RU2168864C2 - Radio communication system - Google Patents

Abstract

FIELD: radio engineering, radio-relay links, space communication lines. SUBSTANCE: given radio communication system has on transmitting side switch, analog-to-digital converter, generator of modified Reed- Muller code, modulator-transmitter, transmitting antenna, four-digit counter, two double input AND gates, adder, modulo 2 adder, three-input AND gate and controllable inverter. EFFECT: increased noise immunity of radio communication system by improvement of correlation properties of signals-information carriers by way of reduction of amplitude of side peaks of autocorrelation functions of these signals. 8 dwg, 1 tbl

Description

 The invention relates to communication technology and can be used in microwave and space communication lines.

 A known communication system containing on the transmitting side information sources, channel modulators, an adder, a transmitter, a sync block, a sequence generator, switches, on the receiving side is a receiver, optimal processing units, symbol shapers, recorder units, a switch, adders, storage devices, a subtraction unit, synchro block, shaper of clock pulses (see USSR author's certificate N 1622949, class H 04 B 7/00, 1989).

 However, this communication system uses orthogonal signals without taking into account their autocorrelation functions, which leads to low noise immunity of the entire radio communication system.

 Closest to the technical nature of the present invention is a radio communication system containing on the transmitting side a switch, an analog-to-digital converter, a modified Reed-Muller code generator, a modulator-transmitter, a transmitting antenna, the switch inputs being information inputs of a radio communication system, the output of the switch connected to the input of the analog-to-digital converter, the outputs of which are connected to the inputs of the modified Reed-Muller code generator, the output of which is connected to the modulator input a-transmitter, the output of the modulator-transmitter is connected to the input of the transmitting antenna, and on the receiving side is the receiving antenna, receiver, delay line, decoding matrix, synchronous generator, maximum signal detector, digital conversion matrix, indicating and recording equipment, and the output of the receiving antenna connected to the input of the receiver, the output of which is connected to the input of the delay line, the information outputs of the delay line are connected to the inputs of the decoding matrix, the outputs of which are connected to the information inputs of the detector The peak of the maximum signal, the synchronous input of which is connected to the output of the synchronous generator, the input of which is connected to the clock output of the delay line, the outputs of the maximum signal detector are connected to the inputs of the digital conversion matrix, the outputs of which are connected to the inputs of the indicating and recording equipment (see Transmission of digital information. Per. from English M.N. Arone, B.N. Kurochkina and A.V. Tatarinova. Ed. S.I. Samoilenko. - M .: Publishing house of foreign literature, 1963, p. 189).

 However, in this radio communication system, orthogonal signals are used, which are described by sequences of the modified Reed-Muller code, and they are not sufficiently high noise immunity, since they have poor correlation properties, since the amplitudes of the side peaks of the autocorrelation functions of these signals are only slightly less than the amplitudes of the central peak.

 1. The aim of the invention is to increase the noise immunity of a radio communication system by improving the correlation properties of information carrier signals by reducing the amplitude of the side peaks of the autocorrelation functions of these signals.

 This goal is achieved by the fact that in a known radio communication system containing a switch on the transmitting side, an analog-to-digital converter, a modified Reed-Muller code generator, a modulator-transmitter, a transmitting antenna, the switch inputs being information inputs of a radio communication system, the output of the switch is connected to the input of the analog-to-digital converter, the outputs of which are connected to the inputs of the modified Reed-Mueller code generator, the output of the transmitter-modulator is connected to the input of the transmitting antenna, and the receiving side is a receiving antenna, a receiver, a delay line, a decoding matrix, a synchronous generator, a maximum signal detector, a digital conversion matrix, indicating and recording equipment, and the output of the receiving antenna is connected to the input of the receiver, the output of which is connected to the input of the delay line, information outputs of the line delays are connected to the inputs of the decoding matrix, the outputs of which are connected to the information inputs of the maximum signal detector, the synchronous input of which is connected to the output of the synchronous a nerator, whose input is connected to the clock output of the delay line, the outputs of the maximum signal detector are connected to the inputs of the digital conversion matrix, the outputs of which are connected to the inputs of the indicating and recording equipment, a four-digit counter, two two-input elements And, an adder, an adder modulo two, three-input element are introduced And a controlled inverter, and the clock output of the modified Reed-Muller code generator is connected to the counter input of the counter, the direct output of the first discharge of the counter is connected to the first at the input of the first two-input element And and to the first input of the three-input element And, the direct output of the second discharge of the counter is connected to the second input of the three-input element And, the direct output of the third discharge of the meter is connected to the first input of the second two-input element And and to the third input of the three-input element And, direct output the fourth discharge of the counter is connected to the second input of the first two-input element And, the inverse output of the fourth discharge of the meter is connected to the second input of the second two-input element And, the outputs are two new elements And are connected to the inputs of the adder, the output of which is connected to the first input of the adder modulo two, the second input of which is connected to the output of the three-input element And, the output of the adder modulo two is connected to the control input of the controlled inverter, the information input of which is connected to the information output of the modified generator Reed-Muller code, the output of the controlled inverter is connected to the input of the modulator-transmitter.

 In FIG. 1 is a structural diagram of a radio communication system; FIG. 2 is a timing diagram illustrating the process of generating a signal S (10, θ) in the proposed radio communication system, FIG. 3 is a timing diagram of the signals of the prototype; FIG. 4 - autocorrelation functions of the signals used in the prototype, in FIG. 5 is a timing chart of the signals of the proposed radio communication system, FIG. 6 - autocorrelation functions of the signals used in the proposed radio communication system.

 The radio communication system contains on the transmitting side a switch 1, an analog-to-digital converter 2, a modified Reed-Muller code generator 3, a four-digit counter 4, a first two-input element And 5, a second two-input element And 6, adder 7, adder 8 modulo two, a three-input element And 9, a controlled inverter 10, a modulator-transmitter 11, and on the receiving side, a receiver 12, a delay line 13, a synchronous generator 14, a decoding matrix 15, a maximum signal detector 16, a digital conversion matrix 17, indication and indication equipment 18 istratsii.

 A radio communication system operates as follows. Information in analog form is fed to the information inputs of switch 1, which connects the corresponding input to its output, whereby the output voltage of the switch is supplied to analog-to-digital converter 2. Information from the outputs of converter 2, defined by five binary symbols that appear in parallel as signals " 0 "and" 1 ", is fed to the inputs of the generator 3 of the modified Reed-Muller code. In accordance with the value of the binary symbols of the five-bit group supplied to the inputs of the generator 3, one of the signals generated by the sequence of the modified Reed-Muller code is generated at its output.

 From the clock output of the generator 3 of the modified Reed-Muller code to the counting input of the counter 4, a sequence of clock pulses (Fig. 2a) is received that determine the duration of the signals described by the sequences of the modified Reed-Muller code generated by the generator 3. At the discharge outputs of the counter 4, pulse sequences of the corresponding duration and frequency. The sequence of pulses from the direct output of the first discharge of the counter 4 (Fig. 2b) is fed to the first input of the first element And 5, the second input of which is fed a signal from the direct output of the fourth discharge of the counter 4 (Fig. 2e). The pulse sequence from the direct output of the third discharge of the counter 4 (Fig. 2d) is supplied to the first input of the second element And 6, the second input of which is fed a signal from the inverse output of the fourth discharge of the counter 4 (Fig. 2e). As a result, during the first half-cycle of generating the sequence of the modified Reed-Muller code by the generator 3, the output of the adder 7 generates a sequence of pulses coming from the output of the And 6 element (Fig. 2g), and during the second half-cycle - the sequence of pulses coming from the output of the And 5 element (Fig. 2h). The signal from the output of the adder 7 (Fig. 2i) is fed to the first input of the adder 8 modulo two. The second input of the adder 8 modulo two at the eighth and sixteenth clock cycles of the generator 3 receives the characters "1" (Fig. 2nd), because at these times on all three inputs of the element And 9 there are characters "1" from the outputs of the first, second and third digit counter 4.

 As a result, at the output of the adder 8 modulo two, a signal appears (Fig. 2g), which arrives at the control input of the controlled inverter 10. The control inverter 10 upon receipt of its control input "O" generates a signal at its output that does not differ from that received at its information entrance. Upon receipt of "1" at its control input, the output signal is inverted (for controlled inverters see the Basics of discrete ACS and communication technology. Under the general editorship of GF Grinenko -L .: VIKI, 1980).

 Thus, the signals S (i, θ) are generated at the output of the controlled inverter 10 (Fig. 2m), the shape of which differs from the signals described by the sequences of the modified Reed-Muller code R (i, θ) (Fig. 2l). The signals R (i, θ) carry out phase modulation of the carrier in the carrier modulator. In this case, the modulation index is selected so that the carrier power in the transmitted signal is a small fraction of the total transmitted power (see Transmission of digital information. Translated from English by M.N. Arone, B.N. Kurochkina, and A.B. Tatarinov. Edited by S.I. Samoilenko. -M.: Publishing House of Foreign Literature, 1963, p. 193).

 The received signal is fed to the input of the receiver 12, which monitors the phase of the carrier frequency of the incoming signal. The envelope of the signals from the output of the receiver 12 is fed to the input of the delay line 13, the outputs of which are connected to the inputs of the decoding matrix 15. The combination of the delay line 13 and the decoding matrix 15 is a set of matched filters (the filters are matched with the analogs generated at the output of the controlled inverter 10. The outputs of the matrix 15 are connected to the inputs of the maximum signal detector 16, which detects the most probable transmitting signal.The detector 16 generates a voltage at its output corresponding to a matched filter, in which The maximum voltage is detected.The synchronization of the samples by the maximum signal detector 16 is controlled by the synchronous generator 14. The digital conversion matrix 17 converts the output number of the detector 16 corresponding to its input number, on which the maximum voltage is detected, into five binary symbols that appear in parallel in the form signals "0" and "1" at the outputs of matrix 17. This five-digit combination coincides with the combination applied to the information inputs of the generator 3 sequences her modified Reed-Muller code on the transmitting side. Further, the signals from the outputs of the digital conversion matrix are fed to the inputs of the indicating and recording equipment that converts the digital signals into analog form (see Transmission of digital information. Transl. From English. M.N. Arone, B.N. Kurochkina and A. B. Tatarinova Edited by S.I. Samoilenko. -M.: Publishing House of Foreign Literature, 1963, p. 193).

In FIG. 2 is a timing diagram illustrating the process of generating a signal S (10, θ) in the proposed radio communication system. The diagrams show the temporary state:
a) the clock output of the generator 3 of the modified Reed-Muller code;
b) direct output of the first discharge of the counter 4;
C) direct output of the second discharge of the counter 4:
d) direct output of the third category of the counter 4;
d) direct output of the fourth category of the counter 4;
e) the inverse output of the fourth discharge of signal 4;
g) the output of the second two-input element And 5;
h) the output of the first two-input element And 6;
i) the output of the adder 7;
j) the output of the three-input element And 9;
j) the output of the adder 8 modulo two;
k) the information output of the generator 3 of the modified Reed-Muller code on which the signal R (10, θ) is generated;
m) the output of the controlled inverter 10, on which the signal S (10, θ) is generated.

 It is known that the condition for high noise immunity of a communication system using complex signals is reliable synchronization of the transmitting and receiving parts (see Dikson R.K. Broadband systems. - M .: Communication, 1979).

 To establish reliable synchronization of the transmitting and receiving parts, it is necessary to use signals having small side peaks of the autocorrelation functions. Such signals are called signals with good correlation properties (see L. Varakin, “Detection of complex signals and measurement of their parameters. Radio engineering and electronics, N 8, 1973, p. 1591-1597).

 Indeed, in the radio communication systems of this type, to ensure synchronization, a set of special code combinations is used that have a specific autocorrelation function that allows you to determine the timing of synchronization (see Digital Information Transmission. Transl. From English M.N. Arone, B.P. Tatarinova. Edited by S. I. Samoilenko. - M.: Publishing House of Foreign Literature, 1963, p. 190, paragraph 2 above).

где где τ - величина временного сдвига сигнала.It is known that the autocorrelation function of a signal is determined by the expression:

where where τ is the value of the time shift of the signal.

 From expression (1) it can be seen that R (i) characterizes the degree of connection (correlation) of the signal with its copy shifted by the value of τ along the time axis.

т. е. максимальное значение автокорреляционной функции равно энергии сигнала (см. Гоноровский И.С. Радиотехнические цепи и сигналы. М.: Советское радио, 1971, с.68).It is clear that the function R (i) reaches its maximum at τ = 0, since any signal is completely correlated with itself. Wherein:

i.e., the maximum value of the autocorrelation function is equal to the signal energy (see IS Gonorovsky, Radio Engineering Circuits and Signals. M.: Soviet Radio, 1971, p. 68).

For the case of signals normalized by energy with E = 1 taken into account, the autocorrelation function of the FM SLM consists of a central peak with amplitude 1 located in the interval (-τ _0, τ ₀ ) and side peaks distributed in the intervals (-T, -τ ₀ ) and (τ ₀ , T) The amplitudes of the side peaks take different values, but for signals with good correlation properties they are small, i.e. significantly less than the amplitude of the central peak, equal to 1 (see Varakin L.E. Communication systems with noise-like signals. - M .: Radio and communication, 1985, p.30).

 The values of the side peaks of the autocorrelation function, which are usually less than the main one, depend on the actual used code sequence (in our case, the carrier signal) and are the result of a partial correlation of the code sequence with the same code sequence shifted in time. With the occurrence of such lateral peaks of the correlation function, the ability of the receiver of the system to establish reliable synchronization deteriorates, since in this case it must distinguish between the main and maximum lateral peaks of the correlation function (see Dikson R.K. Broadband systems. - M.: Communication, 1979, p. 67).

 The autocorrelation function is of greatest interest in the choice of sequences to obtain the least probability of establishing false synchronization (see Dikson R.K. Broadband systems. - M .: Communication, 1979, p. 64).

 The correlation properties of the code sequence characterize the distinguishability index (PR), defined as the difference between the values of the autocorrelation function corresponding to the main and maximum side peaks. Obviously, the larger the PR, the better the code sequence (see Dixon R.K. Broadband Systems. -M.: Communication, 1979, p. 65, and also p. 66, Fig. 3.11).

 The sequences of the modified Reed-Muller code used in the prototype have low indistinguishability indices. To obtain signals with high distinguishability indices, the proposed radio communication system changes the shape of the sequences of the modified Reed-Muller code by using certain signal elements for inverting them, generated at the output of the adder 8 modulo two.

 The resulting signals have improved correlation properties.

 For the signals used in the prototype (sequences of the modified Reed-Muller code), and the signals used in the proposed radio communication system, energy-normalized taking into account E = 1, the autocorrelation Functions and distinguishability indices were calculated. The calculation results are presented in the table.

(см. с. 1594, соотношение (10)),

- отношение сигнал-шум
(см. с. 1592, соотношение (1)).In the proposed radio communication system, the distinguishability indicator is 37.5% higher than in the prototype (as can be seen from the table), which leads to an increase in its noise immunity, since in order to increase the noise immunity it is necessary to provide a given probability of occurrence in the correct synchronism or a given probability of correct signal detection (see Varakin LE "Detection of complex signals and measurement of their parameters". Radio engineering and electronics. N 8, 1973, S. 1591-1597). The presence of large peaks of the autocorrelation function affects the decrease in the probability of correct detection of the signal P _rights . The marked article indicates that the lateral peak P _{max has} practically no effect on P _rights , if:

(see p. 1594, relation (10)),

- signal to noise ratio
(see p. 1592, relation (1)).

R _max for the signals generated by the prototype, has a value of 0.5, and for signals generated by the proposed radio communication system, 0.3125 (see table).

From relation (3) it follows that in order to ensure the same P _rights for the prototype and the proposed radio communication system, it is necessary to provide a signal-to-noise ratio in the prototype q> 12, and in the proposed radio communication system q> 8.727. Thus, the gain in signal-to-noise ratio is 27.27%, that is, the proposed radio communication system is more noise-resistant.

Claims (1)

 A radio communication system containing a switch on the transmitting side that connects the corresponding input to its output, an analog-to-digital converter, a modified Reed-Muller code generator, a modulator-transmitter, a transmitting antenna, the switch inputs being information inputs of a radio communication system, and the switch output connected to the input converter analog - digital, the outputs of which are connected to the inputs of the generator of the modified Reed-Muller code, the output of the modulator-transmitter is connected to the input of the transmitter a receiving antenna, and on the receiving side, a receiving antenna, a receiver, a delay line, a decoding matrix, a synchronous generator, a maximum signal detector, a digital conversion matrix, indicating and recording equipment, the output of the receiving antenna connected to the input of the receiver, the output of which is connected to the line input delays, information outputs of the delay line are connected to the inputs of the decoding matrix, the outputs of which are connected to the information inputs of the maximum signal detector, the synchronous input of which is connected to the output ohm of a synchronous generator, the input of which is connected to the clock output of the delay line, the outputs of the maximum signal detector are connected to the inputs of the digital conversion matrix, the outputs of which are connected to the inputs of the information and recording equipment, characterized in that a four-digit counter, two two-input elements And, an adder are introduced into it , adder modulo two, three-input element And and a controlled inverter, moreover, the clock output of the modified Reed-Muller code generator is connected to the counter input of the counter, direct output before the first discharge of the counter is connected to the first input of the first two-input element And and to the first input of the three-input element And, the direct output of the second discharge of the meter is connected to the second input of the three-input element And, the direct output of the third discharge of the meter is connected to the first input of the second two-input element And to the third input three-input element And, the direct output of the fourth discharge of the counter is connected to the second input of the first two-input element And, the inverse output of the fourth discharge of the counter is connected to the second input of of the two-input element And, the outputs of the two-input elements And are connected to the inputs of the adder, the output of which is connected to the first input of the adder modulo two, the second input of which is connected to the output of the three-input element And, the output of the adder modulo two is connected to the control input of the controlled inverter, the information input of which connected to the information output of the generator of the modified Reed-Muller code, the output of the controlled inverter is connected to the input of the modulator-transmitter.

Images