DE1456186C - Device for one-way time-of-flight distance measurements enabling absolute synchronization of the transmitter clocks of radio stations that are movable relative to one another - Google Patents

Description

3 4

witness sent out pulses and receive notification that another aircraft is so close

to avoid personal impulses. found that there was a risk of a collision

However, there are already synchronizing devices. The pilot then has enough time to

gene known in which a first radio station signals to avoid this.

sends out and a second radio station these signals 5 by eliminating the reception of pulses

receives and uses it to synchronize. from distances beyond the critical collision

With these facilities the synchronization zone and by using an altitude code in

however not possible if the distance between the connection with the transmitted pulses is around the

is unknown at both stations and if the altitude of the aircraft sending the impulses can be specified,

two stations move relative to each other so that io can track the number of other planes passing by any

their distance changes. Airplane spotted limited to those

So z. B. with a conventional Loran, through which an immediate risk of collision System, as it is known (»The electron consists in knowledge. Thus, the pilot of the question schaft und Technik ", 4 [1950], no. 12, pp. 417 to 426), aircraft can only be operated with those aircraft Synchronization between the main and follow-up 15 grasp, by which an imminent danger is given. station only possible because previously the distance between the direction of an aircraft in relation to one of the two Stations have been measured and never their aircraft can also be determined when changed. If both stations are relative to each other, for example by measuring the received pulses With this system it is not possible to move them by known methods such as interferometric synchronize with each other. 20 radio measurements. As each plane covers the distance

In a similar known system (telefunken- height and direction of all other aircraft within

Zeitung, 25 [1952], 94 (March), pp. 27 to 32) once the end of the danger zone has been determined, an indicator for

stood between the main and the following stations warning pilots and a procedure for avoiding

also known. Realize the duration of the collision (via a cable),

transmitted signals is therefore known. A syn- 25 By applying similar procedures to radio

chronization is in this known facility beacons or any other ground stations,

therefore also not possible if the two who are synchronized with the radio beacon can be a

Move stations relative to each other. Air traffic control system are implemented, which-

In a device, as it is also known art, that the ground stations distance, direction (French patent 1,337,227), a passive receiver is used at a 30 and height of each aircraft within the line of sight of the station, so that no ground stations also with the radio beacon syn response is possible. This facility can be chronized, transmitted,
also not for synchronizing stations. According to the invention, the determination of those that move relative to one another can be used. distance, direction and altitude without the use of an extremely stable oscillating radio beacon. Furthermore, all board gates can be used as a clock generator and a control station. Transmitter in the area of a ground station with the transmitter. All other stations are synchronized as follow-up stations to the ground station with the help of electronic devices and do not send any signals for synchronization, which are also transmitted from the aircraft to the control station. 40 are carried, with essentially only such

The invention is therefore based on the object to be used that are already known in the transmitter

to enable synchronization even if impulse radio navigation systems are available,

the distance between the stations is unknown.

is or is constantly changing. other synchronized, so that all on-board transmitters

According to the invention, this task is thereby also 45 synchronized with one another. The same solved that in a manner known per se in the first impulse transmitter, which are already present, a receiver station can also be used to send out in aircraft to determine the altitude and other response signals to the reception of the information signals,
second station and in the second station the running developments of the invention are identified in the sub-times of the signals of the second station and the response claims.

signals of the first station measuring timepiece in front of The invention and its further developments are in the

has been seen and that the running time determined in this way can be determined in more detail than the following on the basis of drawings

wrote the first mentioned transit time of the signals of the first station.

control signal to be taken into account when synchronizing F i g. 1A to IG show the chronological sequence

tion serves. 55 different impulses when the on-board transmitter with the

This has the advantage that each of several is synchronized with the transmitter of the ground station;

such a device equipped aircraft F i g. IH provides the mode of operation of the system

Measure the distance to all other aircraft together with a radio beacon and some moving ones

can, from which it receives impulses. The determining stations represent;

The distance can be determined simply by measuring 60 F i g. 2 A to 2 G show the temporal relationships

the running time between the sending of the own and various impulses if the on-board transmitter is not with

the reception of the interrogation pulses of that flight is synchronized with the transmitter of the radio beacon, which is

stuff, the distance of which is to be determined, is expressed by the fact that the interrogation pulses

Follow. Since, as a result of the synchronization, both pulses of the aircraft compared to the reference pulses of the

are sent at the same time, the measurement gives 65 radio beacons lagging by a time Δ t;

the running time the distance. Such a development Fig. 3A to 3G show the temporal relationships

Distance measurement between aircraft is particularly different from impulses when the on-board transmitter is not

advantageous because it synchronizes a pilot in time with the transmitter of the radio beacon, what

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is expressed by the fact that the interrogation- The second fundamental transmission pulse is the Βέ-

pulses of the aircraft compared to the reference pulse train pulse 15 tb, which was sent in front of the ground station 1, lead the radio beacon by a time Δ t ; (index b ^ = from the beacon). This impulse is in

F i g. 4 is a block diagram of the aircraft transmitter FIG. 1B and to explain the invention Receiver synchronization system; 5 dashed vertically.

Fig. 5 is a detailed block diagram of the fre- The third transmission signal is the alarm pulse 20 ib

quenz- and phase control circuit of F i g. 4; the radio beacon shown in FIG. ID diagonally ^{1 shown with} dashed

Fig. 6 shows the time sequence of the impulses provided. The Antwöitiriipüls 20 tb is derived from the transfer of the Höheniriformätion; Radio beacon as Alitwoft on an interrogation oil pulse of one

Fi g. 7 A to 7 H show the temporal relationships 10 aircraft sent. The from the radio beacon received impulses of a modification of the system, if the. The query pulse 10 rb (index r = received) is the query pulse sent by the aircraft with in FIG. 1C shown. The amplitude of the received pulse 10 rb synchronized with the reference pulse of the ground station is due to the attenuation in the room; smaller than the amplitude of the transmitted pulse

Fig. SA to 8Μ show the time relationships 1510ia.

the system of FIG. 7, if the interrogation pulse is sent to the navigation systems, such as TACAN, nor *

Reference pulse of the ground station for a time Δ t, formerly irripulse pairs with fixed distances, distributes; to increase the average radiation power! and around

F i g. 9 A to 9 ti show the temporal relationships of the system. Less sensitive to errors or int 'of the system according to FIG. 7, If the interfering impulse becomes too distant causing interference; this reference pulse of the ground station by a time Δ t pulse pairs are lagging behind for the sake of clarity; calmly. Otherwise, the Ah, FIGS. 10A and 10B according to the invention may belong to a block switching position both with individual signals and with a pulse pattern of an embodiment of the system; groups are operated.

F i g. II is a block diagram of a noise 25 To explain the principle of operation of the

generator, which is in the plant of F i g. 1ÖA undlÖB invention, it is assumed that the query pulse

is used; 10 ία and the Fünkbakehrefererizirhpuls 15 tb begins

F i g. 12 shows the voltage gradients are lent synchronized, as it is in cells A and B.

different points of the pulse generator of FIG. H the F i g. 1 is shown. These impulses appear

and at other points in the facility; 30 simultaneously at time t = 0. At time t == * Z ₁ becomes

F i g. 13 is a diagram in which the ratio of the reference pulse 15 ra of the radio beacon of the

nis of signal amplitudes and the requirements for aircraft (Fig. 1 E) and the aircraft interrogation pulse

Ghost signals received as a function of the distance lOrb from the radio beacon (Fig. IC). Both

are applied between multiple stations. Received impulses have been attenuated in the room.

F i g. 1H represents the basic principles of the invention. 35 The time ij is equal to the oblique distance between

according to the system. A radio beacon 1 (or Boden- the aircraft and the radio beacon divided by the station) sends the reference pulse through at a fixed time - the speed of propagation of the transmitted signal

points that from one or more stations 2 the transmission medium.

or la to 2 «can be received. After the radio beacon has received the query pulse lOrb

For example, aircraft can be aircraft that has received relatively 40 (FIG. 1 C), it sends as a response the move to the radio beacon or to one another. Each station 2 response pulse 20 tb (Fig. 1 D). In this Darsends interrogation signals at different times, the position is assumed that the response pulse both from the ground station and from other stations 2 are received simultaneously with the reception of the interrogation pulse. After receiving one is generated. In reality there is a short time * the interrogation signal from a station 2 sends the radio delay 45, but this is combined with a response signal in the system. According to the invention, one is perized so that it has no effect and therefore an un-device is provided which all of them can be observed. At time t ₂ , the interrogation signals sent to the answer stations 2 are synchronized with each other impulse 20 ta by the Bordfuriknävigatiönseiripfärigor, whereby each station 2 receives its input (FIG. 1 E). The time i ₂ - I ₁ is equal to the distance to the radio beacon 1 and to every other station 2 50 distance between the radio beacon and the aircraft can be measured. The synchronism also enables each divided by the OüsbreitürigsgeschWindigkeit of the station 2 to transmit the query signal in an AtttWortimpulses of the radio beacon, a predetermined time corresponding to a. In the aircraft there are circuits for measuring the

ordered information and all other stations time between the transmission of the interrogation pulse to derive this information. 55 10ta and the receipt of the reference pulse 15ra and

In Fig. 1 shows the basic transmission signals of the time between the transmission of the aircraft to an aircraft navigation system. Ob- query pulse 10 ta and the reception of the radio welfare the invention on the basis of a TACAN system beacon response pulse 20 ra provided. These two is described, it should be pointed out that they are not time differences in each case with Tttüf and Trpy is limited to them alone, but that they also represent 60. The circuits located in the aircraft, other flight navigation systems, can be used for time measurement, circuits known per se, which also include distance measurement systems. like a circuit with a capacitor that charges itself The navigation signals contain an interrogation to a voltage corresponding to the time, impulse 10 ία, which is sent by an on-board transmitter (from one. The generated in this way and the respective station 2) is sent ( Index t - sent; Index a 65 times corresponding voltages are with Eaüp '= on board). For the sake of clarity, this impulse is labeled Erpy . In the last-mentioned circuit, dashed horizontally, which has no electrical significance, a capacitor begins at the point in time when it is sent. of the interrogation pulse is based on a DC voltage

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to charge, and the charging process becomes in time and flattened. This is the Eref tension. The point of receipt of the reference or response F i g. 1G shows the analog voltage that proportionally terminates the pulse. The charge of the capacitor is proportional to the time between the transmission of the interrogation and the time between the output pulse 10 ta and the receipt of the response pulse, sending the interrogation pulse and the reception of the 5 20 ra is. In this case it is the linear voltage reference or response pulse. It can also rise half as great as that of Fig. IF and ends counting circuits are used which provide a corresponding number of pulses to be spoken during the reception of the pulse 20 ra and flattened during the times Erpy. In the present case, where the pulses 10 count ta and Tref and Trry. 15 tb were initially synchronized, Eref = Erpy,

If the interrogation pulse 10ta and the radio beacon io it follows that Trpy = ITref .
reference pulse 15 tb are initially synchronized, The F i g. 2 and 3 show how an error voltage as assumed in the present case, then Trpy is derived if the query and reference = 2Tref- This becomes clear when assumed impulses are not synchronized. In the F i g. 2A and that Tref is the time between the transmission of the 2 B, the case is shown that the interrogation pulse 10 ία radio beacon reference pulse at time t = 0 and the 15 is transmitted a time A t later than the radio reception of the reference pulse by the aircraft beacon reference pulse IStb. The interrogation pulse 10ία at time t = I ₁ is. This time Tref = h - 0 equals the distance to the radio beacon in a time I ₁ to the inclined distance between the aircraft and the back, and after receiving the interrogation pulse radio beacon divided by the propagation speed (Fig. 2C) at time J ₁ + At , the radio beacon sends the duration of the reference pulse sent. Since the 20 response pulse 20 tb (Fig. 2D). The reference pulse 15 ra sent by the radio reference pulse and the query pulse initially beacon at time t ₀ = 0 needs to be received at time t = 0 by the aircraft at time i _x as it sent the query pulse for the route of the aircraft in FIG. 2E is shown, and the beacon response to the beacon at the same time as the reference pulse pulse 20 ra is from the aircraft at time i ₂ + At from the beacon to the aircraft. Received when receiving the 25th.

With the interrogation pulse at time ^ ₁ , the radio beacon sends the time between the transmission of the interrogation response pulse (at time J ₁ ). The response pulse is received impulses 10 ta and the reception of the reference pulse from the aircraft at time t ₂ , and the time, 15 ra, time Tref, is measured according to Fig. 2F, which the response pulse takes to see the distance from Man that the analog voltage Eref to travel the radio beacon to the aircraft is 30 time A t, the time of the transmission of the query equal to the time it takes the reference pulse to pulse 10 ία begins. The voltage Eref flattens the distance from the radio beacon to the aircraft back at the time of receipt (i _x ) of the reference, or that the interrogation pulse needs to generate the pulse 15 ra.

Distance from the aircraft back to the radio beacon - The analog voltage for the time between the laying out; ie t _± - 0 = i ₂ - ty. Since now the interrogation 35 transmission of the interrogation pulse 10 ία and the reception

pulse initially with the beacon reference pulse of the response pulse 20 ra, the time Tbpγ, is in

has been synchronized, the time Trpy between the F i g. 2G shown. The analog voltage Erpy for this

Interrogation pulse (at time t = 0) and the reception of the time, which is half the speed of Eref

Response pulse (at time ί = t ^ equal to the two increases, begins at time A t, the time times the time Tref between the sending of the 40 and the emission of the interrogation pulse 10 ta and ends

Radio beacon reference pulse (i.e. at time t = 0) and at the time of receipt of the radio beacon response

its reception by the aircraft. Therefore, in impulses 20 ra at time i ₂ + A t. As you can see it is

Case of synchronization Tref - t _lz Trpy == i ₂ and voltage Erpy as a result of the later appearance of the

Trpy = 2Tref query pulse 10ra greater than the voltage Eref

If an analog circuit for generating the 45 from Fig. 2 results Trpy = i ₂ + At - At. The voltage representing time Trpy is half as fast as It follows that Trpy is, independent of the synchro, an analog circuit for generating the TREF voltage. On the other hand, Tref = h ~ At a function is working, then at the moment the synchronization error is received. If the interrogation catch of the response pulse 20 ra the charging voltage impuls 10 ία is delayed, the voltage Erpy of the two capacitors will be the same: ie Eref 5 ° greater than Eref · The other case that the interrogation = Erpy. This is correct, since as a result of the initial impulse 10 ία leads by the time A t , in FIG. 3 Synchronization of the pulses I ₁ - i ₀ = i ₂ - I ₁ and shown. In this case, Eref is bigger than Erpy. h - h = 2 (ii - i ₀ ) or Trpy = ITref , since in In FIGS. 3 A and 3B that at the time ί = 0 in this example is Tref - h ^UIQ d Trpy = i _a . sent radio beacon reference pulse 15 tb to the

If the interrogation pulse 10 ία and the reference 55 interrogation pulse 10 ία of the aircraft that is at the time ί = - A t

impulse 15 bt not synchronized, then appears a was sent to the time At after. For now

Voltage difference across the two capacitors t _x - A t (FIG. 3C), the interrogation pulse 10 ra of

after receiving the response pulse 20 ra. This received the radio beacon, and the radio beacon sends

Voltage difference is using a suitable at the same time (Fig. 3D) a response pulse

Device, e.g. a servo system, for synchro- 60 20 tb. The reference pulse 15 ία is from the aircraft

nization of the transmission of the interrogation pulse 10 ία to ZeUi ₁ (Fig. 3E) received. The time t _x is the same

with the transmission of the radio beacon reference pulse of the slope distance between the aircraft and the

15 tb used. Radio beacon divided by the propagation speed

F i g. IF shows the analog voltage, the proportionality. The response pulse 20 ra is given by the flight

tional of the time between the transmission of the interrogation tool at time i ₂ - A t (Fig. 3 E) received since the

impulses 10 ία and the reception of the radio beacon interrogation pulse 10 ία by the time A t ahead.

Reference pulse 15 ra. The linear increase in the F i g. 3 F shows the formation of the analog voltage

Voltage ends with the reception of the impulse 15 ra Eref, which is proportional to the time (Tref) between the

9 10

Interrogation pulse 10 ta and the reception of the reference component in the opposite direction, ie of pulse 15ra . The formation of this voltage before the radio beacon has gone can be taken into account at time t = - Δ t, the point in time that V is replaced in the above equations by sending the interrogation pulse 10 to, and ends at - V .

Time t = t _lz the time of receipt of the radio 5 Therefore, in the event that query and reference

beacon reference pulse 15 ra. The course of Erpy renzimpuls 10 ta and 15 tb are synchronized, the

is in Fig. 3G shown. Here is the voltage that occurs with the outward and return time of the query or response

half the speed as Eref increases, pro impulses equal to twice the running time of the

proportional to the time (Trpy) between the transmission of the reference pulse from the radio beacon to the aircraft,

of the interrogation pulse 10 ta and the receipt of the anti-io regardless of whether the aircraft is stationary or

word pulse 20 ra. This tension begins to move.

Time Z = —Δ t and ends at the time of receipt In F i g. 4 a system is now shown that is on board

of the response pulse 20ra at time t = t ₂ -At. That of an airplane to synchronize the frequency

F i g. 3 F and 3 G it can be seen that for the case and the phase of the aircraft interrogation pulse with the

that the interrogation pulse 10 ta the radio beacon reference 15 radio beacon reference pulse can be used,

renzimpuls 15 tb ahead, Erpy is smaller than Eref · In F i g. 4 is the transmission part of the on-board system in the

In summary, with respect to the dashed rectangle 30 included. The transmitter includes FIG. 2 and 3 shown asynchronous cases of the Ab- an interrogation pulse generator 32, for which any interrogation pulse and the reference pulse are said, known pulse generator, z. B. a multivibrator that if the interrogation pulse is sent later than 20 can be used. The phase and frequency of the radio beacon reference pulse from the flight of the interrogation pulses from the generator 32 is further removed from a frequency and phase control circuit 40 with the aid of the received pulses 15 ra and 20 ra, proportional to the Radio beacon reference pulse generator synchroni delay time. This is measured by the time. The starting material of the interrogation pulse circuits on board is determined by the fact that Erpy 25 generator 32 is fed to a code generator 34, which is greater than Eref . This can lead by adding further impulses, then the impulses from the aircraft are at certain impulse intervals or due to received impulses closer together. This will be accomplished by other suitable methods, some of which will be described later by using the analog timing circuitry. Given that Erpy is smaller than Eref · The voltage-coded output signal of the code generator 34 is Erpy in any case at a given distance fed to an interrogator 36 in which there is an equal. Eref, on the other hand, depends on how much the carrier wave is modulating. The modulated carrier wave deviation of the interrogation pulse and the response is amplified and by an antenna 38 for interrogation pulse from the synchronism. The 35 is therefore sent to a ground station (not shown).
Difference or the ratio of Erpy to Eref. The radio beacon sends reference and response as to whether the output pulses sent by the aircraft, which are anticipated by a receiving antenna 42 interrogation pulse, the radio beacon reference pulse that occurs with the input of the receive or lags behind. catcher 44 of the radio navigation system is connected.

In the above investigation it was assumed that the aircraft itself is stationary with regard to the radio beacon. The known, so that a further description does not take into account the investigation is also required. The receiver 44 contains in itself flow of the movement of the aircraft with respect to the known circuits for amplifying the received radio beacon and shows that the original sub-signals. The output signal of the receiver 44 is searching for is still valid. First of all it is assumed 45 once a radio beacon reference pulse decoder46 that the interrogation and the reference pulse 10 ία and and on the other hand a radio beacon response decoder 15 tb are synchronized and that the aircraft is supplied with a rer 47. Which has a radio beacon from the radio beacon in response to an interrogation pulse sent by a speed component V in the direction of the aircraft. The time Tref is then transmitted pulse is determined by the radio beacon antenna

50 word decoders 47 on board the aircraft of others Response impulses, which the radio beacon as response

j. _ j ^ _ VR / - | \ sends polling pulses from other aircraft,

CC ² ' separates. This is in the radio beacon response deco

dierer 47 realized by course search circuits 55 known per se, as they are in TACAN navigation receivers

,. _ j. .. ... _r ., j VR,. like to be used. This is discussed in detail in

where R is the initial distance and -? r is the ^ö,. _A * * · π ♦ · 1 / -1 · * · u

^{6 &} C above article in "Electrical Communication"

Distance is by which the distance (written in the first

Approximation) during the running time of the reference The output variable of the radio beacon response deco pulse 20 tb from the radio beacon to the aircraft 60 dierers 47, which changes the selected output pulse. C is the speed of propagation. 1, 2 and 3 as pulse 20 tb . The time Trpy is now set, a radio beacon distance memory circuit 49 is supplied. The memory circuit 49 er 2 R 2VR cold also query pulses via a further input

TRPY = = 2Tref- (2) 65 output from the query pulse generator 32. The response

CC ² word distance memory circuit 49 measures the time

between sending out an interrogation pulse and

The case that the aircraft has a speed - the receipt of this interrogation pulse from the radio

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bake in the same way as a conventional generator 32 so that Trpy = ITref . In real-TACAN receiver and derives the voltage from this, in practice a fixed delay erpy results . As already said, the distance time t3 in the radio beacon, which is required to decode the interrogation pulse received by the circuit 49 and which is required for the aircraft, can be borrowed in the period between these two pulses. This delay time is all radio beacons loads. It can, for example, be shared by the arrival and is torpedoed in the aircraft by no interrogation pulse from the generator 32, that the start of the measurements Trpy and circuit open which connects the capacitor to a Tref at tß before the time of the transmission of the DC voltage source . The capacitor interrogation pulse is placed. This can be done by charging a suitable device, e.g. B. delaying the time constants of the circuit. The chain of arrival to be realized. The servo control of a response pulse at the output of the radio beacon F i g. 4 then operates in the already described response decoder then terminates the charging manner.

of the capacitor by closing the gate circuit. In Fig. 5 is a control circuit shown in the in

The capacitor is therefore at a voltage. 4 shown system for synchronizing the

loaded, which are used proportionally to the time between the off interrogation and reference pulses

transmission of the interrogation pulse and the reception of the can. The device of FIG. 5 compensates for the

Response pulse is. Influence of the movement of the aircraft on the synchro

The reference pulse deconization of the pulses selects in a similar way. In connection with F i g. 5

dierschaltung 46 the radio beacon reference pulse. 20 it is assumed that the radio beacon reference pulses

In every aircraft that transmits with a radio beacon together with the frequency / _r. Due to the Doppler

is working, the same decoder 46 is located, since this will have an effect when the aircraft is moving

these aircraft only changed from frequency to a new frequency fi at the reference pulses,

interested in this particular radio beacon. In all- The frequency of the received by the on-board receiver

In general, each radio beacon transmits a specific impulse that results from taking into account the

Operating frequency, so that the receiver 44 so ab- Doppler effect in a first approximation
can be tuned that he only receives the broadcast signals
the desired radio beacon receives. The exit

of the reference pulse decoder 46 is connected to the in / ·. , V_ \ ^

The output of the reference distance storage circuit 48 results in 30 Ji - Jr · \ ^ r
bound, which also receives the output signal of the interrogation pulse generator 32 as a second input signal.

The reference distance storage circuit 48 is shown in FIG. 5, the received Referenceich of the radio beacon distance memory circuit 49 pulses with the frequency / j, which is taken from the reference and measures the time Tref by forming the voltage 35 pulse decoder 46 of FIG. 4 were selected, Eref in a manner similar to that of circuit 49. The charging speed of circuit 48 is, however, reference distance circuit 48 also receives Im double that of circuit 49 to make Eref pulses with a frequency f _g of the interrogation pulse equal to ERPY when Trpy = 2Tref , generator. As shown in FIG. 4, that is, when the reference and interrogation pulses have been synchronized, the distance circuit 48 generates a sated. Tension eref proportional to the time between

The output signals of the memory circuits 48 of the generation of an interrogation pulse by the and 49 are fed to a comparison circuit 50, the generator 32 and the reception of a reference switch compares the output voltages by being impulses from the radio beacon. This tension is preferably the difference between them and 45 Eref = KTref, where K is a constant. The radio beacon response pulses are supplied to the control circuit 40 in such a way that the error voltage of the frequency and phase is loaned. Selected as a comparison circuit by the response pulse decoder 47, and one of the many comparison circuits known per se can be fed to the circuit 49 which use a voltage circuit. The size and Polari- Erpy = 0.5 KTrpy generated. This means that the actual error voltage generated by the comparison 50 circuit 49 half as fast as the circuit 48 circuit 50 determines the correction, works. The output signals of the circuits 48 and those relating to the frequency and phase of the output 49 are fed to the comparison circuit 50, the signals of the query generator 32 must be made from the difference between the two voltages. As already mentioned above, with synchronism Erpy - Eref derives an error voltage. The error voltage of the interrogation pulses and radio beacon reference pulses 55 is generated in a low-pass filter 55 Eref = Erpy. In this case, the comparison smoothing and then for controlling a motor 57 interconnection 50 do not emit an output signal, and it is turned over. The motor 57 controls a phase shifter frequency and phase control circuit 40 and no network 59, which is fed to a phase-locked interrogation oscillator signal to the frequency and / or phase gate 53 is connected downstream. The oscillator 53 oscillates to change the query pulse 32. If the Ab- 60 is synchronized with a frequency fi, which is equal to the repeat question pulse and not with the radio beacon reference pulse frequency of the received radio beacon reference pulses, then Erpy is greater than E _RE f- after taking into account the Doppler effect. This means that the circuit 50 an error oscillator 53 is generated by the input voltage from the aircraft, which is fed to the frequency and phase catcher and the reference control circuit 40 routed via the line 58. 65 pulses in a known manner at this frequency

The in F i g. The device shown in FIG. 4 compares synchronized. The phase of the output voltage of the Zeitdifferenezn between Trpy and Tref and oscillator 53 is regulated by the phase shifter 59 controls the frequency and phase of the interrogation pulse. Since the reference pulses from the radio beacon

13 14

be sent at a frequency / _r that is calibrated accordingly. It should too

the frequency fi which is mentioned by the on-board oscillator 53, so that the distance can also be read directly

transmitted interrogation pulses differ, get down by a digital measuring instrument in per se known

question and reference impulses from synchronism. Kind can be displayed.

This drift is shown in the comparison circuit 50 in FIG Hand of fig. 4 described manner and according to testify receives sent interrogation pulses, needs the explanations relating to FIG. 1, 2 and 3 just a broadband receiver with low drafts. To be strengthening. The gain of the receiver

The phase shift between interrogation-reference can be relatively small as each aircraft impulses is corrected by the phase shifter 59, io only needs to receive signals from one area, which is the risk of collision from the motor 57 according to the error signal. This area changes the comparison circuit 50 is controlled. Further up yourself with the relative speed of the planes was described as the transmitters of all aircraft with each other and can be changed accordingly be synchronized with the transmitter of one and the same earth station, but in general a distance It should be ensured that all query and reference 15 from 30 to 50 km are used as a basis. If the pulses are sent at the same time. Essentially, the invention is based on existing TACAN systems If the beacon reference pulses are to be used, then the bandwidth would be used Frequency standard with which all on-board transmitters synchronize the on-board receiver 1025 to 1150 MHz and be sated. Once the aircraft transmitters have captured the current 126 air-to-ground transmission channels, with one and the same or more synchronous 20 As already described above, each synchronized radio beacon transmitter, then the aircraft is when the impulses of the on-board transmitter once Measure the distance between aircraft that are synchronized, easily the distance from each whose transmitters are synchronized is no longer difficult. other aircraft in the area of low amplification you only need each aircraft with a kung of the broadband receiver of their distance measuring distance receiver to accommodate the interrogation devices. It may be desirable to provide information on avoiding impulses from the other aircraft and avoiding collisions Circuits to measure the time between being worth that each aircraft is able to his the appearance of its own interrogation pulse (the direction in relation to every other aircraft in the at the same time as determining a synchronized query collision space. This can be done through this pulse of another aircraft is sent) and 30 realize that an interferometric measuring device receiving the pulse from the other aircraft at the range finder broadband receiver Mistake. Since the interrogation pulses of all aircraft circuit is connected. The interferometer are synchronized with each other, the measuring determined determined from the received from other aircraft to aircraft the point in time at which the time measurement genen impulses the direction angle. For investigation this time interval begins. The distance between the directions can be based on methods known per se Aircraft is then simply the same as being turned over, such as B. a procedure (»probing speed of the signal multiplied by ceedings of the Institute of Radio Engineers, ”June the measured time interval. 1956, p. 755), in which the measurement of the angle of the

To describe a typical example of a transmitter in relation to a group of radio receivers

Distance measurement is assumed that this can be measured by measuring the phase shifts between

send aircraft with a range receiver and see signals at the location of the receiver,

an "A" -view radar screen display and -meßeinrich- But other radio angle measuring devices can also be used

device is provided. The timing interval in which to be used.

measuring aircraft is based on the on-site's own by sending out the above statements Interrogation pulse initiated. At the same time, the assumption that two planes are not equidistant from one det the aircraft, the distance of which is measured by the beacon station. If it does should also be an interrogation pulse. If that is and both planes at the same time interrogation pulses Send the interrogation pulse from the aircraft, its range, then set the response pulses from the radio beacon is to be measured, is received, then appears off. The effects of this type of interference it on the screen as an "A" screen image ". The time 50 can be reduced as much as possible by and thus the distance is then on in the fold the transmission times of the query pulses of the Radar measuring technology known way measured. Aircraft as explained below.

Typical circuits for converting the time It is assumed that the aircraft for course differences in distance display are known ("Ra determination query pulses with a frequency from the System Engineering" from Ridenour to 55 _{22 5 Hz sends Dfes hl} l of _{the p nz of the} S . 527 ff., And other standard literature). But it is ^& 6 ⁿ
noted that there was a difference between the radio beacon reference pulses. Generally sends

■ ** ■ ^

since according to the invention only one-way propagation 60 selects an arbitrary point in time from six time

the impulse takes place from airplane to airplane, -Jr ₁ -J 1 t> -jt-cj

.., K,. j, ⁶ , ⁶ . "J ti. ■ score every penode of- ^ r-TT see. In the invention

while with the known radar method a * ^J 22.5 ^&

Two-way propagation of the impulses from the transmitter to the is the beginning of the six sub-intervals, which are all

System a given time difference on a Α screen - transmission of the radio beacon reference pulses synchronously

is

15 16

divided into six subsections, so that each of this schedule can take full traffic control

_TT . . . "" 1 . ,, .. ~ “. capacity of the ground station can be used, and

Subinterval _{repeated every w} see. The beginning _in £ _{rferenzen between} transmit pulses of individual airports

each sub-section coincides with the point in time when the testimony in the area of a beacon continues to be reduced.

transmission of a radio beacon reference pulse. It should be pointed out again that the

men, if the interrogation pulses, which with a frequency special pulse time sequence by known per se

of 22.5 Hz, with which radio beacon drives and circuits can be implemented.

Reference pulses in the manner described above syn- Now to the F i g. 7 to 9. When each aircraft syn-

, · ■ · .. j -, Tr-I jj 1 T ^ -j chron with the reference pulses of a radio beacon Ab-

be chromed. During the -sec period, _{jo sends interrogation pulses) then reach all interrogations} .

duration of consecutive periods, a flight impulse can be generated within a time of 370 · 3.33 = 1234 min.

generate ab- sseconds after each reference pulse in any of the six subsections, where 370

questions. So z. B. during the first greater than the maximum distance of an interrogating flight

1 ., . . ^ j, · · ^ ■ η j ■ ■ · ΐ stuff from the radio beacon in kilometers and 3.33 die

--- sec-section the synchronized sending with ... _KZ ^ _{tokt the} speed of light in microseconds /

The start of the second beacon reference pulse is at the kilometer. Since the interval between the radio time begins t = -ψςτ sec, and during the second beacon reference pulses -γ ^ - sec = 7400 microsecuri-

the transmission of the transmission can be larger section, it results that all interrogation pulses min-

question pulse with the beginning of the fifth subsection 20 at least after 1234 microseconds of the 7400 microseconds

take place what is timed to a radio beacon reference seconds that are used to transmit the response pulses

, ".. · .. 11 ■■ 4. ■ ■ · u * r \ ■ u * ^{ζατ are} available to reach the radio beacon. This corresponds to impulse at time t = - _{m see.} Since it doesn't _mean | _{As a result, a} reduction in the likelihood of the indiscriminate selection of appropriate traffic control capacity, since the interrogation pulses by aircraft of equal range as the radio beacon cannot send to the same subsection during each major response pulse during those 1234 microseconds. This difficulty 1 _T , “* 1-i t_ * ■!. * J · w i- ti ·; ^w ill corrected characterized in that the number of possible - ^^ - Lake interval takes place, there is the possibility _MTV ^ _{kt &} (positions) at which interrogation pulses

that at the same distance between two aircraft can be transmitted from one, only one of six response factors is increased by a predetermined and the same radio beacon. In which impulses to be described are lost. That's right because the scanning system is this the factor 6. In other way, that only one interrogation pulse of words, rather than each aircraft during the course Six pulses of both aircraft _sec simultaneously from the _{limited hours every} 1 _{choice of 6 time.} Radio beacon is received. When there are three aircraft ° 22.5

are at the same distance from the radio beacon, score 35 for sending an interrogation pulse

then it would be possible for each aircraft to leave on average, as described above, whereby the

on five of nine interrogation pulses a radio beacon - one of these times occurring interrogation pulse

Receives response pulse. synchronized with the beacon reference pulse

Sending by the arbitrary method, the frequency of which is 135 Hz, can now

Selection of one of six subsections during 40 of _{each injection every} _l_ _{sec among 36 points in} time

every larger - ^ y-sec interval can be replaced by a ' ^

j τ- ^ -1. Select i-'i αϊ · 1 τ-, ^ j (positions). The distance of - ^ r = - see between

the F1 g. 4 similar system can be realized. ^v ' 135

The interrogation pulse generator 32 would therefore see the reference pulses again per se

would deliver 135 pulses and in the above-described 45 _{subdivisions of} 1 _sec duration.

in a similar manner by the radio beacon reference pulses 810

be synchronized. An arbitrarily operated tool divides. The aircraft interrogation pulses are then with the

(not shown) is between the interrogation pulse genes radio beacon reference pulses into integer dividers

rator 32 and the transmitter 36 switched. The gate can _of 1 _{hr gec which in the present} examples

m a statistically selected subsection of 50 135 ^J

-Sec duration during each ^ r - ^ - sec interval one play to integer multiples of -öirrsec

Interrogation pulse to the transmitter 36 through. This can result between the reference pulses. Different from each conventional AND element (gate circuit) that, when pressed, every sixth permissible interrogation pulse transmission for this purpose is suitable, or that is later at one point in time from 810 points in time with a radio single gates described are used. It beacon reference pulse synchronously, and the other

it should be noted that the distance and _subsections appear every - ^ sec between two

Directional measurements with this type of system in the 810

above described manner can be realized. successive beacon reference pulses.

In a preferred embodiment of the invention, 60. Using this time sequence, it is also possible to

the on-board transmitter only during the course determination distance and direction measurements in the above

and not synchronized during the search process. described manner. In the case of this

To increase the data transmission capacity of the system; The arrangement is the transmission sequence in FIGS. 7 to 9

d. i.e., the capacity of a ground station with which shows.

several aircraft are synchronized for control 65 F i g. 7 relates to the state in which the six sub To fully exploit traffic, the in F i g. 7, 8 sections for the interrogation pulse transmission 9 and 9 for the transmission of the im- borrowed synchronipulse with the radio beacon reference pulse can be used. Are sated by Realization. In Fig. 7A the beacon signals appear

17 18

",. , ■.:, _., "1 __., .., the radio beacon reference pulses or their sub-

Reference pulses 15/0 every - ^ ₇ - see. In row A are. _It,,,., *,, ".

^ 135 multiple times leading or lagging, or of the amount

also the six points in time given that between the time shift. In Fig. 8 is the case

j r ι u ι π c ■ ι 1 shown that the query pulse compared to the transmit radio beacon reference pulses by - ^ r ₇ T see off, ⁶ ..? ' , - ,,, K, _c ·,

^r 810 5 positions of the radio beacon reference pulse by one

lying on top of each other. The interrogation pulses 10 ta lead the aircraft time At ahead. This is in Figures 8A and 8B

can occur at any point in time that is a whole-. _ ". "Ι. .,

^J ^ ' ⁶ shown. The airplane generates every - ^ r- see an number multiple of-τγττγ see ist. In Fi g. 7 B is at-. ,. ,,. ,, _o , ,, ....,. "., _
⁶ 810 ^e pulse to the measuring circuits for the time Tref

For example, a pulse shown to trigger the second io. The start of the scan is coincident

Intermediate time / = - ^ see after sending the 5 * ^the intermediate time of the interrogation pulses of the

^F 810 aircraft, which is now the intermediate times of the

Beacon pulse appears. Beacon reference pulses ahead by the time Δ t

In Figure 7C, the beacon reference pulse will rush. The message of the tension Eref that of the time

received from the aircraft at time t-Tref , which corresponds to 15 Tref , is shown in FIGS. 8 C and 8 D shown.

A sawtooth loading process is currently starting according to the distance of the aircraft from the

τ- ,,, ,,. , l - ^ r--, η -,. j · t ■ = At before each of the six intermediate times

The radio beacon is smaller than _w see. F 1 g. 7D shows the _{between the} pVbaken reference pulses. _The ^P _Ark .

Formation of Eref to measure Tref. This is achieved during an intermediate section in that at the beginning of each sub-20 the reception of the reference pulse is interrupted, as is the case

,,..." 1 . _o .., shown in Fig. 8D.

section all - ^ - pr see a sawtooth voltage from- _T ,?. _o >, · jj c ~ ι. »*

810 ^e ^ ^e in F1 g. 8 G the saw tooth is used to measure

is resolved. This can be achieved, for example, by Trpy when the interrogation pulse of the flight

j jo · τλ j i-j 1 t-1 stuff (Fig. 8 B) triggered. Let it be on again

be that a capacitor every time after - ^ - r-sec,. ° \ °, i,. ^β _o _,,. , ,, _o . ·

^J 810 25 pointed out that this saw tooth is half the pitch

_t1 , Ji-Jj 1 jj of the sawtooth of F i g. 8 D has. When the beacon

recharged and at the end of the permanent-5T ₇ T-lake, _a t _c. , _1n ^b ,, ... ,. .

⁶ 810 receives the query pulse IO rb , it sends a

Subsection is unloaded again. In the time response pulse, the short time later from the flight point at which the aircraft received the reference pulse. The reception of the radio beacon starts, the sawtooth voltage remains constant. The response pulse ends the sawtooth measurement of the value Eref, which is proportional to the time Tref Trpy. If the in the F i g. 8 D and 8 G is shown. This can be achieved in the manner described above. Voltages measured in a differential circuit by opening a capacitor in a sawtooth shape, charging an error voltage of positive polarity and generating a reference pulse which is interrupted proportionally to the difference 2 Tref - Trpy. The tension Eref will be in the 35's. This is in FIG. 8H shown. This error voltage is stored in the reference distance memory circuit until it is used to control a servo circuit in order to make a comparison with the voltage Erpy . the interrogation pulses with the radio beacon reference

In Fig. 7 E, the radio beacon receives the interrogation pulses or to synchronize with their intermediate times.

impulse IO rb and sends a reply impulse from chronize. When this is achieved, no error

the aircraft a short time later (FIG. 7F) received 4 ° more voltage output, as in FIG. 7 shown

will. To measure the time Trpy , FIG. 9 shows the formation of an error voltage,

tool triggered a sawtooth, z. B. by charging their polarity opposite to the polarity of the

of a capacitor at the time of emission error voltage of F i g. 8 is. This is the case

of each interrogation pulse and by termination when the interrogation pulse of an aircraft corresponds to a radio

45 of the charging process when the radio beacon intermediate section is received by the time At .

Response pulse 20ra (Fig. 7G). As already stated above, this is shown in FIGS. 9A and 9B. As in the

described, Erpy is at half speed F i g. 9 C and 9 D shown, the sawtooth is the

formed by Eref . This means that the scarf measurement Tref changes during each intermediate time of the

tion or the capacitor that forms eref , triggered and terminated half as interrogation pulses of the aircraft,

charges quickly like the one who takes to measure 50 when the aircraft receives the reference pulse 15 ra.

Eref serves. F i g. 9 G shows the sawtooth for measuring Trpy,

The plant, the timing diagrams of which are shown in FIGS. 7, which are shown at the time of the transmission of the interrogation pulse to 9, works in the same way as that of the aircraft (FIG. 9 B) is triggered. The funk above on the basis of FIG. 1 to 5, namely, bake receives the interrogation pulse and sends a voltage if ITref is equal to Trpy , then no error response pulse, which interrupts the sawtooth curve, is generated. If there is an error voltage when the aircraft receives it (Fig. 9F).
results, because ITref is not equal to Trpy , then if the in Figs. The chip shown in 9D and 9G shifts this error voltage by means of a frequency voltage of the differential circuit, and the phase synchronism servo circuit produces an error voltage with a negative value of the six permissible transmission positions between 60 characters, because Erpy is greater than Eref- This is in the Beacon reference pulses, ie, they synchro- line H shown. Again, the error voltage is used to nize the interrogation pulses with the permissible intermediate control of a frequency and phase synchronization times between the radio beacon reference impulse servo circuit in order to pulse the interrogation pulses of the aircraft. synchronize the beacon reference pulses.

F i g. 8 and 9 show the formation of the error signals, 65. When this has occurred, there is no more error voltage

which are generated to be different in sign and amplitude, and the interrogation pulse of the aircraft is with

be able. Sign and size of the error voltage of a radio beacon reference pulse or one of its

depend on whether the interrogation pulses are synchronized with respect to intermediate times.

19 20

The on the basis of FIG. 7 to 9 described from 1959, pp. 9 to 16, in particular FIG. 7) and that too Implementation of the invention still offers a variety that can be used here. That in this essay The addition of a provides further advantages besides increasing the number of procedures described Control capacity. One of these advantages consists in the third pulse in front, reducing its spacing to a point the time it takes to synchronize a 5 interrogation pulse pair that is normally sent by the flight-on-board receiver with a radio beacon is required, stuff is sent, proportional to the altitude of the flight afterwards he is in sync with a radio beacon and is stuff.

goes over to course determination. This results in It is desirable to have the elevation data without additional

from the fact that the maximum synchronization time error lent pulses to send. One way to do this

is decreased from -4-sec to '- ±, see. The time ¹⁰ real is according to the invention by the

135 810 ⁵ pulse transmission time diagram of FIG. 6 and

Shortening when searching, d. H. how to search for and below. An attachment showing the timing diagram

synchronizing with the correct response pulse of the FIG. 6 realized, offers the further advantage

Due to its own aircraft interrogation pulse, not every aircraft is the transmission data of all others

proportional to the time error. 15 planes to decipher it takes to alone the

Another advantage of the invention is to separate out important data of the aircraft that that the likelihood of interference between them is at the same or approximately the same level as the Impulse from two aircraft to trigger a radio- first aircraft is located. With the help of this execution bake from the same distance by a factor of 6, the ground stations can also transmit the data from is wrestling. This is because now 36 instead of 20 aircraft from different heights without additional .6 Separate the time periods for the transmission of each decoder from each other. Be on it question impulse for course determination to the selection indicated that the plant to be described stand. This is equivalent to a further expansion of the capacity to send altitude data for the control of air traffic around a development of the in the F i g. 7 to 9 shown time sequence Factor 6. For the same reason, the probability is 25 returns.

possibility of interference between two or more The installation, the pulse time diagram of which is shown in FIG. 6th

Aircraft that is shown equidistant from limits the transmission of interrogation

Another aircraft are located in order to send the same impulses to certain permissible transmission positions

Factor decreased. (Points in time) and on aircraft at certain altitudes.

An installation for realizing the in the F i g. 7 30 It should be noted that the

to 9 can be in the basic diagram of FIG. 6 and in the other figures

trains to the in Fig. 4 lean against the system shown. indicated pulses by any suitable one

In this system, the interrogation pulse generator 32 is a known circuit of a pulse generator.

adjusted so that it can generate pulses with a frequency of.

Delivers 810 Hz. The generator 32 is connected to the radio 35 In F i g. 6 A is the baseline in sections of each

beacon reference pulses by the frequency and 1 r> · <. * * · Ι ± * i_ yj n · *

τ ,. 4 i_ \ Z Λη. ■ i_ u t. · IL til ■ -rr ^sec width divided according to the times in

Phase control circuit 40 m as described above 15 ' ^v

synchronized. The reference distance memory 48 of a TACAN system to which the radio beacon Ost is triggered by each pulse from the generator 32. Direction reference pulse E sends. The impulses E

However, the answer distance memory 42 now becomes 40, u j π r · 1 j-n 1

j α uc ■ ία jcj · »* are next to the reference pulses, which all - = - see

from the interrogation pulse at the output of the transmitter 36 ^ 135

triggered. A randomly statistically released sent will be sent by the radio beacon. the

Gate (not shown) is between the generator 32 pulses E differ from the other transmission

and the transmitter 36 switched. While the aircraft are pulsing the radio beacon by, for example

determines its course, the gate lets an interrogation 45 "1"" ■ _n _" · _{10 T} _ _le " _oTc , ·, -> _{Λ / Γ}

, j "O1ATJT oj in all-r ^ see m groups of 12 pulses each as 12-Mi-

Pulse of the frequency of 810 Hz to the transmitter 36 15 ^{vv J} ■ ^v

through to one of the statistically arbitrary microsecond twin pulses spaced apart by

selected intermediate times of the 36 intermediate times are sent exactly 30 microseconds to each other.

TIME POINTS DURING A ¹ SEC SECTION A ^{The transmission of the} impulses E in coded form er times, during a - ^ - see section, tine _{5o enables the} decoding and recognition of the gate circuit suitable for this purpose, which is later a receiver. The sending of coded pulses can be described in detail as in. It should be noted that many conventional radio beacon transmitters can be used to carry out distance and direction measurements by using an aluminum disk and an antenna that rotates through in the manner described above on the drive shaft of an embodiment. Again, the system 55 of the periphery of the disk is an iron core in a line during the search operation, preferably not chronologically synchronized with the direction of maximum radiation from the antenna. is attached. A fixed pick-up head is attached to the information required to warn pilots or to avoid disc periphery east of the center line of the andung of collisions. As a result, for each complete, the height of each aircraft must be determined 60 revolutions of the antenna and, according to the angle in relation to any other aircraft or in absolute opposite order, the fixed pick-up coil in the latter via a fixed reference point, an impulse induced in the distance measurement. Some methods are already known for determining the transmission of the specially coded radio message of the altitude, e.g. B. a method in which beacon reference signals E triggers. This is also described in the distance between two impulses as a measure of the height.

Engineers, Transactions for Professional Group on In the present system, one of the 15 Hz reference

Aeronautical and Navigational Electronics ”, March renzimpulse E in some way in the radio beacon

21 22

marked by ζ. B. one opposite the north. .,. ,. 1 . ,,, ",. _1crv

Sometimes different number of impulses sent ^divides ' ^{the by} W ^Sec ' ^{according to} P ^{50 to 15} ° ^m >

will. Instead of, for example, 12 pulse pairs spaced 150 to 250 m etc. apart. The middle

Stand of 30 microseconds to send, height of each area can be shown in FIG. 6 C.

24 pairs of pulses with an interval of 15 microseconds 5 Is the querying aircraft in one of these

be sent. This particular impulse is shown in FIG. 6 A altitude ranges, then it sends its interrogation pulse

Designated with E and can in the on-board receiver.,. . , rr * ι * j 1 _T ■ * ■

,,.,. j i_i_, · - r i_ τ IJIJ- m the corresponding time of the ^ nrr-sec-Inter-

also easily by conventional pulse decoders ^rr 135

can be decoded and distinguished. The fading out of the pulse E by the radio beacon, which corresponds to its special height, is followed by an io radio beacon pulse E , which is sent in the time interval assigned to the eye-preferred embodiment of the invention, after which an electronic counter counts 2s pulses and will.

after every 15th pulse E emits a trigger signal. The time interval from 0 (point in time of transmission E can also be achieved by means of appropriate mechanical pre-reference pulse E) to the next radio beacon direction, such as one on the drive shaft of the radio 15. . "... 1 ■ ■. . _TT ...,. ,, _Λ
Beacon antenna attached reduction gear with ^{in the} P ^{uIs at time t} = W ^{sec is high bls to 55} ° ^m a meter, or any other suitable electrical,. _Λτ 1 i_ j τ- t. · J tronic, mechanical! or electromechanical pre- «W» idiieL From _w sec after the appearance of the

direction to be formed. _T , - ==;,. ■ · u * · τ i ^ 1. 1

Fig6B is an expanded time scale on _{which 20} pulses are until the next pulse is after- ^ sec

several radio beacon reference pulses between Im- is subject to the emission of interrogation pulses of the pulses E and Έ are shown. In a conventional aircraft, there are no restrictions, and during this time the TACAN system is used as the radio beacon reference, the on-board transmitter is shown in the FIG. 7 to 9 impulses with 135 Hz and the impulses E with 15 Hz as described with the radio beacon reference. In Fig. 6 B is synchronized at time / = 0 and after every 25 pulses. With the next pulse E, a pulse E is emitted for another second. One will consider a different transmission period for altitude information, that any impulse E is passed as impulse E ; In this interval, aircraft can be faded out if only the time sequence send query pulses that are in the altitude range between successive pulses E from 550 to 650 m. Aircraft that will hold in. 30 are located in one of the five following altitude ranges, Fig. 6C shows an even further expanded time scale, the latter are assigned in steps of 100m to a range of between successive radio beacon references up to 1150 m altitude, send their query

Renz pulses into sections each with 4, sec divided ⁱⁿ P ^{u 's} _t ^to to-Jen timings these altitudes

^{r J} 810 ° are arranged. In general, every aircraft sends

is. As already shown in FIG. 7 to 9, 35 an altitude indication to others once per second

can send an interrogation pulse from an aircraft to any aircraft and to the ground station while the

one of six intermediate points in time (positions), other pulses from the synchronization of the on-board transmitter

the same distances of ^ sec from each other are reserved for ^ L ^ radio beacons.

^J 810 You can see that 15 broadcast groups for high

have, within each - ^ - sea interval between ⁴ ° ^an s ^{even distributed over one second} ' ^ents P ^re <* end radio beacon reference pulses are sent. The ^{the 15 periods with a} period _w sec method in one of the six time points between after the 14 pulses E and the single pulse E. beacon reference pulses to be transmitted is generally in each group five times for Höhenais "jitter" are known. According to the invention, information is reserved for 45, so that a total of 90 height transmission of height information controls the "jitter". areas are covered. In the assumed case

The six points in time between two radio beacons can give altitude information for altitudes of up to 9000 m Reference pulses are to be transmitted with altitude for explanation. The system is not subject to any details provided (Fig. 6C). An intermediate point in time is restricted to the effect that it corresponds to each time so ± 50 m difference in altitude. Be constant for the over- 5 ° point associated height section In the case of altitude information, the query pulse or altitude information is sent every second On-board transmitters of which, for example, must be barometric. The altitude information can also be given by everyone Altimeter controlled in the airplane. The 2 seconds sent, so that 180 altimeter measured height is preferably ranges during a period of 2 seconds by known devices as they are, for. B. in 55 are to be distinguished. It should also be noted Autopilot systems are used, or by one that the individual altitude areas are smaller or larger Angle of rotation analog-to-digital converter in an electrical than 100 m can be to the total measuring range converted into a signal. To subdivide this electrical signal more finely or coarsely. The entire measuring service To control the transmission times, the query area could be used for coarser measurements, for example impulses. 60 in steps of 150 m and for finer measurements in

To explain the special type of the in F i g. Divide 6 steps 50 m high. It would be in principle

altitude coding shown, may the airplane, which has any suitable subdivision conceivable, as long as only in

sends the altitude information, at an altitude between all aircraft and ground stations a uniform

Fly 0 to 50 m and is used synchronously with the query code.

impulses the impulses Έ in the above-described 65 The reason for the division of the transmission times

Send out way. The interval from 0 to - ^ - sec after ^for altitude information on 15 groups with a duration

the impulse Έ is in five height positions below - ^{of l3T sec during an interval of a Se} "

23 24

The duration between the transmission of £ -Im- of the receiver is carried out by the same or similar pulses, instead of using a continuous period time to borrow control signals from the altitude measuring device of the aircraft, is to be derived from the attempt to interrogate the interrogation pulse transmitter for the time at the Repetitive search course - switch off the transmission of altitude information, determination method of the navigation system of the flight - 5 This is described in detail below,
avoid stuff if possible. It has been found out from the aircraft described above that the elimination of altitude information sent by 15 time-wise can also be done by

. _A,. η ι j -1 TN frt. central ground stations to control the air

_{Intervals yerkehrs used} per second to each _w lake duration for over-. _{This lets} ^ h by

Carrying altitude information, and in which none io realize that the range and direction repetitive search and course determination scans are receivable on the ground during certain sections. ,. , j. . ~. 1 _T. ,, r- be steered to be carried out in separate air traffic, is sufficient. _{To divide the} - ^ - sec-intervals for auditory areas. Distance and direction

The altitude information can also be made shorter or longer for each aircraft in an area, if the same information is correct, in order to determine the exact position (distance, information transmission frequency. For example, after each altitude and Direction) of each aircraft in the pulse E altitude information intervals with a width close to the air traffic control center.

For example, J ₅ -see can be used, where ^ _{Figl0A and 10B together give} .

each interval has three height positions. 20 is a block diagram of a system for the excess number of positions in each altitude information transmission of altitude-coded pulses and for the interval can also be doubled or tripled reception of altitude-coded pulses from other flights. The advantages that are evident from the assignment, with the aid of which altitude, distance and specific sampling times for aircraft can be carried out in certain direction measurements. Height are obvious, since the development of 25 In F i g. 10, the components that have the same function distance, altitude and direction (through interferometric components like components in the other figures, also with measurements) of an aircraft are provided with a single pulse with the same reference number. In Fig. 10 a transmission can be determined. In accordance with the invention, the 810 Hz clock generator 60 of a servo system is used in a particular borrowed from that of FIG. 4 and 5, in frequency and phase altitude located aircraft sent scanning or 30 synchronized. A multivibrator designed for 810 Hz in response to an interrogation pulse received from other aircraft can serve as the clock generator 60, which is then controlled in frequency and phase by the and these then derive distance, direction of the servo system, and altitude. When the transmission plane ER- the course A receiver 44 receives the averages of the radio beacon, and it sends the interrogation pulses having a frequency transmitted information, the reference, response, E- frequency from 22.5 to 30 Hz, the pulses , 35 and Γ-pulses.

The information received by the receiver 44 does not indicate the transmission of a certain altitude

position (this includes in the above a reference pulse decoder 46 and an example all pulses except for one per second), fed to the response pulse decoder 47, which uses only the reference and response with the radio beacon reference pulses at their synchronization of the interrogation pulses of the aircraft respective outputs . The radio beacon emits 40 pulses. The output of these unreserved interrogation pulses can also be used as reference pulse decoder 46 with input for range and heading measurements from other reference range memory circuitry 48 and the aircraft. The altitude of an aircraft with the output of the response pulse decoder 47 is determined by another aircraft by input of the response distance memory circuit 49 that it determines at which a particular altitude 45 is connected. As already described above, the circuits 48 and 49 each deliver the span interrogation pulse that is received; on the other hand, the names .E ^ e * · and Erpy. These voltages distance between aircraft by measuring the speak, as already said, the times 2Tref time from the beginning of the subinterval to reception and Trpy.

of the interrogation pulse determined. If a display is required to avoid collisions, it is preferable to the reference distance memory circuit 48 to supply the clock pulses of the clock pulse generator on the input side with regard to the height-coded pulses only with regard to the height-coded pulses. The generation of Eref is increasing. In this way, a measurement is carried out in accordance with FIG. 7 to 9. To generate three coordinates, namely distance, height and 55 from Erpy , the input of the response distance direction is based on a single height-coded memory circuit 49 via line 65 and a pulse. Switch 86 with the output of the query pulse

The above-described transmission from altitude generator 32 is connected. The formation of the voltage information can easily be done from an airplane. Erpy is also shown in FIG. 7 to 9 are rated in order to derive from their height information.

know whether there is a risk of collision. This can be The output voltages of the memory circuits

achieve that the comparison circuit 50 is fed to the avoidance of accidents 48 and 49, collide and serve to warn the pilot. This forms the difference Eref - Erpy. The receiver only when the aircraft is at the same altitude, the synchronization circuit 50 therefore supplies an output voltage or when it is switched on when it is in adjacent altitude areas 65 which are either positive, negative or zero. Because, depending on how the interrogation pulses of the flight collisions are interested, no aircraft that behave in relation to the radio beacon reference pulses fly very different altitudes. The activation as already shown in FIG. 7 to 9

25 26

would. This error voltage becomes the frequency and output variable of the converter 75 in accordance with the transmission phase synchronization a servo control circuit 40 sequence of the altitude information is encoded. In front of, The converter delivers, for example, one version of the system that is already lying down Control of the frequency and phase of the clock pulse - the number 36 for an altitude of 700 m generator 60 on the basis of FIG. 4 and 5 in detail 5 he would deliver the number 37 for 800 m, 38 for 900 m, has been described. There are also other suitable 39 for 1000 m, etc. For 200 m he returns the number 1, the known servo synchronization circuits, each number 2 for 300 m, 3 for 400 m, 4 for 500 m, 35 for can be used as desired. 600 m etc.

To determine whether E-pulses are received, the comparator 77 triggers a coincidence is an E-pulse decoder 67 with the output of the io monostable multivibrator 79, which has an AND element 81 Receiver 44 connected. As already explained, it opens so that the next clock pulse through this each S-impulse can reach an OR-element 83 compared to other radio beacons in the AND element. the pulses are coded differently and are therefore easily too monostable multivibrator 79 is held by the AND element 81 identify. The output signal of the E-Impulsdeko is open so long that the next 810 Hz clock pulse dierers 67 serves as the start pulse of a preferably 15 can get through, and then it closes it binary counter 69. The counter 69 are also clocked again. In the example described is the next pulses from the clock pulse generator 60 supplied. Clock pulse the 37th clock pulse, which is the height of the Counter 69 is initially assigned by a 2? Pulse to position of 700 m. The starting zero is set and then counts clock pulses of the gene pulse of the OR element 83 is passed via a cursor 60 until 810 clock pulses are counted. In this 20 search switch 85 in the "course position" at the query moment Another Zs pulse from the de-pulse generator 32 hits. The encoder encoded by the OR element 83 67 a, which resets the counter to zero, long clock pulse triggers the generator 32, so that so that the counting process starts all over again. That generated the interrogation pulse and sent the transmitter 36 to the aircraft is equipped with an altimeter 70, is guided.

which is preferably based on a barometric principle 25 In this way, the works, the altimeter 70 is with an output 37th transmission time of the 810 times in one shaft 72, the angular position of which is provided in an interval of one second for the transmission of an analog-digital converter 75 individual query pulse into a digital variable, which is converted to an altitude of the aircraft. The altimeter 70 measures the height of 700 meters corresponding to selected. In a similar way of the aircraft against a reference point, and the 30 will be the interrogation pulses in the other altitude-altitude is then determined by the angular position of the shaft 72. Points in time corresponding to that of the altimeter 70 reproduced. This angular position of the shaft 72 is sent to the measured altitude of the aircraft. This is used then individually sent interrogation pulse by the digital-to-analog converter 75 is used by others in preferably converted into a binary code. Received and sent to aircraft in the vicinity The input code of the analog-to-digital converter 75 is selected in this way. that numbers are shown, which the aircraft evaluated. The sending and receiving time Display altitude information transmission positions as the pulse corresponds to the altitude of the transmitting aircraft.

it is described below. It should be noted that the period from - ^ - see

The binary output quantities of the analog-to-digital '810
The converter 75 and the counter 69 are fed to a converter 40 between two successive altitude transmission simulators 77, which compensates the two binary numbers for reception for aircraft up to a level. Any suitable distance of about 144 kilometers can be used as comparator 77,
circuit known per se can be used (for example, in order to synchronize the clock pulse generator 60 with the radio beacon model no. 120A from the company "Navigation Computer Reference pulses, the an-Corp."). The output code of the converter 75 is used with 45 their interrogation pulses, which are sent by the Flugdem code of the counter 69 shortly before the transmission time witness during the course operation, as identical, which is assigned to the altitude in which it has already been described. The interrogation pulses that the aircraft is currently flying. For example, if the aircraft are not assigned any altitude positions, so will

flies wisely at an altitude of 700 m, then it would. * j _o · λ 1 τ * π

α 1 · ur getnggert in τ 1 * T ~, inter alia, in that they - ^ r ₇ - sec intervals ER-

an interrogation pulse at the 37th point in time after the 50 ^{& 6b} 810

Send Ε pulse. Therefore, a query pulse should appear to be sent out in order to synchronize the clock generator 60 when the counter reaches the number 37 as shown in FIG. 7 to 9. One has reached beer. The converter 75 is now coded in such a way that u * uj ο · j 1 τ * n ι. η c

f. j. , ·, _TT .., _nnri ■ 1 11 · but make _{sure that every ^ 5} --sec interval after reception

for the same height of 700 m a ^J 135 r ε-

Returns number as 37; In this example, the conversion of an E or IT impulse to the transmission of the elevation setter delivers the number 36 for an altitude of 700 m. The "jitter" of the expression when the aircraft flies at a height of question pulses and the restriction of their transmission 700 m, then appears at the output of the Um- for certain periods with the help of the statistics set 75 the number 36. With the 36th pulse of the Clock gate pulse generator 87 and the AND element 89 on generator 60 after the pulse E, which realizes the transmission time 60 in the following way:

point corresponds to a height of 600 m, the structure and the voltage curve of the reverse number of the counter 69 is also 36. Thus, rators 87 are in the Fi g. 11 and 12 shown. Be it before the comparator 77 coincidence, so that it pointed out a. that the one yet to be described Output signal in the transmission time (the 36th) from statistic pulse generator also for the hand of the which immediately precedes the one in which the flight 65 F i g. 7 to 9 described pulse transmission sequence and the stuff sends the height-coded interrogation pulse, the above-described pulse transmission system, in which only 135 transmission positions are provided at a height of 700 m (the 37th transmission time) is ordered. It should be noted that the can be.

27 28

First of all, let F i g. 11 considered. The statistics-led. The multivibrator 100 has two inputs

gate pulse generator 87 includes a noise generator provided. One is with the beacon reference

90, which in a known manner on the noise generation pulse decoder 46 and the other with an E and

a gas discharge tube is based. The course of the pulse decoder 102 is connected. The decoder

The output voltage of the noise generator 90 is "recognized" in 5 102 and identifies the pulses E and Έ,

F i g. 12, line A. The output signal of which has previously been selectively encoded in the radio beacon

Noise generator 90 is a limiting circuit, and outputs a corresponding to these pulses

92, which sends an appropriate tube, transistor output pulse to an input of the multivibrator

or diode circuit may contain the off 100 from. By an output pulse from the decoder

output signal of the noise generator to a constant io 102, which means the receipt of an E or! "pulse

Limit the amplitude value. The output signal indicates the multivibrator 100 is tilted and delivers

of the limiter 92 is then the input of a band an output signal which the AND element 89 for the

Pass filter 94 supplied, the bandwidth of which is the number of duration of six altitude information transmission periods

of the independent noise pulses per second at the locks. In this way, the gate impulses of the

The output of the filter is determined. The number of independent 15 generators 87 rendered ineffective, and the altitude

gigen values is roughly equal to the band information transmission periods after each pulse E

width of the filter. The course of this output signal and E are the selective transmission of the individual

is in Fig. 12, line B. Reserved for the interrogation pulse, which is determined by the altitude

The noise signal of the filter 94 triggers a knife 70, the comparator 77 and the AND element 81 monostable blocking oscillator 96, the bias voltage 20 of which was generated as described above,
is usually so large that it remains locked. The upon receipt of the next radio beacon reference blocking oscillator 96 contains an adjustable trigger pulse after a pulse E or Έ, the multi-bias level is set so that the vibrator 100 tilts back again, so that the AND oscillator responds to noise pulses with the corresponding Am - Link 89 is "prepared". When simultaneously appearing plitude responds to the desired average frequency of a gate pulse from the generator 87 and a frequency of interrogation pulses, ie 22.5 to 30 Hz in the preparation pulse from the multivibrator 100 course mode and approximately 150 Hz in the search mode, the And -Ground 89 to generate a clock pulse. The trigger bias level is shown in Fig. 12, OR element 83 through. The OR element 83 leads the line B shown by the dashed line. The clock pulse on to the interrogation pulse generator 32, trigger level can be switched on at the blocking oscillator 96 where an interrogation pulse is triggered. This is to be put in. When the blocking oscillator 96 of FIG. 12, lines D, E and F are shown. It should also be mentioned a noise pulse of sufficient amplitude that every gate pulse of the statistics is triggered, an exponential voltage generator 87 appears only one clock pulse through the And course on its control grid. This is in line C of link 89. Furthermore, the AND element becomes so pre-F i g. 12 shown. The exponential voltage 35 prepares that it only lets through clock pulses, which only prevent the oscillator from being triggered by the first reference pulse after a pulse E or during its duration. The duration of the exponential Έ until the appearance of the next E or E pulse voltage curve can be triggered by setting the time interrogation pulses. During the search operation constant RC of the grid circle can be determined. the interrogation pulses that are not for height-This time constant is set so that the duration 40 information transmission positions are provided for the exponential voltage curve to synchronize the clock generator 60 with the radio is slightly greater than the time between two clock pulses or in beacon reference pulses or their interim

present example greater than - ^ - see. points used as it was described with reference to FIGS. 7 to 9 ^b 810. It should also be mentioned that the output signal of the monostable blocking frequency 45 that the height-coded pulse is also used for synchronizer 96 is an inverted reproduction of the exponential purposes,
tial stress curve on the grid. The output In search mode, the switch 85 in the search signal of the blocking oscillator is turned to the input of a position. This provides the input of the interrogation gate pulse generator 98. The gate query pulse generator 32 with the output of a pulse generator can have any suitable circuit, 50 AND gate 105 connected. In search mode, the z. B. be a monostable multivibrator that generates a trigger level of the statistic pulse generator 87 as interrogation gate pulse, as shown in FIG. 12, line D, is set so that an average of about 150 gate pulses is shown. The gate impulse begins with the front-per second generated. This is flanked by the exponential voltage curve and is sufficient that the bias of the blocking device simply ends when the exponential voltage curve is lowered below 55 oscillator 96 to such an extent that a certain value has fallen per Se. In the present example, 150 noise impulses would be a sufficiently high amplitude

* "," ,. λ-λ ~~ ^ "r" j 1 _"ar be via a separate line to one of the inputs

takes a little longer than - ^ pr-sec. _{,, TT} , J?,. , _λ λ ₌ r ?,. - ^. ~,,.

^ö 810 60 gange des And-Ghedes 105 supplied. The tact "

Let it now again be FIG. 10 considered. When the impulses are sent to the other input of the And-

System is working in course operation, the gate pulse element 105 is fed. Therefore the AND element is 105

of the generator 87, which prepares itself 22.5 to 30 times per se in such a way that the interrogation pulse generator 130

announce repeatedly, an input of an AND element feeds about 150 clock pulses and 150 interrogation

89, which has three inputs. The other 65 pulses are sent to the radio beacon when the

Both inputs of the AND element 89 are once the aircraft's TACAN system is working in search mode,

the clock pulses of the generator 60 and on the other hand when the switch 85 is brought into the search position

Another gate pulse of a multivibrator 100 is closed, separates a mechanically connected one

29 30

Switch 86, interrogation pulse return line 65 from deflection generator 114 controls a display device in memory circuit 49. During search mode 118, which deliberately avoids synchronization with a cathode ray tube as panorama, viewing device ("PPI") is executed. The cathode ray so that other aircraft can determine that a tube has preferably a relatively long aircraft in the search mode with the navigation system 5 persistence, or there is still a memory that is not synchronized. This means that it uses a tube.

Aircraft with non-synchronized clock generator 60 The interrogation received by the receiver 116 is not allowed to transmit interrogation pulses with such a pulse through the range circuit 119 frequency that the range and altitude of the aircraft appear as stationary on the display device 118 during the time aircraft. io deflection period at a distance from the zero point of the Thus, an aircraft in search mode generates a statistical screen image that shows the distance of the distributed impulses on the screen of an aircraft, inquiring aircraft from the receiving aircraft operating in course mode, these statistically distributed reproduces. The distance can be determined in this way. Impulses are easy to determine precisely from interrogation impulses of those because the beginning of the flight planes that determine their course distance measuring period (start of the time deflection) and altitude, distance and direction information can be distinguished the interrogation pulses are synchronized with the individual height-coded pulse. The interferometer 120 measures the direction of the send. Pulses of the last-mentioned aircraft are received pulses during this period and regularly received every second and these preferably also appear on the same appear relatively stationary on the measuring screen 118 , so that a combined descreening of other aircraft. distance and direction measurement is available. Every aircraft that receives the individual impulse in the transmission interval reserved for altitude information with the help of the PPI display device can use it to control the distance, direction and altitude of the screen image signal that is sent by the transmitting aircraft derive. Usually 25 represents the direction of the captured aircraft. The time is interested in any aircraft that flies at a certain altitude of the arrival of the signal from the sending aircraft, only for aircraft that fly approximately at the same height controls the radial distance of the cathode ray, since these would be the only aircraft from the point of origin of the deflection. That way with whom it could possibly collide. Both the direction and the distance are therefore displayed. The coordinate measuring system of the aircraft that is sending the pulse must therefore be displayed. Depending on the receiving aircraft only to receive interrogation - if desired, the distance and direction impulses of those aircraft can be set, which are also displayed digitally, as is known per se, are located at the same height. If this is selective. It should be noted that the altitude of other broadcasts are received, then aircraft are included in this measurement, since the distance and the direction of the aircraft located in this 35 the viewing device 118 is only determined during the time in the controlled altitude range. One will be assigned to the altitude range in which the system to accomplish this is the receiving aircraft is flying. To fix the height also in Fig. 10 shown. all that needs to be done is the altimeter 70 when the comparator 77 of FIG. 10 an initial aspiration to be.

signal delivers, then this also triggers a mono- 40 Should the distance and the direction of flight-stable multivibrator 110 be displayed, which produce an AND element 112 regardless of their altitude,

.., jl ι. ν j - 1. * τ 1 then becomes the time deflection generator 114 of each

during - ^ ₇ - see prepared to the next bar- ^ w 1 j · ι_ * j ^ 1 * · 1

810 'clock pulse and not only from the clock pulses

pulse to a time deflection generator 114 triggers that a certain altitude range or

allow. This clock pulse controls the distance 45 are assigned to certain altitude areas,

and direction measuring circuit. It should also be mentioned that the pilots are used to

during the preparation of the AND element 81 in order to avoid collisions only before the flight

the next clock pulse as height-coded interrogation witnesses need to be warned that are within

to let impulse through and to send. It should be a limited distance from your own aircraft

it should be noted that the measurement circuits are only 50. Therefore the time diversion needs the

during the interrogation pulse transmission period that the display device only responds to the display of those

Transferring the aircraft altitude is reserved> to be expanded into aircraft that are within

Are operating. Therefore, distance and the critical distance, z. B. 40 km, are located,

measurement of only those aircraft that are reflected in signals from aircraft outside this range

are at the same height. 55 does not need to take into account the measuring aircraft.

An interrogation pulse receiver 116 receives all intentions as far as it is the measurements of distance

interrogation pulses sent by airplanes and the direction of the sending airplanes. Also the

that are within its reception range. How ground station needs to control air traffic

already explained above, the on-board transmitters are also only a limited area or the entire

Monitor other aircraft with the respective radio beacon 60 370 km range. Because in any case

station synchronized so that distance information can be taken from the time deflection of the viewing device in the flight

their interrogation pulses can be derived. The tool or the ground station is set accordingly

Clock pulse, which passes the AND element 112 , can be triggered.

the timing generator 114 so that a timing variable can be used in many cases

with a duration equal to the time between two distance and direction measuring circuits of one

successive clock pulses takes place. In the an- aircraft to steer in such a way that other altitude ranges

Example, these are ^ see. De, time- £, ** £ ·

31 32

aircraft in question from an altitude range to determine whether it is suitable for landing.

wants to transfer another. This aircraft would have This can be achieved by having the output

Therefore, the adjacent altitude range should be set codes so that the lower altitude

to check whether there is an aircraft in it that areas can be examined, although the

due to its distance and direction, an aircraft flies even at a higher altitude. the

could cause a collision. This can be arranged in the same way for investigation

Realize the lying system as follows: or several arbitrary layers of height are used

The output of the comparator 77 can be.

again to trigger the display device 118 via Another advantage of the invention is that the monostable multivibrator 110 and the AND element io that other aircraft in the immediate vicinity can be sent data based on a clock pulse according to the environment, in which the current Altitude of the aircraft, as stated above, intending to climb or write, serve to under- land the altitude range. When an aircraft z. B. wants to ascend, search in which the aircraft is currently flying. The trigger can examine its own and the two next-higher tion of the display device 118 to determine data 15 height areas. The impulse, which indicates the aircraft in the next higher and the next own altitude of the ascending aircraft, would be, lower altitude ranges or the two next - as described above, coded in the usual form, higher or the two next lower heights - the and- Member 89 would be blocked and the output areas could be encoded in the most varied of ways. So z. B. in one device several 20 impulses for the two next higher altitude ranges display devices as in the converter 75. The interrogation pulses for these two are seen. Each converter is set in such a way that the areas would be coded differently, which generates a coded output number that corresponds to the interrogation aircraft in these altitude areas, which corresponds to the Abimpuls transmission position immediately before the impulse interrogation pulse in the position intended for the ascent the area to be examined is received prior to the upcoming high-altitude area. When another aircraft climbed into the altitude range, the converters are connected to the comparator 77, the other input of which is warned. Therefore the system is not only connected to the output of the counter 69. The output codes of the converter are passively investigated by other altitude ranges, but they can also act actively, in that the comparison in the comparator 77 sends out pulses warning other aircraft in the ranges that are using the multivibrator 110 so trigger in which to ascend or descend. The coding that clock pulses corresponding to a large number of different combinations of the pulses for adjoining height areas height areas would be such that two types of information would pass through element 112 in order to divide the time deflection of the picture; firstly, whether the aircraft that trigger the in-screen. So z. B. in a flight 35 sends pulse, intends to ascend or descend, and stuff that wants to change its flight plane, the Umsetzer- secondly, to how many altitude ranges the possible codes are chosen so that a distance and wise maneuvering aircraft is removed. The co-direction measurement in the current elevation can be done by any known code in the area of the aircraft, in the next higher and in a manner known per se,
the next lower altitude range. In the present system, the measurement of an aircraft that wants to fly downwards can be the distance and direction of aircraft, the wrong codes represent the actual flight altitude and the two targets, ie, which is not in a critical or next lower range or also the Fly three next lower distances, largely switched off. When specifying height ranges. In the case of an ascending two aircraft have the possibility, in points in time aircraft the codes can indicate the actual flight altitude 45,,,. 1 . ,,.
and the two next higher or the ^abzufra three S ^s> W ^sec apart put ^the thing a

Specify the next higher altitude range. The output one-way propagation distance of 370 km, the comparator's signal would then trigger a measurement on it is possible that more than 370 km away flying the display device 118, so that Ent-aircraft, i.e. 370 + R km, closer than 370 km distance and direction of any airplane in 50 seem. In general, an aircraft flying 370 + R km away as a whole from one of the altitude ranges of interest can be set as the wrong target in R km . It should be pointed out once again that the distance, if it is permitted to do so, indicate the height of the aircraft in any way. , 1 , ". , ". _t -,
Feich is included in the measurements, since ^{time point} W ^{sec is sent before the} test, in which it is possible to determine in which altitude range the measurement 55 a distance-altitude measurement was made with respect to one by simply setting the aircraft. Such a wrong target of the translator is considered. Let the implementers be referred to here as "ghost",
adjust yourself in such a way that one or more arbitrary The reception of ghosts is limited: a) can be examined by height ranges. the increased attenuation caused by these signals as a result of the It must also be said that one can be subject to as many 60 longer distances as one wants, and b) through the altitude ranges one can examine as one likes, the intervening of the horizon, which the line of sight, regardless of whether these ranges are entirely interrupts above or between transmitter and receiver. The one that lies below the actual flight altitude or that is adjacent to the first effect in the measurement compares this, in that the output code of the short distances is simply changed to avoid converters. So z. B. a bump in 7000 m 65 is of greater importance, and the second effect has altitude flying aircraft have the intention to control the air traffic higher altitude layers above the adjoining environment.
to investigate the area of a specific airfield, F i g. 13 shows the numerical influence of these

33 34

Effects on the elimination of ghosts. Seen the curve ground station, appear above the horizon to ER 130 with the course. So you want a minimal amplitude

must have a difference of 20 dB in order to distinguish between ghost planes when controlling air traffic

^ ² 5 another for aircraft at altitudes over 10,000 m

(R + 37O) ² measuring methods can be used. A possibility

consists in separating the transmission positions assigned to the very high altitudes from all others.

gives the relative attenuation of the ghost signal in a, "....", .... 1, _, ",

rr ι-τηιηι ·, τ ι · ι_ · If permissible send positions - ^ τκ- sec or 740 km

Distance of 370 + R km compared to an io & r ₈₁₀

real signal from R km away again. The distance between them can be a ghost flight that appears 20 db weaker than a true ratio of the squares of the distances, because the amplitudes appear to be 50 km away in space, although the ghost-spreading electromagnetic waves with the qua- plane 740 + 80 = 820 km away. This drat your distance from the transmitter. The 15 ghost plane must but at altitudes over 33,000 m. Curve 130 shows that it can fly from a distance of, so that the problem could be solved in this way between the signals of a real target and 40 km.

of a ghost plane a difference of at least. The above measurements ghost planes can result in 20 db. This is a considerable distance, and it can be turned off at all, if 20 db is accepted as a receiver operating with time-dependent response sensitivity control to distinguish between true targets, ghost signals from ghost planes can be accepted. It would be effective on this basis. The brief also conceivable to allow spirits aircraft not initially non-curve 131 labeled "h _m i _n CAS" Gibr to taken into account, but to identify them, so the course of the minimum height of Meßflugzeug and that, by an observer or a computer ghost plane which fly at the same height can be excluded in 25. If, for example, it depends on your distance again, from which you can just see the distance between altitude transmission times due to the curvature of the earth. increases with the time following a Ε pulse, and thus at R = 16 km the ghost plane is 370 + 16 with the time following the subsequent £ pulse = 386 km away and must drop at least 2400 m high, A ghost signal can only fly in alternate turns to appear above the horizon, so that 30 high altitude transmission intervals appear and easily visually it can send and receive radio signals. Since they are recognized or automatically,
Much of the air traffic above this altitude should be noted that the individual processing, one can rely on the disappearance of impulse transmission, which is limited to the aircraft altitudes and ghost signals due to the curvature of the earth, not promising times for transmission. The prerequisite here is that the aircraft interrogating each other in times of a large amount of data can be used . For this it is assumed that distance is flying. If this is not the case, the impact and direction of an aircraft can be determined from the data from the ghost signals from aircraft over which the horizon is determined, as described above, even more negligibly. If the accuracy of the distance speaking of the cases that an aircraft flying at high altitude and direction is appropriate, identifies or knows a low flying aircraft in a long distance, this single pulse polls a certain flight times spaced apart. things. When the plane determines its course and

Using the curve of FIG. 13 can be shown, 45 with a normal TACAN frequency of 22.5 to 30 Hz

that sends the difference between ghost signals and real interrogation pulses, each interrogation pulse is off

Signals at a distance of 40 km at 20 db one of 810: 30 = 27 pulse positions selected,

sinks (the ghost plane is in reality 370 -f 40 If an interrogation pulse for the transmission of information

= 410 km away). selected from 27 pulse positions, each of which

With increasing distance, the ratio of the 50 because of its position in relation to the Έ and .E-Refe ghost signals to a real signal decreases. For example, the radio beacon's reference pulses are marked, then the signal of a person flying 740 km away can be sent with each pulse one of 27 different in-plane formations compared to that of a 370 km away aircraft. When two interrogating aircraft are only attenuated by 6 db. One pulse used for each piece of information can be transmitted to aircraft but at a distance of 740 km 55 one of 27 ² = 729 pieces of information with each pulse from an air traffic control ground station, pair. In practice, 27 * 21 must fly at an altitude of 35,000 m in order to, from the " _{T c} . ",. , 1
Ground station seen, information appears to be sensible above the horizon, since _we see

seem, although the signal amplitude difference between the pulses for the recovery of the supply small true signaled and ghost signals 6 db in 60 voltages should be available.
Exceeds reality. If there are 30 departures from each aircraft

The third curve 132 of FIG. 13 is dependent on interrogation pulses per second sent, speed of the distance of an aircraft from each aircraft 15 of these 567 data per second via the ground station can indicate the altitude at which an aircraft is at a minimum. The 15 transmissions per second must at least be sufficient to fly to appear above the horizon from the ground station, which is by far the requirements of an air traffic vision. In a decontrol regarding the information content. This distance of 410 km, R - 40 km, must also mean that the problem of the interference plane has an altitude of 11,000 m to, from that between planes equal distance from the plane

35 36

Air traffic center can be solved by the aircraft synchronization system are in the course that several pairs of pulses for each piece of information avert the operation of any aircraft which avoids all of them and from each aircraft a random question pulse with the reference pulses of those Selection of a pair of pulses per second made Radio beacon synchronized with which it is currently connected, so that in 2 or 3 seconds all data 5 works. Now, however, in a TACAN system the present, even if several aircraft are in the mean interrogation pulse frequency in course operation one same distance from the air traffic control aircraft 22.5 to 30 Hz and not 135 Hz as in Center. Search operation, d. H. when looking for your own

So far, only cooperation has been the query impulse. This means that even an aircraft can be in the Aircraft with a single ground station considered. io course operation to synchronize other transmitters, In reality, those close to one another can serve as a radio beacon transmitter. So if the Query planes from different ground stations, the receiver of a radio beacon queries the frequency and the inquiries do not need to be synchronized with the aircraft being another radio, Unless the ground stations have been polled, the first radio beacon receives synchronized with each other. Since the ground stations 15 receive the interrogation pulses from the aircraft while it is the generally interrogates in relation to each other below the other radio beacon, and processes this in the horizon located, d. H. with each other so not in pulse, as if there are reference pulses from another radio point of view they cannot be mutually referring stations either. In other words, the radio pulses received and mutually synchro- bake also sends a coded interrogation pulse to the nize. There must therefore be another possibility for the aircraft, either on the frequency of the radio beacon, Synchronization of all beacon stations found with which it is synchronized, or on the frequency, to send the reference pulses synchronously. on which the aircraft sends interrogation pulses. The

A simple and effective means of synchronizing the aircraft replies to the reception of the encoded sizing the reference pulses of the radio beacon stations interrogation pulse from the radio beacon by using a is the use of auxiliary transmission frequencies, which sends 25 coded reply pulse. The coded long-wave Auxiliary frequencies (»VLF«) in the »CW« band question pulse from the radio beacon is only provided by one are received by the beacon stations received aircraft flying at a certain altitude, and for their synchronization in per se known and the coded response pulse from the aircraft Way used by delay time differences between received by the radio beacon. The one from the radio beacon the radio beacon and the CW transmitter by an additional 30 interrogation pulse and that of the aircraft introduced delay times can be compensated. sent response and reference impulses are in It is known ("Proceedings of the Institute of Radio of the radio beacon for the synchronization of the radio beacon engineer", June 1957, pp. 794 to 803) that radio beacons, interrogation pulses with the coded aircraft Refedie are about 640 km apart, with the help of the reference pulse and thus with the true reference pulse synchronized by VLF and a simple programmed tag of another radio beacon, namely on borrowed correction to ± 1 microsecond exactly syn- the same way as the reference query and response synchronized can be. impulses for the synchronization of the aircraft disintegration

Another possibility to synchronize impulses with the radio beacon reference impulse prohibit Satellites. In this case it should be turned around.

Satellites act in the equatorial plane in 24 hours. This enables the synchronization of all radios fly once around the earth. The satellite beacon stations to the planes their measurements The reflected signals are then used to synchronize the distance to all radio beacons in the field of vision, currency the radio beacons used. For example, a “PCM” method with timer pulses can only be used to synchronize the aircraft interrogation with the radio beacon reference pulses use as reference pulses for the radio beacons. 45 a radio beacon is queried. This means that a As the distance of each radio beacon to the satellite, simultaneous measurement of the distance to several would be known, the synchronization could be possible through fixed radio beacons. So a It will be enough that each station determines the transmission of its navigation point with greater accuracy Reference pulse are additionally delayed by a time, without the simple division of the TACAN-Verdie equal to the difference between their own methods.

delay time and the maximum delay time If the timing of the beacon reference any The radio beacon is in the system. In this way impulses are shifted to the radio beacon stations all radio beacons are synchronized with each other. to synchronize, the drive of the rotary

A third way to synchronize the generating radio beacon antenna can be set so that Radio beacon reference pulse consists of the flight 55 the time relationships between the occurrence testify even with additional devices to the maximum of the antenna radiation pattern see. The radio beacons only need to be synchronized and the reference impulses to appear to be nized when in sight of two or more. Since the nature of the antenna characters several Radio beacons fly airplanes, which is known in ristics and the antenna is often cylinder-able are, from both radio beacons, response pulses 60 are shaped and arranged in a rotating manner, can trigger. Now, TACAN transmissions are nor- mally easy to do; for example with help sometimes to the field of vision and limited to a servo system that controls the speed and phase that aircraft in the field of vision only controls one radio beacon of the antenna according to the reference pulses, need to target this particular ground station. Therefore a system for navigation was created by Fahrlasst to realize a system that is described in relation to the 65 witnesses that refer to already existing Synchronization of presence and broadcast navigation systems, such as TACAN, can be used and impulses of this aircraft depends. According to an additional option to warn pilots Hand of fig. 4 and 5 described mode of action to avoid collisions and air traffic

to control. The system also enables the synchronization of all inquiries from vehicles with the reference transmission pulses of a fixed radio beacon. In this procedure, a single Interrogation pulse distance, direction and altitude

specification, so that the navigation system does not have to transmit, receive, encode and decode additional Impulse for this information is dependent. The system can therefore also be used on the controller of ground, marine and space transport.

In addition 5 sheets of drawings

Claims (1)

1 2 Stations (2a, 2b, 2 / j) that sent their Claims: Signals to those of the first station (1) synchro nize. 9. Device according to claim 8, characterized in that 1. Device for absolute synchronization 5 'indicates that one of the second stations (2a, of the transmitter clock relative to a first 2b, 2n) has a device (119, 118) for measuring Radio station movable second radio station to the distance to one of the other second Transmitter clock of the first radio station under loading stations by measuring the time between the taking into account the running time of the occurrence of a transmitted by the transmitter. Signals (10) and First station sent signals for receiving io receiving a signal (10) from the other ger the second station to enable a - second station contains. mutual one-way transit time distance measurement 10. Device according to one of the preceding by phase comparison in the second station claims for aircraft, characterized by between the own signals sent out and their application for collision avoidance, in particular the received, originating from the first station- »5 special with display restriction on flight Signals, marked by them (2) of comparable height, η e t that in a known manner in the first Station (1) a receiver-transmitter to transmit
of response signals (20) to the receipt of the Signals (10) of the second station (2) and in the twentieth second station a the running time (Trpy) of the Signals (10) of the second station and the response. - signals (20) of the first station measuring time ' knife (49) is provided and that the ■ .. · ■■ .. Runtime (Trpy) than the first-mentioned runtime 35 The invention relates to a device for absolute (Trbf) of the signals (15) of the first station taking into account synchronization of the transmitter clock of a visual control signal during synchronization relative to a first radio station movable second (40 ; 59) serves. Radio station for the transmitter clock of the first radio device according to claim 1, characterized in that the clock (60, 87, 89) in the 30 transmitters of the first station sent out signals to the second station (2) takes into account the running time of the station Number of receivers of the second station to enable possible transmission times and a mutual one-way transit time distance measuring second station contains a device (81, 83, 32), the solution by phase comparison in the second station, the occurrence of their transmitted signals (10) in between the own signals sent out and the one selected from these transmission time signals as a function of a predetermined information received from the first station,
scores. With some versions of radio navigation 3. A device according to claim 2, characterized in that the aircraft guides an aircraft indicates that the possible transmission times navigation transmitter and receiver with it. In Before assigned position coordinates of the cooperation with the ground station can be through th station (2) and the second station corresponding signaling direction of flight and Enteine Device (77, 79, 81) intended for controlling the distance of the aircraft from the ground station step of the transmitted signal (10) in the one. Such a commercially available radio navigator transmission time, that of the previously (70) measured system works according to the so-called »TACAN« - Corresponds to the position coordinate of the station. 45 procedure. Determined according to the TACAN method 4. Device according to claim 3 for aircraft, an aircraft its distance from a ground station characterized in that the previously (70) to- (radio beacon) by measuring the transit time between the ordered position coordinates the height of the sending of an interrogation pulse and the receipt of a Represent aircraft (2). Response pulse, which is sent by the radio beacon 5. Device according to one of claims 2 to 5 ° fang of the query pulse of the aircraft emitted 4, characterized in that it becomes possible. The direction is determined by measuring the phase transmission times of the clock (60, 87, 89) in the difference between one of a rotating antenna second station (2) all low-frequency signals transmitted between the occurrence of a radio beacon two determined by the first station (1) on each other and a reference signal. The principle of the The following transmitted signals (15) lie and with 55 TACAN method is known (»Electrical Commudiesen are in a synchronous relationship. nication ”, March 1956). The invention is special 6. Device according to one of the preceding, but not only for use in TACAN systems Claims, characterized in that one of suitable. = the first station (1) transmitted signal by As can be seen in the above-mentioned article, a code is specifically identifiable. 60 are those sent out by various aircraft 7. Device according to one of the preceding interrogation pulses not synchronized, so that the Emp claims for flight navigation, the second catching the impulses sent by an aircraft Station is installed on board an aircraft,. by another aircraft not directly to the operator characterized in that the first station (1) mood of the distance between these aircraft a stationary radio beacon of the relay type, which can be used. In fact, the special of the TACAN type. Reception of interrogation pulses from other aircraft in the 8. Device according to one of the preceding general avoided in order to avoid any interference Claims, characterized by several second or mix-ups between the other flight