RU2308164C1 - Start-stop communication system - Google Patents

Abstract

FIELD: radio communications, possible use in various communication systems.

SUBSTANCE: start-stop communication system contains information source, shift register, manipulator, transmitter, two clock impulse generators, pseudo-random series generator, bearing frequency generator, key, receiver, matched filter, synchronization block, demodulator, communication line, solving block, band filter, interrupter, block for phase auto-adjustment of frequency.

EFFECT: increased probability of correct message receipt, simplified manufacture of device.

2 dwg

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 "Discrete message transmission on channels with feedback with interrupts", "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 according to US Pat. RF 2168867, H04L 25/00, publ. 06/10/2001, Bull. No. 16, adopted as a prototype.

An enlarged functional diagram of the prototype device is shown in figure 1, where it is indicated:

on the transmitting side:

1 - source of information;

2 - shift register;

3 - relatively phase manipulator;

4 - transmitter;

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

6 - pseudo-random sequence generator (GPSP);

8 - carrier frequency generator (LFO);

7 - key;

on the receiving side:

9 - receiver;

10 - matched filter;

11 - sync block;

12 - second clock generator (GTI);

16 - demodulator;

18 - communication line;

19 - multiplexer;

21 - multiplier;

22 - binary counter;

23 - storage unit;

24 - delay line.

The prototype device contains on the transmitting side a series-connected information source 1, a shift register 2, a multiplexer 19, a relative phase manipulator 3 and a transmitter 4. In addition, a first GTI 5, GPSP 6, a multiplier 21 and a binary counter 22 are connected in series; a series-connected LFO 8 and a key 7, the output of which is connected to the signal input relative to the phase 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 first GTI 5 is connected to the clock input of the shift register 2, and the third output of the first GTI 5 - with the second inputs of the GPSP 6 and the multiplier 21, the output of which is connected to the control inputs of the block 3 and the key 7. In addition, the first output of the GTI 5 is connected to the installation input of the binary counter 22, the outputs of which are connected to the control bus conductive multiplexer 19 inputs.

On the receiving side, it contains a receiver 9 connected in series, a matched filter 10, a sync block 11, a demodulator 16 and a storage unit 23, the output of which is the output of the device, as well as a second GTI 12, the input of which is connected to the output of the synchro block 11, the first output of the second GTI 12 is connected to the first input of the storage unit 23, and the second output with the second inputs of the demodulator 16 and the storage unit 23. In addition, the output of the matched filter 10 through the delay line 24 is connected to the third input of the demodulator 16. The transmitting and receiving sides connected via a communication line 18.

The synchro block 11 combines the blocks 14, 15, 16, 17, 18 and 19 of the prototype device, and the numbering of the combined blocks is the same as that adopted in the description of the patent for the prototype device.

Start-stop communication system-prototype works 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 formed at the second output of the first GTI 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 initial setting of GPSP 6 is performed and setting all the bits of the binary counter 22 to a single state, and on the third output, a meander consisting of (n + 1 + S) pulses of duration τ / 2 (where S is the number of transitions of the PSP level from positive to negative), which in block 21 is multiplied with a pseudo-random sequence of the same length coming from the output of the GPS 6.

The positive part of the resulting signal coming from the output of block 21 is used to control the operation of blocks 22, 3 and key 7. At the moment of the leading edge of its first pulse, block 22 is set to zero, key 7 is opened, which passes carrier frequency oscillations to block 3 , and from the output of the multiplexer 19 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 22, a binary number equal to one is set, and the multiplexer 19 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 end of the signal when receiving T.

In block 16, demodulation of the filter 10 coming from the output and delayed in the delay line 24 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 16 determines the pulse coming from the sync block 11, and the moments of the 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 the characters and fix them in the memory block 23. The information is received on the trailing edges of these pulses. from block 23 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 serially connected information source and a shift register, a serially connected manipulator and a transmitter, a first clock pulse generator (GTI) and a pseudorandom sequence generator (GPS), a serially connected carrier frequency generator (LFO) and a key, the output of which is connected to the signal input of the manipulator, and the input of the first GTI is connected to the clock output of the information source, the second output of the GTI is connected It is accessible to the clock input of the shift register, on the receiving side a receiver, a matched filter, a sync block and a second GTI, as well as a demodulator are connected in series, and the output of the transmitter is connected to the input of the receiver via a communication line, according to the invention, a second input connected to the transmitter side is connected to the third output of the first GTI, the output of the shift register is connected to the information input of the manipulator, the GPS output is connected to the first input of the key, the second GPS input is connected to the second output of the first GTI; on the receiving side there is a decision unit, a bandpass filter, a chopper and a phase-locked loop, the output of which is connected to the synchronizing input of the demodulator, the input of the bandpass filter connected to the output of the receiver, the control input of the chopper connected to the output of the sync block, the signal input of the demodulator connected to the output matched filter, the demodulator output is connected to the first input of the decision block, the second input of which is connected to the output of the second GTI, the output of the decision block is device output.

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 - breaker;

15 - phase locked loop (PLL);

16 - demodulator;

17 - a crucial unit (RB);

18 - communication line.

The proposed communication system contains on the transmitting side a series-connected information source 1, PC 2, a manipulator 3 and a transmitter 4, connected in series with the first GTI 5, GPSP 6 and a key 7, the output of which is connected to the signal input 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 the third output of the GTI 5 is connected to the second input of the transmitter 4. In addition, the input of the GTI 5 is connected to the clock output of the information source 1. On the receiving side it contains from connected receiver 9, SF 10, synchro block 11 and second GTI 12, serially connected PF 13, chopper 14, PLL 15, demodulator 16 and RB 17, the output of which is the output of the device, and the input of PF 13 is connected to the output of receiver 9, control input the chopper 14 is connected to the output of the synchroblock 11, the signal input of the demodulator 16 is connected to the output of the SF 10, and the second input of the RB 17 is connected to the output of the second GTI 12, while the transmitting and receiving sides of the device are connected via the communication line 18. The manipulator 3 is phase.

The proposed start-stop communication system operates as follows.

At a random moment of time (for example, t = 0), at the output of information source 1, n (n = 30-40) 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 time, a sequence of (n + S + 1) short pulses with a repetition period τ, which are written and then read with a delay for the time Sτ, is output to the output of the S-bit PC 2 n information symbols 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 containing at the beginning 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” symbols, it opens and the carrier frequency from the output of the LFO 8 arrives at the signal input of the phase manipulator 3, but when the symbols “1” are in effect, 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 synchro block 11, the output of which forms a short pulse at a time corresponding to the end of the amplitude-modulated signal through the SRP when receiving T. Relative to it, with a delay of time τ at the output of the second GTI 12, a sequence of n short pulses with a repetition period τ corresponding to the moments of the end of informational symbols is formed tins at reception. The signal from the output of the receiver 9 also goes to a band-pass filter 13 with a passband of approximately 1.5 / mτ and then through an open chopper 14 to the input of the PLL 15, in which the generator contained in it is tuned in frequency (and phase) to the last m radio pulses of amplitude-modulated signal. After the end of the last pulse from the output of the synchro block 11 prohibits the passage of oscillations through the block 14 for a time n The inertia of the PLL 15 makes it possible to obtain a coherent carrier frequency at its output in the time interval (30–40) τ, which is used for phase detection of the information signal from the output of the SF 10 in the phase demodulator 16. In the decisive block 17 at the moments of the pulses at its second input decisions are made on the reception of information symbols and the corresponding binary symbols are generated at the output.

Thus, the use of the proposed communication system can increase the likelihood of correct reception of the message and simplify its production.

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 a higher noise immunity (see, for example, Fig. 4.23 in the book of N.L. Teplova "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. To make such a delay line is difficult 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. For example, the PLL block can be performed according to the optimal or standard design (see Fig. 13.3 in the book of V. I. Tikhonov “Statistical Radio Engineering.” M .: Sov. Radio, 1966).

Claims (1)

A start-stop communication system comprising, on the transmitting side, a serially connected information source and a shift register, serially connected a manipulator and a transmitter, serially connected a first clock generator (GTI) and a pseudorandom sequence generator (GPS), serially connected a carrier frequency generator (LFO) and a key, the output of which is connected to the signal input of the manipulator, the input of the first GTI connected to the clock output of the information source, the second output of the GTI connected to to the input of the shift register, on the receiving side, a receiver, a matched filter, a sync block and a second GTI, as well as a demodulator are connected in series, and the output of the transmitter is connected to the input of the receiver through a communication line, characterized in that the second input connected to the transmitter side is to the third output of the first GTI, the shift register output is connected to the information input of the manipulator, the GPS output is connected to the first input of the key, the second GPS input is connected to the second output of the first GTI, on the receiving side - a deciding unit, a bandpass filter connected in series, a chopper and a phase locked loop, the output of which is connected to the synchronizing input of the demodulator, the input of the bandpass filter connected to the output of the receiver, the control input of the chopper connected to the output of the sync block, the signal input of the demodulator connected to the output of the matched filter, the demodulator output is connected to the first input of the decision block, the second input of which is connected to the output of the second GTI, the output of the decision block is the output of the device, in addition, the manipulator and the demodulator are made phase.

Images