RU2325761C1 - Acoustooptical receiver - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: proposed receiver relates to the radioelectronic and may be used for the reception, bearing finding, spectral analysis, and detection of complex phase shift keying (PSK). The acoustic receiver contains the first (1) and second (2) antennas, frequency converter (3), the first (4) and second (5) heterodynes, the first (6) and second (7) mixers, the first (8) and second (9) intermediate frequency amplifiers, the first (10), second (12), third (25), fourth (26), fifth (34), and sixth (35) multipliers, the first (11), second (13), third (27), and fourth (36) narrowband filters, a correlator (14), the threshold unit (15), the first (16) and second (19) switches, a phase detector (17), the first (18) and second (29) recording units, a laser (20), a collimator (21), the first (22), second (30), and third (31) Bragg cells, the first (23) and second (32) lenses, the first (24) and second (33) photodetector matrices, the first (28) and second (37) low frequency filters, the first (38) and second (39) phase inverters, and a subtractor (40).

EFFECT: increased noise immunity of phase-shift-keyed signal reception due to attenuation of narrowband interference.

3 dwg

Description

The proposed receiver relates to electronics and can be used for receiving, direction finding, spectral analysis and detection of complex signals with phase shift keying (PSK).

Acousto-optical receivers are known (ed. Certificate of the USSR No. 1.718.695, 1.785.410, 1.799.226, 1.799.227; USSR patent No. 1.838.882; RF patents No. 2.001.533, 2.007.046, 2.234.808; "Foreign Radio Electronics", 1987, No. 5, p. 51 and others).

Of the known devices, the closest to the proposed one is the “Acousto-Optic Receiver” (RF patent No. 2.234.808, HB04 10/06, 2003), which is selected as a prototype.

A well-known receiver provides reception, direction finding, spectral analysis and detection of complex PSK signals.

However, the known receiver does not allow suppressing narrowband interference and does not provide noise-stable reception of PSK signals.

An object of the invention is to increase the noise immunity of receiving phase-shifted signals by attenuating narrow-band interference.

The problem is solved in that an acousto-optic receiver containing a laser, in which a collimator, a first, second and third Bragg cell are sequentially mounted on the path of the light beam, while the first lens is installed on the path of the diffracted first Bragg cell of the light beam in the focal plane of which the first matrix of photodetectors is placed, the second and third Bragg cells are located on the optical axis of the device close to each other with the same directions of propagation in them -terrorist waves offset from one another by the amount Δh = V · τ _e, where V - velocity of propagation of acoustic waves; τ _e is the duration of the elementary premises, on the propagation path of the second and third Bragg cells of the light beam diffracted by the second lens, a second lens is installed, in the focal plane of which the second photodetector array is located, as well as the first antenna in series, the frequency converter, consisting of the first local oscillator and the first mixer, first intermediate frequency amplifier, correlator, the second input of which is connected to the output of the second intermediate frequency amplifier, threshold block, first a second key, a phase detector and a first registration unit, a second antenna connected in series, a second mixer, the second input of which is connected to the output of the second local oscillator, a second intermediate frequency amplifier, a first multiplier, the second input of which is connected to the output of the first intermediate frequency amplifier, and the first narrow-band filter the output of which is connected to the second input of the phase detector, the second multiplier connected in series to the output of the first local oscillator, the second input of which is connected to the output of the second get a frequency converter, and a second narrow-band filter, the output of which is connected to the second input of the first key, the second key is connected in series to the output of the first intermediate frequency amplifier, the second input of which is connected to the output of the threshold block, and the piezoelectric transducers of the first, second, and third Bragg cells connected in series to the output of the second key is the third multiplier, the second input of which is connected to the output of the first low-pass filter, the third narrow-band filter, the fourth multiplier, the second input of which It is connected to the output of the second key, and the first low-pass filter and the second registration unit are equipped with a fifth and sixth multipliers, a second low-pass filter, a fourth narrow-band filter, two phase inverters and a subtractor, and the fifth multiplier and the second input are connected in series to the output of the second key which through the second phase inverter is connected to the output of the second low-pass filter, the fourth narrow-band filter, the first phase inverter, the sixth multiplier, the second input of which is connected to the output of the second key, the second low-pass filter and a subtractor, a second input coupled to an output of the first lowpass filter, and an output connected to the input of the second registration block.

The block diagram of the proposed receiver is shown in FIG. 1, a frequency diagram explaining the principle of formation of additional reception channels is shown in FIG. 2, timing charts explaining the principle of detecting a received FMN signal are shown in FIG. 3.

The acousto-optic receiver contains in series the first antenna 1, the first mixer 6, the second input of which is connected to the output of the first local oscillator 4, the first intermediate frequency amplifier 8, the correlator 14, the second input of which is connected to the output of the second intermediate frequency amplifier 9, threshold block 15, the first key 16, a phase detector 17 and a first recording unit 18, a second antenna 2 connected in series, a second mixer 7, the second input of which is connected to the output of the second local oscillator 5, the second intermediate amplifier 9 is often you, the first multiplier 10, the second input of which is connected to the output of the first intermediate frequency amplifier 8, and the first narrow-band filter 11, the output of which is connected to the second input of the phase detector 17, connected in series to the output of the first local oscillator 4, the second multiplier 12, the second input of which is connected to the output of the second local oscillator 5, and the second narrow-band filter 13, the output of which is connected to the second input of the first key 16, connected in series to the output of the first amplifier 8 of the intermediate frequency, the second key 19, the second input which is connected to the output of the threshold unit 15, the third multiplier 25, the second input of which is connected to the output of the first low-pass filter 28, the third narrow-band filter 27, the fourth multiplier 26, the second input of which is connected to the output of the second key 19, the first low-pass filter 28 the device 40 and the second registration unit 29, connected in series to the output of the second key 19, the fifth multiplier 34, the second input of which is connected through the second phase inverter 39 to the output of the second low-pass filter 37, the fourth is narrow-band the first filter 36, the first bass reflex 38, the sixth multiplier 35, the second input of which is connected to the output of the second key 19, and the second low-pass filter 37, the output of which is connected to the second input of the subtractor 40.

A collimator 21, Bragg cells 22, 30 and 31, the piezoelectric transducers of which are connected to the output of the second key 19, are sequentially installed on the path of propagation of the light beam from the laser 20.

Bragg cells 30 and 31 are located close to each other with the same directions of propagation of acoustic waves in them, offset from each other by an amount:

Δx = V · τ _e

where V is the propagation velocity of acoustic waves;

τ _e - the duration of the elementary premises.

On the propagation path of the diffracted first Bragg cell 22 of the part of the light beam, a first lens 23 is installed, in the focal plane of which is placed the first matrix 24 of photodiodes. A second lens 32 is mounted on the propagation path of the Bragg cells 30 and 31 diffracted by the Bragg cells, in the focal plane of which a second photodetector array 33 is placed. Serially connected local oscillator 4 and mixer 6 form a frequency converter 3.

Suppression of spurious signals (interference) taken at the mirror and difference frequencies based on the use of two receive channels, the local oscillators 4 and 5 which are spaced apart in frequency by an amount _pr 2f:

and channel voltage correlation processing. The number of additional (mirror and combination) frequencies doubles (figure 2), but creates favorable conditions for their suppression.

For direction finding of the radiation source of the FMN signals in the proposed receiver, the phase method is used, in which the phase shift between the signals received by antennas 1 and 2 is:

where d is the measuring base (distance between antennas);

λ is the wavelength;

γ is the angle defining the direction to the radiation source.

The phase direction finding method is characterized by a contradiction between the requirements of measurement accuracy and the uniqueness of reference of angular coordinates. Indeed, according to the above expression, the phase system is more sensitive to a change in the angle γ, the larger the relative size of the base d / λ. However, with increasing d / λ, the value of the angular coordinate γ decreases at which the phase difference exceeds 2π, i.e. ambiguity of counting occurs.

The ambiguity of direction finding by the phase method can be eliminated in two classical ways:

1. The use of highly directional antennas.

2. The use of several measuring bases (multiscale).

Direction finding systems with highly directional antennas have a long range and high resolution in direction. However, they require a search for the radiation source before the start of measurements and its tracking in the direction of the antenna beam during the measurement process.

The multi-scale method of reading angles is based on the use of several measuring bases. At the same time, a smaller base forms a rough but unambiguous reference scale, and a large base forms an accurate but ambiguous reference scale. Direction finding systems using this method have a limited range and a complex antenna system.

In the proposed device, a correlation method is used to eliminate the ambiguity of direction finding, which uses the remarkable correlation properties of the FMN signals.

A necessary condition for the synchronous detection of PSK signals is the presence of a constant initial phase and frequency at the receiving point of the reference voltage equal to the frequency of the received PSK signal.

In principle, three methods for obtaining the reference voltage are possible:

1. From a local generator.

2. Using an auxiliary pilot signal transmitted on a separate channel.

3. Directly from the received signal.

The first method does not provide the necessary in-phase and synchronized oscillations, since the phase and frequency of any highly stable generator changes under the influence of various destabilizing factors.

The second method of obtaining the reference voltage also did not find wide practical application, since its technical implementation leads to loss of spectrum and power in the channel for transmitting the pilot signal.

The proposed receiver uses a method for extracting the reference voltage directly from the received PSK signal.

If the duration τ _{e of the} chips that make up the received PSK signal is a priori known, then an acousto-optic demodulator consisting of Bragg cells 30 and 31, lens 32, and photodetector matrix 33 can be used to demodulate the received PSK signals. Moreover, these cells are offset from each other (along the x axis) by:

Δx = V · τ _e

where V is the propagation velocity of acoustic vibrations.

The attenuation of narrow-band interference is achieved by the fact that two phase-spaced channels are formed so that the detected output voltages of the channel phase demodulators are of mutually opposite polarity, and the total output voltage of the demodulator is obtained by mutually subtracting them in the subtractor. As a result of this, the mutually inverse channel voltage of the signal after the subtractor at the common output of the demodulator is added in absolute value, and the unipolar channel interference voltage is mutually subtracted, and the total interference voltage decreases, i.e. at the output of the receiver, the signal-to-noise ratio increases and the noise immunity of the reception of the PSK signal is increased.

Acousto-optic receiver operates as follows.

Received QPSK signals:

U ₁ (t) = V _c · Cos [2πf _c · t + φ _к (t) + φ ₁ ],

U ₂ (t) = V _c · Cos [2πf _c · t + φ _к (t) + φ ₂ ], 0≤t≤T _c ,

where V _c , f _c , φ ₁ , φ ₂ , T _c - amplitude, initial frequency, initial phases and signal duration;

φ _к (t) = {0, π} is the manipulated component of the phase that displays the law of phase manipulation in accordance with the modulating code M (t) (Fig. 3, a), and φ _к (t) = const at К · τ _э <t <(K + 1) · τ _e and can change abruptly at t = K · τ _e , i.e. at the boundaries between elementary premises (K = 1, 2, ..., N-1);

τ _e , N is the duration and number of chips that make up the signal with a duration of T _s (T _s = N · τ _e ),

from the output of antennas 1 and 2 are fed to the first input of the mixers 6 and 7, the second input of which from the output of the local oscillators 4 and 5 are supplied with voltage, respectively:

,

,

,

,

- амплитуды, частоты и начальные фазы напряжений гетеродинов 4 и 5.Where

,

,

,

,

- amplitudes, frequencies and initial phases of the voltage of the local oscillators 4 and 5.

и

гетеродинов 4 и 5 разнесены на удвоенное значение промежуточной частоты:Moreover, the frequency

and

local oscillators 4 and 5 are spaced by twice the value of the intermediate frequency:

and selected symmetrical with respect to the carrier frequency f _{c of the} received signal:

This circumstance leads to a doubling of the number of additional channels, but creates favorable conditions for their suppression due to correlation processing.

At the output of the mixers 6 and 7, voltages of combination frequencies are generated. Amplifiers 8 and 9 are allocated voltage intermediate (differential) frequency:

Where

K ₁ - gear ratio of the mixers;

- промежуточная частота;

- intermediate frequency;

which go to the two inputs of the multiplier 10. At the output of the latter, harmonic oscillation is formed:

U ₃ (t) = V ₃ · Cos (4πf _pr · t + Δφ _g + Δφ), 0≤t≤T _c ,

Where

K ₂ - transfer coefficient of the multiplier;

Δφ = φ ₂ -φ ₁ - phase shift, which determines the direction of the radiation source of the PSK signals.

которого выбирается равной

и поступает на первый вход фазового детектора 17.This oscillation is distinguished by a narrow-band filter 11, the tuning frequency

which is chosen equal

and enters the first input of the phase detector 17.

и

с выходов гетеродинов 4 и 5 подаются на два входа перемножителя 12, на выходе которого образуется гармоническое колебание:Stress

and

from the outputs of the local oscillators 4 and 5 are fed to two inputs of the multiplier 12, at the output of which a harmonic oscillation is formed:

U ₄ (t) = V ₄ · Cos [4πf _pr · t + Δφ _g ], 0≤t≤T _c ,

Where

которого выбирается равной

which is allocated by the narrow-band filter 13, the tuning frequency

which is chosen equal

и

с выхода усилителей 8 и 9 промежуточной частоты одновременно поступают на два входа коррелятора 14, на выходе которого образуется напряжение V, пропорциональное корреляционной функции R(τ). Это напряжение поступает на вход порогового блока 15, где сравнивается с пороговым уровнем V_пор. При этом пороговое напряжение V_пор в пороговом блоке 15 превышается только при максимальном выходном напряжении коррелятора 14 (V_max>V_пор). Так как один и тот же сигнал принимается по двум каналам, то между канальными напряжениями

и

существует сильная корреляционная связь, выходное напряжение коррелятора 14 достигает максимального значения V_max, при котором τ₀≡γ₀, где γ₀ - истинный пеленг.Stress

and

from the output of amplifiers 8 and 9 of an intermediate frequency, they simultaneously enter two inputs of the correlator 14, the output of which produces a voltage V proportional to the correlation function R (τ). This voltage is supplied to the input of the threshold block 15, where it is compared with a threshold level of V _pores . Moreover, the threshold voltage V _then in the threshold block 15 is exceeded only at the maximum output voltage of the correlator 14 (V _max > V _then ). Since the same signal is received on two channels, between channel voltages

and

there is a strong correlation, the output voltage of the correlator 14 reaches its maximum value V _max , at which τ ₀ ≡ γ ₀ , where γ ₀ is the true bearing.

Therefore, the threshold voltage V _pores in the threshold block 15 is exceeded only at the maximum value of the correlation function R (τ ₀ ) and is not exceeded at values of τ corresponding to the side lobes of the correlation function R (τ ₀ ) (V <V _pores ). If the threshold level V _{pores is} exceeded (V _max > V _pores ), a constant voltage is generated in the threshold block 15, which is supplied to the control input of the keys 16, 19 and opens them. In the initial state, keys 16 and 19 are always closed.

In this case, the harmonic oscillation U ₄ (t) from the output of the narrow-band filter 13 through the open key 16 is fed to the second input of the phase detector 17, the output of which is generated by a constant voltage:

U _n (γ) = V _n CosΔφ,

_n where V = _^1/2 K ₃ · V ₃ · V _4;

To ₃ - the transfer coefficient of the phase detector.

This voltage is detected by the recording unit 18. In this case, an increase in the accuracy of direction finding of the radiation source of the QPSK signals is ensured by increasing the measuring base d, and the resulting ambiguity in reading the angle γ is eliminated by correlation processing of channel voltages.

The width of the spectrum Δf _{c of the} received QPSK signals is determined by the duration τ _{e of} elementary premises (Δf _s = 1 / τ _e ), while the width of the spectrum Δf _{g of} harmonic oscillation U ₃ (t) is determined by its duration T _s (Δf _g = 1 / T _s ), i.e. the spectrum of input QPSK signals is convoluted N times (Δf _s / Δf _g = N). This makes it possible, using a narrow-band filter 11, to isolate the harmonic oscillation U ₃ (t), filtering out a significant part of the noise and interference, i.e. to increase the real sensitivity of the receiver during direction finding of a radiation source of FMN signals.

(фиг.3, б) с выхода усилителя 8 промежуточной частоты через открытый ключ 19 одновременно поступает на пьезоэлектрический преобразователь ячеек Брэгга 22, 30 и 31, где преобразуется в акустические колебания, и на первые входы перемножителей 25, 26, 34 и 35. На вторые входы перемножителей 26 и 35 с выхода узкополосного фильтра 27 и фазоинвертора 38 подаются опорные напряжения соответственно (фиг.3, в, д):Voltage

(Fig.3, b) from the output of the intermediate frequency amplifier 8 through the public key 19 simultaneously enters the piezoelectric transducer of the Bragg cells 22, 30 and 31, where it is converted into acoustic vibrations, and to the first inputs of the multipliers 25, 26, 34 and 35. On the second inputs of the multipliers 26 and 35 from the output of the narrow-band filter 27 and the phase inverter 38 are supplied with reference voltage, respectively (Fig.3, c, d):

As a result of the multiplication of the indicated signal and voltages, the following resulting oscillations are formed:

Where

Analogs of the modulating code (Fig.3, g, e):

are allocated by low-pass filters 28 and 37, respectively, and fed to two inputs of subtractor 40. Subtracting one of the other indicated voltages taking into account their opposite polarity, doubled (total) low-frequency voltage is generated at the output of subtractor 40 (Fig. 3, g):

where V _n = 2V ₁ ;

и

.those. obtained by the addition of the absolute value of stress

and

.

In this case, the amplitude additive noise passes through the two demodulators in the same way, changing the amplitudes of the output detected voltages in the same direction. But in the subtractor 40, they are subtracted, remaining unipolar, i.e. suppressed, mutually compensated.

с выхода фильтра 37 нижних частот поступает на вход фазоинвертора 39, на выходе которого образуется низкочастотное напряжение:Low frequency voltage

from the output of the low-pass filter 37 is fed to the input of the phase inverter 39, at the output of which a low-frequency voltage is generated:

и

с выхода 28 нижних частот и фазоинвертора 39 поступает на второй вход перемножителей 25 и 34 соответственно, на выходе которых формируются гармонические колебания:Low frequency voltage

and

from the output 28 of the low frequencies and the bass reflex 39 enters the second input of the multipliers 25 and 34, respectively, at the output of which harmonic oscillations are formed:

Where

These harmonic oscillations are distinguished by narrow-band filters 27 and 36. The oscillation U ₀₁ (t) is fed to the second input of the multiplier 26. The oscillation U ₀₃ (t) is extracted by the narrow-band filter 36 and is fed to the input of the phase inverter 38, the output of which is the oscillation:

which is fed to the second input of the multiplier 35. Thus, synchronous detection of the received FMN signal and suppression of narrowband interference are performed.

. Следует отметить, что на каждой ячейке Брэгга дифрагирует приблизительно 1/10 часть основного пучка света. Каждая ячейка Брэгга 22 (30, 31) состоит из звукопровода и возбуждающей гиперзвук пьезоэлектрической пластины, выполненной из кристалла ниобата лития соответственно Х и Y - 35° среза. Это обеспечивает автоматическую подстройку по углу Брэгга и работу ячейки в широком диапазоне частот.The beam of light from the laser 20, collimated by the collimator 21, passes through the Bragg cells 22, 30 and 31 and diffracts on the acoustic vibrations excited by voltage

. It should be noted that approximately 1/10 of the main light beam is diffracted on each Bragg cell. Each Bragg cell 22 (30, 31) consists of a sound duct and a hypersonic exciting piezoelectric plate made of lithium niobate crystal, respectively, X and Y - 35 ° cut. This provides automatic Bragg angle adjustment and cell operation in a wide frequency range.

On the propagation path of the diffracted Bragg cell 22 of the light beam, a lens 23 is installed, which forms the spatial spectrum of the received QPSK signal, in the focal plane of which a matrix of 24 photodetectors is placed. These elements form an acousto-optical spectrum analyzer. Each resolving element of the analyzed frequency range has its own photodetector.

Bragg cells 30 and 31, mounted on the common optical axis of the device close to each other with the same directions of propagation of acoustic vibrations in them, lens 32 and photodetector matrix 33 form an acousto-optic demodulator of the received QPSK signal. Moreover, these cells are offset from each other (along the X axis) by:

Δx = V · τ _e

where V is the propagation velocity of acoustic vibrations;

τ _e - the duration of the elementary premises of which the received PSK signal consists.

Moreover, the reference voltage for each elementary package is the previous package. Practical implementation of the acousto-optical demodulator is possible only if a priori knowledge of the duration of τ _e chip.

The operation of the receiver described above corresponds to the case of receiving QPSK signals on the main channel at a frequency f _c (FIG. 2).

, то в смесителях 6 и 7 он преобразуется в напряжение следующих частот:If a false signal (interference) is received on the first mirror channel at a frequency

, then in mixers 6 and 7 it is converted to the voltage of the following frequencies:

where the first index denotes the channel through which a false signal is received (interference);

- the second index denotes the number of the local oscillator, the frequency of which is involved in the conversion of the carrier frequency of the received false signal (interference).

, подавляется.However, only the voltage at frequency f ₁₁ falls into the passband of the intermediate frequency amplifier 8, and then is supplied to the first input of the multiplier 10 and the correlator 14. The output voltage of the correlator 14 is zero, since there is no voltage at the output of the intermediate frequency amplifier 9. Keys 16 and 19 do not open and a false signal (interference) received on the first mirror channel at a frequency

is suppressed.

, то в смесителях 6 и 7 он преобразуется в напряжения следующих частот:If a false signal (interference) is received on the second mirror channel at a frequency

, then in mixers 6 and 7 it is converted to the voltage of the following frequencies:

, подавляется.However, only a voltage with a frequency f ₂₂ falls into the passband of the intermediate frequency amplifier 9 and to the second input of the correlator 14. The output voltage of the correlator 14 is also equal to zero in this case, since there is no voltage at the output of the intermediate frequency amplifier 8. Keys 16 and 19 do not open and a false signal (interference) received on the second mirror channel at a frequency

is suppressed.

For a similar reason, false signals (interference) received through other additional channels are also suppressed.

и

, то в смесителях 6 и 7 они преобразуются в напряжения следующих частот:If false signals (interference) are received simultaneously on the first and second mirror channels at frequencies

and

, then in mixers 6 and 7 they are converted to voltages of the following frequencies:

и

, поэтому между канальными напряжениями, выделяемыми усилителями 8 и 9 промежуточной частоты, существует слабая корреляционная связь. Кроме того, следует отметить, что корреляционная функция помех не имеет ярко выраженного максимума, как это имеет место у сложных ФМн-сигналов. Выходное напряжение V коррелятора 14 не превышает порогового напряжения V_пор в пороговом блоке 15 (V<V_пор). Последний не срабатывает, ключи 16 и 19 не открываются и ложные сигналы (помехи), принимаемые одновременно по первому и второму зеркальным каналам на частоте

и

, подавляются.In this case, the voltages with frequencies f ₁₁ and f ₂₂ fall into the passband of the amplifiers 8 and 9 of the intermediate frequency and to the two inputs of the multiplier 10 and the correlator 14. However, the keys 16 and 19 do not open. This is because different false signals (interference) are received at different mirror frequencies

and

, therefore, between the channel voltages allocated by the amplifiers 8 and 9 of the intermediate frequency, there is a weak correlation. In addition, it should be noted that the correlation function of interference does not have a pronounced maximum, as is the case with complex PSK signals. The output voltage V of the correlator 14 does not exceed the threshold voltage V _pores in the threshold block 15 (V <V _pores ). The latter does not work, the keys 16 and 19 do not open and false signals (interference) received simultaneously on the first and second mirror channels at a frequency

and

are suppressed.

For a similar reason, false signals (interference) received simultaneously on other (combinational) channels are also suppressed.

Therefore, by suppressing false signals (interference) received via additional (mirror and Raman) channels, the noise immunity and resolution of the receiver are improved.

Thus, the proposed acousto-optical receiver, in comparison with the prototype and other technical solutions of a similar purpose, provides increased noise immunity of receiving phase-shifted signals. This is achieved by significant attenuation of narrowband interference due to their antiphase interaction in a two-channel demodulator of FMN signals. Moreover, the proposed two-channel demodulator of FMN signals is free from the phenomenon of “reverse operation”, which is inherent in the known devices of A. A. Pistolkors, V. I. Siforov, D. F. Kostas and G. A. Travin, which are also used for synchronous detection of the received QPSK signal is a reference voltage extracted directly from the received QPSK signal.

Claims (1)

An acousto-optic receiver containing a laser, the collimator, the first, second and third Bragg cells are sequentially mounted on the path of the light beam, while the first lens is installed on the path of the diffracted first Bragg cell of the light beam, in the focal plane of which the first photodetector array is located, the second and the third Bragg cell are located on the optical axis of the device close to each other with the same directions of propagation of acoustic waves in them, offset relative to each other's value Δx = V · τ _e where V is the propagation velocity of acoustic waves; τ _e is the duration of the elementary premises on the propagation path of the second and third Bragg cells of the light beam, a second lens is installed, in the focal plane of which the second matrix of photodetectors is placed, as well as the first antenna in series, the frequency converter, consisting of the first local oscillator and the first mixer connected in series , the first intermediate frequency amplifier, a correlator, the second input of which is connected to the output of the second intermediate frequency amplifier, a threshold block, the first the first key, the phase detector and the first registration unit, the second antenna, the second mixer, the second input of which is connected to the output of the second local oscillator, the second intermediate-frequency amplifier, the first multiplier, the second input of which is connected to the output of the first intermediate-frequency amplifier, and the first narrow-band filter the output of which is connected to the second input of the phase detector, the second multiplier connected in series to the output of the first local oscillator, the second input of which is connected to the output of the second get the homeland, and a second narrow-band filter, the output of which is connected to the second input of the first key, connected in series to the output of the first intermediate frequency amplifier, a second key, the second input of which is connected to the output of the threshold block, and piezoelectric transducers of the first, second and third Bragg cells, connected in series to the output of the second key is the third multiplier, the second input of which is connected to the output of the first low-pass filter, the third narrow-band filter, the fourth multiplier, the second input of which connected to the output of the second key, and the first low-pass filter, and the second registration unit, characterized in that it is equipped with a fifth and sixth multipliers, a second low-pass filter, a fourth narrow-band filter, two phase inverters and a subtractor, and connected to the output of the second key in series the fifth multiplier, the second input of which is connected through the second phase inverter to the output of the second low-pass filter, the fourth narrow-band filter, the first phase inverter, the sixth multiplier, the second input of which one with the output of the second key, the second low-pass filter and a subtractor, a second input coupled to an output of the first lowpass filter, and an output connected to the input of the second registration block.

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