RU2316905C1 - Start-stop communication system - Google Patents

Abstract

FIELD: radio communications, possible use in wired, radio-relay and space communication systems.

SUBSTANCE: start-stop communication system contains, at receiving side: information source, shift register, manipulator, transmitter, first generator of clock impulses, generator of pseudo-random series, key and generator of carrier frequency, and at receiving side it contains receiver, matched filter, synchronization block, second generator of clock impulses, band filter, first phase detector, solving block, impulse generator, generator of supporting voltage, phase shifter and communication line.

EFFECT: increased probability of correct receipt of message and simplified manufacture.

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Description

The invention relates to electrical and radio communications and can be used in wired, radio, radio relay and space communication systems.

A well-known start-stop communication system (Z.M. Kanevsky, V.I. Ledovskikh "Transfer of discrete messages on channels with feedback with interruptions", "Electrosvyaz", 1970, No. 8, p.6-8), in which before sending a message a “probe key” is transmitted, which is an amplitude-manipulated signal consisting of several elements. However, this system is designed specifically for channels with interruptions (freezing channels), has low noise immunity in the general case, and a high level of probability of false alarm.

Closest to the technical nature of the proposed is a start-stop communication system, given in [1], adopted as a prototype.

The functional diagram of the prototype device is shown in figure 1, where indicated

on the transmitting side:

1 - source of information;

2 - shift register;

3 - manipulator;

4 - transmitter;

5 - the first clock generator;

6 - pseudo-random sequence generator;

7 - key;

8 - carrier frequency generator;

24 - multiplexer;

25 - multiplier;

26 is a binary counter

on the receiving side:

9 - receiver;

10 - matched filter;

11 - sync block;

12 - second clock generator;

23 - communication line;

27 - demodulator;

28 - storage unit;

29 - delay line.

The prototype device contains on the transmitting side a series-connected information source 1, a shift register 2, a multiplexer 24, a manipulator 3 and a transmitter 4. In addition, a first clock generator 5, a pseudo-random sequence generator 6, a multiplier 25 and a binary counter 26 are serially connected; connected in series with the carrier frequency generator 8 and the key 7, the output of which is connected to the signal input of the manipulator 3. The input of the clock pulse generator 5 is connected to the clock output of the information source 1, the second output of the generator 5 is connected to the clock input of the shift register 2, and the third output of the generator 5 is connected to the second inputs of the pseudo-random sequence generator 6 and the multiplier 25, the output of which is also connected to the control inputs of block 3 and key 7. Moreover, the first output of the generator 5 is connected to the installation input of the binary frequency sensor 26, the outputs of which are connected by a bus to the control inputs of multiplexer 24.

On the receiving side, it contains a receiver 9 connected in series, a matched filter 10, a sync block 11, a demodulator 27 and a storage unit 28, the output of which is the output of the device, and a second clock generator 12, the input of which is connected to the output of the sync block 11, the first output is connected to the second input the storage unit 28, and the second output with the corresponding inputs of the demodulator 27 and the storage unit 28. In addition, the output of the matched filter 10 through the delay line 29 is connected to the third input of the demodulator 27. The transmitting and the receiver side is connected via the communication line 23. (Here, in the device 11 — the synchroblock, the blocks 14, 15, 16, 17, 18 and 19 of the prototype device are combined [1]).

Start-stop communication system operates as follows.

At a random moment in time, at the output of information source 1, n information symbols (“0” or “1”) of duration τ are created.

When t = 0, n clock pulses are generated at the second output of clock generator 5, which is equal to the number of pseudorandom sequence elements (PSP) that write information symbols in shift register 2, a short pulse is created at its first output, on the leading edge of which the generator is initially set pseudo-random sequence 6 and setting all the bits of the binary counter 26 to a single state, and at the third output, a meander consisting of (n + 1 + S) pulses of duration τ / 2 (where S is the number of per SRP level moves from a positive to a negative value), which in block 25 is multiplied by a pseudo-random sequence of the same length, coming from the output of the generator 6.

The positive part of the resulting signal from the output of block 25 is used to control the operation of blocks 26, 3 and key 7. At the moment of the leading edge of its first pulse, block 26 is set to zero, key 7 is opened, which passes the carrier frequency to block 3 , and from the output of the multiplexer 24 to the input of block 3 receives a zero signal. As a result of this, oscillations of the carrier frequency with an arbitrary initial phase during the time interval τ / 2 are formed at the output of block 3. Upon receipt of the second positive edge of the signal in the counter 26, a binary number equal to one is set, and the multiplexer 24 reads from the shift register 2 the value of the first information symbol. In this case, the initial phase of the carrier frequency at the output of block 3 remains the same if the first character has a value of unity, and changes to the opposite - otherwise. Thus, at the output of block 3, a relatively phase-shifted signal of duration T is created in which the first radio pulse does not carry information, but serves as a reference for the second radio information pulse.

On the receiving side, a relatively phase-shifted signal after common filtering in the receiver 9 and matched in the filter 10 for a single radio pulse of duration τ / 2 is supplied to the sync block 11, the output of which forms a short pulse at a point in time corresponding to the moment the signal ends when receiving T.

In block 27, demodulation of the filter 10 coming from the output and delayed in the delay line 29 by the time T of the signal is carried out. If neighboring radio pulses have the same initial phases, then the symbol "1" is formed at its output, otherwise - "0". The start of operation of block 27 determines the pulse coming from the sync block 11, and the moments of comparison of the phases of adjacent radio pulses determine the leading edges of the pulses coming from the second output of the generator 12. The decision is made to receive symbols and fix them in the memory block 28 on the trailing edges of these pulses. Reading information from block 28 to the output of the system is carried out by pulses from the second output of the generator 12.

The disadvantages of the prototype device are the low value of the probability of correct reception of the message and the difficulty in manufacturing.

To eliminate these drawbacks, a start-stop communication system containing on the transmitting side a series-connected information source and a shift register, a manipulator and a transmitter; a first clock generator and a pseudo-random sequence generator, as well as serially connected carrier frequency generator and a key whose output is connected to the signal input of the manipulator, the input of the first clock generator is connected to the clock output of the information source, and its second output is connected to the clock input of the shift register, and on the receiving side, a receiver, a matched filter, a sync block and a second clock generator, connected in series with the transmitter output under for prison to the input of the receiver through the communication line; on the transmitting side of the transmitter, a second input is introduced, connected to the third output of the first clock generator, the output of the shift register is connected to the first (information) input of the manipulator, the output of the pseudo-random sequence generator is connected to the control input of the key, and its second input to the second output of the first generator clock pulses; and on the receiving side, an additional deciding unit, a series-connected bandpass filter, a first phase detector, a comparator, a trigger, a second key, a second phase detector and a deciding unit, the output of which is the output of the device, as well as a pulse shaper and a voltage driver and phase shifter connected in series, are introduced moreover, the inputs of the bandpass filter and the driver of the reference voltage are connected to the output of the receiver, the output of the phase shifter is connected to the second input of the second key, the third input is of the second key is combined with the second input of the first phase detector and connected to the input of the phase shifter, the output of the pulse shaper is connected to the second input of the comparator, and its input and the second input of the trigger are connected to the output of the sync block, the second input of the second phase detector is connected to the output of the matched filter, and the clock input the decider block is connected to the output of the second clock generator.

Figure 2 shows the functional diagram of the proposed device, where indicated

on the transmitting side:

1 - source of information;

2 - shift register (PC);

3 - manipulator;

4 - transmitter;

5 - the first generator of clock pulses (GTI);

6 - pseudo-random sequence generator (GPSP);

7 - key;

8 - carrier frequency generator (LFO).

On the receiving side:

9 - receiver;

10 - matched filter (SF);

11 - sync block;

12 - the second GTI;

13 - band-pass filter (PF);

14 - the first phase detector (PD);

15 - a comparator;

16 - trigger;

17 - the second key;

18 - second PD;

19 - a decisive unit (RB);

20 - pulse shaper (FI);

21 - shaper reference voltage (BACKGROUND);

22 - phase shifter;

23 - communication line.

The inventive device contains on the transmitting side a series-connected information source 1, PC 2, a manipulator 3 and a transmitter 4, serially connected to the first GTI 5, the input of which is connected to the clock output of the information source 1, GPS 6 and a key 7, the output of which is connected to the signal output of the manipulator 3 and the second input - with the output of the LFO 8, and the second output of the first GTI 5 is connected to the clock input of PC 2 and the second input of the GPS 6, and its third output is to the second input of the transmitter 4; and on the receiving side it contains serially connected receiver 9, SF 10, synchro block 11 and second GTI 12, serially connected PF 13, first PD 14, comparator 15, trigger 16, second key 17, second PD 18 and RB 19, the output of which is the output devices, as well as FI 20 and series-connected background 21 and phase shifter 22, and the inputs of the PF 13 and background 21 are connected to the output of the receiver 9, the output of the phase shifter 22 is connected to the second input of the second key 17, the third input of the second key 17 is combined with the second input of the first PD 14 and is connected to the input of the phase shifter 22, the output of FI 20 is connected to the second input of the comparator 15, and its input and the second input of the trigger 16 are connected to the output of the sync block 11, the second input of the second PD 18 is connected to the output of the SF 10, and the clock input of the RB 19 is connected to the output of the second GTI 12; the transmitting and receiving sides of the device are connected via a communication line 23.

Start-stop communication system operates as follows.

At a random time (for example, t = 0), at the output of information source 1, n (n = 50-200) information symbols (0 or 1) of duration τ are created, and a short pulse is generated at the first output of the first GTI 5, along the leading edge of which the initial installation of S characters of the pseudo-random sequence (PSP) in GPSP 6 (S <n). At the same moment of time, a sequence of (n + S + 1) short pulses with a repetition period τ, which are alternately recorded and then read with a delay of time Sτ at the output of S - bit PC2 n information symbols, is created at the second output of the GTI 5. The same pulses are read at the output of the GPSP 6 S-bit SRP (S≥7), which is a time-inverse Barker or Neumann-Hoffman code (see, for example, p.407 in J. Spilker's book “Digital Satellite Communication”, M .: Communication, 1979). Moreover, for the same value of S, a code is selected that initially contains the largest number of characters "0". Thus, first, the memory bandwidth is created in the device, and then n information symbols (respectively, at the outputs of blocks 6 and 2).

Under the action on the first input of the key 7 symbols of the SRP “0” symbol, it opens and the carrier frequency from the output of the LFO 8 comes to the signal input of the manipulator 3, but when the symbols “1” act, it does not. Since a zero signal acts on the first input of block 3 in the time interval equal to Sτ, an amplitude-modulated radio signal with the same initial pulse phases is formed at its output, having at the end a radio pulse of a certain duration mτ corresponding to m last symbols of the “0” SRP ( for example, for the Neumann-Hoffman code at S = 10, the maximum value of m is 5).

After the end of the SRP at the signal input of block 3, the carrier frequency is supplied continuously. Under the action of 3 information symbols “0” at the first input of the manipulator, the initial phase of the signal at its output does not change, and when the symbols “1” act, it changes to π.

At the third output of the GTI 5 at t = 0, a pulse of duration (n + S) τ is formed, which turns on the transmitter 4 for the duration of the transmission of the signal generated at the output of block 3.

On the receiving side, the received signal, after common filtering in the receiver 9 and matched in the filter 10 for a single radio pulse of duration τ, is fed to the sync block 11, the output of which forms a short pulse at a point in time corresponding to the end of the amplitude-modulated signal through SRP upon receiving T. Relatively with a delay of time τ at the output of the second GTI 12, a sequence of n short pulses is formed with a repetition period τ corresponding to the moments of the end of information symbols fishing at the reception. The signal from the output of the receiver also goes to a band-pass filter 13 with a bandwidth of approximately 1.5 / mτ, as a result of which, at the end of the amplitude-modulated signal, a true carrier frequency with a large signal-to-noise ratio will act on its output, and on background 21, which generates a signal at its output with a frequency equal to the carrier frequency, which differs in phase relative to the phase of the true carrier (on the transmitting side) randomly by 0 or π, and constructed according to one of the schemes (see, for example, Fig. 4.8-4.12 (without UPCH) in books e P.I.Penina "Radio Data System", M .: Sov. Radio, 1976). To eliminate the uncertainty of the phase of the carrier at reception, blocks 14-17, 20-22 are used. On the leading edge of the pulse at the output of the sync block 11, the trigger 16 is set to zero, and on its trailing edge at the output of the FI 20, a pulse is generated with a duration equal to a certain number of periods of the carrier frequency. The first PD 14 compares in phase the output signals of blocks 13 and 21, and if the phases coincide (at the time of the pulse at the output of FI 20), then a positive signal is generated at the output of block 14, which creates a logic 1 signal at the output of comparator 15, which translates trigger 16 in a single state. In this case, the output from the background 21 is transmitted to the output of the key 17 (i.e., the true carrier frequency), which allows phase detection of the information signal supplied to it from the output of the SF 10. The GTI 12 creates n short pulses with a delay of τ relative to the output pulse block 11, at the time of which positive or negative signals acting on the output of the PD 18, at the output of the RB 19, message symbols 1 or 0 are formed. If the phases of the signals at the inputs of the PD 14 do not match, then the output signal of the key 17 is transmitted phase rotator (at π) 22 and phase detection of the signal will also be correct.

Thus, the use of the proposed device can increase the likelihood of correct reception of the message and simplify its manufacture.

Unlike the prototype, which uses relatively phase-shift keying and a method of comparing the phases during reception, the inventive device uses phase-shift keying, which, as you know, has higher noise immunity (see, for example, Fig. 4.23 in the book of N. L. Teplova "Noise immunity of transmission systems of discrete information", M .: Communication, 1964). The complexity of the device is significantly reduced due to the exclusion from the receiving part of the delay line, which, for example, at τ = 1 ms and S = 10 should have a delay time of 10 ms. It is difficult to produce such a delay line and, in addition, it will be very cumbersome (see page 359 in the book of L.E. Varakin “Communication Systems with Noise-Like Signals”, M .: Radio and Communication, 1985). All blocks included in the device are known.

Information sources

1. RF patent №2168867, Н04L 25/00.

Claims (1)

A start-stop communication system comprising, on the transmitting side, a serially connected information source and a shift register, a serially connected manipulator and a transmitter, a first clock pulse generator and a pseudorandom sequence generator, also a carrier frequency generator and a key, the output of which is connected to the signal input of the manipulator, in series, the input the first clock generator is connected to the clock output of the information source, and its second output is connected to the clock input at the shift register, and on the receiving side, a receiver, a matched filter, a sync block and a second clock generator, connected in series, the output of the transmitter being connected to the input of the receiver via a communication line, characterized in that the second input connected to the third input is introduced on the transmitting side of the transmitter the output of the first clock generator, the output of the shift register is connected to the first information input of the manipulator, the output of the pseudo-random sequence generator is connected to the control input key a, and its second input is to the second output of the first clock generator, an additional series-connected bandpass filter, a first phase detector, a comparator, a trigger, a second key, a second phase detector and a deciding unit, the output of which is the output of the device, are introduced at the receiving side also a pulse shaper and a series-connected reference voltage shaper and a phase shifter, the inputs of the bandpass filter and the voltage shaper being connected to the output of the receiver, the phase shifter output For connected to the second input of the second key, the third input of the second key is combined with the second input of the first phase detector and connected to the input of the phase shifter, the output of the pulse shaper is connected to the second input of the comparator, and its input and the second input of the trigger are connected to the output of the sync block, the second input of the second phase the detector is connected to the output of the matched filter, and the clock input of the deciding unit is connected to the output of the second clock generator, while at the third output of the first clock generator of the form A pulse is generated, which arrives at the second input of the transmitter and turns it on during the transmission of the signal generated at the output of the manipulator, and message symbols 1 or 0 are generated at the output of the decision block.

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