two movable ones Stations, one fixed and one moving station, or two fixed stations. Ea should be said again that the stations only perform synchronization during times No 200 to No 548. However, if a station once

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ΊΟ

is synchronized, this state will be during the other Points in time No 1 to 199 are maintained by a wide variety of circuits in the station,

IM the stations during the broadcast times No 200 to No 548, each station sends two types of pulses, namely interrogation pulses I and response pulses R. Each station sends interrogation pulses I at several points in time according to No 200 and response pulses R as a response to the reception the first interrogation pulse I from another (second) station, which it receives after sending the first own I-pulse The first! Pulses that would be received would then come from the nearest station of those stations in a network area which send randomly at the same time *

In order to get into the synchronized state, each station tries the transmission time of its own interrogation pulse I.

["" to synchronize with the interrogation pulse of another station. Each station first determines its distance from the other station. Each station measures the transit time between transmission of its own interrogation pulse and reception of the response pulse sent by the second station on the basis of this interrogation pulse. Since the return time between the transmission of the interrogation pulse by one station and the reception of the response pulse sent by the other station as a response to this interrogation pulse multiplied by the propagation speed of the signal is twice the distance between the two stations, the actual distance between the two stations can be can be determined by dividing this result by two. By measuring the distance between two stations

^ Each station can also check the actual transmission time of the ° determine the interrogation pulse I received from the other station,

ο ·

** This is done by determining the time of receipt of the interrogation pulse from the other station in relation to the time of transmission of the ^ Interrogation pulse of the own station and the receipt of the response * impulses reached from the other station. If your own query pulse a station out of sync with the interrogation pulse

the other station was sent, the main oscillator of the station is corrected so that the system pulse transmission time is subsequent Consignments is corrected «It should be noted that normally both stations are trying to achieve synchronism .. so that both can make corrections at the same time.

Pig. 2 shows the synchronized state of two stations X and Y, the pulses sent by stations X and Y are shown on time axes a and b, while the pulses received by stations X and Y are shown on time axes ο and d. At time t = t _Q , both stations X and Y send interrogation pulses Ι _χ and Iy in the synchronized state (time axes a and b). This transmission would take place at any one of the times Ho 201 to No 54-8. The pulses Iy and Ι _χ are received by the respective stations X and Y at time t = t- · The time between the transmission of Ι _χ (or Iy) and the bapfang of Iy (or Ι _χ ) is called 3> _ and can be measured in the form of a voltage Β _{τια φ}

In response to the receipt of the interrogation pulses at time t = »t, station X sends reply pulses R _x and station Y sends reply pulses Ey (time axes a and b) received (time axes c and d). The time between sending Iy (or Iy) and receiving Hy (or Β. _Χ ) is called L ™ and can be measured in the form of a voltage Inw or as the number of clock pulses counted during this time.

ο For the explanation is shown in line e, that the station Xzehn ^ units of time (T ™) and / or distances did _SS and between the instants t = t .., d _e h _e between the transmission of the query - "^ pulses _Ι χ and the reception of the interrogation pulse Iy from the staro tion Y. The station X measures 20 units of the time (^ gpy) ^ or the distance between the transmission of its own interrogation pulse Ι «and the reception of the response pulse Ey.

BADORIQiNAt

ff '. "■■ ■ ■■

query pulses I »and Iy are initially synchronized, the station Y also measures the same number of units of time or the distance (10 and 20) between the transmission of its own query pulses Iy and the receipt of the query pulse Ι _χ and between the transmission of the query pulse I ^ and the receipt of the response pulse R-., In the synchronized state behaves

or like «2 ι 1. These time and / or distance measurements

can be done analog by storing a voltage proportional to the time with the help of a capacitor or digitally by counting the pulses of a high-frequency clock generator. Both methods are known per se. It should be noted that when the stations are synchronized, the distance from station X to station T in station X by measuring the time of flight between the exposure of the pulse I- and the reception of the pulse H-. is determined. Station Y determines the distance to station X by measuring the transit time between AusGendun ^; of Iy and receipt of R _x . The distance between two stations is equal to half the measured time multiplied by the speed of propagation. The distance between two stations is also equal to the time ton from the emission of the pulse Ι _χ (or Iy) to the reception of the pulse I_ (or I _T ) multiplied by the speed of propagation

As can also be seen, when the interrogation pulses Ιγ and Iy are initially synchronized, each station receives the interrogation pulse sent by the other station in the middle of the time between the transmission of its own interrogation pulse and the receipt of the response pulse sent by the other station. This follows from the fact that the Laufljit between the initial broadcast _β an interrogation pulse by a station and the <Reception 'p of the transmitted simultaneously from the other station Abfrageim-ι »pulses equal to the distance between the two stations divided by £ J the off 'rate of spread is. The transit time of the pulses £ * - between the transmission of an interrogation pulse by a station and the reception of a response pulse es, which is sent by the other station when this interrogation pulse is received,

BATH ORIGINAL

is double the distance (the way there and back) of the two Stations divided by the speed of propagation

Finally, it should be mentioned that there is a minor bug in the measurement results when the two stations move relative to each other. This error is proportional to that Distance and the relative speed of the stations »With a typical distance of 300 km between the stations and a relative speed of around 1000 km per hour, this error is only in the order of 10 seconds, which is negligible compared to the overall accuracy of the system is.

If the interrogation pulses of the two stations do not start from the beginning are synchronized with, a station represents after measuring the Duration from the transmission of your query pulse to Receipt of the interrogation and response pulses from the other station determines that its own interrogation pulse in relation to that of the other Station is too late (or too early). The other station determines that its interrogation pulse is relative to that of the first station too fin h (or too late) came. As a result, do not behave in any Station the time or voltage measurement results I-dw or EUpy from the measurement of the larger interval from the transmission of a I-pulse until receipt of an R-pulse at the time or Voltage measurement results based on the measurement of the smaller interval from the transmission of an I-pulse to the reception of a other I-impulse like 2: 1 · '

The unsynchronized state between two stations is shown in FIG. Here station Y sends its query pulse Iy at time t = t _Q + / \ t. This point in time is delayed by / \ t compared to the point in time t = t, * of the transmission of the interrogation pulse Ι _χ. It can be seen (time axis o) that station X receives the pulse Iy at a point in time which is somewhat later than the transmission point in time with respect to the middle point in time

BATH ORIGINAL

809820 / 029Ö ι

AH

of the own interrogation pulse I «and the time of receipt of the response pulse Ry. which was sent by station Y as a response to the interrogation pulse Ι _γ · Furthermore, it can be seen (time axis d) that the station Y received the interrogation pulse I— before the middle time between the transmission time of its own interrogation pulse Ι _γ and the receiving time of the response pulse Hj, which was sent by the station X in response to the interrogation pulse I _T. The size of the deviation of the ratio of the two times measured by the stations X and Y from the ratio 2: 1 in the synchronized state is proportional to the synchronization error. This is shown quantitatively in FIG. 3, from which it can be seen that the station X has 13 units from the time t = t _Q to the reception of the pulse Ι _γ at the time t = »t- + -Δ t and 20 units from the time t . = iL to "aum receiving the response pulse Ε ™, at time t = t _2. The station Y measures 7 units from the time of _{sending t = t Q} + / \ t of the pulse Iy to the time of receiving t = t .. of the pulse Ι _χ and 20 units from time t = t _Q + / \ t to receipt of the response pulse Ry at time t = tp + ^ \ t. This results in the respective time or voltage ratios of 20:13 and 20: 7 for the stations X and Y, from which it can be seen that the stations are not synchronized. If the error in the transmission was reversed, ie that station X transmitted later than station Y, then the measured values and ratios would also be reversed. In both In some cases, the deviation from the measurement compared to the synchronization ratio 2: 1 will be compared to the Sy related to chronization.

The functioning of the system is based on the fact that at each station the time between the transmission of its own interrogation pulse I and the reception of the -from another station Reception of the pulse I generated response pulse R independently from synchronization is and only, as with conventional Radio beacon systems, depends on the distance between the two stations »The measurement of the distance is based on a time measurement.

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Returned · On the other hand, the time of receipt depends of the interrogation pulse sent by the other station depends on the synchronization and the distance between the two stations · If thus the time of receipt of the interrogation pulse from the other Station before or after the mid-point between the time of sending an interrogation pulse and the time of reception one from the other station in response to this one Interrogation pulse sent response pulse is, yields eiöh from the fact that the two stations are not synchronized · 23s The value of the error, whether greater or less than half the time interval, is used to correct the oscillators of both stations used so that the stations are brewed in the synchronized state

The timing error can be measured in several ways. For example, capacitors and Sohaltglieder can be used, the station's own interrogation pulse initiating a charging process of two capacitors to the voltage given by a voltage source by actuating an electronic switch connected between each capacitor and the voltage source. The charging of a capacitor is terminated upon receipt of the interrogation pulse transmitted by the other station by T ™™ ^un ^ causes this pulse for measuring the time ^for Sr ^zeu g ^un g of voltage Eyjjm the switch to the separation of the circuit from the voltage source · the The charging process of the other capacitor is terminated by the response pulse received to the interrogation pulse of its own station for measuring Τ · ηργ and generating 1U ». The capacitor, which measures the time between interrogation and response pulses, charges half the value of the one that measures the time Tjjjrp between the transmitted and received interrogation pulses. In the synchronized state of both stations, the voltages Bopy and ^ TWf ⁸ ^ ¹¹ equal to ^the ^ ^{two capacitors}

S09820 / Ö296

8AD ORfQlNAt

If the stations are not synchronized, then a error voltage generated, which is used for phase control of a query pulse oscillator is used in each station. To the However, other known timing positions can also be used to measure time be used. A circuit of a digital type would be a circuit in which two counters are used to count the pulses a clock oscillator from the interrogation pulse of its own Station being started «The counting process of one counter is followed by the one arriving from the other station Interrogation pulse ended, while the counting process of the other was carried out by the in response to the interrogation pulse of the own station incoming response pulse is terminated. The difference between the two counting results is used to generate a control voltage which in turn controls the phase of the interrogation pulse oscillator. If you want, you can also use the second counter train that it counts every other pulse of the clock, so that the count of both counters is directly subtracted and can be used to generate the fault voltage *

FIG. 4 shows an analog circuit of a station for generating the error voltage, which is used to synchronize the interrogation pulses of the station is used with those of the other station (or stations) operating in the area. The circuit includes an interrogation oscillator 11 which generates an interrogation pulse 10 controls. The pulse generator 10 delivers interrogation pulses an interrogation pulse holding element and a transmitter (not shown in this figure) and to two timing circuits 13 and 15 · The circuits 13 and 15 measure the times Ejjpn and 3? Tjot and. generate the respective voltages E-, · ™, and Bpw · The interrogation pulse of the G-enerator 10 triggers the timing cycle of the circuits 13 and 15 from · As already said, it can be with these circuits to capacitors, which on charge a certain voltage. In the case of voltage 13, the charging process is terminated by another interrogation pulse, the received from the station receiver, received from others Pulses are decoded and fed to the measuring device 13 »

909820/0296

The voltage Ejjjm generated by the measuring switch 13 is a. Measure of the time between the time of sending the station's own interrogation pulse and the time of receiving the interrogation pulse of the other station · The measuring process of the holding device 15 is determined by the response pulse arriving from the other station ended and the voltage ELp ^ generated. As eohon mentioned » The circuit 15 is preferably charged to half the value the hold 13 on, so that when the two stations are synchronized , the tension B-rjrm is equal to the tension L ™ · The synchronization error voltage is generated by a subtracting circuit 19 is generated in which E- ^ is subtracted from Bgpy. When the two stations are synchronized, the output signal is of circuit 19 is zero, and thus no error voltage is generated. But if the two stations don't are synchronized, an error voltage is generated.

The size and sign of the error voltage depend on the order how much the interrogation pulses of the two stations lead or lag each other. »The error voltage is passed through a low-pass filter 2 is supplied to a motor 3, which has a set between the interrogation pulse generator 10 and the interrogation pulse oscillator 11 Phase shifter 14 controls. Depending on the size and polarity of the error voltage generated by the circuit 19, the moves Motor 3 the phase shifter 14 in a certain direction and shifts signals of the oscillator 11 until the Interrogation pulses from the generator 10 are in phase with those of the other station. In addition, each station carries out the Phase shift correction so that the synchronization is achieved at any intermediate value of the total error in the synchronization between the two stations

^ω IV » synchronization of more than two stations

QQ, .., ii, ι.

* · ■> In the previous paragraph, the synchronization of two

>>. Stations discussed. This section aims to show ° den that the synchronization of more than two stations can be reached, although multiple stations address the problem cd '

make it more complicated · Let this be the example of three first

BADORJQINAL

42

of unsynchronized stations X »Y and Z, which are to be synchronized with each other, explained. At any transmission time according to no. 200, each station X, Y and Z sends an interrogation pulse. These interrogation pulses are initially not synchronized. In addition, "each station transmits a response pulse ale response to the receipt of each Abfrageimpulsea. Therefore, each station receives two interrogation pulses that are sent from the other two stations and four answer pulses, namely two response pulses from any other station in response to the two interrogation pulses, each This other station receives "Two of the four reply pulses received by each station are the reply to the interrogation pulse sent by the station itself. If these two reply pulses are separated and each reply pulse is paired with the interrogation pulse sent by the same station which sent the response pulse, the synchronization with any other station can be carried out in the same way as described in Section III using two stations »

It should be noted that there is a difficulty if station X was synchronized with station Y, station Y with Z and Z with X, because not necessarily all Stations need to be synchronized with each other. To overcome this difficulty, each station could use the The possibility are given to correct the transmission time of your query pulse so that it corresponds to the mean transmission time of all three stations coincides in order to possibly achieve synchronism »It could also be a Coding methods are used in which the stations X, Y and Z have identifiable (coded) interrogation and response pulses send, so that one station can decipher the identifiable impulses of another station and thus itself could synchronize »However, such arrangements for time averaging or coding would increase with increasing

9 0 9820/0296

BATH ORIGINAL

The number of τοη stations in a network area is becoming more and more complicated and therefore more impractical and unreliable »A preferred technique for synchronizing multiple stations of a network area, the so-called "red-green" state technology is discussed in Section TI. below bescliriebeno

tim to understand how several unsynchronized stations are synchronized in a convergent manner, the following qualitative explanation is given. Assume that see 200 stations are located in the network area. Each station contains an oscillator to control the interrogation pulse generation, and the output of each oscillator may differ in phase by the same amount with respect to the oscillator whose phase is closest, see above that the phase angles of all oscillators are distributed uniformly are. Then sioh results in 200 unsynchronized Stations in a synchronization interval of 360 °, in which the oscillators are not synchronized, a phase difference · of 1.8 ° between the phase angles of successive Oscillators · Adjusts the output signal of each Oscillator as a time vector or pointer, then there are 200 pointers »whose directions differ from each other by 1.8 °, and if all pointers point in one direction, all oscillators are synchronized. Since the only thing that matters is that all pointers coincide, i.e. point in one direction, it does not matter at which angle all pointers coincide in the interval of 360 °,

If you twist any two hands of the 200 hands up to In the middle of their angular distance, then these two pointers can (Stations) are considered to be synchronized. Such a phase correction of the oscillator of each station can be done with the help of the circuit of Figure 4 can be achieved. The motor 3 is driven so that it via the phase shifter 14 the Phase of each oscillator by half the initial phase difference of the two oscillators up to the middle of the initial

909820/0296

BATH ORIGINAL

Phase difference shifts so that both oscillators are synchronized are. Then any two other pointers are found that are neither the first nor the second pointers contain the first pair, then these two pointers can also be rotated or phase shifted up to Are synchronized in the middle of their original distance »but if the second pair is identical to the first» then if it doesn’t happen, i.e. the synchronous state is retained. However, it becomes a pointer of an already synchronized Pair is used for a further comparison, then the synchronous state of the pair from which the one Pointer was picked out, canceled ..

Duroh continued random selection of pairs of hands and through ·

Shifting the respective phase of each pointer up to the middle of their angular difference changes the uniform angular distribution the pointer of one pointer per 1.8 ° in an uneven distribution in which one or more angular regions with a larger number of pointers are occupied »This is due to the fact that with each further pointer comparison the probability increases for the fact that one of the pointers selected for another pair is already synchronized. That's why If the already synchronized pointer tries to pull the other pointer towards its own angular position eu, i.e. at least half of its original angular distance towards the original synchronization position. Since further comparisons follow between two pointers, the probability increases that a pointer of the selected pair is chosen from a more densely populated or preferred area as more and more pointers move into the YY? rotate more densely populated areas. This has the consequence that all <*> Pointers from the less densely populated areas to the more densely populated

set areas are drawn. At the same time this is looking for> ^:. selection process the Winkelbereioh of the preferred area in which the 5 * Beiger 'be drawn to widen as each originally «*> Synchronized pointer is rotated every time it fir

a comparison is used. But there more and more Pointers rotated to a preferred area increases

the probability that two pointers are out of the same preferred area and not be selected from two non-preferred areas · This leads to the angular range of the preferred area narrows more and more and after several comparisons all pointers coincide · This means that Despite the statistical comparison process, a finite number of comparisons results, so that all stations can be synchronized with one another, even if initially none Station was synchronized with another

The one required for convergence (synchronization) of all stations Time, while adhering to a specified tolerance or a specified error, depends on the number of times the stations to be synchronized in a network area, on the other hand on the number of required comparisons and finally on the speed with which the comparisons can be made »The latter factor changes deal with the maximum expansion of the system, i.e. with increasing expansion of the system or »the network area in which stations are to be synchronized with one another, the time between the individual transmission synchronization times also increases. This also reduces the number of intervals provided for synchronization purposes per second. Even if more times are reserved for data transfers, fewer remain for synchronization purposes, so that the time required to achieve convergence "increases

To use a typical example to explain how much time is required for synchronization (convergence), is reference is made to FIG. In FIG. 5, the synchronization times are plotted for a system in which 350 out of a total of 550 intervals per second for synchronization purposes To be available. The oscillators of all stations vibrate therefore during the synchronization time with a frequency " of 550 Hz, i.e. a period of 1818.1 microseconds

909 820/02 96

S ORIGINAL

- ■ ■

al

or about 1800 microseconds. If the oscillators bie an error of not oscillate in phase synchronism than 0.01 ° more, that is, the pointer all converge on a part of 36,000 parts, the maximum equivalent time-High is error between the oscillators or 0.05 1800/36000 Microseconds. This means a maximum error in the distance measurement of only about 16 meters as a result of incomplete convergence »This error is relatively insignificant at the current flight speeds ·

FIG. 5 generally shows the number S of comparisons required to synchronize R stations, starting from a state of complete asynchronicity (uniform distribution of all temporal errors of all stations over 360 °). It should be noted that this is the most unfavorable state because it assumes that all stations are initially out of sync. Normally, in the worst case scenario, only those situations arise in which the network area contains only a few non-synchronized stations or a few non-synchronized stations are added to many already synchronized stations in the area. The assumptions made in deriving the function plotted in FIG. 5 are: convergence with a maximum phase error of approximately 0.1 °, assuming a state of uniform distribution of the phases of the oscillators of the various stations and a system efficiency of approximately 25 #, that is to say that each Station only carries out a phase correction during a quarter of the synchronization interval. It can be seen that the time required for complete synchronization is relatively short. For example, at 100 stations, 2000 comparisons are required to achieve convergence within an error range of 0.1 °. If 347 intervals per second are available for synchronization comparisons and a system efficiency of $ 25> is present, this means that only two stations are transmitting in one interval, a successful comparison is only carried out during 25 # of the synchronization intervals, and an average of 187.5 ver -

BATH ORIGINAL

33.

the same per second. Under these conditions it takes time. about 12 seconds until 100 initially nicely synchronized stations are fully synchronized. As the number of stations decreases, so does the time required for convergence. For example, with 50 stations whose oscillator phases are evenly distributed, it would only take about 9 seconds for the oscillators of these stations to be synchronized to an error of 0.1 ° or less, while 14 seconds would be required for a maximum error of 0.01 ° are. It should also be noted that the time required for synchronization decreases as the maximum permissible error for oscillator synchronization increases. For example, approximately '20 i> fewer comparisons are required if, instead of a phase error of 0.01 °, only a tolerance of 0.1 ° is required for the convergence can be viewed as relatively accurate within the error limits of such calculation methods. It should be noted that the values plotted in FIG. 5 were only given to explain the invention.

As already said, the worst initial conditions have been assumed for the diagram of FIG. 5, namely that all stations were originally not synchronized. In the normal case, however, the situation is as follows: that in the entire network area only a few unsynchronized Stations are distributed, which are synchronized in a few seconds, or there is a network area with several synchronized stations, to which a few non-synchronized stations are added. In the first case the few stations in the area could possibly be synchronized without a special procedure. In the latter The case can, instead of these few non-synchronized stations, be assigned to the larger group of synchronized stations to allow one or more of the last-mentioned stations to be pulled out of synchronism, a search

§09020 / 0 296 BAD ORIGINAL

- ■ 89--

If the majority of the comparisons made in a station in the network area for synchronization purposes show that an oscillator phase correction is required, which indicates that the station is not synchronized from the start, the station applies the full correction (i.e. the search procedure) an · However, if the majority of the sync comparisons give little or no phase correction, which would mean "the station is locked, then only a fraction of the correction (the entrainment method) is applied. Thus the phase of the oscillator shifts one with several others Stations only synchronized station by a very small amount towards the phase of a newly added, unsynchronized station, since the majority of the phase comparisons in the synchronized station show that no oscillator phase correction is required. On the other hand, any comparison that the ni The newly synchronized station makes a large error and that a significant phase correction is required. This station therefore uses full phase correction in the search process in order to bring its oscillator into synchronism with the oscillators of the other stations.

The synchronization of all stations in a given area can also be achieved more quickly by using a coarse synchronization method in which each new station entering the area observes the arrival time of the received otart pulses and first synchronizes with these pulses before finally turning with _m synchronized with the interrogation pulses. This procedure is described below.
co

ο V. Coarse synchronization

_o As noted above, the two to synchronize ^N> stations durcJi time required can be a rough synchroni- "D organization are reduced" When coarse synchronization is performed in Synclironiaaiionsiiitervall .inc provisional suspension

BATH ORIGINAL

ar

the transmission time of the interrogation pulses of a station below Taking into account the times of reception of the start impulses other stations · Passes rough synchronization errors prevented also the transmission of interrogation pulses by a station before the synchronization with the other stations of the area is carried out

When a new, non-synchronized station that wants to move to an area of synchronized stations that are operated by the other stations in the area observed start impulses B, it will receive some start impulses with a larger amplitude from nearby stations that from an increasing number of S.tart impulses with a smaller Amplitude to be followed by more distant stations. This follows from the fact that the radiation of the stations with a given Traffic density with the square of the distance from one Station increases · When the new, unsynchronized station the distance to the first synchronized Station of the area knew, they could set the time of sending their interrogation pulse so that it is immediately when it is sent would be synchronized with the area. This is easy to do reach when the distance between synchronized and not synchronized Station is known, since the non-synchronized station can determine from this when the synchronized station sent · Therefore the new station can evaluate synchronized »as soon as it sends the first time. SLne such Torriohtung can be used if, for example, a niobtsynchronized Airplane wants to leave an airport * whose airport station synchronized with the stations of the Terbund area and if the new station is the distance of its current position, e.g. at the end of a Hollbahn, to the airport station can. This can easily be done by using railway markings, help funks ignale, etc. provides. In the event that the distance between two stations is known, the rough synchronization method is not conducive.

The rough synchronization is used, warn the new one

009820/029 «

^BAD original

Station their distance to the next synchronized Station of the area does not know. In the coarse synchronization method, the new non-synchronized one shifts Station the phase of your oscillator so that it gets your interrogation pulses synchronized with the first start pulse B (time no. 1), which they synchronized from the first one Station of the area receives. It should be said again that each interrogation pulse is sent in times that are some time behind the transmission of the start pulse (i.e. from time no. 201 on), but with a fixed time relation to. the start impulse, as determined by the main oscillator of the station. That's why the new station sends its own interrogation pulse before Bie receives any other interrogation pulse since the first Start impulse, the synchronized one from the first. »Located Station comes and the interrogation pulse of this station located first is received by the new station before the interrogation pulse any other synchronized station is received. In this procedure, the maximum time error is which a n.ue station can have in terms of synchronization when entering the area, equal to the transmission time one impulse from the next synchronized one Station to the new station

To explain the advantage of the coarse synchronization »ei assumed that the distance of the allowed sync broadcast tent points (Points in time no. 201 etc.) amount to 1800 microseconds and another station 50 km (180 microseconds Transmission time) is away. In this case the possible initial synchronization error would be between the two Stations, if the new station were allowed to transmit at any point in time, plus or minus 900 Microseconds. By using the rough synchronization it is possible to reduce the initial synchronization error in the transmission time between the two stations. In In the example shown, this error is approximately 180 microseconds. This becomes clear when one assumes that,

BAD OR ₁ QINAL

when the station synchronizes its oscillator with the reception timing of a start pulse from the located in close proximity station, the oscillator of the new station is not located further outside the ¹ synchronism when it is determined by the transmission time of the start pulse B from the other station forth. Therefore, only a phase correction needs to be made to compensate for this initial transmission time in order to achieve a coarse synchronization. Once the coarse synchronization has been achieved, the new station carries out the actual synchronization in the manner described above. Because a rough synchronization is carried out first, the absolute synchronization of the new station with the area can take place more quickly, so that the already synchronized stations in the area are not brought out of the synchronized state by pulling their oscillators too far apart, if at all. earth. This also follows from the above description of the synchronization.

Its coarse synchronization also ensures that any station that receives a response pulse from the new station receives the new station's interrogation pulse first, because the new station must send its own interrogation pulse before it can send other interrogation pulses during one Synchronization interval received. In other words, a new station can only send a response impulse to an interrogation pulse from .inc-r and he 3 ι station, and this can only be done after the new station is in its own interrogation, 'Gi . ::}! Uls ^ esundot has. This is very useful in establishing a simple criterion, namely the firmest 3.J. xn ^, öd a certain Abfrageinpuls and a bestirnter Antwortinpuls from _Ο Ίeichen station are sent. I! Ac iden! This is determined, pin synchronization corrections are carried out, inde. · =, the arrival times of these two pulses in the above:, with reference to Figures 1-4

BATH ORIGINAL 909820/0296

ar -

can be observed in the manner described. How a station determines- : determines whether the two impulses originate from one and the same station, is described below

To explain the rough synchronization process, reference is made to FIG. Here three stations X, Γ and Z are shown, which are some distance from each other, but not in a straight line. These stations may not be synchronized at first. The letter indices of the pulses in this figure relate to the transmitting station and the numerical indices to the interval in which the event takes place. In Figure 6 it is assumed that station X is the first to receive a start pulse By- (time axis a) sends during the first 1-second operating interval, and stations Y and Z are to be roughly synchronized with X. The start pulse By- is sent by station Y during the

; first 1-second interval (time axis b) received at a point in time that corresponds to the distance between stations X and Y · Station Y shifts the phase of its oscillator so that it sends its start pulse Βγ._ «when it sends the second start pulse Β _χ _ο ^from station X (time axes b and o) during the next 1-second interval. Station Y. must send its start pulse By_ ₂ one second after receiving the pulse B _{T 1 in} order to coincide with the arrival of the second start pulse Β _χ _ ₂ from station X, since station Y does not receive the first start pulse By * from station X at the same time Turn back the phase of its oscillator and send its own start impulse. Station Z receives the start pulse By _-1 from station X before it _{receives the pulse By?} • can receive from station Y. Station Z sends out

_o a start pulse B ^, "during the second interval. Is at the time of receiving the pulse By_ ₂ · In fact, K> station Z always receives the start pulse from station X first

* v. in the interval that follows the first unless the

_{P | sj} Station Y lies on the connecting line between the J ^ stations X and Z ₀ l <Ian sees that all stations are now up to

BATHROOM OBIGlNAL

1456043

on the maximum error caused by the transfer time "or the transit time between stations X and Z is conditional, gro "b are synchronized. Ba should be noted that stations T and Z are closer in synchronism than stations X and Y or X and Z

Reference is made to FIG. 7 to explain the effects of the coarse synchronization on subsequent attempts at fine synchronization during the synchronization intervals. First, however, it should be remembered that the start pulses B are sent from each station every second at time 1 after the coarse synchronization has been carried out, ie synchronization of each station with the first start pulse received. Eberiso should be told again that the transmission of the query pulses * '! at any point in time from time points 201 to Ur. 548 of FIG. 1 takes place (or does not take place) and that these pulses are used for synchronization in conjunction with the response pulses received in response to these pulses. The I-pulses of the two stations have the same relative position to each other or the same synchronization error as their roughly synchronized start pulses. If the station Z is thus roughly synchronized with the station X, the station Z sends the pulse I "at the same point in time as it receives the pulse Iy, if the stations X and Z happen to send I-pulses at the same point in time ·

In FIG. 7, there are arbitrary intervals or transmission times for stations X, Y and Z, four units between the Stations X and Y, three units between stations Y and Z and six units between stations X and Z » accepted. These arbitrary points in time and units of distance have been chosen for illustration purposes only «

Referring to Figure 7A, assume that the coarse synchronization between the stations X and Z already harp is that, however, corrections to the Fei, nsynohro

• 09820/0296 Γ ^ ^0RI0 ' ^NAL

nization of the interrogation pulses have been made. FIG. 7A shows the state of stations X and Z during a pin synchronization interval after the "second interval", which was described in FIG. 6, when only these two stations are in operation Pulse is received by station Z after 6 time units (time axis d) according to the synchronization error. Since a rough synchronization has already been carried out, station Z sends its interrogation pulse I "(time axis b) at the same time as receiving 1- · Under these circumstances, station Z will not receive the pulse I" and will not respond to it either. The reason is, DAFL the S.tätion Z their interrogation pulse I "sends simultaneously with the receipt of the interrogation pulse I from the station X at the beginning of a point in time and therefore they do not iet able also a response pulse to be sent.

After twelve time units, the station X receives the pulse I "from the station Z (time axis c) and responds to it by sending a response pulse Ry" (time axis a), which is received by the station Z after 18 time units (time axis d). Since station Z receives both an interrogation and a response pulse from station X, it can correct itself or try to synchronize itself with station X. Station X cannot correct itself in the direction of station Z because it has not received a reply pulse from station Z · In this case, station Z shifts the phase of its oscillator so that it sends its interrogation pulse earlier. In fact, station Z cannot synchronize itself if it does not see the pulse I- from station X, ie does not receive I- at the same time as it sends I ". Therefore, the phase of pulse B ₇ from station Z shifted so that the impulse appears shortly before station Z receives the start impulse Βγ »DiHS can easily be achieved by adjusting the phase of the oscillator in station Z ·

BATH ORIGINAL

In a subsequent comparison of these two stations at a later point in time (not shown), the interrogation pulse I "from station Z would be earlier by the value of the time correction introduced. The station would still send its interrogation pulses at the time originally specified for the coarse synchronization, since the oscillator of this station was not corrected. However, since the pulse I "now appears earlier, the station Z sends a response pulse Rgx» u * ¹¹³ · ela every station I and R pulses in response to the pulse Iy. receives from the other station, both stations can now synchronize their respective oscillators. Therefore, with a coarse synchronization, the time required to completely synchronize two stations X and Z or any two roughly synchronized stations is considerably reduced, since both stations assume a far smaller phase error of their respective oscillators than without a rough synchronization would be the case.

FIG. 7B shows the case in which only stations Y and Z are transmitting. In this case, the two stations are still roughly synchronized to a certain extent, since both stations Y and Z synchronized with the first start pulse By that they received from station X. In FIG. 7B, the interrogation pulse Ι _γ (time a) sent by the station Y is picked up by the solution Z (time d) three times after the output. While the two stations are roughly synchronized, station Z sends its query pulse I ₁₇ (Zeit-iChae b) before it sends the query pulse I _v (Zeitacii33 d) e ^ px / .u ^ t. The impulse I ₂ is given by station Y (time ac'ise c) three times later e; upz'a: i, _. Üii. Since the station Z the query pulse Iy a short time after the transmission of the In ^ ulae I ₇ c:.: Pf, '. Ngt, it responds to I _v by sending out an answer pulse Η «γ (time axis b). In a similar way, the S.iiioii Y scides a response pulse Ry ^ (time axis c a) as a response to the interrogation pulse I “ (time axis c) _e

9098 2 0/0296

Since each station receives query and response pulses from the other station, both stations can make corrections run and they will both be fully synced, though. the phase of the oscillator in each station by half the phase difference the phases of both oscillators is shifted in relation to the phase of the oscillator of the other station

FIG. 7C shows the case in which all three stations transmit during a single synchronization interval. An analysis of the case shown in this figure shows that a station only tries to synchronize "when it receives a response pulse in response to its own interrogation pulse and a Receives an interrogation pulse and a response pulse from the same station. The system is so designed that it can automatically determine when this condition has occurred. Let me also say that a station only corrects its oscillator if this condition has occurred Each station only sends a reply pulse in response to the interrogation pulse received first after it has sent its own interrogation pulse. It is "important to note that station Y does not send a reply pulse to Ι _χ because Ι _{χ are received} at the same time is sent like Ι _γ , and since station Z does not send a reply pulse to I_, since I «. at the same time as the transmission of I _{7 is} received. This means that both Y Is and Z are roughly synchronized with X, but the phase position of the oscillators of Y and Z is not suitable for generating an I pulse before receiving Ιγ.

As can be seen from FIG. 7C, each station receives two to
σ I-pulses before they get a response pulse H (time axis d, e and CD \

O ₀ f) receives. Each station cannot tell whether it was sending a £ * R-pulse in response to its own I-pulse or a ^ * in response to the I-pulses of other stations

k> R-impulse receives «. If a station is using one

0, R-pulse that would not respond to ■

BATH ORIGINAL

the own Ϊ-impula was sent, this phase correction would be erroneous »

If we choose, for example, the station T in Figure 70, this station sends impulses _Ι χ and t "before tmpfängt their first response pulse HGY. The reason for this is that I _{T is received} after four time units and I ₇ after 9 time units (Z sends after 6 time units at the time of receiving Ij) · Both times are before the first response pulse Br ™ · »der from the station Z to seven time units sent and received by the station Y by ten time units · the same situation at the station X, the "receives the pulses I 'and I prior to the pulse Ey _2, and at the station Z in front of which the Receives pulses I ~ and Iy before the pulse By «. If, for example, the station Z had not sent any In.- and! "- pulses during this interval, then no pulses Ir" R ", Ήχζ uttd S-TT would have been sent either. Therefore station Y would only _{receive the pulses ϊ χ} ^ ¹ ^ · & χγ ·. Only an I-pulse precedes an R-pulse, and this indicates to the station T that the received I- and Η-pulses come from one and the same station and that the R-pulse is in response to the interrogation pulse I ™ der Station Y was sent »

In Section TI it is shown that the appearance of only one I-pulse received before the R-pulse received first a puncture of the dist; .oides between the observing Station and the other stations in the area. This fact is used to almost establish whether the received I and R pulses come from the same station and the R-impulse as attachment / location on the I-impulse of the observing Station ijesen-Iet was. This allows "the synchronization corrections in the right time

From what has been said above it follows that the robe Synclironisa tion oin a fixed relationship between query and response pulses guaranteed so last if only one query and one

809820/0291 ^ÖAD

• Answer impulse can be received from one station after one den, these interrogation and response pulses from the same Station came «, it also ensures that the response impulse received is a response to that from the observing Station sent polling pulse is sent. Therefore the observation station can determine the phase of its oscillator correct by a suitable shift.

As synchronization progresses, it is possible that a station is roughly synchronized with another station without the first one changing its clock. This is another way of synchronizing two stations without both stations performing a direct comparison. In the case of station Z, for example, this could be done by comparing station Z with other stations (H, N, P, Q, etc.) that are synchronized with station X. Since the station Y is closer to the station Z than to the station X, this has the consequence that the station Z catches the start impulse of Y e: ier e ^ than that of the station X. The station Y appears to the station Z. than the station that sends start pulses first, so that station Z carries out a coarse synchronization correction to ensure that its own interrogation pulse is sent simultaneously with the reception of the interrogation pulse from station Y. As a result, the station Z is more art with X synchroni si, hile Station 2 can then ebrecut ^ v / that your Abfrageiia ^ sleeve earlier and earlier oendet, it can not to wex'den gebx ^# aciit to send before any other station actually sends, that is, it still has to receive a start pulse B from the next station before it can send. If the station Z has meanwhile corrected its clock so that its interrogation pulse is roughly synchronized with the station X, then the above statements also apply to the station Y, if you think of it as being substituted for the station Z. .

BATH ORIGINAL

VI. The synchronization of pairs of stations in a network area with several stations

In Section V it was assumed that the synchronization was carried out during a "certain synchronization interval was only possible if two stations were transmitting · With three or more stations, which all sent during a certain synchronization interval, it seemed impossible, the synchronization in this Interval to achieve · Bs is possible to build systems at which every station randomly sends I-pulses during a fraction of the synchronization interval. This would result in several Intervals result in which only two stations I-pulses send so that a successful phase correction can be carried out. However, as will be described below, this is not necessary, as synchronization can be achieved during an interval if three or more stations are transmitting

As already said in the explanation of the rough synchronization in section V, the observing station is certain that that the response and interrogation pulses were sent by one and the same station, if the station after a single Interrogation pulse receives a response pulse. Further is yourself the observing station also assures that the recipient Response pulse was sent as a response to an interrogation pulse sent by the observing station »This was based on the figure 7 explained in detail.

This state, in your the observing station of the above is safe in both states is called the "green state" of the observing station, since the station allows it in this state

ο is to synchronize with the other station that sent the query and response ^ impulses. Another state is called ¹ ^ "red state" _β In this »state two or more

- ^ rere interrogation pulses from the observing station in front of the floor

i ^ S pfan _ü · einea /uii.v/ortimpulses received. This state is in Fi ^ ur 7C i; cz3Lg-b _t and there was no attempt at synchro-

nization of sub-lines «,

BATH ORIGINAL

When all stations in the area are synchronized, a particular station will only observe the green state under one condition. This condition is met only if the \ station located in the immediate vicinity which transmits during the Syn chroni a at ions interval Is, less than half βο far from the particular station is removed tion than the next closest Sta sending · This will This is clear if one assumes that if the next station is at a distance r from the specific station and the next station is at a distance 2r, the interrogation pulse sent by the next station arrives at the specific station at the same time as the response pulse from the next station. This gives a boost to the red condition. If the next station is at a distance slightly greater than 2r, i.e. the next station is less than half the total distance from the next station, the response pulse from the next station arrives before the interrogation pulse from the next station, so that 3 the green status is fulfilled at a certain station. Since there was synchronism from the start, the interrogation pulse of the next station arrives in the middle between the transmission time of the interrogation pulse of the specific station and the time at which the specific station receives the answer pulse from the next station. Therefore fell · is any station at any interval in which it transmits in the green state when the distance to the next transmitting station is smaller than the distance to the second closest sending station.

Are more different from the red and green zones

State results for a specific station when the SIaco
ο functions in dxi .rouiot are only roughly synchronized. Like Luuu.rid before. Pi _o u, 6 explains, it is certain that if there is a rough synchronization, the query pulse sent by the next station will arrive at a specific station between the time at which the query pulse of the specific station is sent and the point at which the answer pulse is received from the next station »

BATH

therefore the timing error has between the "specific and the next station" does not have much influence to the red and green state. The timing error however, in receiving the interrogation pulses from the second nearest station and more distant stations is considerable. If, for example, the more distant stations send interrogation pulses that are opposite to those of the specific Station are delayed, the interrogation pulses of these stations arrive at the specific station later than the The case would be if all stations were synchronized. This changes some red statuses to green statuses, since the next station, for example, could have less than twice the distance to the next station and its interrogation pulse later than the response pulse of the next station at the specific one Station can arrive. On the other hand, if any station sends its interrogation pulse instead of the next station in relation to the particular station sending earlier, this could a green state can be changed to a roton. Of the The reason for this is to be seen in the fact that the interrogation pulses of the second next station for earlier than the response impulses of the next station aryfler specific station would arrive, so dai3 receive two interrogation pulses before a response pulse would result in a red condition. A completely asynchronous association of the stations in the area can also change the red and green states effect in the manner described.

Ultimately, a coarse synchronization or a complete lack of synchronization of all stations has the consequence that on average more stations that transmit in advance in the phase be shifted towards the lagging, than vice versa. Jedocii is the middle number on the green Zubt line unj- .i'aiix · the same. 3 ο wo iil the red as well as the greenon Zuütündü can easily go through from a specific station Observation of the received impulses in the manner described be boctimiat ·.

809820/029 $

If the transmission of the interrogation impulses of a certain station with a relatively constant frequency takes place on an arbitrary basis, it can be proven methematfsch that with increasing traffic density (number of stations per square kilometer) the number of successful comparisons, a correction (synchronization) of a station to the FoI ^ e also increases and asymptotically approaches about $ 25. This means that a particular station "its synchronization time by 25 $ of the total time during which it transmits interrogation pulses corrected contrast, falls in the same transmission frequency with falling traffic density, _e he at a lower number of stations W.Jir- • aoheinlichkeit for successful comparisons and the resulting correction below the figure of $ 25. This decrease in efficiency is generally poor mbar, since only a few comparisons required s ^ ind, in order to achieve a reasonable Synohronisation and maintain, if only a few stations in the area are present _e For example, v / Ground shown that when more than ten stations on one

- Area of 25 000 square kilometers are distributed, each of these stations their own Clock corrected after $ 25 of their attempts. Even if the traffic is a little denser, this probability remains still essentially unchanged, but the main distance between synchronized stations becomes smaller »With lower traffic density, e. two stations per 25,000 square kilometers, the sinks

'' Probability of successful comparisons with the same

, bender constant number of attempts (Iq pulses) »For example in the latter case it is assumed that each station makes eight synchronization attempts per second. Then it will show that the probability of success is only $ 12.5. Desiialb can only be expected roughly, one success per second »

_However, this is sufficient if there are only two stations in the J ^ area.

^ With low traffic density, the efficiency of the "red-

^ green "systems with the same arbitrary ^ pulse frequency * ° lower, on the other hand the synchronization efficiency increases with it increasing traffic density, and the system works optimally »

BATH ORIGINAL

Finally, it is possible to increase the arbitrary pulse frequency with decreasing traffic density. This allows the efficiency of the system to be increased even further. In the preferred embodiment of the invention, which is described in Sections VIII and IX, this becomes red-green ^M method when the I ₀ pulses are transmitted on a statistical basis, either with a fixed or variable frequency, in order to optimize the probability of success according to the number of stations in the area.

VII. Selection of the number of permissible transmission intervals

As described with reference to FIG. 1 and in Section II, certain transmission times in each 1-second period are reserved for data transmission, while other times (and the interval following this up to the next point in time) are reserved exclusively for synchronization or the Maintaining the synchronism of the stations with each other are reserved. It should be noted that it is desirable to have as many times as possible for the transmission of information pulses, since the amount of data that can be transferred per unit of time increases as the number of transmission times available increases. On the other hand, it is also v.-änschenswert, the number of for Synchronitsationszy / blocks to Verfii ^ college, stall end times so o ^"r ° ß to make as possible as di JS eil · - OU_: Synchronization dor stations with each other eriorLierlich- .; Time minimized. En should be mentioned, however, cL'.J di ζ Vc.:::.iiidoru2l ₀ · the an ^ aiii of the points in time, ie the ver-1-njurunj dor time intervals zv / ijchen dan sending points, ZW - "errir- _o .runj α it contributes to the middle of the 3 do of the stations that e üich :: iitoin; oiaer synchronize, since with a Ό a it is true A: ^ - ^; 1 vo :: at.j.tlo. ¹ .n, die nit j ine; ■ be ..; ti -.;:.; T <jn send pleasure,! ...!. ■ ^ • j 1-- ir. 2n ·: ί: ί :: ο.: Ί beüti. ^ Atüü time ρ unkt, sein become.

909820/0296

⁰ ^ D OFiiQ, _NAL

In any case, by the Srhöhung the number of times for data transmissions .or for ^{synchronization:} purposes, the upper limit of the number of allowable transmission times of a station by the possibility of error in receipt of any pulse is determined, namely, whether this in the "pulse in the straight present transmission time interval or would be sent in the previous interval These impulses occurring attenuation and / or is prevented by interruption of the straight transmission path through the earth's surface. In most cases, the interruption of the straight transmission path due to the curvature of the earth is more reliable. The criterion for the interruption of the straight transmission path due to the curvature of the earth is explained below.

A pulse sent by a station is received by another station at an interval r after t seconds:

where c is the propagation speed of the signal (300,000 km / 3ec). The distance of an airplane from the horizon that flies at a height h above the surface of the earth is:

(2) r _h = (2. ^) ^1/2 . 1.6 km

Therefore, the maximum distance between two aircraft that are in a Ιίοΐΐό of h meters fly and that is just about above the horizon can see:

(3) 2 r _h = 2 (2.

909820/0296

BATH ORIGINAL

If the direct distance r between two stations is greater than 2τ. is, the pulse sent by one aircraft is received by the other aircraft in a strongly attenuated manner as a result of the interruption by the earth's surface. Although the signal received through the earth's surface after the interruption is not zero due to refraction, scattering and reflection of the signal over the horizon, the amplitude is nevertheless greatly attenuated so that it cannot be suppressed by a suitable threshold value circuit 1.

If the curvature of the earth (the radio horizon) is used to separate the transmission pulses from two neighboring network areas, the unsuitable choice of the transmission time sequence frequency for synchronization can result in confusion with or confusion between stations that have already been synchronized. This confusion can arise among the various interrogation and response pulses sent during two successive synchronization intervals by two or more stations using these pulses to maintain the synchronous state. In order to avoid confusion during these intervals, an interrogation pulse sent at that permissible point in time or a response pulse sent in response to a received synchronized interrogation pulse must not be received by any station at a point in time following the next permissible time of sin. The query or response pulse sent in a certain synchronization interval should not be received by another station in the next synchronization interval. Since the response pulses are sent later than the question pulses in each interval, the response pulses can easily be eliminated as a source of confusion by preventing the transmission of the response pulses from a station after a time that _{corresponds to the loaximal distance P max} , up to which the synchronization with other stations take place 3 oll.

909820/0 296

«Ι

To explain this quantitatively, it is assumed that the maximum height of the stations (e.g. aircraft) that the Apply system, is 12000 m. The above equation (3) gives the maximum viewing distance 2r between two stations to 900 km and a transmission or running time of

—-— * 3 milliseconds »If the system is to be designed The transmitter can ensure that the stations do not synchronize with other stations that are further than 160 km away each station can be controlled in such a way that after 0.577 milliseconds, calculated from the time of sending its own query pulse, no longer sends a response pulse. The time of 0.577 Milliseconds is the time it takes for a response or query pulse to cover 160 km. Will the broadcast of the Response pulses interrupted after 0.5.77 milliseconds, then can one station does not respond =. to interrogation pulses from another station, which is more than 160 km away. It follows,

2r, + P that if the synchronization end times - = ~ -

Seconds are away (3 + 0.577 = * 3.577 milliseconds in example above), one from a first station in response to a received interrogation pulse from another Station was sent at a certain point in time, the reply pulse sent not from the .other in line of sight of the first station during the next Time of the following interval can be received. The reason for this is that some response pulse of the first

P.
Station sent seconds ago (0.577 milliseconds)

2r, wox'den his must, v / Jlirend the line of sight asjifc from —-— Seconds (3 LTilliseconds) ensures that the Impulse from a station in sight of the ex-most Station is received in the same interval. For an beyond The plane flying over the horizon will be the answer inipuls interrupted or inoculated from the earth's surface. Even though as an example, a maximum altitude of 12,000 m was chosen it should be noted that this is also general

¹ §00820 / 0296

BATH ORIGINAL

applies to aircraft flying at greater altitudes. For example, if the maximum flight altitude is h = 15000 m, then the viewing distance increases, and the time between Sending times must be increased proportionally to ν Ii Avoid mix-ups (see equations (2) and (3) above) »The time between the transmission times can be correspondingly be decreased when the maximum altitude is decreased.

It should be noted that with an interval of 3 * 577 milliseconds between the individual transmission times, this results in a permissible transmission frequency of only 280 Hz for data transmissions and synchronization purposes. This corresponds to approximately half of the total number of points in time mentioned in the description of FIG. 1, with only about 80 points in time remaining for the synchronization to be doubled. The interrogation and response pulses of the preferred embodiment of the invention are in reality pulse pairs which, as in a TACAN system known per se, would be used to distinguish from noise or interference pulses. By systematically assigning different distances between the pairs of pulses, it is possible to differentiate between various pulses in different times / ground, while the pulse pairs of the odd times (No. 201, 203 etc.) a different distance is arranged. Then dr is pseudoiupuls or the p3eudoi :: ipul3pä., R, read in 'einx ,: straight or an ^ iraden Sendein ceX ^- VaL 1 tJ-jr ο .sti: a: nt: in station appears, ./her in dem u? i ::. ittelba ■ vorj.:ij the whole interval was sent, incorrectly koJlisrt ur.d ^:.: - "'daslralb except Ac .t ^ jl: -33: n. If for example we; e iie 'station A in ciue.n even lateral point to synchro- :! i.; i ->;;: tried and AOiV ^ e- and / o-ier.' ^ ntVyorti. :: J ₁ Ui se e..p_ \ '.'-- jJ, v.ie in de ... vui? an ^ u ^ u: \>' .e ,: α: i _to rad ζ noblemen

BATH ORIGINAL

Time were sent, these will be the wrong pulse spacing code so that they can be withdrawn from station A. The two points in time earlier in one jgr ad numerous point in time sent pulses would be against it sent from a station that is far away from the sd is that the amplitude of these pulses at the receiving station is too small to be detected. Therefore, -,., the number of points in time can be doubled with the help of the coding process, to a total of 560 time., points to stick to the example above.

The above statements regarding the pseudo-questioning and response. impulses also apply in the presence of a non-synchroni si er ·? ten station in the area. As already said before, if ... there are more than a few stations, for example aircraft that are within sight (above the horizon) of one another, the aircraft station is already synchronicized before it lifts off the ground. According to the above, the signals of the unsynchronized station can if they. is at low altitude or on the ground, cannot be received by a station more than 480 km away (if these stations do not fly higher than 12000 m) The distance of 480 km corresponds to a synchronization error of the oscillator of the unsynchronized station of , approximately 180 ° _e This means that this unsynchronized station would have to send its interrogation pulse by half the distance between two transmission times later if its interrogation pulse arrives after the next point in time, which begins at another station 480 km away. As already said before, errors of this size are avoided by a coarse synchronization which precedes the transmission of any pulse from an unsynchronized station.

laughing at this consideration of some criteria that must be observed to determine the transmission frequency to avoid confusion to avoid between the query and response pulses Another possible likelihood of confusion can be considered. This likelihood of confusion arises when

909820/0 296

BATH ORIGINAL

Signals from synchronized ground stations and mobile ones Stations (aircraft) are sent. As explained with the aid of FIG. 1 and also shown in FIG. 8, change the information signal transmission times of the ground stations (even times) and aircraft (odd times) »In order for the system to work accurately, any ground or Flugstation any or each received impulse related to its origin in space (from an airplane or an Ground station) and in terms of its temporal origin (the time or interval at which it was sent) can determine. The first point to be investigated would be the likelihood of confusion that exists in flight stations between Information pulses sent by a ground station and information pulses sent by an aircraft coming 'be received in the preceding Time sent »This is explained with the aid of FIG. In FIG. 8, the time point Ir. 3 represents a transmission time of an aircraft flying at a certain altitude, during the time ¥ r. 4 the time at which the information was sent a ground station B. If a first aircraft at a point in time Mr. 4 following time information pulses can receive that from another synchronized aircraft at time Ur. 3 were sent, the pulses received from the first aircraft can cause confusion. The possibility of confusion is again determined by the height of the flow station, the time between the Transmission times and the distance between the stations'

To stay with the above example, in which the first flight station at which a mix-up can occur is in a Flies altitude of 12000 m, this station is 450 km from the horizon ontx'ernt. For the purpose of explanation it is also assumed that the transmission zoom points are now at a frequency of 440 Hz uuftrotö-n. This means that the time t. zv / ischen this Points in time is 2.27 milliseconds and a signal in dl eser Time covered a distance d of 680 km. So that one of one

BATH ORIGINAL 909820/0298 ^ "

another plane at the time. ITr. 3 transmitted information pulse the aircraft viewed after the time Ur. If 4 is reached and causes a mix-up, the distance between the two stations must be at least equal to the distance covered by a pulse in the time between two transmission pulses. In this example, this is 680 km. Therefore a »further station, which can cause confusion, must be at least d - r, km (or 680 - 450 = 230 km in this example) beyond the radio horizon dex ¹ first station. So that the transmission between two aircraft is not disrupted by the horizon, mxiQ fly the other interfering aircraft in this example at least 3000 m high. This means that there is no interference or confusion in the first station at all those information transmission times and those following intervals that are assigned to possible jamming aircraft flying at altitudes below 3000 m, since the information pulses from the possible jamming stations are interrupted by the earth's surface. If the possible interfering aircraft flies at a higher altitude than is required for the straight line visibility expansion and can cause confusion, then there is the possibility that interference will occur in the first station, namely in the interval following the one following the Information transmission of the aircraft flying at an altitude of 6750 m is assigned *

In general, no interference or confusion of the information impulses of two _{FIu 1} ^ a eu _ö -c can occur if the sum of the distances between the two 3tatIonon to horizon is smaller than the distance that a l covers in the time between two end times. n can. The reason for this is to be seen in the fact that an information pulse is received in the correct interval if the distance between the stations is smaller than the distance that the pulse can cover between two transmission times. If this condition is not met, there is only one thing

909 8 20/0296 BAD ORIGINAL

small fraction of all cases will be the case, namely if both stations fly in relatively large periods of time. and have a large, straight-line viewing distance, pulse coding is sufficient to distinguish the information pulses sent by aircraft from those sent by ground stations. In this case, the odd and even transmission times of the aircraft and ground stations are assigned different pulse codes. This coding can relate to the pulse intervals such as. explained above. Therefore, at any odd or even point in time, an aircraft can pinch whether the information pulses received come from a status that sends at an "odd or even point in time," if the code dsiu. corresponds to the instant transmission point, then the impulse is accepted. If the impulse is encoded according to the previous point in time, it is suppressed "." According to the concept applied here, the expected number of possible interfering information is ... · .; tio? iai :: ipulse kept so low in a station that dia Vtah, .- sclieinlicl'il: eit that two flu ^^ eugimpulsppair zuiälli _o de.i Bodanstation .impulsabötaiid ..lci'byn, is extremely small.

An al dere I-.lü ^ liciikeit zur Ausucjialtunj der .veni ^ -un aircraft information. Indicates the relative difference in intensity of the pulses received by an aircraft, which results from the distances between the stations. Angeno-j-aon, dt. the first considered aircraft and the potential Stor-lu ^ tool is! to b-jide in the worst case in its maximum height · Then, the distance between the two aircraft is Voss ^ so that the amplitude ratio of the soil tation in the interval in the transmitted signal to the. von lau otorf aircraft in advance ^ e ¹ . end interval and in the given interval from the araten aircraft received Inform- yLo :: 3i ,. _: puls a ^ place dos erstüii aircraft minimal '

90 9 8

is. This ratio can be calculated as follows Distance of the receiving first plug stuff from the ground station may r and the distance that a signal in the time between two transmission times in the past, let d be. If one then takes 2.27, for example, for the interval between the transmission times Milliseconds, the distance to the interfering aircraft must be d + r or 680+ r km, so that the interference information pulse sent during the previous interval of the interfering aircraft arrives at the same time as the information pulse from the ground station. The amplitude ratio of the two signals iat

However, with increasing r to _e flying, this ratio increases both aircraft at an altitude of 12,000 m, the maximum distance between the two aircraft (due to the horizon) is 900 km, so that ijich from the difference r, - d the maximum r, ie ' r gives, in this example 220 km. The smallest

r. The ratio of the signal amplitudes is therefore -Tr ^ r - »that itself

P max · in this example therefore to (220/900) or approximately - 12 db results. If the distance between the aircraft and the ground station is less than 80 km, the signal difference is - 20 db, while beyond r "^ (220 km), calculated from the

TTIu. X

Ground station resulted in almost no interference signals at all. You, .On ent Jp. arithmetic setting dor amplification of the E:.: pre: ijers -.iincr FIu ₀ ^- S tat ion, niimlicli uo, that oijnale with a smaller amplitude than corresponds to the smallest signc-lvsrii'-ltnis (-12db), do not turn amplified, All signals that are sent from distances greater than d - 6c0 km can be distinguished and eliminated simply on the basis of their amplitude. In the above description, of course, the same output power was assumed for both the Fln ^ juug- and; also the ■ ground stations, d ·. ^ .; number Trötkde ,. w lit-jjv uie ground stations preferably ..: it greater power rioiiden in order to be as possible

BATH ORIGINAL

large ratio of noise to interference signals, even in extreme ones Obtaining distances for navigation purposes because of this. Interfering signals are more easily distinguished from useful signals and eliminated or can be suppressed «The gain setting of the receiver can also be set automatically with With the help of a suitable automatic gain control or by hand, so that only signals above a certain Amplitude are amplified. This is with broadcasters common"

The next step is to investigate whether there may be interference or confusion in an aircraft between information pulses from another aircraft, which are sent at the point in time under consideration, and information pulses from a ground station, dt e. were sent in the previous time. Since in the example described, the distance of the aircraft from the horizon is 450 km when it flies 12000 m high and the time between two transmission times corresponds to 680 km, such interference cannot occur because a possibly disruptive ground station is on the other side of the horizon. De3! Ialb, interference in itself is not so problematic as long as the time t. Between the times of sin is appropriately selected. The interference of the signals from two ground stations in one ground station is also not problematic at α i _t d ·: ■. Lie signals of the Bod ans tat ionen iia all ^ juai new not

iapfarioöii were because sici · the stations outside , i.e. divided into two parts. of the horizon are located . ooiuit there is also no confusion, v / jil t. not üx'sc'ü.'itteii v / i ^ -d.

Dl-3J-; ADscimitt briefly summarized kai η can be said, da «iii; different criteria for the selection of the sending frequency to minimize the possibility of confusion of impulses, both the impulses of bodunutations and liLic'.ι d ^ r impulses from I'lugstation as a result of the E-ip ^ 'angs an would be discussed by impulses. Generally vvii'd

90 98-20! / 02 9 p

To linearize the confusion, the interruption of the signals by the earth's surface to HiIi "e _O uao,: vaen. On the basis of one example, a system was described in which pulse coding is used for the even and odd times, as is the case with a preferred export Example is the Pail, and it was inclined to see a group of optimal frequencies for synchronization and information impulses for plugs that fly at an axial height of 12,000 m to avoid collisions up to a distance of 50 km 560 Hz or 440 Hz resulted _o, the system 440 operates .lean Hz and 200 points in time are assigned to the Inforniatlonoimpulssn, then these pulses are in a time of

sec sent, while_ for the synchronization t-jtt sec

remain where 305 times with α * einox frequency of 560 Hz uf occur. In Section II 350 points per second fax synchronization purposes were discussed, from -JX * the load of these few points hardly affects the synchronization ability of the stations.

In practice, the number of probe times per zoit unit is selected taking into account the criteria discussed above and can be greater than or less than 440 Hz. In the end, a compromise is sought which enables adequate flight control, avoidance of collisions and the measurement of distance and direction, and in the case of de.i sici ,. the uefuhx · the confusion of transmission pulses according to the maximum speed and altitude at which the aircraft that use this system can; -./urdu, even the entry of a non-synchronized station into the network area and the transmission of information impulses through this non-synchronized

BATH ORIGINAL

- ■

5 /

nized station the problem of a mix-up in the ground or plug stations with itself. It follows that the sichy ¹ erfindungsgeinäße system with any arbitrary! Number of times per unit of time or with different frequencies for the information pulses and the synchronization pulses can be operated. Although different frequencies can be selected for information and synchronization purposes, only a single frequency is preferably used in order to simplify the clock circuits in each station . Therefore, the frequency of 548 Hz given in the description of FIG. 1 can be used, although the shortening of t ₁ slightly increases the likelihood of a mix-up. ,

VIII. Annex _;

Figure 9 shows a block diagram of the. ! -. auteile, die gonaß · der Ei'finduii _t ; in .in station vexnve'idet v / ard-ji, Jude stationary or be \ / e _o xiche station, the lach obi.jeir. Systea should be working, αϊ there is such an ego circuit. The core of every circuit is the synchronized oscillator 130, which is synchronized and kept synchronized with similar oscillators aaideror statiqncn.: With xle _t r description of Figure 4 said, vcrv; end the SynchronisierGChultunjen 132 the interrogation pulses from the station ^ eao - ideten and those from more recent stations u - i: old-ien interrogation and response pulses ^ ur Synchroni sr. tiq-1. The latter pulses are fed from an antenna 146 e. ^ Priaiuvjii and via a transmitter-Bapfüngtr switch 144 to an iS ... pfLinger 14S, where they are first decoded by decoders 150 and danri ■ -doi ;. , -uyncLronisiurachaltungen train \ 2fahrt './c;rdj,:. Die.Dekoder 150 3orti, er3n aucli -, the impulses; - us, lic: "ur die Zwe, cko der I7avig.atioii and avoidance, from ÜUoLCi-üiutöiie: · !, zur Abstanfipaessun ^; etc ;. vcr-, turns -, ve.-aji shall. Dr sy.! CiironiGierte Os ^ illctor 200 controls -VIj J ₁ /.!.- .. z- \ 2 '.: i, 3o * i \ :. ta: \; 134 , ier the clock index

BATH ORIGINAL

809820 / 029S

"or time intervals between the transmission times on the selected frequency according to the number of * 'transmission times per second or another predetermined one Period.

The timing pulses generated by the clock circuit 134 are fed to a plurality of switching elements 136 which receive further data in the form of data pulses corresponding to the station height from an interrogation pulse from another station. When a time pulse occurs at the same time from the circuit 134 and a data pulse, the corresponding pulse generator of the generators 140 is triggered, which then generates the signal for the station's query pulse I, for the altitude iniO ^ mationsinipulse A and the response pulse R. The index "o" should indicate "with aux" the own station that is currently being written. The startup pulse B is also generated at the beginning of every 1 second interval. The output pulses from the generators 140 are first sent to a radio transmitter 142 un-J. then fed to the antenna 146 via the Sender-Smpfangar-Scr.alter 144. As will be described below, the switching elements 136, which control the emission of the I _Q pulses, are switched through statistically in order to ensure that the attempts at synchronization, v.'ie above oeschriobö: n, statictlscl-, ', rfeigen »

Figure 10 is a detailed block diagram of the building blocks used in each moving and stationary station. The 3c ^; iü. Tongues in Part I framed by dashed lines are the standard transmitter-receiver circuits; Part II contains the synchronization and © control circuits; refer to the circuits of Part III "see

ä © ■■ ■ "'

s> on the generation of the pulses for the switching elements in Yer- ^ binding with the transmission of the data and synchronization j ~ information; and the circuits shown in Part IV are β the decoding circuits for separating the data and that of

BAD ORiGlNAt

- se -.

S3

received from other stations for synchronization purposes Impulse * The symbols used to identify the various impulses and circuits are the same as before symbols selected in Section II. The index "o" relates v / iiider on the "own" aircraft in which the individual Blocks are arranged.

First of all, consider the receiver part of Part I. The pulses sent by other stations are received by an antenna 26 and fed to a receiver 28 via an ocndux'-infiinger switch 24. The output pulses of the receiver 28 are decoded, for example, as in the known TACAH system, and the received pulses R and I at the output of the decoder 96 and 98 are output to the dyncaronization pilot control circuit 42. Further, on the Au _o nes of Eijpfängurs 28 before the decoders a oignalpegei-l & Lnetellur 29 arranged to the pulses of small amplitude of stations beyond the horizon which can cause confusion, auszuscneiden and to suppress. This v / uz'de already explained in Absc.mitt 711 «, ■

Di3 in the circuit part II arranged clock and Syncaronisiür circuiteii included a conventional voltage-controlled Oscillator 40, preferably a quartz-stabilized oscillator, its output, .ns frequency or phase from the output voltage of the synchronization error control circuit 42 is controlled. Suitable spaimun ^ s-controlled Oscillators are known per se and therefore need them here not ηΓάΐύχ · besciiriübbn iiU v / e-rden. The syncronization failure

42 erapf, 'ngts the pulses I and R from the

Decoders and the oigoaen interrogation pulses I of the station, which are supplied by the generator 84. The time lapse between these dx'ci pulses v? Ix'd in the manner described with reference to ^{I 1 IgUr 4.} In this case, the outlet 42 generates an output voltage which controls the oscillator 40 in such a way that it works with the oscillators of the others

BATH ORIGINAL

909820/0298

--99 -

Stations in the area is synchronized. As before mentioned, this error voltage shifts the phase of the oscillator 40 either forward or backward to reduce the phase error to half the phase distance to the oscillator the rest of the station. Since all oscillators 40 are designed to be very stable from the start the correction value required to synchronize any oscillator is relatively small.

The output of the oscillator 40 X3t with the input of a Frequency divider 44 connected, which sets the frequency of the oscillator output signal to one of the number of permissible transmission times corresponding frequency reduced. For example, if 548 points in time per second are used, then returns the oscillator 40 is a multiple of this frequency, namely a frequency which is almost in the HF range, so that smaller, more easily stabilizable components can be used. This higher frequency is then used by the frequency divider 44 down to the desired 7 / ert. Such divider circuits are known per se.

The output signal of the frequency divider 44 is a time pulse generator or 46, of which an anaaiii of Pulses per second, which is equal to the frequency of the output signal of the divider 44 is. These inipulse correspond the transmission times. The transmission time pulse generator 46 can, for example, be an asymmetrical one known to us be monostable klul ti vibrator, which from the output signal of the frequency divider 44, for example, in the Eull passage of the output signal is triggered. These transmission time pulses ; Laben preferably a relatively short one Pulse width around the occurrence of each send stop point • to be precisely defined or localized.

The pulses from the generator 46 are stored in a counter 50 counted, which is previously set so that it only · up to a number that is equal to the number of times it was sent

BATH ORIGINAL

- · ■■■■■■

as

is in the selected time period. As stated in the description of FIG. 1, this number can be 548. However, the number of possible transmission times depends on the various operating criteria discussed above. When the counter has counted the set number after a certain time, it is automatically reset to zero. The time required for counting then corresponds to a gröSeren period, for example one second, within which is set on the counter desired number of transmission times undo · Appropriate counters that count up to a preset number, and then automatically & ut zero, are per se known from digital computing technology and therefore do not need to be described in more detail. If the coarse synchronization is used, for example when a station enters a network area, the counter 50 is reset by the 3tartimpulsen'B of other stations. ' These pulses reach the counter via the B-pulse decoder 90 and the synchronization switch 52. In the case of a separate switch 52, the pulses B L-.uch are supplied to the oscillator in order to synchronize with the B-impulses. This way the oscillator is roughly synchronized with the other stations, namely with a clock that is equal to the transmission time between the two stations. 7'ie £ Gsays, this is a selmelleror V / g ^ sur synchronization -jiner station with cinöin Veroundguhict. Dar ¹ 3c.-.vi/itsr 52 is then opened after a short time v / i or so that the final Pein-Syncaronication with the help of the
tax education>: j 42 eri'üljon

nge the itatio: jrob B ^ ^r ; tc ^: xo :: ijiort iöt, are also the following times of the grü.ji; i'ea period with the received 3-Iiapulse :: jynciironi'Si ort, 'uä eier oscillator 40 oils these esapfansc ^ en impulses is in phase. Therefore each of the following sends has ^ eixpunkt and $ eü.Q? sent pulse in the. larger period. same rno.se- ^ föliler in relation to the

corresponding transmission time of the station that received the Pulse B sent. The first part of the second.η period will be for sending and receiving τοη information and the two. · part used for synchronization purposes

Every time the counter 50 is reset, be it automatically "when the set number is reached or when a B-pulse is received, it triggers the B-pulse generator 80 so that it emits a B-pulse that indicates the beginning of the Larger period · Marked · The pulse B ₀ rom ι- generator 80 is fed to a modulator 21 where it is modulated onto a carrier signal · The modulated · carrier signal arrives via a transmitter 22 and the S / E holder 24 to the antenna 26 · The The transmitted pulse B can be used by other j stations for coarse synchronization, as described above. The B pulse generator 80 and all other pulse generators in the system are circuits that generate coded pulses in order to be able to distinguish them from one another Pulse spacing is used, although other types of encoding based on pulse amplitude, frequency, or phase can be used.

_{The pulse B Q} generated by the generator 80 is also fed to a function pulse generator 70. The puncture pulse generator 70 generates a function signal which is fed to an altitude switch 72, an interrogation switch 74 and a response switch 76. The signal of the function simpulsgen orator 70 keeps the altitude element 72 open from the transmission points No 1 to No 200, so that the aircraft altitude information can be sent, and to keep the order and Aviv.vortschaitgli "ciöi 74 and 76 wälik> rend this time ^ cjcj.iioasen. Dor Punk υ ionaiupulagenorator ^ ¹ iot example v / eiiJu ui "i herkoiaialicliur 'uiitabiler' Jultivi- ° brator, who at Σ ι i ';. Ι _ο · des Trigg'eri ^ iuUl-Oo B _Q an co Au3gan _o υ inen po -itiv ^ ri gives impulse, u ^ l- vu;:, point in time

O> 1 * '·' ■ · ■

NO 1 to ITo 200 a. '. This positive L..pulse ./will dem

BATH ORIGINAL

sr

Height control member 72 supplied and opens this. The negative pulse which appears at the other output of the multivibrator is fed to the switching elements 74 and 76 in order to keep these holding elements closed. Ψθώχϊ the positive pulse from the generator ondet, the multivibrator tilts to the other side, so that the switching element is closed and the switching elements 74 and 76 are opened.

The level switching element 72 is also controlled in such a way that it can only be opened at an odd or even transmission time, depending on whether it is a mobile or a ground station. This can be achieved, for example, by the fact that the function generator 70 is followed by a further ¹ odd / even puncture generator, which is connected to the level switching element, so that the level switching element is only opened during the odd or even transmission times. This odd / even function ionagenerator is triggered by the beginning of the pulse from the generator 70 and supplies switching pulses, the duration of which is equal to the time between two transmission times, the switching pulses blanking out the even transmission times for a ground station. The level switching element 72 is then designed or biased in such a way that the action pulse and the odd / even switching pulse must occur simultaneously in order to open the switching element 72.

In a preferred embodiment of the invention, the odd / even transmission function is implemented in that causing the altimeter to generate an output signal only at an odd point in time. In a Ground station, the ground station information generator β is only triggered at the specified even transmission times. Btea is described below

BATH ORIGINAL

909820/0298

A random pulse generator 6Q iat also included in Part II · The random pulse generator is triggered randomly or statistically, e.g. by a noise source, so that it emits as many pulses per second as noise signals from the noise source exceed a certain threshold value. ' The threshold value can be fixed, as a result of which the frequency of the pulses I remains relatively constant. Vox-preferably, however, the threshold value is variable, so that the pulse frequency increases with a decreasing number of stations in the area. This can be achieved by counting the number of B pulses received in a one second period and generating a threshold voltage (A, G, G) in generator 60 that is proportional to the number of B pulses received. As the number of received pulses B decreases, the threshold voltage also decreases, which results in an increase in the I pulse frequency. Each pulse of the generator 60 does not prepare a random switching element 64 (for opening) for quite as long as it corresponds to the time between two transmission time pulses. This means that the next transmission time pulse from the generator 46 passes through the switching element 64 after the random pulse has been generated Generator 60 triggered vvix-d, and a UITD-GIied formed. The output of the monostable multivibrator is connected to the one input of the OTD element (not shown) and the output of the transmission time pulse generator 46 is connected to the other input of the UITO element. When the switching pulse and an oendezeitpunktimpulses occur at the inputs of the AND element 64, the transmission time pulse passes through the AND element to the input of an interrogation pulse switching element 74, which is also an AND element. lenxi the school member 74 receives from the generator 70 a puncture pulse with ontspreeilender polarity at its other input would the times No 200 to No 548, the transmission time pulse comes from the

BATH ORIGINAL

So-holding element 64 through the switching element 74 to the pulse generator 84. The pulse generator 84 generates the station's own interrogation pulse I on the basis of the transmission time pulse . As I said earlier, "Pulse I can consist of two pulses, the spacing of which is coded to enable devcoding to another station." This corresponds to the well-known TACAN system and the circuits. for generating these pairs of pulses are also known per se. In a mobile station, the transmission timing pulses of the generator 70 are fed to one input of the high-level element 72, which is a UIID element with at least three inputs. The other two inputs each receive the puncture signal of the generator 70 and a pulse "h" at a point in time that de .; The area corresponds to where the moving station is located.

The switching member 72 is used to Durci.scJXaItUIi ₀ "oine3 transmission timing pulse d ^ -CH (..vlhrend time points Ito 1 to No 200) of the pulse h, the simultaneous occurrence of Punktionsimpuloes and prepared dex- timing pulses. The switching member 72 passing Lapuls triggers the A ₀ pulse generator, oo that this generates a pulse A at the point of transmission, which corresponds to the height range of the movable station

A circuit for generating the pulses h is shown in Figure 11A. The altitude of the aircraft vvi: i measured with the aid of a conventional barometric altimeter 160, which adjusts the tap 161 of a potentiometer 162 via a mechanical connection 163. The voltage tapped at the tap 161, the magnitude of which is a puncture of the altitude of the aircraft, is fed to one input of a switching element 165, the other input of which is the I ... pulse B generated by the generator 80. ', Venn der Iizpul3 B an. ieLi switching element 165 is present, which is the case at the beginning of every green 1-second period, the voltage at the ... tap 161 of the control electrode of a pulse delay circuit, zS · a Phantastron 167 »

909820/0 296

to

fed. The Phantastron generates an output pulse h at a point in time which is the size of the control electrode supplied input voltage depends. The potentiometer 162 is calibrated to generate a voltage that Phantastron gave its output impulse just before the odd-zaliligsii Time can be given, which corresponds to the altitude range, in dei.i the plug stuff flies. The duration of the pulse h iat less than the time between two transmission times.

The output pulse h of the Phantastron. 167 is fed to an input of the height clip member 72, which also receives the puncture pulses from the generator 70 and the timing pulses from the generator 46. If all three pulses, the pulse h, the function and time pulses, occur at the same time, the time pulse passes through the switching element 72 to the A pulse generator 82, which generates the height information pulse A. The momentum A _Q is as desired

and is transmitted via the modulator 21, the transmitter 22 and the antenna 26. This is how the impulse becomes A at the point in time corresponding to the Holte, the station sent. . .

Be advised that other information besides the altitude information can also be sent by transmitting the pulse A In at the assigned times. For example, the true magnetic or relative course of the station can also be sent by assigning course angles to each information transmission time. When a mobile station 100 Inrorniatiorissendezeit- * ■ * points are available, corresponding to j ^ the time co · 3.6 of a total of 360 ° · if course information sent * d, the altimeter 160 for generating the switching pulse I ^ h replaced by a compass or a similar course measuring device.

ts> ■,. ',,. ■■' '

BATH ORIGINAL

It should be pointed out that other suitable circuits can be used instead of the phantastron for generating the switching pulses h at the appropriate point in time for switching through the point in time pulses which represent the height of the plug-in item. Such as B. Pig. 11B, the altimeter 160 is a analog-to-digital converter connected 170 to the output shaft, the digital wiedergibtτ the angular position of the shaft of the AD converter generates a binary number corresponding to that of the even-numbered time prior to the odd-numbered point in time at which a pulse A _Q which corresponds to the height range of the plug tool. The output number of the converter is compared in a binary comparator 172 with the output number of the instant pulse counter 50. Each time the two even-numbered counting results are equal, the comparator 172 generates an output signal which is fed to an h-pulse generator 174, the for example, can be a multivibrator. After a slight delay, which ensures that the even-numbered point in time pulse is not switched through, the generator 174 generates the switching pulse h, which is fed to the level switching element 72 in order to switch through the next odd-numbered point in time pulse at the correct odd-numbered point in time, which is assigned to the special height of the plug-in item . In this way, the pulse h is always generated in such a way that the correct odd-numbered time pulse is switched through to the generator 82 in order to generate _{the pulse A Q.}

If the system described is to be used in a ground station, then the altitude _{switching element 72 and the A 0} pulse generator 82 are not used, and a ground information switching element 120 and a pulse generator 122 are used to generate the pulses G _Q at the even times assigned to the airport station. These components are shown as blocks 120 and 122. It should be noted that these are optional components that are used in addition to or instead of the components 72 and 82

90982 070296 BATH ORIGINAL

can. In this case, no altimeter 160 and the other circuits need to be used to generate the equivalent switching pulse h at the point in time corresponding to the altitude of the aircraft. Instead, as shown in FIG. 110, the odd-numbered time pulse at the output of counter 50, which is shortly before the even-numbered time pulse assigned to the ground station, is switched through by a comparator 182 which is set to the same even time number. The instant pulse switched through by the comparator is slightly delayed in order to trigger the generation of a stop pulse g by a generator 84, which can be a conventional multivibrator. The switching pulse g is fed to the ground information switching element 120. This switching pulse g has the appropriate duration to switch through the next even point in time pulse of the generator 46, and the even-numbered point in time pulse causes the GQ pulse generator to emit the pulse Gq. As already said, the pulse G _Q can be coded as desired.

The same Phantastron circuit as shown in Figure 11A can be used to generate the stop pulse g, in which a control input with variable voltage is created, which the Phantastron in the one assigned to the ground station even time triggers. The preselected timing control input of the comparator 182 is adjustable so that the same device can be used in different ground stations that have different even-numbered transmission times assigned.

The response pulses R ₀ are generated by a generator 86 which is controlled by the switching element 76. The response switching element 76 receives the function pulse from the generator 70, so that it is only opened during times No 200 to Fo 548. The interrogation pulses received from an I-pulse decoder 98 are also fed to the switching element 76, and it is these I-pulses that trigger the pulse generator 76 when

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they supplied thereto * To reduce the possibility of confusion between the signals received from the decoder 98 interrogation pulses, as explained in section YII, the response switching member 76 is prepared so that it can only open when the station has an interrogation pulse I ₀ is sent . The first interrogation pulse from decoder 98 then passes through response switch 76 and triggers response pulse generator 86 so that it generates a pulse R ₀ for transmission. The pulse R ₀ is fed back to the switching element 76 in order to close it until it is opened again with the next emission of a pulse I ₀ . This is achieved, for example, with the aid of a bistable multivibrator 87 (plipflop), which generates the response pulse. The I ₀ generator 84 is connected to the set input of the multivibrator and the R _Q generator 86 to the cancel input, the output of the multivibrator being connected to the response switching element 76. An I ₀ pulse "sets" the multivibrator and prepares the response switching element 76 in such a way that the next I pulse is switched through to the pulse generator 86 when the puncture pulse is present. The pulse R ₀ resets the multivibrator so that the switching element 76 is closed ··· *! jlfird until the next IQ pulse is generated. ·

It can be seen from this that the respective synchronization and information pulses are sent by the station at the correct point in time. The pulses A ₀ , B ₀ and I _Q are controlled directly by the time pulse generator 46 so that they are synchronized for generation at a specific time, while the pulse, R _Q when the first I pulse is received after an I ₀ - Impulse is generated. Furthermore, the information _{pulse A 0 is} generated at the ... time corresponding to the altitude of the aircraft, while the pulse G _{0 is} generated at the time assigned to the ground station. Fenner pointed out that although the I ₀ pulses are synchronized, they are also sent at random times

009020/0296

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(M

because of the random pulse generator 60 and the switching element 64. The mean end frequency of the I ^ pulses can be changed by changing the number of pulses from the generator 60. This is achieved, for example, by changing the trigger threshold of the generator 60 by the statistical noise source. The trigger threshold can also be changed automatically from the average number of response pulses received, with the system automatically _{adjusting itself to the optimal I Q} transmission frequency.

Part IV of the diagram contains the various decoding and information circuits, some of which have already been described. The output of the receiver 28 to each of the B _T A, R, I and G-Impulsdekodierer 90, 94, 96, 98 and 99 supplied via the Pegeleinstellglied 29th However, separate level or threshold value setting elements can also be provided in front of each individual decoder, so that the pulses which are below a certain amplitude are suppressed. This contributes, as described above, different to avoid confusion at stations. As already said, each decoder sorts the received pulses according to the coding method used, depending on whether the received pulses are distance, amplitude, frequency or phase modulated.

As mentioned before, all stations can transmit with the same frequency. This simplifies the amplifier 28 and the Transmitter 22 in each station considerably. The first received pulse B, which is decoded by the decoder 90, becomes the Resetting the counter 50 and synchronizing the oscillator 40 used when coarse synchronization is used. The rough synchronization is only proportionate during one applied shortly after the station has re-entered the area, so that the switch 52 after open for a short period of time and allow the station

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light is, siteh with the received interrogation pulses exactly to synchronize. A monostable multivibrator (not shown) preferably blocks the output pulses of the B-pulse decoder 90, approximately for a larger period after the first pulse B was received. Instead of this or, in addition, an amplitude discriminator can also be provided at the output of the B-pulse decoder 90 to only to pass the pulse with the greatest amplitude received during a larger period. This impulse will normally sent by the nearest station. None of these circuits are shown for the sake of clarity the drawing would affect.

The outputs of the R and I pulse decoders 96 and 98 are the input of the synchronization error control circuit 42 supplied, which supplies the error & voltage to control the Oscillator 40 generated. This is described with reference to FIG. The I pulses from decoder 98 also become the responder 76 in order to trigger the pulses Rq at the appropriate time. This feature has also been seen described.

The output signals of the A and Gr pulse decoders 94 and 99 » each of the A-pulses from the aircraft and the G-pulses from Decode ground stations are used to measure the respective distance of the station to the other aircraft and / or the Ground stations. After decoding, the received Α-pulses are fed to an altitude-range switching element 102, while the decoded G-pulses are fed to a ground station distance switch element 108. Generally concerned a station only works with other aircraft flying in the same altitude range or with a certain ground position, to whom she wants to determine distance and / or direction. The altitude and ground station selection circuits are used for this purpose 104 and 106. These circuits control the range finder gates 102 and 108 to only measure the distance to the desired stations.

909820/0296

A circuit that measures the distance to certain aircraft as well as to certain ground stations is shown in Figure 12A, while Mg. 12B shows the various output voltage waveforms of this circuit shows. A BQ pulse from generator 80 (line a of FIG 12B) switches the output voltage of an altitude or aircraft position transducer 190 through a switching element 192 to a Phantastron 194. The transmitter 190 can use the in Fig. 11A shown arrangement of altimeter and potentiometer, where the circuit for measuring the distance of another is used in the same altitude range of flying aircraft. The circuit is used to measure the distance too a ground station, then the transducer 190 is a device that generates a voltage that is in that of the concerned Ground station assigned even-numbered transmission time triggers a pulse of the Phantastron. This device can also be a potentiometer.

The Phantastron 194 generates a switching pulse (line c), the duration of which is shorter than the time between two transmission times, and which is fed to one input of a switching element 196. The time (send time) of generation of the Phantastron pulse is transmitted by the transmitter 190 supplied voltage determined so that the correct transmission time pulse of the generator 46 (line b) via the switching element 196 is switched through (line d). The one about the switching element 196 transmitted transmission time pulse is the one Input of a bistable multivibrator or other suitable point in time (distance) measuring device 198 is supplied to initiate the start of the distance measuring cycle. The distance measurement after the triggering of the distance measurement by the transmission time pulse The received A or G pulse is fed to the other input of the multivibrator, at the end of the distance measuring cycle (Line e) to be determined. The output of the A multivibrator is a pulse with a pulse width or duration that corresponds to the distance between your own station and

6 »

corresponds to the stations whose A or G pulses receive ' were (line f). This is true because the A or G pulse was sent by the station at the same time, in which the send time pulse (line d) to the circuit 102 o4er 108 was switched through because the stations are all synchronized are. This corresponds to the width of the output pulse (Line f) the distance between two stations. The output signals of the distance switching elements are used to control any one suitable analog or digital distance display device 199, e.g. B. a voltage driven analog or Digital knife that is calibrated in meters, kilometers, etc.

In many cases a plug stuff wants the presence and the Determine the distance of another plug tool in a different height range into which the first plug tool ascends or descends want. Information of this kind is extremely desirable in order to avoid collisions between plug-in generators that use change their height. To make this possible, the transmitter 190 from Pig. 12A adjustable, e.g. B. by the Höhenvqualleohaltung 104 to generate a voltage that triggers the Phantastron, so that another altitude switch results, which is similar to the h-gate element and h-gate element is called. The transducer 190 controlled by the selector circuit 104 is set so that the h -switching element dem corresponds to the changed height range into which the plug-in wants to descend. Therefore, those from the other plug stuff at the correct transmission time in relation to the changed altitude range and according to the time of triggering of the h -chnltimpulses on the distance measuring switching element 102 switched through, so that the distances of these plug-in tools can be determined. Then it can be determined whether it is safe to change to the h -height range.

The? from Figure 10 su ^ e leads to the plug stuff, which the height range

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sr

want to allow other aircraft to be informed of this change. When the η stop signal is fed to the switching element 72, the jtation sends an information pulse A _Q at the end time which is assigned to the altitude range h to which the aircraft wants to change. In a preferred embodiment of the invention, the aircraft stations are provided with circuits with which both the h and the h stop signals can be generated in each period. Therefore, each aircraft can measure and transmit the desired information both in its own altitude range and in that altitude range to which it wants to change.

If desired, the setting element on the transducer 190 can be mechanically coupled to the altimeter and adjusted so that that a voltage is generated which triggers a switching signal which triggers a transmission time pulse that corresponds to a transmission time which is in front of or behind the actual flight altitude. Therefore the h -switch signal is used as a function the changing altitude of the aircraft to indicate to other aircraft whether the own aircraft is ascending or flies downwards and also to the distance to these other aircraft at a higher or lower altitude range to determine. It should be noted that while your aircraft is moving to a different altitude range, the Generation of the normal h-stop impulse changes automatically. Through this other stations in the new altitude range notice your own aircraft, and your own aircraft can also use this measure the distance to these aircraft.

Similarly, the circuit of Fig. 12A can be used to measure the distance to any other station, which sends at a fixed time. Now the selector circuit 106 would be set to output of the Phantastron 194 triggers a pulse g that would switch through a transmission time pulse that of that ground station

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he

is assigned whose distance the own station wants to measure. The distance measurement is carried out in the manner described above Way, only that now the one sent by the selected station and by the decoder 99 in its own station decoded pulse G to terminate the switch-on period of the multivibrator 198 is used. The distance is determined by the Display device 199 reproduced.

IX. Detailed circuit descriptions

Reference is made to FIGS. 13 to 25 for a further description of the circuits according to the invention in a station. The circuits shown in Figures 14-25 can be used in place of the components of Figure 10, and these additional circuits are particularly described with regard to a synchronization method in which the pulses of a high-frequency clock counted "" who the.

A. Synchronization circuits

As already mentioned, the present system is based on the precise synchronization of transmission timing pulses in all in operation located stations. Basically, there are two different requirements for the synchronization circuits in each Station. Firstly, the clock of your own Ahfrageimpulse Iq, which with the transmission time pulses of your own Station coincide so controlled that an interrogation pulse I received from another station in the middle between the own query pulse and the received response pulse R ("green" state). With exactly one group of impulses Iq, I and 1 a full correction must be made. Second, it has been shown above that if there is only one interrogation pulse sent from another station between the interrogation pulse own station and the first received response pulse R is the query pulse sent by the other station and the reply pulse must have been sent by one and the same station. However, if more than one of one

909820 / 029S

interrogation pulse sent to another station in this interval. or occurs in this period, a mix-up can occur. In this "case" there is no need to correct the clock pulses to be made ("red" state).

The synchronization of the S _e ndezeitpunktimpulse by means of a pulse count will be described with reference to FIGS 13A, 13B and fourteenth Pig. 13A shows the case that the "own" interrogation pulse precedes the interrogation pulse of the other station by a time Δ. This means that the transmission time pulses of the own station and the other station are not synchronized and it would be desirable to synchronize one's own transmission time pulses with those of the other station. ATJf of the time axis 1 of FIG. 13A is shown: an interrogation pulse coinciding with one of the transmission times after No 2 ^ Q1, an interrogation pulse received from another station and the receipt of a response pulse which was sent by another station as a response to its own interrogation pulse. When it occurs, your own interrogation pulse coincides in time with the transmission time pulses from your own station, which occur at the assumed frequency of 548 Hz and which can lead or lag behind the transmission time pulses from other stations. A time synchronization error is denoted by Δ. The time interval between the time of receipt of the interrogation pulse from the other station and the mean, or synchronized, transmission time is regarded as an error.

A synchronization counter 200 (FIG. 14) is used to measure the time error ^. The measurement takes place in the on the time axis 2 in Figure 13A. At the moment when a separate interrogation pulse occurs, which in one of the transmission times is sent, a main oscillator or clock 210, high-frequency clock pulses, begins Example in the order of magnitude of 484 MIIz, added to the counter 200

9 0 3 8 2 0/0296

respectively. The number counted by the counter 200 increases until an interrogation pulse from another station is received. From this moment on, the clock pulses are subtracted from the value counted up to that point until the answer pulse is received. At this point in time, the number stored in the synchronization counter 200 is proportional to the time error A.

In the Pail shown in FIG. 15A, the own interrogation pulse I _{0 leads} the point in time that it should have in the synchronized state. As stated in Section IV, the phase shift of the master oscillator 210 is only half corrected in each station that performs a "green" comparison. Therefore, the measurement result plotted over the time axis 2 must result in the correction of Δ / 2 plotted over the time axis 4 in order to shift the transmission time pulse of the own station up to half in the direction of the synchronous time.

The transmission timing pulses, the frequency of which is 548 Hz, are by electronically counting the output pulses of the oscillator 210 generated in a transmission time pulse counter 220. Of the Counter 220 generates 548 transmission timing pulses per second. In order to generate each transmission timing pulse, there is a larger number of pulses from the oscillator 210, e.g. E.g. 1635 pulses required. The counter 220 counts this set number, e.g. B. 1635, and generates an output pulse. This is done in synchronized State of the station 548 times per second. After the 548 transmission time pulses have been generated, the counter automatically resets itself to start over, provided it is not reset earlier by another signal. Counting circuits of this type are known per se.

In order to achieve the time correction of Δ / 2 perform, the high-frequency Trktimpulse are interrupted for the time of ^ i / 2, so that the transmission time pulse counter 220 no clock pulses are supplied. The counter 220 is made up of flip-flops, the position of which

809820/0296

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14BB043

hold for a long time until counting starts again. As a result, the next and the following transmission timing pulses are delayed by / λ / 2.

The time o / 2 begins when the response pulse is received, in that the synchronization counter 200 is counted back by clock pulses that arrive at four times the frequency compared to the normal frequency. When the counter 200 reaches zero, the time that has elapsed since the accelerated count began is just Δ / 2. This is explained as follows. The number reached in synchronization counter 200 when receiving ^{1 of} an interrogation pulse from another station is proportional to T + Δ (time axis 1). Until the response pulse arrives, a number corresponding to the time T -Δ is subtracted from this number. The number in the synchronization counter 200 when the response pulse arrives is therefore proportional to 2 / X. If the synchronization counter 200 were to be counted back to zero with the same clock frequency, then the time elapsed when the number zero was reached would be 2 _J ^ · As a result, the counting frequency must be quadrupled in order to generate the time & / 2 , as shown in line (or time axis) 2 . The correction pulse of line 3, which is present as long as four times the pulse frequency is supplied, is used to close a clock switching element 21, which is connected upstream of the transmission time pulse counter 220 in order to shift the T ^ kt of the transmission time pulses.

This is described below.

FIG. 13B shows the F 11 of a delay in its own transmission time pulses compared to the transmission time pulses from another station by a time of Δ. Again, a time interval of ^ ± / 2 is generated in that instead of interrupting the clock pulses to time counter 220 during this interval, the frequency of the supplied pulses is doubled. This increases the counting speed and lets the next transmission time pulse of the counter 220 and the next interrogation pulse lead by a time ^ λ / 2. The in the synchronization

909 820/029 6

counter 200 stored as a function of time 'number iBt over plotted on the time axis 2 of FIG. 13B. You can see that the Number goes through Hull while subtracting and becomes negative. Therefore the counting direction is during the duration of the correction pulse of line 3 reversed with respect to the lall of the lead of Figure 13A, i. H. the pulses become the content of the counter 200 added to bring it back to zero. Both the counting direction the clock pulses (i.e. whether subtraction or addition) during correction, as well as the type of clock signal correction of the transmission time counter are determined by whether a Zero crossing of the total number of the synchronization counter 200 (time axis 2) takes place before the arrival of the response pulse or not »No zero crossing means an advance the phase error (fig. 13A), whereas a zero crossing means lagging the phase error (Fig. 13B). A more detailed one Description of the "'required for synchronization Devices will follow later.

B. Block diagram of the synchronization circuits

A block diagram of the circuitry for performing the synchronization after the counting method is shown in FIG. Both the synchronization counter 200 and the timing pulse counter 220 is driven by the same signal from master clock oscillator 210. The output of the oscillator 210 has twice the frequency (e.g. 8.96 MHz) of the clock pulse frequency and half the frequency of the quadrupled pulse frequency. The oscillator 210 supplies the clock pulses in the synchronization counter 200 and in the transmission time counter 220 can be counted. Both counters can be designed in a manner known per se, for. B. as a ring counter from several bistable trigger circuits (flip-flops). The counter 200 can contain, for example, 13 flip-flops, while the counter 220 contains 15. The counter 200 can also subtract on command (count down). As already mentioned,

909820/0206

the transmission time counter 220 generates 548 output pulses or any other desired number of transmit timing pulses per second.

The switching element 211 is connected to the output of the oscillator 210, and a second switching element 212 is the first Switching element 211 connected downstream. Both switching elements are normally opened, so that the pulses of the clock oscillator 210 are continuously switched through to the counter 220 after it by a frequency divider 215 by half normal counting frequency were divided down. The downward counting of the counter 220 takes place in such a way that at the output of the counter 548 pulses appear per second. These are the end time pulses required by the system.

The time synchronization of the transmission time pulses is emeicht by appropriate control of the switching element 211 and a switching element 213 which is normally closed. The latter switching element 213 receives clock pulses at twice the frequency directly from the oscillator. 210. If there is a leading error is to be corrected, the clock pulses with normal frequency by closing the switching element 211 and kept away from the counter 220 by maintaining the closed state of the switching element 213. A delay bug is corrected in that the switching element 211 is closed and the normally closed switching element 213 is opened is, causing the clock pulses to double frequency the transmission time counter 220 can be switched through.

In a similar manner, switching elements 201 and 202 control the clock pulses at the input of the synchronization counter 200. The output signal of the switching element 201 is with the help of a frequency divider 203 divided down by half, while the switching element 202, the T ktimpulse with four times the frequency of one Frequency doubler circuit 214 receives. During the response

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word pulse preceding counting operation of the counter 200 is the switching member 201 is opened. The switching process of the switching element 201 is controlled by a stop pulse generator 205. The generator is switched to the "on" state (on) by its "own" interrogation pulse and by the response pulse received triggered in the "off" state (closed). While the "on" time of the generator 205, from the "own ©« "query, impulse on until the response impulse arrives, the Synchronization counter 200 laktimpülae supplied. The own" Interrogation pulse is also a command circuit 207 for the commands "add" or "subtract" are fed to the to issue the command to reversible synchronization counter 200, add or subtract the clock pulses. The received "other" interrogation pulse is fed to the command circuit 207, around the liynchronization error from addition to subtraction to switch, as shown ea in line 2 of Figures 13A and 13B. ■■ - .; ■

When the response pulse is received, it closes the Switching pulse generator 205 and triggers a second switching »pulse generator 208 so that it opens the switching element 202. This allows the quadrupled Tp.ktsignale from the doubler 214 to the synchronization counter 200. At the end of the correction period, the switching pulse generator 208 it is triggered by the trailing edge of the correction pulse. and the switching element 202. is closed. The duration of the correction period is determined by the leading and trailing edges of the output pulse of a correction pulse generator. the Correction period is determined by the incoming response pulse initiated and terminated by a pulse of a circuit 206 which responds to the number zero of the synchronization counter. the Circuit 206 contains an AND gate of diodes with several inputs to the states of a corresponding number of bistable To sample flip-flops in the synchronization counter 200. In the example described, the AND element contains

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BAD OiIIQlNAL

13 diodes, since the counter 200 is made up of 13 "flip-flops. If all flip-flops assume the state assigned to the binary number zero, which means that the count is zero, is the AND gate 206 from a pulse that switches off the generator 209. If the count of the counter 200 before the arrival of the Response pulse reaches zero, which in the event of a delay error is the case, the output of the zero sampling circuit has 206 has no influence on the state of the generator 209, which therefore generates the correction pulse, since this is already in the "off" state. The reset input (for switching off) the generator 209 generating the correct pulse is connected to the AND gate 206 and the set input (to switch on) receives the response pulse.

ffier correct pulse from generator 209 will be on several different Circuits distributed that are operated during the correction cycle to synchronize the transmission timing pulses Need to become. These circuits contain the following:

(1) AND gate 223 - Before the correct pulse from generator 209 is fed to this AND gate, it is fed by an inverter or NOT element (not shown) inverted or negated. The other input signal of the AND gate 223 is the zero signal the sampling circuit 206. The gate 223 has an output signal if a zero crossing occurs before the response pulse arrives.

(2) Zero Crossing llipflop 225 - This bistable multivibrator is "set" by an output signal of the AND gate 223 and "reset" again by the trailing edge of the correction pulse. The dip-flop 225 thus remains for the duration of the correction period is set and by tilting it back indicates that the count of the counter 200 is going through zero. this shows aleo whether the time correction is leading or lagging got to.

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U66CH3 - τ * -

(3) AND gate 227 - The input signals of this AND circuit are the correction pulse of generator 209 and the output of zero-crossing lip-flop 225. Both Input pulses must be present at the same time so that the AND gate 227 only emits an output pulse when a Correction should be made for a delay operation of the system.

(4) Switching element 211 - As already stated in the description of the mode of operation of the clock switching elements, the holding element 211 is always closed during the correction cycle in order to prevent the counter 220 from continuing to count the Hormalfre.frequenz clock pulses. The correction pulse from the generator 209 is fed to the switching element 211 in order to achieve this mode of operation, so that the switching element 211 only. is open when no time correction is performed.

(5) Switch Pulse Generator 208 - This generator controls the switching element 202, dfxs in the open state the synchronization counter 200 Caktimpulses with fourfold frequency supplies. The trailing edge of the correction pulse then closes the switching element 202 by triggering circuit 208 back to the off state.

Another circuit is indirectly controlled by the correction pulse B actuated. This is the AND gate 230. It should be remembered that that the counting direction of the synchronization counter 200 during the correction cycle depending on the type of synchronization error to be corrected, whether leading or lagging depends. During the correction pulse shown in Figure 13A must be at -einem leading errors are counted backwards, while in Fig. 13B are counted up in case of a lagging error got to. If there is no zero crossing in counter 200, then there is a leading error. As shown in Figure 14, the received "other" interrogation pulse changes the adding command

909820/0296

ORIOJNAL

of the circuit 207 in a hlerarten subtract, optionally for both F _e. The AND gate 230 emits a pulse which coincides with the response pulse when a zero crossing has occurred (lagging error). In this case, the subtract command must be switched to an add command when the response pulse arrives, and this is achieved in that the output pulse of the switching element 230 is fed to the addition trigger terminal of the command circuit 207.

Other circuits shown in Figure 14 which perform an edge function of the synchronizing function include the following:

1) Switching element 221 - This AND circuit is normally opened and is blocked by the "reverse voltage", whose Education is described below. "The reverse voltage is present if other than a" different "interrogation pulse between the "own" interrogation pulse and the response pulse received first. The reverse voltage closes the switching element 221. When the switching element 221 is closed, the correction pulse not applied to the other circuits described above, so that no time correction is made. The reverse voltage is also used to disable the switching pulse generator 208, so that the switching element 202 does not open. The switching element 202 is closed because it is not necessary! kt correction pulses to be given to the synchronization counter 200 at four times the frequency if no correction has been carried out should be, which is the case when other than an "other" interrogation pulse is received.

2) Switching element 212 - This switching element is used for rough synchronization (described below). When the circuits for coarse synchronization / indicate that the transmission time counter 220 should start counting, the triggering voltage which is fed to the switching element 212 goes to zero, so that the switching element is opened. The triggering or starting voltage is used

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BATH ORIGINAL

also to clear the transmission time counter 220 so that it starts counting from zero, or when another is set Pay if you want it. If the coarse synchronization is not used, the switching element 212 remains open.

3) Erase Delay Generator 232 - This is a monostable Pulse generator that is triggered by the "own" interrogation pulse and shortly before the next "own" interrogation pulse time falls back to its normal state. The generated erase pulse is sent to the circuits 200, 205, 208, 209 and 225 fed to su ensure that whatever has happened previously, the bistable flip-flops of the various parts of the synchronizer reset or deleted before the next synchronization attempt is made.

Before proceeding with this description, let us consider the processes for both leading and trailing synchronization errors examined.

Before reilender ff & hleff (Pigur

When the station's "own" 4bfrageimpuls the switching element 201 is opened via the switching pulse generator 205, and the synchronization counter 200 begins to count up the single frequency clock pulses from the divider 203 counting. If a "different" interrogation pulse arrives, it is fed to the command circuit 207 in order to change the addition command into a subtraction command. In the case of a leading error, there is no zero crossing (no number Hull) before the response pulse arrives. Thus the sampling circuit 206 does not respond. When the response pulse is received and fed to the switching pulse generator 205, the generator closes the switching element 201. The response pulse switches on the switching element 208 to open the switching element ZQZ and thereby the Taki pulses with a higher frequency (quadrupled price) on the synchronization counter 200

90 98 20/0 206

ORIGINAL

$ 0

to switch through, which is still counting downwards (subtly). In addition, the response pulse triggers the correction pulse via the generator 209, which in turn closes the switching element 211 via the blocking voltage switching element 221. Closing the switching element 211 initiates the correction of the leading error. I ^{1 For} the duration of the correction, no pulse pulses get into the transmission time counter 220. The correction is ended when the circuit 206 determines that the counter reading of the synchronization counter is zero. This will make the of the. Correction pulse supplied to generator 209 terminated or blocked. The trailing edge of the correction pulse switches off the switching pulse generator 208 and closes the switching element 202 in order to prevent the synchronization counter 200 from counting until the next "own" interrogation pulse opens the switching element 201. The switching element 211 is also opened again by the trailing edge of the correction pulse and the time correction is thereby ended.

Lagging error (Figure 13b)

In the case of a leading error, the mode of operation of the circuit up to the zero crossing of the counter reading of the synchronization counter is identical to that in the case of a leading error. At the moment of this zero crossing from. The zero pulse supplied to the circuit 206 is switched through via the AND gate 223 and sets the zero-crossing flip-flop 225. The voltage output by the flip-flop 225 in the set state is fed to the AND gates 227 and 230. When the response pulse then arrives, the switching element 230 passes and switches the command circuit 207 from subtraction to addition. The response pulse also triggers the correction pulse via the generator 209, which closes the switching element 211. However, the correction pulse can now also pass through the AND element 227 in order to open the switching element 213. As a result, the clock pulses doubled in frequency can be transferred to the third time

909820/0 296

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1406043 - «β -.

ff

Score 220 and perform the time correction. As in the case of a leading error, the counter reading is also HuIl of the counter controlled with fourfold frequency 200 is decoded or sampled by the zero crossing latch 206 during correction to that of the correction pulse generator 2Ό9 to interrupt the correction pulse supplied and thereby to close the switching element 213. This will make the feeder the double frequency pulses to the counter 220 are interrupted. The correction is carried out and the switching element 211 opened again.

G. Binary addition and subtraction in the synchronization counter 200 ■

As already mentioned above, the synchronization takes place through Addition and subtraction in the synchronization counter 200.

The counter can be used for binary counting if it is composed of flip-flops which are connected as shown in the block diagram of FIG. 15A, for example. Differentiating circuits 252 are connected between the flip-flops 250 dos counters, which differentiate the output voltage of the flip-flops, so that when a flip-flop is tilted, a needle pulse results, the polarity of which depends on the direction of the change in state of the flip-flop. As a result, a frequency reduction of 2: 1 is achieved if the pulses of one polarity are suppressed by an OR-GIiAd 254 that can be selected to + or -, and the subsequent 5 ¹ Iipflop 2-50-1 with each trigger pulse of the other Polarity that is allowed through changes its state. The choice of addition or subtraction is made by choosing the polarity of the pulse pulses that are transmitted between the flip-flops, carried out by the addition / subtraction control 207, which prepares the ODUR-G-Iied 25 so that this is positive or lets through negative impulses.

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SS

Pig. 15B shows some voltage curves of a three-stage V up-down counter, which counts "to 2. The upper one Group are impulses that change their state when the previous one Positive impulses. In the middle group of impulses, the states of the impulses change if the preceding ones Impulses go negative and you can see that the middle group represents the negation or inversion of the upper group. So if a number from the middle group is added to the corresponding number from the upper group, is the binary sum always 111. If therefore that of the middle The number shown in the group, which increases steadily from left to right in the diagram, must be that shown by the group above Gradually decrease the number in the same direction. In other words: in the upper group the pulses are subtracted, whereas in the middle group they are added. As an example, the. lowest group 5 impulses added and subtract 4 pulses starting from 000.

The running time of the flip-flop chain of the counter of FIG. 15A is approximately equal to the sum of the rise times of the plip-flops up to the last changing digit. This term can can be reduced to almost a rise time if the circuit shown in FIG. 150 is used for adding or subtracting Up and down counting is used. In this counter the trigger impulses are not relayed through the ilipflops, but via switching elements 260-1, 260-2, 260-3 ... for positive trigger pulses and via switching elements. 262-1, 262-2 and 262-3 ».. for negative trigger pulses. The rise time or holding speed of these switching elements can be kept very short. The trigger pulses are through Differentialion of the single frequency clock pulses obtained. The command circuit 207 controls the supply of the trigger pulses to the corresponding switching elements, depending on whether they should be added or subtracted. The switching songs

909820/0 296

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260-1, 260-2 and 260-3 are opened when the output signal of the respectively connected flip-flop 264-0, 264-1 and 264-2 is a binary "1", ie when the J ¹ flip-flop is "set", while the switching elements 262-1, 262-2 and 262-3 are opened when the respectively connected flip-flop is reset. The counting speed of the circuit of FIG. 15G is limited only by the rise time of a single flip-flop, since the flip-flops which are to be converted, ie to be flipped, are triggered almost simultaneously. The counter chain can be expanded or supplemented by any number of counter stages.

The mode of operation of the counter of FIG. 150 is based on one simple binary numerical example described once for an addition and then for a subtraction. In the addition example, an arbitrarily chosen binary number becomes a "1" is added and to another in the subtraction example arbitrarily chosen binary number a "1" subtracted:

Addition subtraction

100111 101100

+1 - 1

101000 101011

It can be seen that when adding an "i ^rt , starting from the right," the first four flip-flops must be flipped. In the subtraction example, however, the first "three flip-flops" must be flipped} different number examples were chosen to better demonstrate the carry formation. In Fig. 15c the trigger impulses, which command whether to add or subtract, run flurcTv the switching elements ^ 60 and 2.6 :: until they hit the last flip-flop stage, which must be flipped all previous flip-flops in the opposite state closes the following switching element and thereby prevents the trigger pulse from continuing

909820/0296

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Wf

However, the tilting process of the plip-flop will "until" disappear of the trigger pulse delayed. The rise time of the plip-flop for this purpose is purely very fast trigger impulses - sufficient.

D. Reverse voltage retention

As mentioned above, the purpose of the reverse voltage is! prevent a time correction from being carried out in the station becomes if '0,2,3,4 ... OO «other" query pulse in the period between an "own * query pulse and the arrival of the response pulse. A time correction should only take place if a single "other" interrogation pulse arrives in this time period. Pig. 16 is a Block diagram of a circuit for generating the blocking voltage. At the beginning the two plip-flops 270 and 272 deleted or reset. Venn a "different" interrogation pulse is received, it is initially slightly in a delay circuit 274 delays and then triggers or sets the flip-flop 270. In addition, the "other" interrogation pulse is used an AND gate 276 is supplied, but does not go through this OBD member through, there at the other input of the UHD member 276 there is no signal. If a second "other" interrogation pulse hits one, then he can pass the UHD link, since that Plipflop 270 is now set. This second interrogation pulse then sets the flip-flop 272, which then emits the reverse voltage. This tension is applied to the holding member 221 of Pigur 14 fed to close this and to prevent the correction pulse to the remaining part of the Synchronizationssohaltung is transmitted. If there is no correction pulse, the transmission time counter is corrected.

If no "other" interrogation pulses are received, the first response pulse received triggers the plip-flop 272, in order to close the switching element 221 (Pig. 14), so that the interrogation pulses received outside the appropriate interval

909820/0296

· ■■■. ■■■■ *. - · ♦ - .; ■. ■ · ■

cannot effect a correction. If, referring to FIG. 14, neither an “other” query pulse nor a response pulse is received in the interval or in the period, then the monostable release generator 232 automatically interrupts the dialing process in the counter 200. If the synchronization counter 200 does not have any in the counter sequence If the zero-durohgang takes place, then no correction pulse is generated by the circuit 209, and no correction is made either.

E. Choice of the transmission times for the pulses B, A and Q

As explained with reference to FIG. 10, each station sends a start pulse Bq and an altitude information pulse A _Q or a ground information pulse G ₀ , depending on whether it is an aircraft or a ground station. Whether the interval following a "{! ending point in time pulse is used for aircraft or ground station information purposes. With this system, the cycle sequence is repeated approximately every second and begins with a start pulse Β", which is followed alternately by altitude information and ground station intervals? the beginning of each Interval (each period) is determined by a transmit timing pulse, as shown in Figure 1. From about the middle of the 1 second period, the time Mr. 201, the alternating sequence ceases and the rest of the time is used for synchronization purposes.

FIG. 17 shows the block diagram of a circuit which derives the _{pulses B Q} , A _Q and / or G ₀ from the transmission time pulses supplied by the counter 220 during the em th half of the sequence. In FIG. 17, the sequence is generated by a continued scaling down of the output pulses of the transmission time counter circuit 220. A frequency reduction of a total of 2 ^ is effected by a counter or rope operator 279, which also consists of three consecutive! The individual coaster stages contain

ten llipflops to reduce the frequency to the. Factors 2,. ί

71
.2 'and 2. The frequency divider or frequency divider

279 generates the start impulse B with twice the JPrequtnz of the input impulses or 548 Hz. The start impulse B is triggered when the count of counter 279 changes from 111111111 to 000000000. The count of the counter 279 is scanned by an AND gate 284 with nine inputs, each of which is connected to one of the nine plip-flops in the counter. As long as the binary number 111111111 is pending, the AND element has a "1" as its output signal. For every other number, the output signal is ⁿ 0 ⁿ . The 1 signal of the AND element is somewhat delayed in an EC delay network 286 and fed to a further switching element 287, the input signal of which is the transmission time sequence from the counter. The delay element; , 286 holding the switching member 287 during the transition of]? ^Requenzte% of ilereingangsBignals 111111111 000000000 open on, so that the next timing pulse corresponding to the start pulse B, via the switching member

287 is switched through with only a slight delay. This switched through pulse corresponds to the start pulse Gq and is also used to generate it.

The aircraft transmit timing pulses A and the ground station transmit timing pulses G are generated in a similar manner. They alternate in time, so that two switching elements

288 and 289 can be opened and closed alternately. After a reduction in the frequency of the pulsating with 548 Hz The square wave at the output of the counter is converted into a square wave at the output of the counter The delay circuit 290 is delayed and fed to the switching element 288. The other switching element 289 is of the in one Inverter 29I (NOT element) inverted (negated) square wave voltage curve the same delayed square voltage driven. The transmission time output pulses of the switching elements 288 and 289 then oscillate in antiphase, with the output signal of the switching element 288 the? aircraft information pulse

909820/0296

iff

train A and the output signal of the other switching element 289 represents the ground station information pulse train G.

The definition of the special plug-in or ground station _{impulse for the transmission of an A Q} or GQ impulse for identification of the station is achieved by determining the flip-flop states in the frequency divider at the moment the impulse appears. This is described in more detail below.

A switching pulse generator is also attached to the frequency divider 281 and 282 292 connected for information synchronization. This circuit also decodes the count of the counter 279 "and if it is below 201 is located, indicating that the station information pulses (B, A, G) should send and receive, the circuit supplies an information pulse of one polarity. If the count is greater than 201, the circuit switches and generates a synchronizing hold pulse to allow the transmission and reception of I and R pulses.

F. It generates "own" query pulses

The "own" interrogation pulses are from the one shown in FIG Circuit delivered. This circuit corresponds to the random switch generator 60 and the random switch 64 of FIG FIG. 10. The transmission timing pulses of the counter 220 are from the synchronization switch voltage of circuit 287 the switching element 300 held through. This will make the "own" /, query pulses during the information half of the Cycle sequence interrupted. The 3rd time pulse at the output The switching element 300 are also converted into a switching element 304 linked to a voltage curve whose pulse spacing fluctuates statistically and whose pulse length is fixed to one smaller value than the time between two transmission timing pulses is set. The random switching impulse is from

909820/0296

a noise generator 305, whose output pulses, which exceed a certain threshold value, a monostable Trigger blocking oscillator. If the stop pulse is applied to switching element 304, it will certainly occur only a single transmission time pulse during the hold pulse on and is switched through (unless it is blocked by the above-mentioned Sohaltelement 300) the Average value of the frequency of the stopping impulses from the stopping link can duroh setting the trigger threshold of the Sperrohwingers 307 can be changed and is set, for example, to 10 20 Hz. This is done with the aid of a counter 303

in .

performed, which counts the received and dim decoder 486 decrypted B-pulses. The decoder 486 is described below. The counter 308 is _{reset by the B n} pulse generator 287 every second. The output signal of the counter 308 is converted in a digital / analog converter 309 into an output voltage proportional to the counter reading. Converters of this type are known per se. This analog voltage is stored for the duration of the 4- second period in a threshold value circuit 310, which varies the level at which the pulses from the noise generator 305 are held on the blocking oscillator 307. With a suitable number of B-pulses received, the threshold voltage also falls, which also has an increase in the frequency with which the blocking oscillator 307 is triggered, and with which the number of IQ pulses is also increased.

G. Start pulse (B) synchronization

When using coarse synchronization, your own start pulse Bq must match the start pulse received first synchronized with other station before actuating the transmitter of the own station. Therefore, the first to be received must Start impulse always trigger a correction if it occurs before the "own" start impulse is triggered. Fijur 19 is a block diagram of a preferred start pulse; n-

909820/0296

BATH ORIGINAL

earring, on the left in the picture the received and decoded start impulses from other stations and the Inforaationaaynoh3coniaationa - gaktapaTfnnng from the circuit 292 of FIG. 17 "in ·" υΒΦ-GHied 320, ao that the received Start pulse, e only during the synchronization part of the sequence of actions are held by the holding member 320 * MeB aind the start impulses that were generated before the generation of the own start impulses a Bq can be received · Venn a start pulse from the So holding member 320 is held, it triggers a flip-flop 322 and thereby opens a UHD oil song 324 for any impulse, who appears at its other entrance. The information synchronizatione-5akt voltage is obtained from a circuit 321 differentiated in order to loadelimpulae from the front and rear flanks to derive the corresponding polarity. The other entrance dea AND gate 324 becomes the differentiated form of the information syncronization clock counter voltage supplied, with a positive impulse the beginning and a negative impulse the Indicates the end of the synchronization period. When the next positive, differentiated pulse at the input of the TJED-SIiedea 324 appears (at the beginning of the next synohroniaation period, one second later), it is held by the switching element 324 and triggers a second flip-flop 326. Daa output gas signal of the plip-flop 326 closes the switching element 212 {! ig, 14) and resets the counter 220. Thus, the transmission time counter can 220 be aynohronized.

Since the flip-flop 326 at the beginning of the synchronization period after the period in which the first start pulse is decoded, triggered the first start impulse in the second period * de of the UHD slied 320 and of the UHD element 328 durohgesohalte, which is opened when the Hipflopa 326 is set. This start pulse triggers the llipflopa 322 and 326 into the normal state aurüok. As a result, the holding element 212 is opened again and the payment process in the transmission time counter 220 is started again. The desired coarse synchronization is carried out, since the transmission time counting process in the counter 220 "is j will be granted if the he ate start impula in the second i earring period is received,

909820/0296

BADORIOiNAt

«Μ
If ttoith is to be attempted to roughly synchronize with a single start impulse, but with a group of impulses, then the flip-flop "322 can be replaced by a conventional staircase generator. When the desired number of start impulses has been received, the output voltage of the Srep * pengenerators exceed a critical voltage and open the UHD-Glie.d 324. From then on, the mode of operation of the hold is the same as described above, such a circuit could be necessary if interference pulses occur during the scattering or control start pulse decoding.

H. Main Oscillator - (210) -! Frequency Control

It is possible to control the frequency of the master clock oscillator 210 so that constant corrections in one direction are minimized can be. This reduces the possibility that synchronization will not exist due to drift of the main oscillator remain. A circuit with which this can be achieved is shown in FIG. Here the correction pulse from Generator 209 of Figure 14 is used to control the oscillator frequency. With this procedure, the correction pulse of the Generator 209 (FIG. H) generated by the zero-crossing flip-flop 225 ; output zero constant voltage via a switching element 340 duroh. The polarity of the zero crossing voltage is determined by the direction of correction, either leading or lagging, there the zero-crossing flip-flop is either set or cleared. Bipolar pulses appear at the output of the switching element 340, the duration of which corresponds to the duration of the correction cycle used in FIG is equivalent to. Are the corrections of the phase shift in one direction over a longer period of time equal to the corrections of ! Phase shift in the other direction, then the mean value approaches the DC voltage component in the output signal The switching element 340 has the value zero. If, on the other hand, one type of phase lead or lag correction predominates, then will the same current component is not zero, but its polarity

j depends on the type of phase shift. i

In Mg.20 the DC component is used to control a electromechanical servo system used to drive the oscillator. correct sequence. When the switching element 340 is open, becomes a capacitor 342 from the switched voltage

809820/0296

BATH

¹ M.

charged through a resistor 344. This partially charges the capacitor 342. The closing of the switching element 340 interrupts the charging process, so that the capacitor begins to discharge. The discharge takes place much more slowly because the resistor 344 is not earthed during the closed pearlode and a second resistor 346, which is connected to the capacitor "Much larger than" resistor 344 is. The error equilibrium voltage of the capacitor is chopped up with the aid of a chopper 348, for example at 400 Hz, then amplified in an amplifier 350 and finally fed to a servomotor 352 - "drove. The gear ratio of the transmission is chosen so that it takes a relatively long time, about 30-60 seconds in the system described as an example, to. "drive through" the entire potentiometer range. The voltage tapped at the potentiometer is fed to a voltage-dependent capacitor (shown below) of the clock oscillator 210 in order to regulate the frequency of the oscillator in a limited range. This type of voltage-dependent frequency control is known per se.

If there is no control deviation (error residual voltage), the motor is not driven, so that no frequency correction is carried out either. If a control deviation occurs, the motor 352 adjusts the tap of the potentiometer 354 so that the control deviation is reduced by feeding back the correction voltage via the resistor 346 to the capacitor 342. Since the correction pulses have a frequency of approximately 2 Hz, the time constant of capacitor 342 and resistor 346 must be large enough to allow some smoothing, for example 2 or 3 seconds. However, this time constant must not be so large that the control loop becomes unstable when the control loop is closed via the clock oscillator. The integration of the frequency correction voltage on the right-hand side up to the actual phase error on the left-hand side must also be taken into account when considering the stability of the control loop. The manipulated variable of the motor amplifier combination v / ird is fed back in order to prevent a double integration in the control loop. Me. ■ DC gain of the servo amplifier

909820/0296

BATH ORIGINAL

Is so high that the system deviation even in the vicinity of the * beat or the connection socket of the potentiometer remains small. ι All of these procedures are known to sioh. As a result of the low. Sensitivity (amplification) of the lacto oscillator is enough .Easy integration and the delay time of the RÖ link generally not enough to make the control loop unstable.

However, the frequency of the master clock oscillator 210 can also be other types are regulated, for example with the help of ter-. mos tat en, t emp er aiwirmess circuits and other similar to sioh ! »• knew procedures. These procedures can be used alone or in conjunction can be applied with that shown in FIG.

I. Generation of the plug-in information pulse (A)

When the synchronization is carried out, the information impulses sent according to the altitude range in which sioh. the station is located. In? Ig.21 the aircraft altitude information via a three-phase synchro running at two speeds 370-1 and 370-2 inserted from an altimeter 271, e.g. B. from a Kollsmantype Ir.1686-05 «The Synchro 370-2 turns see faster to transfer small «units of the altitude measurement eu · The height information of the two synchros appears again amplified as an analog direct voltage on a potentiometer 374, that from a booster servo motor 375 via a gear train 376 is driven. The largest angular rotation takes place via the servo motor 375 through the signal of the fast synchro 370-2, which is fed via a relay 377 and a drive amplifier 378. Then when a quick cycle is pushed in, when the error output of the slow synchro 370-1 exceeds a certain critical threshold value, a relay driver stage 379 is actuated to the state fies relay change. The relay 377 picks up and connects the slow synchro 370-1 with the servo 375 to zero the synchro error bring to. If this is the case, control is passed back to the high-speed synchro 370-2 using relay 377

^aMallen · 809820/0296

The transmission time of the plug-in information pulse (A _Q ) relative to the start pulses B _Q is programmed according to the plug's own height. As mentioned in Solion, the synchronized transmission time pulses are generated with a frequency of 548 Ha. Any aircraft information pulses _t that are transmitted must coincide in time with these transmission time pulses. More precisely, only one information pulse Aq is sent in the time abs olinitt between two start pulses Bq and this pulse Aq is generated by selecting one of the odd-numbered transmission time pulses that occur in the time segment between the transmission times Hr. 3 to Kr.199 occur (see fig. 1). The transmission time selector divider 279 (Mg. 17) is shown at the top left in FIG. The attenuation or division factor of the attenuation element or voltage divider 380 decreases by a factor of 2 with each frequency divider stage of the middle frequency divider 281 from left to right, ie from the high-frequency outputs in the direction of the low-frequency ones. The attenuated output signals are added directly, so that the sum signal is a staircase voltage that begins with the start pulse at zero.

The analog high voltage from the potentiometer 374 is fed to an input of a precision comparator 383 via a low-pass filter 381. Bas other input to the Yergleiohers is the staircase voltage from the attenuator 380. If the two input voltages are equal, the Vergleioher 383 generates a pulse which is supplied to a Sehaltimpulsgenerator 335 to the switching pulse generator 385 "on" either - or ^W from "-zutriggern, depending according to the size and polarity of a height anticipation voltage.

When the plane ascends or descends, it is desirable to eat Information impulses in the approached altitude next to the current altitude range of your own aircraft

ÖQ9820 / 029ß

to send. Therefore, a proportional control is provided in which the number of altitude areas in which AQ pulses are sent depends on the rate of change of the aircraft }. ' . height depends. The rate of change of height is determined by

Differentiation of the analog high voltage at the output dee Filters 381 obtained in a differentiator 387. Since the ί 'velocity voltage at the output of the differentiator

is usually very small, it will be in a conventional one; chopper-stabilized, feedback amplifier 389 amplifies, demodulated in circuit 391, and then the analog

High voltage in the summing circuit 393 added. The sum voltage at the output of the summing circuit 393 is fed to a further precision voltage comparator 395 which emits a pulse either before or after the output pulse of the other comparator. The duration of the output pulse of the second comparator 395 depends on the indexing speed of the aircraft altitude and on whether the aircraft is ascending or descending. The latter determines whether the Höhenänderungsgeschwindigkeits- _£% voltage to the analog voltage is added or subtracted. _% The first pulse of one of the two ¥ ergleicher 383 or 395 'triggers the S cha It pulse generator 385 into the "on" state (in jr which it emits a switching pulse), while the second pulse _t of the other comparisons "the generator resets again. The interval determined by this switching pulse is the altitude-coded transmission time for the aircraft information pulses.

The information pulses are transmitted in the following manner. The information B synchronization hold pulse from the counter 292 (FIG. 17), inverted by an inverter 396, and the odd transmission time switching pulse from the switching element 289 (FIG. 17) are fed to the inputs of a UFD element. The UED-Ölied 397 only emits a pulse at odd-numbered transmission times during the information period. The output pulses from the UHD element are fed to a pulse generator 393 to shape the pulses if necessary, and the shaped pulses are fed to a second TOD element 401. Since » TJWD-

! 809820/0298

8ADORlGlNAt. |

■ i

ι · »

fr

Element 401 also receives the altitude control pulse from generator 385 and the transmission timing pulses from counter 220 (Fig. 14). Therefore the UHD-Gliea 401 only kept it during the altitude stop pulse and at an odd-numbered transmission time a transmission time pulse. These transmission time pulses control the A ₀ information pulses "which are to be transmitted.

pie rio mains voltages from a suitable source (not shown) are fed to the comparators 383 and 395 to the Generation of the height stop impulse by hand on one or more set the desired height range. The reset voltages control the time of pulse generation for each comparison.

It is not advisable to end the plug-in information pulse θ A _q until your own station is fully synchronized with the other stations in the system. Referring to Pig. The transmission of the pulses Aq can be prevented by interrupting the input signal of the pulse generator 399 so that it never reaches the AND gate 401. An A _Q information pulse interrupt circuit is shown in FIG. The switching voltage from the AND gate 397 is fed to an AND gate 410. If there is no signal at the other input of the AND element 410, the holding voltage cannot pass through the AND element. As can be seen, this state can occur when the start reset voltage from flip-flop 326 (Pig. 19) or the voltage from a monostable multivibrator 412 is present at the input of a NOR element 413. The NOR element is an OR element with a connected inverter (NOT element). Therefore it does not provide an output signal if one or more input signals are present. The start reset voltage is at an input of the NOR element 413? N when the coarse synchronization takes place. "Since it is desirable that the information pulses are not sent during this time, the start reset voltage blocks the AND Element 410. The transmission of an A ₀ pulse is preferably also prevented if the station is subject to the pin synchronization corrections to be carried out

98 20/0 2 9 $

ORIGINAL

are great. This prevents incorrect information from being sent. Here is the received reply pulse delayed and to irrigate a stop pulse generator is used via a delay circuit 417. The delay time is equal to the maximum synchronization error, the can be tolerated, and this time is set. When the correction pulse from generator 209 (fig · H)> which is triggered by the • response pulse, is still pending when the hold pulse arrives from generator 416, a switching element 418 is opened and the monostable multivibrator -412 is triggered in such a way that that it opens the AND gate 410 and the generation of dep information impulse it prevents Aq.

It should be noted that the Pig. 22 either in front of or behind the AND element 401 of FIG. 21 or ar any other suitable place can be switched, uiii to prevent the generation and / or transmission of the Ap pulses.

It should also be pointed out that if your own station is a ground station, the altitude chart arrangement of fig. 21 is not required. Instead, the switching pulse is specified by the generator 385 in such a way that it triggers at a predetermined time in order to switch through the transmission time pulse at an even-numbered time associated with the ground information time of the station. Here the odd-even switching pulse would come to the AND gate 397 from the odd switching generator 288 of FIG. If you want, you can also use the same sub-cup as shown in fig. 22 only use the prevention of the transmission of the G ₀ pulses if your own station is not synchronized.

J. Pulse Coating and Decoding

Pulse coding is preferably used to identify the various types of pulses which ^{are transmitted in the S3 r Btem.} With every single asterisk (B),

. 909820/0296

BATH ORIGINAL

Query- (I) | Answer - (B) and information pulse (A or G) a pair of pulses is sent, the transmission delay between the pulses of each pair being determined by the type of pulse is. The block diagram of a pulse encoder for a single station is shown in FIG. For every Pulse type are supplied by two blocking oscillators pulse pairs, by the one oscillator from the delayed pulse The trigger pulse of the first oscillator is triggered. Since every blocking oscillator has a relatively long recovery or price gain time, the blocking oscillator is not the same used for both pulses.

As shown in FIG. 23, a blocking oscillator 450 (blocking oscillator BO) is triggered directly and a second blocking oscillator 452 is triggered via a delay element 451 by the _{transmission timing pulse that is switched on by the circuit of FIG. 17 to generate the pulse B Q} at the correct point in time. The transmission timing pulses can be sharply shaped before they are fed to the various oscillators. Both vibrators generate individual pulses of a predetermined duration. The delay element 451 determines the coding delay in the case of a B-pulse, so that the oscillators 450 and 452 generate two pulses with a certain delay interval. The two pulses are switched through to the modulator of the transmitter via an OR gate 455. In a similar way, the send time pulse of the circuit of FIG. 18 assigned to the IQ send time triggers the oscillator 452 directly and via a delay element 456 the oscillator 450. The delay time of the delay element 456 is different from that of the delay element 451 by the coding of the pulse I realize. The pair of pulses Iq is also switched through by the OR gate 455 to the modulator of the transmitter.

To generate the coded pulse pairs for the pulses Eq and A ₀ (or G _Q ), two further blocking oscillators 460 and 462, which are again set differently, are used. This blocking rate »

909820/0298

A R ₀ delay element 464 and an A ₀ delay element 466 are often connected upstream, each of which forfeits a certain time delay for the pulse pairs an AND element 468. A holding pulse from a monostable holding pulse generator 470 opens the AND element 468 when its own interrogation pulse Iq appears and switches the interrogation pulse of another station through when it arrives The trigger pulse for the pulse pair (Aq or Gq) is the information transmission time pulse passed through by the circuit of the ligur 21,

The pulse decoding takes place at the output of the station receiver with the aid of the circuit of FIG. 24. The video signal from the receiver is fed to a threshold value detector 480 which changes its state when the video voltage exceeds a critical value. Received pulses below a certain threshold are blocked in order to reduce the possibility of mix-up or confusion, as explained above. The received signal is passed from the threshold value detector to two delay chains 482 and 484, the delay chain 484 being tapped at points which correspond to the delay of the pulse pairs B, I and R. Three AND gates 486, 488 and 490 are used to determine a coincidence between pulses of the two delay chains. As far as the AND gates are concerned, the difference in the time delay between the two input pulses is equal to the time delay between the pulse pair to be decoded. The first and last impulses then coincide, so that only one impulse on the! The output of each AND element appears. Two delay [chains are used instead of one to the Dekodierverzögerungs-

time regardless of the type of pulse that is decoded, ! to keep stant.

«08820/0296

BATH ORIGINAL

K. Receiver - transmitter

In the Syatem according to the invention, only a single transmission channel is used. As a result, both the transmitter considerably simplified and the receiver. As a receiver-transmitter is a known calibration execution. The block diagram is shown in FIG. The coded pulses from FIG. 23 are fed to a modulator 500 via a delay element 502 with a small delay. The encoded pulses are modulated onto a carrier wave generated by a carrier wave oscillator 504, and the composite wave is radiated via an antenna 506.

The transmit and receive antennas 506 and 508 are preferred attached to different places of the plug stuff, z. B. at the top and bottom of the plug-in tool body. This makes them up ?! U isolated from each other to some extent. But to the To protect the first mixer stage 510 in the superheterodyne receiver is a varactor holder 509 between the receiving antenna 508 and the first mixer stage 510 switched to an additional Introduce attenuation during the duration of the transmitted pulse. This switch is controlled by an impulse of a switch pulse generator 520 triggered, which in turn is triggered by the pulses of the pulse encoder. The one from the delay element The slight delay introduced in the modulator input circuit in 502 causes switch 510 to turn on of the transmitter switches off.

After the first mixer stage 510, the received signals are received in a broadband intermediate frequency amplifier 512 amplified, demodulated in a demodulator 514 and amplified in a video amplifier 516. The gain of the intermediate frequency amplifier 512 is time-variable Gain signal generator 518 varies over time, from 0, during the occurrence of the transmission pulse to Maximum at the time of reception of the pulses from the most distant stations, so that the received pulses at the demodulator 516 all have approximately the same amplitude '. A self-

909820/0296

Claims (26)

400 active shrinkage adjustment regulation 522 (ΙΥΟ) is also provided for medium or slowly occurring changes in gain balance. XI. Accessibility • With the help of the system according to the invention, the oseillators (Clock generator) of several both fixed and "moving stations," which initially do not synekroni-be with one another are to be synchronized. This takes place without a main synchronous beer machine, e.g. an atomic clock with which you can see all stations have to synchronize. Synchronize instead of deeeen the different stations in an area mutually "until they are all synchronized with each other are. If this is the pail, jode Station can measure the distance to other stations with high accuracy. It should also be noted that the system can also work without a fixed station The system according to the invention also allows all stations whether fixed or movable, to transmit or receive on the same frequency. As a result, that for Message transmissions available frequency spectrum effective use is made of the technical equipment guidance is simplified, maximum receiver sensitivity results and a minimum transmission power is required. 909820/0296 BATH ORIGINAL JfH An ep r U c Ii e λ J System for the synchronization of the generation of the first signals of two stations in a network area of several stations, in which each station contains means for measuring the time difference between the generation of the first signals of each station, characterized in that means respond to the measured time difference and the point in time move the generation of a subsequent first signal of one station closer to the time of generation of a subsequent first signal of the other station. 2. System according to claim 1, daduroh gekenn-ζ e i ο h η e t that the time of generation of the first subsequent signal of a station brought forward and the time the generation of the subsequent first signal of the other station is delayed. 3. System according to Anspruoh 2, characterized in that each station the time of "generation of their next following first signal by half of the measured Time difference shifts. 4. System naoh claim 3, characterized g β ke rCn. zeiohnet that the shift takes place in such a way that the following first signals from two stations coincide in time. 5. System according to one or more of the preceding claims, characterized in that that means;} each station interrogation signals with predetermined temporal relation to the first sins of the station send and means to receive the interrogation signals of the other station and the received interrogation signal for measuring the 9098 2 0/0 296 Use the time difference necessary for setting "or shifting the time of generation of the subsequent first signal is used. 6. System according to claim 5, characterized in that the time of generation of a subsequent first signal in each station by an interrogation signal Another station is set, which is received after the Alis transmission of its own query signal. 7. System according to claim 6, characterized that a station sends the interrogation signals on a statistical basis and each interrogation signal sent has a predetermined time relationship with a first signal from the station. 8. System according to claims 6 or 7, thereby geke.nnzeich that in each station a response signal in response to the receipt of an Abfra ^ e-signples one is sent to another station, and the time from the end time an interrogation signal until a response signal is received the other otation is measured to determine the point in time of generation of the subsequent first signal. 9. System according to claim 8, characterized that the timing of the generation of a subsequent first signal each of two stations that are mutually exclusive receive their interrogation and response signals, is set so that a subsequent interrogation signal to a of the two stations arrives approximately half the time from the time of sending an interrogation signal Station until the time of reception of the from the other station response signal sent as a response passes, 90982Ö / 0296 BATH ORIGINAL 401 10. System according to claim 9, characterized in that in both stations, depending on the time difference measured in each station, the times of the subsequent first signals are added to one another, so that subsequent interrogation signals from the Hun stations are transmitted and almost synchronously the following ljf || en signals of the two stations are generated almost synchronously **, 11. β j "breath em according to one or more of the preceding aneprtiohi, characterized in that sioh ipAe station in a network area of several stations .4.1 located, and each station the time of generating its first signal at any time in relation to only one sets another station in the network area. 12. System naoh claim 11, characterized e i e-h net that the interrogation signals of a station on random statistical basis with a predetermined time ratio in relation to the first signals sent by the station. 13. System according to claim 12, characterized t that the timing of the generation of the first Signals of a station set by the harvest interrogation signal from another station in the network area to Sending out an inquiry signal every time the station arrives. 14. System according to claim 13, characterized in that a station a response signal in response to ala since ^r ^ irst of a εηΛβΓβη station of the composite region incoming Aijfra ^ sends eSignal. 909820/0296 15. f'jitem according to claim 14, characterized in that the first interrogation signal received in a station is sent by another station in the network area and in response to this, a response signal is sent by the receiving station before the next first signal is generated by this station . 16. System according to one or more of claims 5-15, characterized in that an Abfregenignal of a station occurs almost simultaneously with a first signal. 17. System according to one or more of the preceding claims, characterized in that that the first signals are generated periodically. 18. System according to one or more of the preceding claims, characterized in that that a predetermined number of first signals during a Side section (interval, period) is generated and during of a rope of this time segment at a point in time with a predetermined time interval to one of the first signals Information signal is sent. 19. System according to claim 18, characterized in that a station, the setting of the timing of the Auftretenä performs its first Cignals in the manner according to one or more of the preceding claims, during a T _e ils of the time segments. 20. System according to one or more of claims 11-19, characterized by an arrangement for Synchronization of the generation of the first signals of a station that enters a network area of several stations, whose first signals are already synchronized, and by means in each station for periodic transmission 909820/0296 BATH ORIGINAL $ 40 characteristic signals, means in the station entering the network area for receiving the characteristic signals Signals and by means in the station that enters the network area, to stop the transmission of their characteristic Signals in accordance with the received "-" s characteristic signals. 21. System according to claim 20, characterized in that the first signals of the station which are in the network area enters, a predetermined time ratio in relation to the characteristic signals of the station. 22. System according to claim 21, characterized in that the first signals of the station in the network area enters, are synchronized with the characteristic signals of the station and several first signals occur between two characteristic signals. 23. System according to claims 20-22, characterized in that the station in the network area occurs, adjusts their characteristic signal so that it occurs at the point in time at which the characteristic Signal from another station in the area of synchronized stations (network area) is received. 24. System according to claim 23, 'characterized that the station from the area of synchronized stations is the station that the station, who enters the area is closest. 25. Procedure for synchronizing the end times several stations, characterized that synchronization signals are initially sent from each station at random statistical times and then one after the other two stations from the multitude 909820/0 296 BATH ORIGINAL JOB selected by stations and the transmission times of a each static pair can be synchronized with the help of the synchronization signals. 26. The method according to claim 25? characterized that the end times of each selected pair of stations approximately "to the middle their original time interval are shifted, 909820/0296 BATH