Start-stop communication system

 

(57) Abstract:

The invention relates to electro - and radio and can be used in wired, radio, microwave and satellite communication systems. The technical result consists in increasing the noise immunity and reducing energy costs. Introduction to the device on the transmission side series-connected multiplexer and relative phase of the manipulator, as well as multiplier and a binary counter, and at the receiving side drive, electronic differentiator pulse shaper, a storage unit and a delay line reduced energy costs. 3 Il.

The invention relates to electro - and radio and can be used in wired, radio, and microwave and satellite communication systems.

Known start-stop communication system (H. M. Kanevsky, V. I. Ledovskikh "Transmission of discrete messages over channels with feedback from the interrupt. "Electrosvyaz", 1970, N 8 (C. 6 - 8), in which before sending the message is transmitted probing key" representing the amplitude-shift keyed signal, consisting of several elements. However, this system is specially designed for channels with preryvanii anxiety.

The closest in technical essence to the present invention is start-stop communication system described in "communication Systems with noise-like signals", L. E. Varakin, M.: Radio and communication, 1985, pp. 323 - 325, 281 - 287 adopted for the prototype.

The block diagram of the device of the prototype is shown in Fig. 1, where indicated:

on the transmission side:

1 - source of information;

2 - the shift register;

3 - adder;

4 - modulator;

5 transmitter;

6 is the first generator of clock pulses;

7 is a pseudo - random sequence generator;

10 - generator carrier frequency;

11 - key;

at the receiving side:

12 receiver;

13 - coherent filter;

14 - amplitude detector;

15 - search block;

16 - threshold block;

18 - breaker;

the 20 - second clock pulses;

22 - demodulator;

24 - line.

The device prototype contains on the transmission side connected in series source 1, the shift register 2, the adder 3, a modulator 4 and the transmitter 5. Thus synchrolift information source 1 connected in series through the first clock 6 and the pseudo-random sequence generator the m input of the shift register 2. The third output of the first clock pulse 6 is connected to one of the outputs of the key 11, the output of which is connected with the second input of the modulator 4, the second output of which is connected to the input of the generator carrier frequency 10, the output of which is connected to another input key 11.

At the receiving side includes serially connected receiver 12, a coherent filter 13, the amplitude detector 14, the search block 15, the circuit breaker 18, the threshold unit 16, the second clock 20 and the demodulator 22 whose output is the output device. The second input of the demodulator 22 is connected to the output of receiver 12. The output of the threshold unit 16 simultaneously connected to a second input of circuit breaker 18.

The transmission and reception side are connected through the communication line 24.

Function prototype as follows.

Consider a communication system for the case of signal transmission by frequency-shift keying.

In the information source 1 generates a sequence of n binary information signal duration . At the time of its inception in the first clock 6 produced by n clock pulses equal to the number of elements pseudorandom polainas sequence 7, on the other exit - n clock pulses for recording information in the shift register 2 and the point in time corresponding to the end of the formation of the SRP, - n clock pulses, the read out of it n information symbols at the first input of the adder 3. The aggregate signal is used to manipulate the frequency of the oscillator carrier frequency 10 by means of the modulator 4. The key 11, controlled by the signal from the third output clock pulse 6, transmits the vibrations of the generator carrier frequency 10 to the second input of the modulator 4 during the time interval equal to the total duration of the SRP, and informational messages. After appropriate filtering in block 4 of the oscillations of the generator carrier frequency 10 is fed to the input of the transmitter and then to the input line 24. The output signal from the receiver 12 after matched filtering frequency-shift keyed SRP oscillation and its amplitude detection is supplied to the search block of the SRP time on the observation interval equal to the duration of the SRP. At the moment the search is completed through the switch 18 to the input of the threshold unit 16 receives a short pulse with an amplitude equal to the maximum signal value of the observation interval, is the interruption of the output pulses 20 are formed of n clock pulses, required in block 22 for demodulation FM messages.

The disadvantage of this device prototype is a low noise immunity and higher energy costs.

To address these shortcomings in the device containing on the transmission side, the United source of information and a shift register connected in series generator of clock pulses and the pseudo-random sequence generator, connected in series generator carrier frequency and the key, as well as the transmitter, and synchrolift information source connected to the input of the first clock, the second output of which is connected to a clock input of the shift register; at the receiving side, the United receiver, coherent filter and amplitude detector, and a threshold unit, the circuit breaker and connected in series with the second clock and the demodulator, thus the output of the transmitter connected to the receiver input line entered on the transmission side, the United multiplexer and relative phase manipulator, as well as the multiplier and a binary counter; at the receiving side; drive, differencer the side of the output of the first clock pulses simultaneously connected with the installation input binary counter, n outputs which the bus is connected to the control inputs of the multiplexer, n other input of which is connected to the n outputs of the shift register; the output of a pseudorandom sequence generator connected to the first input of the multiplier, the output of which is simultaneously connected to a second input of the binary counter and control inputs relative to the phase of the manipulator and key, the output of which is connected to the signal input relative to the phase of the manipulator, in addition, the third output of the first pulse generator simultaneously connected with the second inputs of the pseudo-random sequence generator and multiplier.

At the receiving side output of the amplitude detector connected in series through the drive, the threshold unit, differentiating chain breaker and a pulse shaper simultaneously connected to the input of the second clock and control inputs of the breaker and the demodulator, the output of which is connected to the first input of the memory block whose output is the output of the device, and the second and third inputs of the storage unit connected to respective outputs of the second clock pulses; besides, agreed the proposed device, where indicated:

on the transmission side:

1 - source of information;

2 - the shift register;

3 - multiplexer;

4 - relative phase manipulator;

5 transmitter;

6 is the first generator of clock pulses;

7 is a generator of pseudorandom sequences;

8 - multiplier;

9 is a binary counter;

10 - generator carrier frequency;

11 - key;

At the receiving side:

12 receiver;

13 - coherent filter;

14 - amplitude detector;

15 - drive

16 - threshold block;

17 - differentiating chain;

18 - breaker;

19 - the pulse shaper;

the 20 - second clock pulses;

21 is a storage unit;

22 - demodulator;

23 - delay line;

24 - line.

The inventive device includes on the transmission side connected in series source 1, the shift register 2, the multiplexer 3, relative to the phase manipulator 4 and the transmitter 5. In addition, connected in series, the first clock pulse 6, the pseudo-random sequence generator 7, the multiplier 8 and the binary counter 9; connected in series generator carrier frequency 10 and the preset pulse 6 is connected with engravida information source 1, the second output of the generator 6 is connected to the clock input of the shift register 2, and the third generator output 6 - with the second inputs of the pseudo-random sequence generator 7 and the multiplier 8, the output of which is simultaneously connected to the control inputs of the block 4 and key 11. Moreover, the first output of the generator 6 is connected to the installation by the input of a binary counter 9, the outputs of which are connected to the bus control inputs of the multiplexer 3.

At the receiving side includes serially connected receiver 12, a coherent filter 13, the amplitude detector 14, a memory 15, a threshold unit 16 differentiating the chain 17, the switch 18, the pulse shaper 19, the second clock 20, and a storage unit 21, the output of which is an output device. Moreover, the output of pulse shaper 19 is simultaneously connected to the control inputs of the circuit breaker 18 and the demodulator 22. The second output of the second generator of clock pulses 20 are simultaneously connected to the corresponding inputs of the demodulator 22 and a storage unit 21, the first input connected to the output of the demodulator 22.

In addition, the output of the matched filter 13 through the delay line 23 is connected to the third input of the demodulator 22.

At a random point in time at the output of the information source 1 are n information symbols ("0" or "1") duration (for example, n = 3, Fig. 3A).

At t = 0 on the second output clock pulses 6 are formed of n clock pulses (Fig. 3b), which record information symbols in the shift register 2, at its first output is created by a short pulse (Fig. 3b), on the leading edge of which is the initial installation of a pseudorandom sequence generator 7 and setting all bits of the binary counter 9 in one state, and the third output is a square wave is composed of (n+1+S) pulse duration /2 (Fig. 3G, S = 1), in which the block 8 is multiplied by with a pseudo-random sequence of the same length coming from the output of the generator 7 (Fig. 3D).

The positive part of the resulting signal fed from the output of the unit 8 (Fig. 3E), is used to control the operation block 9, 4, and key 11. At the time of actions leading edge of the first pulse unit 9 is set in the zero state, opens the key 11, which transmits the vibrations of the carrier frequency in unit 4, and the output of the multiplexer 3 to the input unit 4 receives a zero signal. In the result, the output of block 4 FD is of the second positive edge triggered (Fig. 3E) in the counter 9 is set to a binary number equal to the unit and the multiplexer 3 reads from the shift register 2, the value of the first information symbol. During this initial phase of the carrier frequency at the output of block 4 remains the same, if the first character is the unit value and is changed to the opposite otherwise. Thus the output of block 4 has a relatively photomanipulating signal (Fig. I), in which the first radar pulse information does not, and serves as a reference for already the second radar pulse information.

At the receiving side relative to photomanipulating signal after filtering in the receiver 12 and the agreed - in filter 13 for a single radar pulse duration /2 is supplied to the amplitude detector 14 with the output of the separation capacity. Its bipolar output signal type (Fig. 3E), but with triangular pulses optimally accumulate in the block 15 and its output signal is formed, having a form of the autocorrelation function of the fluctuations at the output of the amplitude detector 14, with a maximum value at time T (Fig. 3i). The signal that exceeded the threshold V in the block 16, and then differentiated. At the moment of passage of the differentiation through N. the crime of the signal at its input during the time interval TC. In block 22 is demodulated received from the output of the filter 13 and delayed in the delay line 23 at time T of the signal. If the neighboring radio pulses have the same initial phase, it outputs the symbol "1", otherwise "0". Getting started unit 22 determines the pulse received from the pulse shaper 19 and moments comparing the phases of the neighboring radio - fore fronts of the pulses from the first output of the generator 20 (Fig. 3K.) Trailing fronts of these pulses is the decision on the admission of the characters and their fixation in the storage unit 21. Reading data from the block 21 to the output of the system is supplied with pulses from the second output of the generator 20 (Fig. 3l).

Length SRP in the communication system (n+1+S), or large (this value is determined by the total number of transmitted information symbols and one reference signal and the number of transitions in its level from a positive to a negative value S.

Thus, the application of the proposed start-stop communication system can improve its robustness when data reception and reduce energy costs during transmission.

In start-stop communication systems pause between sessions intended to provide reasonable values of probability of false alarms (of the order of 10-5- 10-8) would significantly increase the length of the timing and energy costs for its transfer.

In the proposed system (n+1) radio pulses are used for joint transmission of messages and parts of the clock and only S - for other elements of the clock. Even with very short lengths of messages n = 12 - 15 this allows you to provide a value of probability of false alarm 10-8- 10-10when the interval of a few hours. Moreover, the value of S does not exceed 30% of the total length of the transmitted signal (see, e.g., Barker codes and Neumann-Hoffman in table. 14.4 books ... Spilker "Digital satellite communications", M.: Communication, 1979). Thus, we achieve a reduction in energy costs for the transmission signal.

In addition, in the communication system elements synchronization signal is transmitted using Manchester code (S. 427, D. Spilker), which allows for passing in time information of radio and used to transmit information relative phase shift keying (with no pauses between impulses when there significantly increase out-of-band radiation and intersymbol distortion, which does not allow you to implement it is: Link 1970). Compared to orthogonal signals when they are incoherent reception in the known system there provides 1 - 2 orders of magnitude greater noise immunity.

All devices included in the communication system are known. Principles and devices there provided in the book by N. T. Petrovich "Transmission of discrete information channels with phase shift keying". M: Owls. radio, 1965. The drive 15 is aligned with the envelope of the received signal and can be performed on the delay line with taps with corresponding phasers at them and the adder (see the book of L. E. Varakin "communication System with noise-like signals", M.: Radio and communication, 1985, Fig. 21.4).

Start-stop communication system containing on the transmission side connected in series source of information and a shift register connected in series of the first clock and the pseudo-random sequence generator, connected in series generator carrier frequency and the key and the transmitter, synchrolift information source connected to the input of the first clock, the second output of which is connected to a clock input of the shift register at the receiving side connected in series receiver according to the second clock and the demodulator, thus the output of the transmitter connected to the input of the receiver communication line, characterized in that the input on the transmission side connected in series multiplexer and relative phase manipulator, as well as the multiplier and a binary counter, the n outputs of which are connected by a bus with n control inputs of the multiplexer, respectively, n the other input of which is connected by bus with n outputs of the shift register, the first output of the first clock pulses is connected to the adjusting input binary counter, the third output of the first clock pulses is connected with the second inputs of the pseudo-random sequence generator and the multiplier, a first input connected to the output of a pseudorandom sequence generator, thus the output of the multiplier simultaneously connected to a second input of the binary counter and control inputs key and relative phase of the manipulator, a signal input connected to the output of the key, and the output relative to the phase of the manipulator is connected to the transmitter, at the receiver side entered the drive, differentiating chain, a pulse shaper, a storage unit and a delay line, the output of the amplitude detector through the POS pulse is connected to the input of the second clock and control inputs of the breaker and demodulator, the output of which is connected to the first input of the storage unit, the second and third inputs of which are connected to the respective outputs of the second clock pulses, the output of the storage unit is output, in addition, the output of the matched filter through the delay line is connected to the third input of the demodulator.

 

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