RU2280326C2 - Method and device for receiving pseudorandom operating frequency tuning signals - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: device implementing proposed method designed for use in pseudorandom operating frequency tuning radio communication systems and in monitoring systems of the latter has first and second band filers 1 and 3, respectively, first and second multipliers 2 and 16, respectively, demodulator 4, first, second, third, and fourth delay lines 4, 5, 7, and 9, respectively, adjustable frequency synthesizer 6, first, second, third, and fourth spectrum analyzers 10, 11, 12, and 13, respectively, first and second subtracters 14 and 15, respectively, comparator 17, and maximal higher-than-threshold component searching unit 18.

EFFECT: ability of signal reception and demodulation in case of a priori uncertain pseudorandom operating frequency tuning program.

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Description

The proposed method and device relate to the field of radio engineering and can find application in radio communication systems with pseudo-random tuning of the operating frequency (PFC) and in control systems of radio communication systems with PFC.

Known methods and devices for receiving signals with pseudo-random tuning of the operating frequency (ed. Certificate of the USSR No. 403084, 1291984, 1381721, 1742741, 1760471; RF patents No. 2161863, 2215370, 2219656; US patents No. 5077538, 5379046; WO patents No. 96/10309, 96/19877. "Foreign Radio Electronics", 1979, No. 3, p. 42-51; Chistyakov NI Radio receivers. - M .: Sov. Radio, 1978, p.29-30; Borisov V.I. 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. - M.: Radio and Communications, 2000, p.24, Fig. 1.7, b and others).

Of the known methods, the closest to the proposed one is the method for receiving signals with pseudo-random tuning of the operating frequency, implemented in the device described in the monograph by V.I. Borisov and others. "Interference immunity of radio communication systems with expanding the spectrum of signals by the method of pseudo-random tuning of the working frequency" - M. : Radio and communications, 2000, p. 24, Fig. 1.7, b, selected as the base.

The structural diagram of the device in which the prototype method is implemented is presented in figure 1, where the following notation is introduced:

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 band-pass filter 1, the signal input of which is the input of the device, a multiplier 2, a second band-pass filter 3 and a demodulator 4, the output of which is the output of the device, as well as a pseudo-random code generator 5, n outputs of which are connected to control n inputs tunable frequency synthesizer 6, the output of which is connected to the second reference input of the multiplier 2.

A device that implements the basic method works 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 ₀ , modulated by information, the carrier frequencies of which change according to a given pseudorandom code (pseudo-random tuning program), as well as narrow-band interference whose frequencies coincide with signal frequencies.

и демодулируется в блоке 4, с выхода которого подается на выход устройства.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 enters the input of block 2, the second reference input of which receives a reference signal with a pseudo-random tuning of the operating frequency generated by block 6, to the control n inputs of which a pseudo-random code with n outputs of block 5, which determines the frequency tuning law of block 6, is supplied As a result of multiplying the input signal with a reference signal synchronous with it, the input signal is convolved with a pseudo-random tuning of the operating frequency to an intermediate frequency, which is filtered by block 3 in the band transmittance ΔF, consistent with the duration τ ₀

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

Narrowband interference due to multiplication with a frequency-tunable reference signal is converted at the output of block 2 into radio pulses of duration τ ₀ , which can differ from the radio pulses of the useful signal only in amplitude. The radio pulses generated in block 2 are filtered by block 3 and demodulated by block 4, while their influence is reduced to distortion of the received information.

The basic method implemented in the device shown in Fig. 1 is based on filtering the input mixture containing a signal with pseudo-random tuning of the operating frequency and interference in the frequency band ΔF equal to the frequency band occupied by the signal with pseudo-random tuning of the working frequency, followed by filtering the result of multiplication in the frequency band ΔF (ΔF≪Δƒ), consistent with the spectrum width of the intrapulse information modulation of the signal at each of its N frequencies, and its demodulation.

The basic method is the following sequence of actions on the input mixture.

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 ₀ , the carrier frequencies of which are changed according to the pseudo-random program (code), and the interference is filtered in the frequency band Δƒ occupied by the signal with pseudo-random tuning of the working frequency. The filtering result is multiplied with synchronous reference oscillation, which is a signal with a pseudo-random tuning of the operating frequency, the frequency of which ƒ _op differs from the frequency of the input signal ƒ _s by a constant value ƒ _pr equal to the intermediate frequency:

The result of multiplication, which is a convolution of the input signal with pseudo-random tuning of the operating frequency to an intermediate frequency equal to ƒ _CR , is filtered in the frequency band ΔF, consistent with the width of the spectrum of the intrapulse information modulation. In this case, interference at frequencies other than ƒ _c does not fall into the passband of the second band-pass filter and does not pass to the demodulator. The signal filtered in the frequency band at the intermediate frequency is demodulated.

However, the basic method does not provide the ability to receive and demodulate the signal under conditions of a priori uncertainty of the program of pseudo-random tuning of its operating frequency.

An object of the invention is to provide the possibility of receiving and demodulating the signal under conditions of a priori uncertainty of the program of pseudo-random tuning of its operating frequency.

The problem is solved in that according to the method of receiving signals with pseudo-random tuning of the operating frequency, based on filtering the input mixture in the frequency band Δƒ occupied by the signal with pseudo-random tuning of the working frequency, multiplying the filtering result with a synchronous reference signal, followed by filtering the result of multiplication in the frequency band ΔF , coherent radiation with a duration signal hopping operating frequency τ ₀ on each of the N adjustment frequency and demodulation sps rayut measuring time interval τ _AC input filter result in a mixture Δƒ frequency band successively delayed by intervals τ _AC τ ₀ -τ _AC and τ _AC, thereby forming four measurement interval duration τ _AC each is determined at measuring intervals sliding amplitude spectra S ₁ (ƒ), S ₂ (ƒ), S ₃ (ƒ) and S ₄ (ƒ), respectively, and the differences of the amplitude sliding spectra S ₂₁ (ƒ) = S ₂ (ƒ) -S ₁ (ƒ) and S ₃₄ (ƒ ) = S ₃ (ƒ) -S ₄ (ƒ), multiply the resulting differences in the amplitude of the sliding spectra among themselves

S ₂₁₃₄ (ƒ) = S ₂₁ (ƒ) × S ₃₄ (ƒ),

the obtained spectral function S ₂₁₃₄ (ƒ) is compared with the threshold level S _POR , which is chosen in such a way as to avoid exceeding it due to fluctuation of only noise components of the spectral function S ₂₁₃₄ (в), in case of exceeding the threshold level S _{POR, it} is decided that the frequency spectral component of the spectral function s ₂₁₃₄ (ƒ), exceeds the threshold s _ERP is the carrier frequency of the received pulse signal ƒ _c, the obtained value of the carrier frequency ƒ _c of the current pulse signal is used for generating a reference sig ala _op with frequency ƒ = ƒ _c -ƒ _etc., wherein the filtering result in the input mixture Δƒ frequency band before multiplying synchronous reference signal delayed in time by an amount

τ ₃ = τ ₀ + τ _AC + τ ₂₁₃₄ ,

where S ₂₁₃₄ (f) is the time spent on the formation and processing of the spectral function S ₂₁₃₄ (f).

The problem is solved in that the device for receiving signals with pseudo-random tuning of the operating frequency, containing a first bandpass filter, the input of which is the device input, a tunable frequency synthesizer, a first multiplier, a second bandpass filter and a demodulator, the output of which is the output of the device, is equipped with four delay lines, four spectrum analyzers, two subtractors, a second multiplier, a comparator and a maximum spectral search device with which exceeds the threshold, and the output of the first bandpass filter through the first delay line is connected to the second input of the first multiplier, the second delay line, the second spectrum analyzer, the first subtractor, the second input of which is connected to the output of the first through the first spectrum analyzer, are connected to the output of the first bandpass filter a band-pass filter, a second multiplier, a comparator and a search device for a maximum spectral component exceeding a threshold whose output is connected to a control input a tunable frequency synthesizer, to the output of the second delay line connected in series with the third delay line, the fourth delay line, a fourth spectrum analyzer and a second subtractor, the second input of which the third through spectrum analyzer connected to the output of the third delay line, and an output connected to the second input of the second multiplier.

Due to the fact that with an increase in the duration of the measurement interval τ _{AC, the} accuracy of the measurement of the carrier frequency increases, and the quality of selection of input pulses decreases in duration, the value of τ _AC is chosen in such a way as to provide a compromise between these parameters.

The value of τ _AC is selected on the one hand based on the required accuracy of estimating the carrier frequency of the signal pulses with frequency hopping due to the fact that the duration of the measurement interval is proportional to the realized accuracy of the frequency measurement, and on the other hand, on the basis of the required quality of selection of input pulse signals for the duration that the quality of selection is higher, the shorter the analysis interval.

By the current amplitude spectrum of the input mixture is meant the amplitude spectrum formed at the current time point t _TEK from a fragment of the input mixture in the interval from t _TEK -τ _AC to t _TEK .

As spectrum analyzers forming a moving amplitude spectrum of the input mixture in the analysis interval τ _AC , devices can be used that include a series-connected analog-to-digital converter and a computer for fast Fourier transform in the interval τ _AC . In this case, the operations of calculating the differences of the amplitude spectra, calculating the product of the obtained differences, comparing with the threshold level and choosing the maximum spectral component that exceeds the threshold can be implemented using arithmetic-logic devices.

The structural diagram of a device that implements the proposed method is presented in figure 2. Timing and frequency diagrams explaining the principle of operation of the device are shown in figure 3, 4, 5, 6, 7 and 8.

The device contains a series-connected first band-pass filter 1, the input of which is the input of the device, the first delay line 5, the first multiplier 2, the second band-pass filter 3 and the demodulator 4, the output of which is the output of the device. The second delay line 7, the second spectrum analyzer 11, the first subtractor 14, the second input of which through the first spectrum analyzer 10 is connected to the output of the band-pass filter 1, the second multiplier 16, the comparator 17, the device 18 for finding the maximum spectral component, are sequentially connected to the output of the first bandpass filter 1 , exceeding the threshold, tunable synthesizer 6 frequencies, the output of which is connected to the second input of the first multiplier 2. To the output of the second delay line 7 are connected in series to the third delay line 8, even ertaya delay line 9, the fourth spectrum analyzer 13 and a second subtracter 15, the second input of which the third through the spectrum analyzer 12 connected to the output of the third delay line 8, and an output connected to the second input of the second multiplier 16.

The proposed method is implemented as follows.

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 ₀ with intrapulse information modulation and a spectral width Δƒ, the carrier frequencies of which vary in accordance with a given program of pseudo-random tuning of the operating frequency, as well as narrow-band interference and interference radio pulses duration different from τ ₀ is input to a first bandpass filter 1, where it is carried out filtering in the frequency band occupied by the sig scarlet with hopping operating frequency.

From the output of the first band-pass filter 1, the input mixture is fed to the input of the first delay line 5, which provides a signal delay for the interval τ _AC , to the input of the first spectrum analyzer 10, which calculates the amplitude moving spectrum of the input mixture in the time interval τ _AC , and to the input of the second delay line 7 providing a delay for the time interval τ _AC . From the output of the second delay line 7, the input mixture is fed to the input of the second spectrum analyzer 11, which calculates the amplitude moving spectrum of the input mixture in the time interval τ _AC , and to the input of the third delay line 8, which provides a signal delay in the interval τ ₀ -τ _AC (Fig. 3 )

From the output of the third delay line 8, the input mixture is fed to the input of the third spectrum analyzer 12, which calculates the moving spectrum of the input mixture in the time interval τ _AC , and to the input of the fourth delay line, which provides a signal delay by the interval τ _AC , from the output of which it enters the fourth a spectrum analyzer 13 that calculates a moving spectrum of the input mixture over a time interval τ _AC . The time diagram shown in Fig. 3 shows the main time relationships during signal processing with a pseudo-random tuning of the operating frequency, consisting of radio pulses of duration τ ₀ . In this diagram, the intervals at which the corresponding moving spectra are formed by the first, second, third, and fourth spectrum analyzers are indicated by the numbers 1, 2, 3, and 4, respectively.

The amplitude sliding spectra S ₁ (ƒ) and S ₂ (ƒ), formed at the current time in the first 10 and second 11 spectrum analyzers, respectively, are fed to the two inputs of the subtractor 14, in which their difference

S _2l (ƒ) = S ₂ (ƒ) -S ₁ (ƒ).

The amplitude sliding spectra S ₃ (ƒ) and S ₄ (ƒ), formed at the current moment of time in the third 12 and fourth 13 spectrum analyzers, respectively, are fed to two inputs of the subtractor 15, in which their difference

S ₃₄ (ƒ) = S ₃ (ƒ) -S ₄ (ƒ).

The differences in the amplitude spectra S ₂₁ (ƒ) and S ₃₄ (ƒ) from the outputs of the subtractors 14 and 15 go to the two inputs of the multiplier 16, which calculates the spectral function in the form of a product

S ₂₁₃₄ (ƒ) = S ₂₁ (ƒ) × S ₃₄ (ƒ).

In the comparator 17, the spectral function S ₂₁₃₄ (ƒ) is compared with the threshold level S _POR .

The principle of the formation of the spectral function S ₂₁₃₄ (ƒ) for the mutual position of the intervals of formation of the amplitude spectra and pulses of the signal with pseudo-random tuning of the operating frequency shown in Fig.3, is illustrated in Fig.4.

Exceeding the threshold level S _{then is} possible only if the relative position of the current signal pulse with pseudo-random tuning of the operating frequency and the intervals for the formation of the sliding spectra by the first 10, second 11, third 12, and fourth 13 spectrum analyzers corresponds to the position shown in Fig. 3. In this case, the value of the spectral component of the spectral function S ₂₁₃₄ (ƒ), which exceeds the threshold S _POR , is equal to the carrier frequency ƒ of _the received signal pulse with pseudo-random tuning of the operating frequency. The obtained value of the carrier frequency ƒ _{from the} current pulse of the signal is used to configure the synthesizer 6 frequencies in such a way as to ensure the fulfillment of the conditions:

ƒ _OP = ƒ _s -ƒ _pr

The delay value τ _{3 of the} first delay line 5 is selected based on the duration of pulses τ ₀ constituting the signal with pseudo-random tuning of the operating frequency, the analysis interval τ _AC required to form the current moving spectrum with the fourth 13 spectrum analyzer and the time τ ₂₁₃₄ spent on determining the spectral function S ₂₁₃₄ (ƒ), comparing it with a threshold level S _POR and estimating the carrier frequency of the current pulse

τ ₃ = τ ₀ + _AC + τ ₂₁₃₄ .

The threshold value S _POR is chosen in such a way as to exclude its excess due to fluctuations in the noise spectral components of the function S ₂₁₃₄ (ƒ).

With the relative position of the current signal with pseudo-random tuning of the operating frequency and the intervals of formation of the sliding spectra by the first 10, second 11, third 12 and fourth 13 spectrum analyzers that do not correspond to the position shown in figure 3, for example, as shown in figure 5, the threshold is exceeded S _POR does not occur, as illustrated by the diagrams in FIGS. 5 and 6.

If the input mixture contains a narrow-band signal with a fixed carrier frequency, it is not detected due to the use of the algorithm for determining the spectral function S ₂₁₃₄ (ƒ) and, therefore, does not affect the operation of the device. If the input mixture contains a pulse signal with a duration other than τ ₀ , it is also not detected due to the use of the algorithm for determining the spectral function S ₂₁₃₄ (ƒ) and does not affect the operation of the device. These positions are illustrated by diagrams in Fig.7 and 8.

Thus, the proposed method and device in comparison with basic and other technical solutions of a similar purpose provide the ability to receive and demodulate signals with a pseudo-random tuning of the operating frequency with a given radiation duration equal to τ ₀ at each of N frequencies without a priori knowledge of the pseudo-random tuning of the working frequency against the background of interfering radio signals in the form of narrow-band and pulsed interference, possibly being elements of other signals with pseudo-random tuning of the operating hours simplicity. This ensures the measurement of the carrier frequencies of the pulses of the received signal with pseudo-random tuning of the operating frequency, which can be used additionally to open the pseudo-random tuning program.

Claims (2)

1. A method of receiving signals with pseudo-random tuning of the operating frequency, based on filtering the input mixture in the frequency band Δƒ occupied by the signal with pseudo-random tuning of the working frequency, multiplying the result with a synchronous reference signal, and then filtering the result of the multiplication in the frequency band Δƒ, consistent with the duration of the signal a hopping operation frequency τ ₀ on each of its N frequency adjustment program, and demodulation, characterized in that the calculated measuring at intervals of

amplitude sliding spectra

the result of filtering the input mixture, where

- the spectrum calculated on the first measuring interval,

- spectra of the filtering result of the input mixture, delayed by

respectively, and the differences of the amplitude sliding spectra S ₂₁ (ƒ) = S ₂ (ƒ) -S ₁ (ƒ) and S ₃₄ (ƒ) = S ₃ (ƒ) -S ₄ (ƒ) multiply the obtained differences of the amplitude sliding spectra between by myself S ₂₁₃₄ (ƒ) = S ₂₁ (ƒ) S ₃₄ (ƒ), the obtained spectral function S ₂₁₃₄ (ƒ) is compared with the threshold level S _POR , which is chosen in such a way as to avoid exceeding it due to fluctuation of only noise components of the spectral function S ₂₁₃₄ (в), in case of exceeding the threshold level S _{POR, it} is decided that that the frequency of the spectral component of the spectral function S ₂₁₃₄ (ƒ), which exceeds the threshold S _POR , is equal to the carrier frequency of the received signal pulse ƒ _c , the obtained value of the carrier frequency ƒ _{c of the} current signal pulse is used to form the reference signal ala with a frequency of ƒ _OP = ƒ _C -ƒ _PR , where

- intermediate frequency, and the result of filtering the input mixture in the frequency band Δƒ before multiplying with a synchronous reference signal is delayed in time by the value τ ₃ = τ ₀ + τ _AC + τ ₂₁₃₄ , where τ ₂₁₃₄ (ƒ) is the time spent on the formation and processing spectral function S ₂₁₃₄ (ƒ). 2. A device for receiving signals with pseudo-random tuning of the operating frequency, comprising a first band-pass filter, the input of which is the input of the device, a tunable frequency synthesizer, a first multiplier, a second band-pass filter and a demodulator, the output of which is the output of the device, characterized in that it is provided four delay lines, four spectrum analyzers, two subtractors, a second multiplier, a comparator and a search device for the maximum spectral component exceeding the threshold, and the output of the first bandpass filter through the first delay line is connected to the second input of the first multiplier, the second delay line, the second spectrum analyzer, the first subtractor, the second input of which is connected to the output of the first bandpass through the first spectrum analyzer, are connected to the output of the first bandpass filter a filter, a second multiplier, a comparator and a search device for a maximum spectral component exceeding a threshold whose output is connected to the control input of the tuning frequency synthesizer, the third delay line, the fourth delay line, the fourth spectrum analyzer and the second subtractor are connected in series to the output of the second delay line, the second input of which is connected to the output of the third delay line through the third spectrum analyzer, and the output is connected to the second input of the second multiplier.

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