DE2537136C3 - Radio telephony system with several corresponding stations, preferably designed as mobile systems - Google Patents

Description

The invention relates to a radio telephony system with several corresponding stations, preferably designed as mobile systems, wherein the stations are arranged a number of discrete radio carrier frequencies, preferably in periodic time intervals are changed in which the messages by means of digital signals, how the pulse code or pulse delta modulation are transmitted and each station has an electronic computing device has, in the memory of which the transmit / receive frequencies of all the stations involved in the system as Frequency change schemes for a longer period of time are included and in which each station has its own, quartz-controlled f; Timing device provided is that in the form of a synchronous generator the Electronic calculating machine controls such that the switching times of the frequency change scheme are observed will.

Such a system is described in DE-AS 19 54 754. There are also search procedures for the specified optimal route transmission, which consist, for example, in digitized messages to check a test code for optimal understandability. There are also the possibilities to optimal field strength, similar to frequency diversity systems, determine the transmission route.

The invention is based on the task of specifying a method based on such a system, which makes it possible, especially in the case of a frequency change scheme with brief change periods in the call phase to find the optimal transmission conditions in order to improve the reliability of the Optimize message transmission.

According to the invention, this object is achieved in that the digital output signals of the synchronous generator in a processing unit by other digital signals sent to a subscriber in the communications network are permanently assigned, are influenced in such a way that the output signals of the processing unit via a memory and an encoder to control a synthesizer, the RF outputs of which reflect the current transmission and / or reception frequency of the station concerned, so that for each cycle at each station an anterior transmission and reception frequency results in that furthermore the stations are set to reception in normal operation are and are set to send when a call is wanted, with the arithmetic unit via a switch is switched to a station selector, in which the preprogrammed switch programs of the to be called Stations are stored so that when the appropriate station code is selected (e.g. using a dial) the frequencies given by the synthesizer in chronological order both in the Frequency and the timing with the receiving frequencies of the selected station are identical, that also to monitor the transmission conditions between the stations on the assigned to them Radio frequency channels test broadcasts carried out and test results exchanged and this at the output of the actual receiver on each station an evaluator with memory and regenerator for the digital characters are connected and the regenerator continues via its output with one as well a memory having decoder is connected that also the evaluator each for one provided connection, the most favorable reception frequency and the decoder that of the opposite station the transmitted cheapest end-of-day frequency is saved and the evaluator at reception and the decoder at Sending in the period of perfect transmission ver ratios via a changeover switch the effect of de. Computing unit on the synthesizer prevents and

- So that the content of the memory, which determines the synthesizer frequency, no longer experiences any change and, in the event of transmission disruptions, the connection between the arithmetic unit and the memory is used to set additional frequencies via the switch

ίο is restored.

Further advantageous refinements of the invention are contained in claims 2 to 9.

The advantage achieved with the system according to the invention is that at the time the

i) Operating frequencies of all unoccupied stations all other stations in the network are known and thus the establishment of a new connection is reliable and can be done quickly.

Based on an embodiment that is shown in the drawing, the invention is intended in will be explained in more detail below. In the drawing mean

F i g. 1 shows the block diagram of a subscriber station, FIG. 2 a frequency change scheme.

One shown in FIG. 1 with 2 designated synchronous generator, the z. ??. is controlled via a punch card in a first punch card reader 1, generates a new digital basic number G approximately every second. This number is defined by the station number transmitter 4 and

jo changed such that at the output of the computing unit 5, the currently only one station assigned channel number K appears Here, if K> 10 is (at z. B. 10 the power available frequencies), for example, the first digit suppressed (eg 12 = 2).

The operating frequency on the synthesizer 10 is set from the channel number K via a memory 7 and an encoder 8, which can also be controlled by means of a punch card in a second punch card reader 9.

In the »idle state« all stations are on reception, with their frequencies in chronological order adopted frequency plan according to F i g. 2 should correspond. In this way, all stations check for the communications network available RF channels and determine which RF channels are occupied or whether they are called, switching from one to the other RF channel for all participants time-synchronized, but is preferably individually different. A carrier frequency is only used when Recording a connection broadcast on a free channel. If z. B. the station 1 to a message If station 2 wants to deliver, station 1 is switched from receiving E to sending 5 by pressing the send button switched and instead of the station number transmitter 4 the station selector 3 is switched to the computing unit 5. On station selector 3, number 2 becomes the desired remote station set (z. B. by means of a dial of a telephone), so that now these generated on the synthesizer 10 and sent to the transmitter

mi frequencies given in chronological order both sird identical in frequency as well as in timing with the receiving frequencies of station 2. on RF channels already in use by other stations will of course not be called. To increase

To ensure security when establishing the connection, it is possible to work with very small bitrals in conjunction with narrow IF filters during the call phase, so that the associated increase in the

Noise-to-noise ratio and the lower signal distortion in the first place can take place.

When recording a frequency hopping sequence of /. B. ts it can be expected that after η χ I s at the latest - where η indicates the number of available frequencies (RF channels) - the call was received by station 2 at the latest. The first characters of a call contain the coded details of the sender, which signal the sender / .. B. on a lamp panel 14 on station 2. This coding and display is intended to provide security that the received sender belongs to its own message network. On station 2, an evaluator 12 with a memory is connected to the output of the receiver, which from the usable frequencies the optimal frequency for the direction 1-2 (station I to station 2) with the corresponding criteria as well as occupied

chert. In addition, the central regeneration of the digital signals can advantageously be accommodated here at the same time. After the call from station 1 has expired, station 2 resounds to transmit - station 1 to "receive" - and also traverses all available frequencies, with the identifier and the determined usable frequencies 1–2 being communicated. The evaluator 12 at the station I now determines the frequencies usable for the direction 2-1, which can coincide with 1-2, and stores them. and the decoder 13 stores the frequencies usable as transmission frequencies for the direction 1-2. Only the frequency for the connection 2- I, which is stored in the decoder 13 on the station 2, is communicated before the message transmission from station I to station 2 begins. If the switch 6 is now operated, the synthesizer 10 is controlled according to the criteria of the evaluator 12 (when receiving) or the decoder 13 (when transmitting) and no longer by the synchronous generator 2. However, this continues so that after the connection is terminated stations I and 2 are running again in sync with the other stations. This forward and backward transmission ensures that optimal and undisturbed RF channels are used for both directions in the context of data backup.

Occur during the transmission of messages within the RF channel z. B. discrete disturbances. the z. B. recognized with the known procedures of data backup and reported back to the sending station depending on the type of signal transmission task, there are several options for a system organization to clean up this problem.

First of all, by reducing the data flow and thus the occupied RF bandwidth attempts are made to suppress the interference frequency. The bandwidth can be changed once by switching the IF filter in the transmitter and / or in the receiver is reduced and, on the other hand, by corresponding influencing of the synthesizer's nominal frequency can be shifted within the RF channel. Through this targeted Multiple use of the RF channel with reduced bandwidth makes it possible to ensure the security of the Significantly increase data transmission, especially when preprogrammed at the receiving location Form is determined which sub-areas are undisturbed and this is communicated to the "sender" on the return channel

In parallel with the reduction of the bandwidth of the signal spectrum in the transmitter and receiver, the transmission speed is reduced accordingly be transmitting digital messages and practice Geschwindigkeitswiindler 11 and 15 are on Dateneinganj DE (.Senderichtung) uiul on Dutcnausgang D / (Empfanpsrichtung) the data terminals accordingly adapted . If the limitation of the bandwidth does not lead to the elimination of the interferer or is not permitted because of the transmission task, a frequency change can be initiated automatically. It is possible to limit the usability of another frequency band either only when the disturbance occurs in the frequency band used or schoi beforehand during the data transmission through targeted! To ensure tests. It is even grundsälz borrowed possible during data transfer eini second Gerätcgarniiur similar to the Connection setup continues while the free available RF Kanäli on ihrp Rpnii! Z /} virlf nit out nruipn vii laccpn iinH rta result. B of the 1 set at the receiving location to give feedback, in order to give her the opportunity for a quick frequency change to a usable one! To give frequency, however, it is fundamentally better to use the hit rate / per second in the speed converter 11 compared to the message bit rate / per second to be transmitted by a small amount /. B. 10 "ι · increase and thus create the possible wedge for Z'itlückcn / u, in which - without the transmission task is disturbed - the other RF channels can be checked for their usability with the help of a short test signal that is displayed. The receiver , who knows both the configuration of the test signal and the frequency / plan for changing the frequency - /. B. as when establishing the connection, determines the transmission quality, saves the result and communicates this to the partner station (sender) via the return channel the gaps for the test program for the organization of the transmission system are then closed again in the speed converter 15 by slowing down the increased message bit rate / sec Tests on the other unoccupied RF channels are preferred based on the individual transmission stations of the entire network to be staggered in time to avoid the Test! of the individual communication links on their common RF reserve channels interfere with one another. The time staggering can be ^{brought about exactly as with A} ei connection establishment depending on the station number of the sending station.

As long as the bandwidth is not significantly reduced, this system is very suitable for the transmission of digital messages up to a relatively high baud rate (e.g. 2400 bit / s). As a result, a message contained in the memory of the speed converter 11 at the data input DE can also be repeated aul different RF channels recognized as useful for the connection. This memory can also be used to transmit a slowly flowing message (e.g. 50 tape) in time-compressed form on one or more frequencies at a higher speed (ζ. Β 2400 bit / s).

Another advantage that should be mentioned is that the basic number G of the synchronous generator 2 after no *

fixed scheme must be formed and also z. B. via an exchangeable punch card in the first Punch card reader 1 can be changed. This can result in an intentional disruption of the communication link be made more difficult.

A broadband antenna is assumed as antenna A in FIG. When using F'eitschen antennas, an antenna adapter is also required anyway. This antenna adaptation must be switchable for transmitter S and receiver E within the settling time. If this leads to difficulties, two matching devices (not shown) can be provided, one of which is in operation and the other is tuned to the new frequency by the memory 7 in advance. To switch the antenna from transmitting to receiving or from the first antenna

Fast circuit breakers are required to pass the second device.

In principle, the stations can also be equipped for ΠιιρΙρχ propulsion. In this case it is a second synthesizer is required and the distances between the transmit and receive frequencies should then be> 10% if reception should also be possible during the transmission phase. This However, this requirement does not apply if a corresponding logic in the system organization z. Am 12 and / or 13 ensures that there is no transmission during the reception phase (time gap). It For these cases, two additional reception filters are required, which switch over like the antenna adapters will.

For this purpose 2 sheets of drawings

Claims (9)

Patent claims: 1. Radio telephony system with several corresponding stations, preferably designed as mobile systems, the stations ί being assigned a number of discrete radio carrier frequencies that are changed at preferably periodic intervals, in which the messages are sent by means of digital signals such as pulse code or pulse delta modulation and each station has an electronic computing device in whose memory the transmit / receive frequencies of all the stations involved in the system are contained as a frequency change scheme for a longer period of time and in which each station is provided with its own, quartz-controlled timing device in the form of a synchronous generator the electronic calculating machine controls in such a way that the switching times of the frequency change scheme are observed, characterized in that the digital output signals of the synchronous generator (2) in a computer unit (5) by other dig Ital signals that are permanently assigned to a subscriber in the communications network are influenced in such a way that the output signals of the processing unit (5) control a synthesizer (10) via a memory (7) and an encoder (8), the RF outputs of which control the current transmission - Determine and / or receive frequency of the station in question, so that for each clock at each station a different transmission and reception frequency results, that furthermore the stations are set to receive in normal operation and are set to transmit when a desired call is made, whereby by a Switch the arithmetic unit (S) is switched to a station selector (3) in which the preprogrammed switchover programs of the stations to be called are stored, so that when the appropriate station code is selected (e.g. B. by means of a dial) the frequencies given by the - »o synthesizer (10) in chronological order both in frequency and in timing with the receiving frequencies of the selected station are identical, that also to monitor the transmission conditions between the stations on them assigned radio frequency channels, test transmissions are carried out and test results are exchanged and for this purpose an evaluator (12) with a memory and regenerator for the digital characters is connected to the output of the actual receiver (EE) on each station, and the regenerator is also connected to a decoder, which also has a memory, via its output (13) is connected so that the evaluator also stores the most favorable reception frequency for a given connection and the decoder stores the most favorable transmission frequency transmitted by the opposite station and the evaluator when receiving (E) and the decoder when transmitting (S) \ m period of time flawlessly. eo he transfer conditions via a changeover switch (6) prevents the processing unit (5) from acting on the synthesizer (10) and thus the content of the memory (7) which determines the synthesizer frequency no longer experiences any change and that μ when transmission disturbances occur via the changeover switch (6) the connection between the processing unit and the memory for setting further frequencies is re-established. 2. Radio telephony system according to claim 1, characterized in that in the case of discrete interference signals, the evaluator (12) reduces the bandwidth in the receiver (EE) and at the same time a speed converter (15) with memory arn data output (DA) to a speed adapted to the reduced bandwidth reverses. 3. Radio telephony system according to claim 1, characterized in that in the case of discrete interference signals, the decoder (13) reduces the bandwidth in the transmitter (SE) and at the same time a speed converter (11) with memory at the data input (DE) to a speed adapted to the reduced bandwidth reverses 4. Radio telephony system according to one of the preceding claims, characterized in that the reduction of the bandwidth in the transmitter (SE) and / or receiver (EE) is done by switching preferably IF filters or that the nominal frequency of the transmitter and for partial utilization of the RF channel / or receiver moved in the RF channel and thus a variable bandwidth setting is achieved. 5. Radiotelephony system according to one of the preceding Claims, characterized in that a lamp panel at the output of the evaluator (12) (14) is connected, which from the coding contained in the test signal the calling remote station indicates and ensures that the received signals are from a communications network belonging Station come. 6. Radio telephony system according to one of the preceding claims, characterized in that when using narrow-band antennas, for. B. whip antenna, to adapt the transmitter (SE) to the antenna (A) a quick-change adapter is used, the control line of which is connected to the output of the encoder (8) or that two adapter devices are optionally connected between the transmitter and the antenna so that in each case one is in operation and the other is preprogrammed from the memory (7) for the next following RF channel. 7. Radio telephony system according to one of the preceding claims, characterized in that for Duplex operation for the transmission and reception path separate processing units (5), changeover switch (6), Memory (7), encoder (8) and synthesizer (10) are present. 8. Radio telephony system according to one of the preceding claims, characterized in that a rapidly switchable reception bandpass filter is used in duplex operation, the control line of which is connected to the output of the encoder (8) for the reception path or that two reception bandpass filters between the receiver (EE) and the antenna (A) can be switched optionally so that one is in operation and the other is preprogrammed from the memory (7) for the reception path to the next frequency. 9. Radio telephony system according to one of the preceding claims, characterized in that the clock generator (2) and the encoder (8) via a digital signal device, e.g. punch card reader (1, 9) being controlled.