DE2303989B2 - Two-way communication system - Google Patents

Description

Polling signals from the control center to the stations should be used as effectively as possible. In addition and the other for the transmission of response - it is necessary that from the remote status signals from the stations to the control center, the retrieved data are received in the order they are these response signals can be generated after the transmission, in which the retrieval commands from the a polling signal have been sent to a remote control center. Also allowed to 15 respondents sent by different stations from the control center Receives delay time, so signals do not overlap in time, marked that those stations with known two-way communication transmission

(4, 14, 18; ...), with which about the same, by systems the request signals are either with about the same distance from the zenith - such a constant, temporal distance central (100) specific delay times sent to the individual stations that are guaranteed each delay group ensures that the response signal from the am are summarized and that the center (100) most distant station in the center one after the other only the response signals from the hit before the next polling signal is sent out individual stations (4, 14, 18; ...) of a delay. In other known such systems, gerungsgruppe before sending polling signals to 25 the arrival of a response signal in the control center the stations (10, 12, 16, 19; ...) monitored by a next one and the sending out of a new one Delay group gives up. Response signal controlled. The disadvantage of such systems

2. An asterisk message transmission system is that the maximum running time of the claim 1, characterized in that the sta signals to and from the furthest from the centions a delay group in time intervals- 30 central remote station with a much larger one len are queried, which are about twice as long as the weight for querying all stations like the time interval between the borders,

in which the transmission delay times of the stations belonging to the delay group lie. 35

3. Message transmission system according to claim 1 or 2, characterized in that, that the two channels are each formed by a transmission line.

4. Message transmission system a recognition pulse is sent out after arrival at the control center, claim 1 or 2, characterized in that the by a closed loop in the participant two channels of two returns a frequency spacing to the control center. The term, i.e. the person rejecting it Carrier waves are formed. stood between sending and receiving the part

5. Message transmission system after acceptor recognition pulse, is for the currently in Claim 4, characterized in that the two subscriber stations taken into operation feature carrier waves via a bilateral coaxial cable table. However, this does not result in the sub-distribution network be transmitted. different maturities from the different

6. Message transmission system according to the spatial distance of the subscribers from the Zens claim 5, characterized in that the code ^fal e, but through a number of 50 seen in the subscriber stations pre-axial cable distribution network, different delay elements containing relay stations. ^{one characteristic} of each individual participant

Cause the duration of the participant identification pulse. The use of delay elements would, however, make the best possible use of the

₅₅ Central station contradict.

Accordingly, it is an object of the invention to provide the capability of a large-scale two-way communications system to treat

The invention relates to a two-way post-data improvement and more particularly the cycle time Directional transmission system with a center and 60 for connections between a center and a a number of stations remote from the central station, large number of remote stations interrogated one after the other those with the headquarters, which of the individual wards wards reduce.

sequentially retrieves signals via two channels. This object is achieved according to the invention

are bound, one of which is released for transmission, that those stations that are roughly the same, of polling signals from the control center to the stations at approximately the same distance from the Zennen and the other delay times are assigned to the transmission of the response center, Signals from the stations to the control center are used, which are each summarized in a delay group these response signals after sending out one and that the central unit only receives the response one after the other

required system cycle time than it is with regard to the actual distribution of the various Distances of the stations corresponding running times would be necessary. The headquarters will therefore be very badly used.

From US-PS 27 23 309 a telephone system with a control center and a number of participants is known in which to recognize the participant of

signals from the individual stations of a delay group before sending polling signals to the Stations of a next delay group. By the summary according to the invention of stations that are essentially determined by their distance from the control center, for example the same cycle or delay time are characterized to so-called delay groups, whose Stations are interrogated one after the other before the stations of a next delay group are interrogated are, the advantage is achieved that the time interval between the polling signals, one after the other are fed to the stations of a delay group, can be much smaller than the Duration of the request signals to the stations or the response signals from the stations to the control center and only needs to be so large that the individual response signals can be received separately. When doing this, the individual delay groups in the order of greater distance from their stations are queried one after the other by the control center, this time interval is also required during the transition not to be increased from one delay group to the next, since then that of the The response signal coming from the first station of the next delay group has a longer transit time anyway has as the reply signal sent by the last station of the previous delay group and therefore cannot overlap with this when received by the control center. The temporal one The minimum distance between the polling signals is essentially the maximum difference between the inside delay times occurring in a delay group, but not due to their absolute Size, and in practical cases can be a small fraction thereof. Accordingly becomes the contribution of the delay time to the total cycle time of the two-way communication system reduced to a small fraction by the invention, which is a considerable improvement allows the use of the control center of the two-way communication system according to the invention.

The invention will be based on the following description of the exemplary embodiments shown in the drawing explained in more detail. It shows

F i g. 1 is a block diagram of a two-way communication system to explain the invention,

F i g. FIG. 2 shows a timing diagram of the query and response signals of the system according to FIG. 1,

F i g. 3 shows a timing diagram to explain further features of the invention,

F i g. 4 is a simplified block diagram of a further two-way communication system, which illustrates the grouping of the stations,

F i g. 5 shows a timing diagram to explain the technique of the delay groups;

F i g. 6 a further timing diagram with additional messages,

F i g. 7 a and 7 b the formats of typical query signals,

8a and 8b show the formats of typical response signals,

Fig. 9 is a block diagram of another two-way communication system according to the invention and

10 shows the block diagram of a for the inventive Two-way communication system typical control center.

In the one shown in FIG. 1 to explain the general principles of the present invention Central 100 includes the main communication and control center for a plurality of remote stations 1, 2, 3, ... 19. It goes without saying that in FIG. 1 only 19 stations for the sake of clarity

ίο are shown and that in practice many hundreds or thousands of such stations can be used in conjunction with a central office.

As shown, the stations 1, 2, 3, ... 19 are at different distances from the control center 100 and connected to the control center by two-way transmission paths 101, 102, 103, ... 119. If the transmission medium is air or space, then this is the length of the transmission paths 101, 102, 103, ... 119 essentially the same as that

ao physical distance between the control center 100 and the corresponding station. However, if other transmission media such as wire lines, Coaxial cable or waveguide can be used, then the equivalent electrical length of the Transmission path 101, 102, 103, ... 119 from the actual physical distance of the stations from of the central 100 differ. In practice, such a deviation will generally also exist be.

In view of this fact, the following is made Description of the invention on the equivalent electrical length of the various transmission paths and, more precisely, referred to the amount of time it takes a signal to complete the To traverse the transmission path between two points. If the system is described that way then such factors as speed of propagation, delay times in devices and the like can be taken into account more easily.

As indicated above, in many modern communication systems it is desirable to have to operate remote stations of the system individually and at periodic intervals, for example to check the status of the stations, to receive data or requests from the stations or to send responses or commands to the stations. As known, through the application of time division multiplexing techniques in the case of wireless or microwave links bandwidth and in the case of wired transmission paths, lines are saved. It will therefore Assume that there is one communication channel in each direction for two-way communication exists between the control center 100 and the multitude of stations 1, 2, 3, ... 19. For simplification messages or signals that go from the control center to the stations are referred to as "downstream", whereas messages and signals that are sent from the stations to the control center are called Are referred to as "upstream".

To create a system as shown in FIG. 1 is shown to make the best possible use of it, it is desirable that for cycle time required for a message exchange or the time interval between successive ones To reduce communication links between the headquarters and one of the stations to a minimum. In other words, the advantages of time division multiplexing can be lost if the control center is too long

needs to satisfy the demands of a given station, or the station's required ones To transmit commands.

F i g. FIG. 2 shows the timing diagram of typical question-and-answer messages in a system as shown in FIG. The four lines A, B, C and D illustrate the time sequence of the exchange of messages between the control center 100 and the first three stations 1, 2 and 3. The simple question-and-answer process according to FIG. 2 can be described as follows. The center sends a message downstream to the first station. This station receives the message. The station forms and then sends a response upstream. Finally the control center receives the upstream response. It is of course assumed that the downstream message from the center contains information in the form of an address in order to address the station for which the message sent is intended.

The timing sequence described above is shown in FIG. 2 shown. At time T _TOl , the control center begins to send a message to station 1. This message, the envelope of which is indicated by the line A , has a duration denoted _{by L 0 x.} After a transmission delay T ₁ , station 1 begins to receive the message, as shown in line B. After the message has been completely received by station 1, a switching time t _v elapses during which the station compiles its response message. At time T _{TU t} , station 1 begins sending the upstream message, as line C shows. The upstream message from station 1 has a length L _vv

After a further transmission delay τ /, the control center 100 begins to receive the message from the station 1, as line D shows. The transmission _{delay T 1} downstream and the transmission delay τ / upstream are usually essentially the same, especially when using microwave or wireless transmission paths. However, if transmission lines are used with relay stations, switching devices and the like switched on, or if the upstream transmission path is physically different from the downstream transmission path, these delays may be different. In most systems, however, such a difference is small and the two delays can be considered to be the same (T ₁ = T ₁ ').

In any case, the upstream message is completely received by the center 100 at the time T _RU1 , so that the two-way transmission cycle between the center and the first station is completed. The cycle duration is _{denoted by C 1} and results from the sum of the length of the individual messages and the delay time, so that

C ₁ = L ₀₁ + T ₁ + t _t + Ly ₁ + T ₁ '. (1)

Assuming that T ₁ = T ₁ ', then
C ₁ = L ₀₁ + 2T ₁ + ^ + Lu ₁ . (2)

At time 7> _θ2 , the control center 100 triggers a new message to the station 2, and the process is repeated. The time span between the time T _{RU t of} the complete reception of the last upstream message from the station 1 and the time T _{TD 2 of} the start of the next interrogation cycle to the station 2 can be reduced in various ways. It can be seen, however, that the cycle duration from the beginning of the downstream message to the complete reception of the upstream message is a direct function of the transit times T ₁ and T ₁ 'to and from the station.

It is further from FIGS. 1 and 2 that ίο the length of the transmission path 102 and, as a result, the transit times T ₂ and T ₂ 'for station 2 are shorter than for station 1. In general, the transit times τ and τ' assigned to the individual stations are be unequal, so

Ηφτ ₂ φ _Η ... φτ _η (3)

and

_τι 'φτ ₂ ' φτ ₃ '... φτ _η '.

(4)

The different runtimes are distributed over a large range of values. In the system according to FIG. 1 it is to be expected that the transit time T ₁₃ to station 13 is the shortest and the transit time T ₅ to station 5 is the longest. The other runtimes are somewhere between these two extreme values.

It is easy to see that the differences in the transit times identified above represent a considerable problem when the stations of such a system are to be interrogated one after the other. There is a requirement that the messages directed upstream, which are transmitted via a common channel, must reach the central station separately. If the stations according to the in F i g. 2 are interrogated in too fast a sequence, there is the possibility that the response from a station only a little distant will arrive at the same time as the response from a previously interrogated, distant station because of the short transit time, because its response signal has a long transit time. The signals arriving at the same time would of course interfere with each other, and the content of both messages would be lost. In order to bring the interrogation-response cycle time for an entire system with η stations to a minimum without such interference occurring, using the basic method of time allocation according to FIG. 2 the following techniques can be used. According to the first technique, the maximum cycle time C _{max can be determined} for the various stations in the system. In the example of the restricted system shown in FIG. 1, C _max would correspond to the cycle time C ₅ for station 5. The control center can then be set in such a way that successive stations are queried at time intervals of C _{max seconds.} this means

(Jtd 2 ~ Ttd 1) - (

(J TD η ~ ^ TD π-1) ~

Max ·

For the sake of simplicity it is further assumed that the various downstream messages have the same length, so

L ₀₁ = L ₀₂ = ... L ₀₁ = ... L _0n = L ₀ . (6)

Furthermore, the messages directed upstream should also have the same duration, so that

-υ χ

- Ln η - ... Lin -

- ¹ U 2

Vl

= L "

Finally, the switching times t should all be the same, namely

(8th)

Then the total system cycle time

= n (L _D +1 + L ₁ ]) + 2nx _m

(9)
(10)

(H)

After that, the total system cycle time is to a large extent a function of the runtime at the furthest remote station.

Another technique for reducing the overall system cycle time is to have the control center send out an interrogation message as soon as it receives the upstream message from the immediately preceding station. According to FIG. 2, this means that T _TD2 = T _RU1 - L ₁₁₁ etc. If this is done, the expression is for the entire system cycle time

(12)

This system cycle time is of course shorter than the system cycle time for the previous one Example according to equation (11). How much this time is shorter, however, depends on the distribution of the runtimes of the stations of the entire system.

However, a difficult problem in using this technique appears to arise when, for some reason, no response is received from a station. In such a case, the center must wait a certain time, usually C _max , until it can determine that no response has arrived in order to resume the interrogation process. Even so, this technique can result in a significantly reduced system cycle time. However, the condition L ₀ + t> Ly must be fulfilled if the possibility is to be excluded that two messages directed upstream reach the control center at the same time. If this condition is not met, there would be the possibility that a response that was only slightly delayed would arrive at the same time as, or overlap, an earlier response with a longer duration.

Of the two techniques given above, the second can be considered the simplest form of the invention The concept of overlapping messages. In other words, the downstream messages overlap the center 100 chronologically the upstream messages from the respective preceding ones Stations. Equation (12) shows, however, that the running times are still a considerable Have an impact on the total system cycle time, even when using the simple overlap scheme of the timing diagram according to FIG. 2 is useful.

According to a further aspect of the invention, the transit time τ can by a refined method of Overlapping of query and response messages are used to cover the entire system cycle time to decrease further.

F i g. 3 shows the timing diagram of an improved query-response method using the principle of overlapping messages. Since some of the time intervals and signal lengths have already been defined above, these expressions are derived from FIG. 2 taken over. As in Fig. 2, in FIG. 3 too, the center 100 begins its first message to the first station at time T _TDa . Regardless of whether an upstream message is received or not, the control center triggers the next query message to the second station at time T _TDb , which begins <5 seconds after the end of the query message to the first station. So is

= T _TDa + L _Da + δ.

(13)

It should be noted that the use of the terms "first station," "second station," and so on, does not is intended to mean that the order of the polling corresponds to the order given in the timing diagram according to FIG. 2 has been used. In other words, the first needs to be downstream Directed message not necessary for station 1 according to FIG. 1 still need the following downstream messages necessary to other consecutively numbered stations of the illustrated system to be directed. The order in which the stations are called or forming a queue will be discussed in detail later.

In any case, query messages are sent periodically from the control center to the stations at intervals L _Da + ' d, L _Db + δ, L _Dc + δ, ... .etc. directed. As line B in FIG. 3 shows, the first downstream message arrives at station α at time T _TDa + T ₀ . At time T TDb + x _b the second downstream message reaches station b _{etc. It goes without saying} that these downstream messages also reach all other stations, however, as stated above, these messages contain addresses so that they only address the one addressed Trigger station or stations.

After a switching time t , each station triggers an upstream response based on the query received. Accordingly, the station α sends its response at time T _Wa , as indicated by line C in FIG. The upstream response messages are received by the control center 100 after corresponding transit times x _a \ x _b ... etc., as line D in FIG. 3 shows. The times at which the control center received the messages from the two stations a and b are T _RUa and T _{RUb, respectively} . The condition applies so that the messages directed upstream do not overlap at the control center

TRUb ~ Li

Vb ^ Z ^J RUa

(14)

In other words, the first bit of the response from station b must not arrive at the control center 100 earlier than the last bit of the response message from station α.

Generally speaking, this condition reduces to

δ> 2 (T ₀ -T ₆ ) + (La-L ₀ ), (15)

if the validity of equations (6), (7) and (8) is assumed and it is further assumed that

t _e = r ₀ ', T ₆ = τ / ... etc. (16)

With the further obvious condition that δ> 0, various methods for reducing the overall cycle time can be considered. A first method can be used as the principle of »orderly

509514/327

ίο

neten term «. This principle requires the allocation of query slots with increasing transit times τ to the stations. Then the first station to be queried is the one with the lowest total travel time, there and back. In the example according to FIG. 1 would be the first station is station 13. In the order of increasing transit times, the next ones would be queried Stations the stations 17, 8, 4 etc.

gen etc. In Fig. 1 are six delay groups, for example through concentric areas I to VI shown, which are separated by dashed lines. Group I includes the stations with the 5 lowest transmission delay times, namely the stations 8, 13 and 17. The delay group II comprises the stations 4, 14 and 18, etc. The Transmission delay times are not the same for all stations in a group, but lie within

It is easily seen that by applying io know predetermined limits. The dividing line the principle of the ordered transit time of the simulta- neous between the transmission delay times of term reception or the overlap of response stations in adjacent delay groups Signals from successive stations do not need to be sharp. In fact, one is geden will. Although this principle of the orderly freedom of choice in the assignment of stations, Duration is attractive in some respects and a 15 that is on the limit is desirable. For example impressive ability to handle the bot it may be useful to station 8 in FIG. 1 of the It is subject to several possible Delay Group II instead of the Delay Restrictions. These restrictions include group I assignments.

the fact that the stations are from the center The formation of delay groups is in more than one increasing order of the transit times addressed 20 different points of advantage. As the stations become internal have to. This measure requires the delay groups to be stored in any order Earning and reading the list of station addresses can be queried in the control center the order of the runtimes for each query response no ordered table to be present, so that word cycle of the system. The problems with storage - no disk and no other storage required Earning and reading this data for a full 25 is to control the interrogation process. Rather geSystem, Hundreds or thousands of stations need a simple hard-wired meter to display the are not without consequences. Successive station addresses must also be queried in the entire address sequence of the system can be changed to form a cycle. Furthermore, during the evening, when new stations are added or ask for no access to the memory of a computer existing stations are removed from the system. 30 required, as is the case with the technique of the orderly For practical reasons, <5 can never be the transit times where the station addresses would be required Assume the value 0, because in practical systems they are always read out one after the other from a memory, some uncertainty in determining the equation (15) defines the properties of the

There are transit times to the stations. Therefore, when using delay even using the technique, query schemes must overlap groups. In this case it is assumed that the messages with ordered transit times for δ a stations α and b two stations are assumed to be within a certain minimum value to be unequal delay groups. The value of the safeguards and "calming times" to be taken into account between query messages for a Vertigen, which the stations need to distinguish between the delay group can be based on the limits of one message and the next, between which the transmission can be correct. Accordingly, the minimum value for δ delay times within the delay may approach the value O to the extent that the group is accurate. If necessary, a suitable run-time between the control center and the different order of the stations into delay groups can be determined and how much the »occupational single value <5 for all delay groups clearance time« can be reduced. The total of 45 ben. For example, the transmission delay time for an interrogation-response cycle of a delay time of the stations in a group can be determined in various ways between 10 and 20 μβ, for another group between 20 and 20. For example, a time counter in 30 μ, ς, another group between 30 and 40 μβ of the control center can be triggered at the time when and for yet another group between 40 and a downstream message begins, and 5 ° 50 μβ are, etc. The fluctuation of the transmission can be stopped at the moment by adding a delay time in each of these delay groups.

speaking upstream response is received. This time interval represents the sum of the Represents transit times downstream and upstream plus the switching time of the station.

Many of the above-mentioned disadvantages of the ordered delay time method can be overcome by dividing the stations of the system into so-called "delay groups". However, the basic pen is 10 μβ. Therefore, the stations in each delay group can be interrogated in an arbitrary sequence with equal intervals δ> 10 μβ. It can be seen that the variation in the round trip delay time, and consequently the sampling interval, can be different for each of the various delay groups without appreciably complicating the structure of the system. For systems with

In addition, this method consists of a disproportionately strong concentration of

sen query of the stations. In detail, a station with essentially identical running times

Number of station groups created artificially, the fluctuation of the transmission delay can be

which each stations with the same delay times in some delay groups very much

includes. They each form a delay group - be much smaller than in other groups in the system,

the stations are cleared in any order. 65 Such a state can occur, for example,

asks, and your answers will be received. if a number of stations in an apartment

Then the stations of the next delay house, office building or the like are clustered together.

management group queried and their responses received. 4 shows a simplified block diagram

question messages that are sent to the stations of the delay groups Π, III etc. are sent.

The response messages from the stations of the various delay groups on arrival 5 at the control center are in line B of FIG. 5 shown. As can be seen, the first response messages from the stations in delay group I arrive at the control center a short time after the first query messages have been sent out. As in Fig. 3

Intersections in the lines representing the transmission paths 410 and 411 are intended to indicate the possible presence show a variety of additional stations that are not shown for simplicity.

The transmission paths 410 and 411 can, for example, be coaxial cables, waveguides or others Transmission media include the frequency range used for the intended operation

different system structure with a control center and a number of remote stations. In the system according to FIG. 4, the center 400 is connected to a number of stations 401, 402, 403,... M by transmission paths 410 and 411. In this embodiment, the first transmission path 410 transmits the downstream signals from the center 400 to the remote stations. The second transmission path 411 takes the upstream signals

represented by stations 401, 402, 403,... m io, the time interval is the printout to central 400. The dashed Ab- (2τ _α + t _a + L _DA ) are the same, in which the index α indicates the first station of delay group I to be interrogated in this case. Because of the increasingly longer transit times for the stations of delay groups II, III, etc., the time intervals between the envelopes of line A and the envelopes of line B in FIG. 5 continuously larger. As stated above, however, it is not necessary that the delay groups be in increasing

are suitable. The transmission paths can be queried in relays, but it can Contain stations, the number and reinforcement of which the interrogation takes place in any desired sequence, factor of the length of the transmission paths, the In some systems it may be necessary that

Attenuation on these paths and other factors affecting the central data or responses to inquiries depend. delivers or provides other services that

The block diagram according to FIG. 4 is useful because 25 responses are requested from the stations, it clearly illustrates the principle of grouping the stations. These services can be illustrated by the control center in the timers in delay groups. In the case of intervals between the interrogation of each other in the exemplary embodiment shown, the gender groups are performed. Fig. 6 shows the first three stations 401, 402 and 403, the delay example, the time diagram of a system in which of the delay group I, the stations 404, 405 and 406 the 30 of the control center depending on the previous delay group II, the stations 407, 408, etc. stations received messages Dienstbotschaf the delay group III, etc., up to the delayed in the form of commands or data broadcast group M, in which the station m falls. will.

In operation, the control center 400 initiates an interrogation of the relative length or time that the service radio cycle by devoting it to the stations of the delays, can be larger or smaller than group I sends messages. The consequence of being the time it takes for polling the stations of the downstream messages is used in rows, depending on the respective delay group the F i g. 3 shown. As indicated above, according to the number of stations the services can request According to the teachings of the invention, the stations of one of the stations and the length of the stations to be used at these stations are determined Delay group in any 40 dend service messages. Furthermore, it is the Zen sequence addressed. This means that the output is possible during the time intervals between query sequence for example 401, 403, 402, but also the queries of the delay groups or 402, 403, 401, etc. can be. After the stations between the end and the beginning of a complete Delay group I queried and their current group query cycle off further functions to receive directed messages from the headquarters. Such functions can for example have been caught, the stations of a system diagnosis, the localization of errors, other delay group can be queried. Which include printing out data, etc. next set of delays in polling can contain As indicated above, the

delay group II, although Adresim as well as neutral messages sent to the stations In the case of the stations within a group, the 50 sensor information that addresses the station, The order of the groups is not critical. The one who should process the message. Some typical The question-answer cycle then runs from group to format for messages in numerous syste-group in such a way that all stations of a menu of the type considered here are used Delay group queried before they can are shown in FIGS. 7 a, 7 b, 8 a and 8 b Darge headquarters transferred to a next delay group. The formats shown are all in the same goes. Are shown on a time scale, set a pulse modulus

An example of a query-response sequence below lation, through which the information content of the use of the technique of delay group messages in the modulation of a certain para- and overlapping messages is shown in FIG. 5 changes in a series of regularly recurring im-viewing light. Row A in Fig. 5 shows that 60 pulses have been converted into compressed. The pulses themselves are the envelopes of the interrogation messages usually sent to an RF carrier for transmission on for various delay groups, which are characterized by the time scale. In such systems that originate upstream and central. The one labeled VI-Abf enveloping the same transmission medium downstream is the enveloping area of all interrogation messages, such as the room or a kot, which axial cables from the control center downstream to the stations 65, have the carrier waves for the various delay group I. be sent. Frecher put the sequences with VU-Abf, VUl-Abf etc. in different directions in the same propagation directions. designated envelopes the envelopes of the Ab- Fig. 7a illustrates a signal that is typi-

see standard downstream message can be designated. The message consists of three sections, which can be assigned to the »group address«, »station address« and the »query code«. the Group address specifies the delay group in which the addressed station is located. If that Principle of the delay groups is used according to the invention, the one containing the group address remains Section for all individual stations of the

The invention is shown in the form of a block diagram in FIG. 9 shown. The system according to FIG. 9 has a control center 900 which is connected to a main line 901 . Two-way amplifiers 910, 911, 912 ... are switched into the main line at certain intervals. The two-way amplifiers 910, 911, 912 ... serve to amplify the downstream and upstream signals that propagate along the main line 901 . The two-way rep delay group the same. The station address io ker 910, 911, 912 ... can also be provided with one or more taps corresponding to the address of the respective station, around branch lines half of the delay group. The combination of 920, 921, 922, 923 and 924 to dine. Group and station address form an address. The branch lines can also be on their length

which is unique for each station. It should be noted that 930 are provided with two-way amplifiers. Even if the technique of the delay groups 15 of these two-way amplifiers 930 is not used to tap the address parts of the downstream message into a single address part
can be summarized. The query code
contains the information to be transmitted.

As indicated above, the interrogation code can connect one of these 930 branches. Request, command or data for the station For the sake of clarity, the individual station

include. the first delay group with 1-1, 1-2, 1-3

The format shown in FIG. 7b is denoted by expanded, etc. The stations of the delay message corresponds to the standard downstream group II are then designated with II-1, II-2, II-3 etc. format according to FIG Delay group G stations borrowed a fourth section labeled GI, G-2, G-3, and so on for extended bot- ts. It ver

Have additional amplifiers or individual stations. The individual stations are connected to the amplifiers with the help of stub lines 940 via suitable coupling devices or dividers 950.

is reserved for the station that are too long for a standard format. A typical application find formats with an extended message during the in F i g. 6 service periods shown.

The in the F i g. The formats shown 8 a and 8 b are for the standard upstream format and the extended upstream format characteristic. The formats are typical of those from the wards

it is clear that in a practical transmission system there are many more amplifiers, splitters, and stations can be used. They are systems of 30 hundreds, thousands, and even tens of thousands individual stations possible with a corresponding increase in the above-mentioned associated components. Furthermore, transmission lines of many kilometers in length can be used in such a system

used in the upstream traffic to the control center 35 are required.

will. 8a and 8b show that the clear division of the individual stations

a plurality of delay groups are provided in the embodiment of FIG. 9 not as clear as in the systems presented above. The streaked

the formats do not contain a section with the group address. The group address can be omitted because the station knows which delay group is being queried at a certain time and that as a result a response is necessary. Delimitation of the various delay groups to be made clearer by one station from this delay group.

must come from. Except for the two-way interrogation-response message, since the central office can receive the responses in the same way that are transmitted by the system The order received by the query bot 45 at the same time in the system other message links emits, it may appear that the fertilizing on channels also takes place at a different frequency. Station address is superfluous. The station address is, for example, image and frequency or however, because of the possibility that amplitude-modulated radio signals of general or several stations are out of order or due to pure or limited interest downstream or for other reasons no upstream response will be transmitted 5 ° upstream, in which case the generate word. If such a condition results from a two-way messages between the headquarters and the Whatever reason occurs, there is a risk that stations will receive signals to determine the subscriber flow Directed response messages from the quote and the participant's judgment, blocked and free headquarters registered incorrectly. Therefore, for input signals for a program, charge information is also the messages directed upstream include a general and numerous other messages and messages ID required. This identifier can be shafts.

by the inclusion of a part or the complete stations, which take place in connection with the station address required here, as the system written in Fig.8a can be used, and 8b show. are in the older German patent application It goes without saying that the formats according to 60 P 22 60 621.9 are described. A simplified block fig. 7a, 7b, 8a and 8b comprise further parts of a circuit diagram of a control center which can be used for a system according to the invention, as is suitable for the transmission of messages, is shown in FIG. Which are common through pulse modulation. For example, the control center contains a relatively small all-purpose can encoded information in the form of Si digital computer 960 with the perignals assigned to it, the beginning and the end of the message 65 pheren devices. In the control center according to Fig. 10, phase bits, clock pulses, parity bits, these peripheral devices contain a block memory and the like can be added if necessary. 970, a card reader 971, a teleprinter 972, Another, more special embodiment of a perforated tape punching and reading device 973, a magnetic

handset 974, a digital clock 975 showing the time of day, and a disk storage controller 976. All of the above peripheral devices are connected to the digital computer 960 by a common input-output bus 961.

A display device, which can contain a cathode ray tube for the visual representation, is also connected to the bus line 961. The bus line 961 ends at a connection device 990, which in turn is connected to a modem 1000.

The modem 1000 is used to modulate the signals coming from the station onto an RF carrier and to demodulate the incoming signals. The connection device 990 enables the digital computer 960 to monitor and control the individual stations of the system. It carries out the series-to-parallel and parallel-to-series conversion, which is necessary to convert the parallel words of the computer into series words for the connection with the stations. A first review of the responses received from the stations also takes place in the terminal device. This improves reliability and reduces the workload of the digital computer 960. When the terminal device detects that an additional service is required from a station, it queues the requested data in the digital computer 960 .

The display 980 provides a dynamic representation of system operations such as station activity, system errors, and other events of interest. The display device 980 can be a memory display device in which the information is reproduced on a cathode ray tube and stored there without being refreshed by the digital computer. The traffic between the computer 960 and the display device 980 is comparable to that of a high-speed printer.

Disk storage and disk storage controller 976 provide high-speed access storage for such information that is frequently accessed and updated, such as current information on the stations.

The 975 digital clock provides precise information about the time of day. For example, program selectable interrupts are effected in the connector of the clock 975 to interrupt the digital computer 960 at predetermined time intervals

ίο how 0.1 and 1.0 s have elapsed. This feature enables the digital computer 960 to be notified when significant activity is about to be initiated.
The tape recorder 974 is commonly used to store information that does not require quick access or frequent correction. In the case of a subscriber television system, information on billing, new stations, daily programming

and the like can be stored in this way. The teleprinter 972 can serve as a border device between the operator and the system in the control center. The other peripheral devices are essentially standard devices for the digital computer and serve the usual purposes when the digital computer is operated.

It goes without saying that the center shown in FIG. 10 is only one possible arrangement of components illustrated. Depending on the structure of the system, peripheral devices can be added or removed or be replaced by others. The center of FIG. 10 can be set up so that it Performs a variety of automated messaging services using suitable software. For the present invention is a significant part of the peripheral devices insignificant. The software can be easily used by a programmer be created in such a way that the delay groups are formed and the interrogation messages such Get a distance, as required by the invention.

In addition 6 sheets of drawings

509514/327

Claims (1)

Patent claims: 1. Two-way communication system with a central office and a number of the Central of distant stations, those with the central, those of the individual stations one after the other Retrieves signals via two channels connected, one of which is used to transmit Polling signal after a dependent on the distance of the addressed station from the control center Delay time receives. Such a two-way message transmission system can be used, for example, as a central station Contain data processing equipment that retrieves data generated by the remote stations and evaluates according to certain programs. The headquarters often includes expensive facilities that