RU2210861C1 - Signal receiving device using pseudorandom operating frequency control - Google Patents

Abstract

FIELD: radio engineering; communication systems using pseudorandom operating frequency control. SUBSTANCE: second, third, and fourth band filters, second and third multipliers, pulse noise blanking unit, attenuator, first and second subtracters, limiter, synchro-phase filter, first, second, third, and fourth delay circuits newly introduced in device have made it possible to generate estimate of narrow-band noise followed by its correction using estimate obtained with the result that information characters transferred at frequencies suffering narrow-band noise are not distorted. EFFECT: enhanced immunity to narrow-band noise. 1 cl, 2 dwg

Description

 The invention relates to the field of radio engineering and can find application in communication systems with pseudo-random tuning of the operating frequency.

 Known devices for receiving signals with pseudo-random tuning of the operating frequency, described in the article V.I. Borisov "Radio communication systems with the expansion of the spectrum of signals", Theory and technique of radio communication, issue 1, 1998, p. 24, Fig. 9, p. 25, fig. 10, p. 26, fig. 11, in the monograph by R.K. Dixon's Broadband Systems, Moscow, Svyaz, 1979, pp. 191-192, the disadvantage of which is low noise immunity to narrowband interference.

 The closest in technical essence to the proposed device is a device for receiving signals with pseudo-random tuning of the operating frequency, described in a monograph by V.I. Borisova et al. "Interference immunity of radio communication systems with the expansion of the signal spectrum by the method of pseudo-random tuning of the operating frequency", Publishing House "Radio and Communication", Moscow, 2000, p. 24, Fig. 1.7b, taken as a prototype.

The structural diagram of the prototype is shown in figure 1, where indicated:
1, 3 - the first and second band-pass filters;
2 - multiplier (mixer);
4 - demodulator;
5 - pseudo-random code generator;
6 - tunable frequency synthesizer.

 The prototype device contains a series-connected first bandpass filter 1, the input of which is the input of the device, a multiplier 2, a second bandpass filter 3, a demodulator 4, the output of which is the output of the device, and a pseudo-random code generator 5, n outputs connected to n control inputs of a tunable synthesizer frequency 6, the output connected to the second, reference input of the multiplier 2.

 The prototype device operates as follows.

The input mixture contains an input mixture containing a signal with a pseudo-random tuning of the operating frequency, which is a sequence of N radio pulses of duration τ _o , modulated by information, the carrier frequencies of which change according to a given pseudo-random code (tuning program), as well as narrow-band interference whose frequencies coincide with signal frequencies.

 The input mixture enters the input of block 1, where it is filtered in the frequency band occupied by the signal with pseudo-random tuning of the operating frequency. From the output of block 1, the input mixture goes to the first, signal, input of block 2, to the second, reference, the input of which receives a reference signal 1 with a pseudo-random tuning of the operating frequency generated by block 6, to the control inputs of which a pseudo-random code is supplied from the outputs of block 5, which determines frequency tuning law of block 6.

 As a result of multiplying the input signal with a reference signal synchronous with it, the input signal is convolved at an intermediate frequency.

, и демодулируется в блоке 4, с выхода которого подается на выход устройства.The signal at an intermediate frequency is filtered in block 3 in a frequency band that is consistent with the duration

, and is demodulated in block 4, the output of which is fed to the output of the device.

Narrow-band interference due to multiplication with a frequency-tunable reference signal is converted at the output of block 2 into pulsed interference of duration τ _o .

 The disadvantage of this device is the low noise immunity to narrowband interference.

 To eliminate this drawback, a device for receiving pseudo-random tunings of the operating frequency, comprising a first band-pass filter, the input of which is the input of the device, a pseudo-random code generator, n outputs of which are connected to n control inputs of a tunable frequency synthesizer, as well as a first multiplier and a second band-connected a filter and a demodulator, the output of which is the output of the device, a second multiplier, a third band phi, are connected in series tr block blanking pulse interference, and the third multiplier, a fourth bandpass filter and attenuator; the first delay element, the first subtractor, the limiter, the synchronous-phase filter and the second subtractor, the output of which is connected to the first, signal input of the first multiplier; the third delay element, the input of which is connected to the output of the tunable frequency synthesizer and the second reference input of the second multiplier, and the fourth delay element, the input of which is also connected to the second reference input of the third multiplier, and the output of the fourth delay element is connected to the second reference input of the first multiplier. A second delay element has been introduced, the output of which is connected to the first input of the second subtractor and to the first, signal input of the synchronous-phase filter. At the same time, the output of the attenuator is connected to the second, reference input of the first subtractor. In addition, the output of the first bandpass filter is connected to the first signal input of the second multiplier and to the first inputs of the first and second delay elements.

The structural diagram of the proposed device is shown in figure 2, where indicated:
1, 3, 8, 11 - the first, second, third and fourth band-pass filters;
2, 7, 10 - the first, second and third multipliers (mixers);
4 - demodulator;
5 - pseudo-random code generator;
6 - tunable frequency synthesizer;
9 - block blanking (notching) impulse noise;
12 - attenuator;
13, 16 - the first and second subtractors;
14 - limiter;
15 - synchronous phase filter;
17, 18, 19 and 20 - the first, second, third and fourth delay elements.

 The proposed device contains a first band-pass filter 1, the input of which is the input of the device; the second multiplier 7, the third bandpass filter 8, the pulse interference blanking unit 9, the third multiplier 10 and the fourth bandpass filter 11, the output of which through the attenuator 12 is connected to the second input of the subtractor 13; a series-connected pseudo-random code generator 5, n outputs of which are connected to n control inputs of a tunable frequency synthesizer 6, the output of which is connected to the second, reference input of the second multiplier 7 and the input of the third delay element 19, the output of which is connected to the second, reference input of the third multiplier 10 and with the input of the fourth delay element 20, the output of which is connected to the second, reference input of the first multiplier 2; the first delay element 17, the first subtractor 13, the limiter 14, the output of which is connected to the second reference input of the phase-synchronous filter 15, the output of which is connected to the second input of the second subtractor 16, the first input of which is connected to the output of the second delay element 18 and c the first signal input of the synchronous-phase filter 15, and the output of the second subtractor 16 is connected to the first multiplier 2, the second band-pass filter 3 and the demodulator 4, the output of which is the output of the device stv; in addition, the first signal input of the second multiplier 7 and the inputs of the first and second delay elements 17 and 18 are combined with each other and with the output of the first band-pass filter 1.

 The proposed device operates as follows.

The input mixture contains an input mixture containing a signal with a pseudo-random tuning of the operating frequency, which is a sequence of N radio pulses of duration τ _o , information-modulated carrier frequencies of which change according to a given pseudo-random code (tuning program), as well as narrow-band interference whose frequencies coincide with the frequencies signal. The input mixture enters the input of block 1, where it is filtered in the frequency band occupied by the signal with pseudo-random tuning of the operating frequency. From the output of block 1, the input mixture is supplied to the first, signal, input of block 7, to the second, reference input of which a reference signal with a pseudo-random tuning of the operating frequency is supplied, synchronous with the input signal generated by block 6. In block 7, the input mixture is multiplied with the reference signal .

. В то же время узкополосные помехи, частоты которых совпадают с частотами входного сигнала с псевдослучайной перестройкой рабочей частоты на выходе блока 7, за счет перемножения с опорным сигналом с псевдослучайной перестройкой рабочей частоты также превращаются в радиоимпульсы, длительностью τ_o, которые также фильтруются блоком 8. Амплитуды радиоимпульсов длительностью τ_o, образовавшихся из узкополосных помех, на выходе блока 8 значительно превышают амплитуду радиоимпульсов полезного сигнала.The result of multiplication (mixing) of the input and reference signals is a sequence of N radio pulses of duration τ _o , which are filtered by the block 8 at the intermediate (difference) frequency. The bandwidth of the block 8 ΔF is consistent with the duration

. At the same time, narrow-band interference whose frequencies coincide with the frequencies of the input signal with pseudo-random tuning of the working frequency at the output of block 7, due to multiplication with a reference signal with pseudo-random tuning of the working frequency, also turn into radio pulses of duration τ _o , which are also filtered by block 8. The amplitudes of the radio pulses of duration τ _o formed from narrow-band interference at the output of block 8 significantly exceed the amplitude of the radio pulses of the useful signal.

 From the output of block 8, the radio pulses of the signal and the radio pulses formed from narrow-band interference arrive at block 9, where the blanking of radio pulses is carried out, the amplitudes of which significantly exceed the expected level of the useful signal. Blanking is carried out by locking the path for a time during which the voltage at the input of block 9 exceeds a threshold value.

 From the output of block 9, a sequence of radio pulses, from which radio pulses excluded by powerful narrowband interference are excluded, are fed to the first, signal, input of block 10, and to the second, reference, the input of which goes through block 19 to the reference signal generated by block 6. Frequency tuning program block 6 is determined by the code sequence generated by block 5, which is supplied in parallel code from n outputs of block 5 to n control inputs of block 6.

 The result of the multiplication (mixing) of the radio pulses of the input signal with the reference signal from the output of block 10 is fed to the input of block 11, where it is filtered at the total frequency in block 11, the passband of which is equal to the frequency band occupied by the input signal with pseudo-random tuning of the operating frequency. At the output of block 11, a signal estimate is extracted — a restored signal with a pseudo-random tuning of the operating frequency, from which radio pulses affected by powerful narrow-band noise are excluded. Evaluation of the signal from the output of block 11 through block 12 is fed to the second input of block 13, where it compensates for the signal in the input mixture supplied to the first signal input of block 13 from the output of block 1 through block 17.

 The delay value of block 17 is selected in the process of setting up the device so as to ensure alignment in time of arrival of the signal with a pseudo-random tuning of the operating frequency and its evaluation at the inputs of block 13.

 The transmission coefficient of block 12 is selected in the process of setting up the device in such a way that the amplitudes of the input signal are aligned and evaluated in such a way that the signal is effectively compensated at the output of block 13.

 By subtracting in block 13 from the input mixture the signal estimates, a narrow-band interference estimate is generated at its output, which is fed through blocks 14 and 15 to the second input of block 16, the first input of which is fed through blocks 1 and 18 to the input mixture. At the same time, the input mixture from the output of block 18 is fed to the first, signal input of block 15.

 In block 14, due to the limitation, the levels of narrow-band interference estimates are fed to the second, reference input of block 15, which is necessary to ensure the constancy of its transmission coefficient when changing the levels of narrow-band interference at the input of the device.

 At the same time, due to the restriction in block 14, the suppression by narrow-band interference (allocated at the output of block 13) of uncompensated signal pulses in block 13 corresponding to those signal pulses that have been detected is suppressed.

 Thus, a level-normalized narrow-band interference estimate is supplied to the second, reference input of block 15, and the input mixture is fed to its first, signal input. Only narrow-band interference is transmitted to the output of block 15, since only they are fed to its second, reference input, and their phases and amplitudes coincide with the phases and amplitudes of the corresponding noise of the input mixture supplied to its first, signal input, i.e., the block 15 provides automatic adjustment of amplitudes and phases of interference estimation to the amplitudes and phases of the corresponding interference in the input mixture.

 From the output of block 16, a signal with a pseudo-random tuning of the operating frequency, cleared of narrow-band interference, is fed to the first signal input of block 2, and a second, reference input of which is supplied with a reference signal with pseudo-random tuning of the working frequency from block 6 through series-connected blocks 19 and 20. In block 2, due to the multiplication (mixing) of the input and reference signals, the input signal is convolved with a pseudo-random tuning of the operating frequency into a sequence of radio pulses, which is at an intermediate frequency filtered by block 3 and demodulated by block 4, the output of which is fed to the output of the device.

 Block 15 can be made as presented in the monograph by V.M. Svistova "Radar signals and their processing", M., "Sov. Radio", 1977, p. 123.

 Block 17 provides time alignment of the signal arrival and its evaluation at the inputs of block 13.

 Block 18 provides alignment of the arrival time of narrowband interference and their assessment at the inputs of block 16.

 Blocks 19 and 20 provide synchronization of the input and reference signals at the inputs of blocks 7 and 2, respectively.

 The delay values of the blocks 18, 17, 19, 20 are selected in the process of setting up the device.

 Block 7 can be made as indicated in the monograph "Mobile Radio Communication Systems". / Edited by I.M. Pyshkina. Moscow, Radio and Communications, 1986, p. 190, Fig. 4.34.

Claims (1)

 A device for receiving signals with a pseudo-random tuning of the operating frequency, comprising a first band-pass filter, the input of which is the input of the device, a pseudo-random code generator, n outputs of which are connected to n control inputs of a tunable frequency synthesizer, as well as a first multiplier, a second band-pass filter and a demodulator connected in series, the output of which is the output of the device, characterized in that the second multiplier, the third bandpass filter, the blanc block are introduced in series pulsed interference, a third multiplier, a fourth bandpass filter and an attenuator, a first delay element connected in series, a first subtractor, a limiter, a phase-synchronous filter and a second subtractor, the output of which is connected to the first signal input of the first multiplier, a third delay element is connected in series, the input of which connected to the output of the tunable frequency synthesizer and to the second reference input of the second multiplier, and a fourth delay element, the input of which is also connected to the second input of the third multiplier, and the output of the fourth delay element is connected to the second reference input of the first multiplier, a second delay element is introduced, the output of which is connected to the first input of the second subtractor and to the first signal input of the synchronous-phase filter, while the attenuator output is connected to the second reference input the first subtractor, in addition, the output of the first bandpass filter is connected to the first signal input of the second multiplier and to the first inputs of the first and second delay elements.

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