RU2439811C1 - Acousto-optical receiver - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: acousto-optical receiver has receiving antennae 1 and 2, a frequency converter 3, heterodynes 4 and 5, mixers 6 and 7, intermediate frequency amplifiers 8, 9 and 42, multipliers 10, 12, 25, 26, 34, 35, 50, 54, 58, 59, 64, 65, 70, 71, 76 and 77, narrow-band filters 11, 13, 27, 36, 51, 55, 60, 66, 72 and 78, correlator 14, threshold unit 15, switches 16, 19, 45, 47, 49, phase detectors 17, 52 and 56, recording units 18, 53 and 57, a laser 20, a collimator 21, Bragg cells 22, 30, 31, 82, 85, 86, 89, 92 and 93, lenses 23, 32, 83, 87, 90 and 94, photodetector arrays 24, 33, 84, 88, 91 and 95, low-pass filters 28, 37, 61 and 67, phase inverters 38, 39, 68 and 69, subtractors 40, 62 and 74, and built-in intermediate frequency amplifiers 41 and 43.

EFFECT: wider range of operating frequencies without widening the frequency tuning range of heterodynes by using reception image channels.

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Description

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

Acousto-optical receivers are known (author's certificate of the USSR No. 1718695, 1785410, 1799226, 1799227; USSR patent No. 1838882; RF patents No.2001533, 2007046, 2234808, 2291575, 2325761; "Foreign radio electronics", 1987, No. 5, p. 51 and others).

Of the known devices, the closest to the proposed is the “Acousto-optic receiver” (RF patent No. 2323261, H04B 10/06, 2006), which is selected as a prototype.

A well-known receiver provides reception, direction finding, spectral analysis, synchronous detection and determination of the main parameters of complex PSK signals. At the same time, it allows you to suppress narrowband interference, increasing the noise immunity of complex QPSK signals, and additional receiving channels.

However, in some cases, for example, from the point of view of expanding the range of operating frequencies without expanding the range of frequency tuning of local oscillators, it is advisable not to suppress, but to use additional receive channels.

An object of the invention is to expand the range of operating frequencies without expanding the range of frequency tuning of local oscillators by using mirror channels of reception.

The problem is solved in that an acousto-optical receiver containing, in accordance with the closest analogue, a laser, in which a collimator, a first, second and third Bragg cell are sequentially installed in the path of the light beam, while a part of the light beam is diffracted in the first Bragg cell in the path of propagation the first lens, 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 the boards for the propagation of acoustic waves in them are shifted relative to 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,

a second lens is installed on the propagation path of the second and third Bragg cells of the light beam diffracted by the second lens, in the focal plane of which the second photodetector array is placed, as well as the first antenna in series, a frequency converter consisting of a series of the first local oscillator and the first mixer, 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 and a first key, connected in series w I have an antenna, a 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 first narrow-band filter, the first phase detector and the first recording unit, connected in series to the output of the first local oscillator, the second multiplier, the second input of which is connected to the output the second local oscillator, and the second narrow-band filter, connected in series to the output of the first intermediate frequency amplifier, a second switch, the second input of which is connected to the output threshold unit, and piezoelectric transducers of the first, second and third Bragg cells, connected in series to the output of the second key is a 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 is connected to the output of the second key, the first low-pass filter, the first subtractor, the second input of which is connected to the output of the second low-pass filter, and the second registration unit, connected in series to the output of W of the key, the fifth multiplier, the second input of which is connected to the output of the second phase inverter, 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, and the second low-pass filter, the output of which is connected to the output of the second phase inverter, differs from the nearest analogue in that it is equipped with a third intermediate frequency amplifier, two triple intermediate frequency amplifiers, three amplitude detectors, third, fourth and fifth keys, seventh, eight eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth and sixteenth multipliers, fifth, sixth, seventh, eighth, ninth and tenth narrow-band filters, second and third phase detectors, third, fourth, fifth and sixth blocks phase inverters, fourth, fifth, sixth, seventh, eighth and ninth Bragg cells, third, fourth, fifth and sixth lenses, third, fourth, fifth and sixth photodetector arrays, the second input of the first multiplier being connected to the first key, the second input of the first phase detector is connected to the output of the second narrow-band filter, the first amplitude detector and the third key are connected in series to the output of the second intermediate-frequency amplifier, the second input of which is connected to the output of the first intermediate-frequency amplifier, and the output is connected to the second input of the first key , the third amplifier of the intermediate frequency, the fourth switch, the seventh multiplier, the second input of which is connected to the output of the second the amplifier of the triple intermediate frequency, the fifth narrow-band filter, the second phase detector, the second input of which is connected to the output of the second narrow-band filter, and the third block of registration, the first amplifier of the triple intermediate frequency, the second amplitude detector, the fifth key, the second input are connected in series to the output of the first mixer which is connected to the output of the second intermediate frequency amplifier, an eighth multiplier, the second input of which is connected to the output of the first amplifier of the triple intermediate frequency, a clean narrow-band filter, a third phase detector, the second input of which is connected to the output of the second narrow-band filter, and the fourth recording unit, the ninth multiplier is connected in series to the output of the fourth key, the second input of which is connected to the output of the third low-pass filter, the seventh narrow-band filter, the tenth multiplier, the second input of which is connected to the output of the fourth key, the third low-pass filter, the second subtractor, the second input of which is connected to the output of the fourth low-pass filter stot, and the fifth registration unit, the twelfth multiplier is connected to the output of the fourth key, the second input of which is connected to the output of the third phase inverter, the fourth low-pass filter, the fourth phase inverter, the eleventh multiplier, the second input of which is connected to the output of the fourth key, and the eighth narrow-band filter, the output of which is connected to the input of the third phase inverter, the thirteenth multiplier is connected in series to the output of the fifth key, the second input of which is connected to the output of the fifth filter low pass filter, ninth narrow-band filter, fourteenth multiplier, the second input of which is connected to the output of the fifth key, the fifth low-pass filter, the third subtractor, the second input of which is connected to the output of the sixth low-pass filter, and the sixth recording unit, connected to the output of the fifth key the fifteenth multiplier, the second input of which is connected to the output of the sixth phase inverter, the tenth narrow-band filter, the fifth phase inverter, sixteenth multiplier, the second input of which is connected to the output the fifth key, and the sixth low-pass filter, the output of which is connected to the input of the sixth phase inverter, the fourth, fifth, sixth, seventh, eighth and ninth Bragg cells are sequentially installed in the path of the laser beam, while part of the beam is diffracted by the fourth Bragg cell a third lens is installed, in the focal plane of which a third photodetector array is located, the fifth and sixth Bragg cells are located on the optical axis of the device closely to one another with the same voltage the phenomena of the propagation of acoustic waves in them are shifted relative to each other by Δх, a fourth lens is installed on the path of propagation of the fifth and sixth Bragg cells of the light beam, the fourth photodetector array is located in the focal plane of the part of the light beam, diffracted by the seventh Bragg cell a fifth lens is installed, in the focal plane of which the fifth photodetector array is located, the eighth and ninth Bragg cells are located on the optical axis of the device in dense one to the other with the same directions of propagation of acoustic waves in them, shifted relative to each other by Δx, the sixth lens is installed in the focal plane of the sixth photodetector array, the fourth piezoelectric transducers, located on the propagation path of the diffracted eighth and ninth Bragg cells of the light beam the fifth and sixth Bragg cells are connected to the output of the fourth key, the piezoelectric transducers of the seventh, eighth and ninth Bragg cells are connected to the output of the heel th key.

The structural diagram of the proposed receiver is presented in figure 1. A frequency diagram explaining the principle of formation and use of mirror reception channels is shown in FIG.

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, the first multiplier 10, the second input of which is connected to the output of the second intermediate-frequency amplifier 9, the first narrow-band filter 11, the first phase detector 17 and the first recording unit 18, sequentially turned on The second antenna 2, the second mixer 7, the second input of which is connected to the output of the second local oscillator 5, the second intermediate frequency amplifier 9, the first amplitude detector 44 and the third key 45, the second input of which is connected to the output of the first intermediate frequency amplifier 8, and the output is connected to the second input of the first key 16. 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, are connected in series to the output of the first local oscillator 4 the first phase detector 17. To the output of the first mixer 6, a third intermediate frequency amplifier 42, a fourth key 47, a seventh multiplier 50, the second input of which is connected to the output of the second intermediate frequency amplifier 43, a fifth narrow-band filter 51, a second phase detector 52, and a second input are connected in series which is connected to the output of the second narrow-band filter 13, and the third registration unit 53. The output of the first mixer 6 is connected in series to the first amplifier 41 tripled intermediate frequency, the second amplitude detector 46, the fifth key 49, the second input of which is connected to the output of the second amplifier 9 intermediate frequency, the eighth multiplier 54, the second input of which is connected to the output of the first amplifier 41 triple intermediate frequency, the sixth narrow-band filter 55, the third phase detector 56, the second input of which is connected to the output of the second narrow-band filter 13, and the fourth registration unit 57. To the output of the second mixer 7, a second triple intermediate frequency amplifier 43 and a third amplitude detector 48 are connected in series, the output of which is connected to the second input of the fourth key 47. A second key 19 is connected in series to the output of the first intermediate frequency amplifier 8, the second input of which is connected to the output of the threshold block 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 second key 19, the first low-pass filter 28, the first subtractive device 40, the second input of which is connected to the output of the second low-pass filter 37, and the second registration unit 29. A fifth multiplier 34 is connected to the output of the second key 19, the second input of which is connected to the output of the second phase inverter 39, the fourth narrow-band filter 36, the first phase inverter 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 input of the second phase inverter 39. The ninth multiplier 58 is connected to the output of the fourth key 47, the second input of which is connected to the output of the third low-pass filter 61, the seventh narrow-band a filter 60, a tenth multiplier 59, the second input of which is connected to the output of the fourth key 47, the third low-pass filter 61, the second subtractor 62, the second input of which is connected to the output of the fourth low-pass filter 67, and the fifth registration unit 63. The eleventh multiplier 64 is connected to the output of the fourth key 47, the second input of which is connected to the output of the fourth phase inverter 69, the eighth narrow-band filter 66, the third phase inverter 68, the twelfth multiplier 65, the second input of which is connected to the output of the fourth key 47, and the fourth low-pass filter 67 the output of which is connected to the input of the fourth phase inverter 69. The thirteenth multiplier 70, the second input of which is connected to the output of the fifth filter 73 of the lower hour, is connected in series to the output of the fifth key 49 from the ninth narrowband filter 72, the fourteenth multiplier 71, a second input coupled to an output of the fifth switch 49, the fifth filter 73 the lower frequencies, a third subtraction means 74, a second input coupled to an output of the sixth filter 79 low-pass, and the sixth unit 75 registration. The fifteenth multiplier 76, the second input of which is connected to the output of the sixth phase inverter 81, the tenth narrow-band filter 78, the fifth phase inverter 80, the sixteenth multiplier 77, the second input of which is connected to the output of the fifth key 49, and the sixth low-pass filter 79 are serially connected to the output of the fifth key 49. the output of which is connected to the input of the sixth phase inverter 81.

A collimator 21, Bragg cells 22, 30, 31, 82, 85, 86, 89, 92 and 93 are sequentially installed on the path of propagation of the light beam of laser 20. The first lens 23 is installed on the path of propagation of the diffracted first Bragg cell 22 of the beam of light, in the focal the plane of which is placed the first matrix 24 photodetectors. The second 30 and third 31 Bragg cells 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 by

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 second 30 and third 31 Bragg cells of the light beam diffracted, a second lens 32 is installed, in the focal plane of which the second photodetector array 33 is placed. On the propagation path of the fourth Bragg diffracted fourth cell 82 of the light beam, a third lens 83 is installed, in the focal plane of which a third photodetector array 84 is located. The fifth 85th and sixth 86th Bragg cells 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 from each other by Δx. On the propagation path of the diffracted fifth 85th and sixth 86th Bragg cells of the light beam, a fourth lens 87 is installed, in the focal plane of which a fourth photodetector array 88 is located. On the propagation path of the diffracted seventh Bragg cell 89 of the part of the light beam, a fifth lens 90 is mounted, in the focal plane of which a fifth matrix of photodetectors is placed. The eighth 92 and ninth 93 Bragg cells 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 from each other by Δx. On the propagation path of the diffracted eighth of 92 and ninth of 93 Bragg cells of the light beam, a sixth lens 94 is installed, in the focal plane of which is placed the sixth matrix 95 of photodetectors. Piezoelectric transducers of the first 22, second 30 and third 31 Bragg cells are connected to the output of the second key 19. Piezoelectric transducers of the fourth 82, fifth 85 and sixth 86 cells of Bragg are connected to the output of the fourth key 47. Piezoelectric transducers of the seventh 89, eighth 92 and ninth 93 Bragg cells connected to the output of the fifth key 49.

Acousto-optic receiver operates as follows.

Received signals, for example, with phase shift keying (PSK):

u _c1 (t) = U _c · cos [w _c t + φ _к (t) + φ _с1 ],

u _c2 (t) = U _c · cos [w _c t + φ _к (t) + φ _c2 ], 0≤t≤T _c ,

where U _c , w _c , φ _c1 , φ _c2 , T _c - amplitude, carrier frequency, initial phases and signal duration;

φ _k (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), and φ _к (t) = const for Kτ _e <t <(K + 1) τ _e can change stepwise at t = Kτ _e , i.e. at the borders between elementary premises (K = 1, 2, ..., N-1);

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

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

u _g1 (t) = U _g1 cos (w _g1 t + φ _g1 ),

u _g2 (t) = U _g2 cos (w _g2 t + φ _g2 ),

where U _g1 , U _g2 , w _g1 , w _g2 , φ _g1 , φ _g2 are the amplitudes, frequencies, and initial phases of the local oscillator voltages 4 and 5.

Moreover, the frequencies w _g1 and w _{g2 of the} local oscillators 4 and 5 are spaced at twice the intermediate frequency:

w _g2 -w _g1 , = 2w _up

and are selected symmetrical with respect to the carrier frequency of the main receiving channel:

w _c -w _g1 = w _g2 -w _c = w _up .

This circumstance leads to the formation of the first w _Z1 and second w _Z2 mirror reception channels. Moreover, the conversion coefficient K _{pr of} signals received via the mirror channels is the same as the conversion coefficient K _{pr of} signals received via the main channel at a frequency w _c (Fig. 2).

At the outputs of the mixers 6 and 7, voltages of combination frequencies are generated. Amplifiers 8, 42 and 9 are allocated voltage intermediate (differential) frequency:

u _up1 (t) = U _pr1 · cos [w _up t + φ _к (t) + φ _up1 ],

u _up2 (t) = U _pr2 · cos [w _up t-φ _к (t) + φ _up2 ], 0≤t≤T _c ,

;Where

;

w _up = w _c -w _g1 = w _g2 -w _c - intermediate (difference) frequency;

φ _up1 = φ _c -φ _g1 ; φ _up2 = φ -φ _{r2 with,}

which are supplied to the two inputs of the correlator 14, the output of which produces a voltage U proportional to the correlation function R (τ).

This voltage is supplied to the input of the threshold block 15, where it is compared with the threshold level U _then . Moreover, the threshold voltage U _then in the threshold block 15 is exceeded only at the maximum output voltage of the correlator 14 (U _max > U _then ). Since the same signal is received on two channels, there is a strong correlation between the channel voltages u _up1 (t) and u _up2 (t), the output voltage of the correlator 14 reaches its maximum value and exceeds the threshold voltage in the threshold block 15 (U _max > U _then ). If the threshold level U _pores is exceeded, a constant voltage is generated in the threshold block 15, which is supplied to the control inputs of the keys 16, 19 and opens them. In the initial state, keys 16, 19, 45, 47, 49 are always closed.

The voltage u _up2 (t) from the output of the second intermediate-frequency amplifier 9 is fed to the input of the amplitude detector 44, the detected voltage of which is supplied to the control input of the third switch 45, opening it. The voltage u _up1 (t) from the output of the first intermediate frequency amplifier 8 through public keys 45 and 16 is fed to the input of the first multiplier 10, the second input of which is supplied with the voltage u _up2 (t) from the output of the second intermediate frequency amplifier 9. At the output of the multiplier 10, harmonic oscillation is formed:

u ₃ (t) = U ₃ · cos (2w _up t + Δφ _g + Δφ), 0≤t≤T _c ,

;Where

;

Δφ _g = φ _g2 -φ _g1 ;

Δφ = φ ₂ -φ ₁ is the phase shift that determines the direction (azimuth) to the radiation source of the PSK signals.

This oscillation is distinguished by a narrow-band filter 11, the tuning frequency w _{n1 of} which is chosen equal to twice the intermediate frequency 2w _up (w _n1 = 2w _up ), and is fed to the first input of the phase detector 17.

The _voltages u _g1 (t) and u _g2 (t) from the outputs of the local oscillators 4 and 5 are fed to the two inputs of the second multiplier 12, at the output of which a harmonic oscillation is formed:

u ₄ (t) = U ₄ · cos (2w _up t + Δφ _g ), 0≤t≤T _c ,

;Where

;

2w _up = w -w _{r1 r2;}

Δφ _g = φ _g2 -φ _g1 ;

which is allocated by a narrow-band filter 13, the tuning frequency of 2w _{n2 of} which is selected equal to twice the intermediate frequency 2w _up (w _n2 = 2w _up ), and is fed to the second input of the phase detector 17. A constant voltage is generated at the output of the latter

u _n (γ) = U _n · cosΔφ,

;Where

;

,

,

d is the distance between antennas 1 and 2 (measuring base);

λ is the wavelength;

γ — direction (azimuth) to the radiation source of the QPSK signals.

This voltage is detected by the recording unit 18. Moreover, improving the accuracy of direction finding of the radiation source of the FMN signals is provided by increasing the measuring base d, and the resulting ambiguity in the reading of the angular coordinate 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 _c = 1 / τ _e ), while the width of the spectrum Δf _{g of} harmonic oscillation u ₃ (t) is determined by its duration T _c (Δf _g = 1 / T _c ), i.e. the spectrum of input QPSK signals is folded N times (Δf _c / 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.

The voltage u _up1 (t) from the output of the first intermediate frequency amplifier 8 through the public key 19 is simultaneously supplied to the piezoelectric transducers 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 outputs of the narrow-band filter 27 and the phase inverter 38 are supplied with reference voltage, respectively:

u ₀₁ (t) = U ₀ cos (w _up t + φ _up1 ),

u ₀₂ (t) = - U ₀ · cos (w _up t + φ _up1 ), 0≤t≤T _c .

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

u _Σ1 (t) = U ₁ · cosφ _to (t) + U ₁ · cos [2w _up t + φ _к (t) + 2φ _up1 ],

u _Σ2 (t) = - U ₁ · cosφ _to (t) -U ₁ · cos [2w _up t + φ _к (t) + 2φ _up1 ],

;Where

;

Analogs of the modulating code:

u _н1 (t) = U ₁ · cosφ _to (t),

u _Н2 (t) = - U ₁ · cosφ _к (t),

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

u _n (t) = u _н1 (t) -u _н2 (t) = U _н3 · cosφ _to (t),

where U _n3 = 2 _U1 ;

those. it turns out the addition in absolute value of the stresses u _н1 (t) and u _н2 (t).

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.

The low-frequency voltage u _Н2 (t) from the output of the low-pass filter 37 is fed to the input of the bass reflex 39, at the output of which a low-frequency voltage is generated

u _н3 (t) = U ₁ · cosφ _to (t).

Low-frequency voltages u _н1 (t) and u _н3 (t) from the outputs of the low-pass filter 28 and the phase inverter 39 are supplied to the second inputs of the multipliers 25 and 34, respectively, at the outputs of which harmonic oscillations are formed:

u ₀₁ (t) = U ₂ · cos (w _up t + φ _up1 ) + U ₂ · cos [w _up t + 2φ _to (t) + φ _up1 ] = U ₀ · cos (w _up t + φ _up1 ) ,

u ₀₃ (t) = U ₂ · cos (w _up t + φ _up1 ) + U ₂ · cos [w _up t + 2φ _to (t) + φ _up1 ] = U ₀ · cos (w _up t + φ _up1 ) ,

; U₀=2U₂.Where

; U ₀ = 2U ₂ .

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

u ₀₂ (t) = - U ₀ cos (w _up t + φ _up1 ),

which is fed to the second input of the multiplier 35. Thus, the synchronous detection of the received PSK signals and the suppression of narrowband interference are carried out.

The suppression of narrowband interference is achieved due to their antiphase interaction in a two-channel demodulator of FMN signals. In this case, the two-channel demodulator of FMN signals is free from the phenomenon of “reverse operation”, which is inherent in the well-known demodulators of FMN signals, for example, A. Pistolkors demodulators, VI Siforov, DF Kostas and Travina G.A., who also use the reference voltage extracted directly from the received FMN signal for synchronous detection of the received PSK signal.

The attenuation of narrowband 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 their mutual subtraction 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 signals is increased.

The beam of light from the laser 20, collimated by the collimator 21, passes through the Bragg cells 22, 30, 31, 82, 85, 86, 89, 92, and 93 and diffracts on acoustic vibrations excited by the voltage u _up1 (t), which is supplied from the output of the first an amplifier 8 of an intermediate frequency through a public key 19 to the piezoelectric transducers of the Bragg cells 20, 30 and 31.

It should be noted that approximately 1/10 of the main light beam is diffracted on each Bragg cell. Each Bragg cell 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, the lens 32 and the photodetector array 33 form an acousto-optic demodulator of the received FMN 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 is composed.

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 w _c (Fig. 2).

If the QPSK signals:

u _z11 (t) = U _z1 · cos [w _z1 t + φ _k1 (t) + φ _z11 ],

_Z12 U (t) = U _P1 · cos [w _P1 t + φ _k1 (t) + φ _z12], 0≤t≤T _P1,

are received through the first mirror channel at a frequency w _s1 , the following voltages are allocated by amplifiers 42 of an intermediate frequency and 43 of a tripled intermediate frequency:

u _up3 (t) = U _pr3 · cos [w _up t-φ _к1 (t) + φ _up3 ],

u _up4 (t) = U _WP4 · cos [3w _up t-φ _{k1 (t) + φ up4],} 0≤t≤T _P1,

;Where

;

w _up = w _g1 -w _z1 - intermediate frequency;

3w _up = w _g2 -w _z1 - tripled intermediate frequency;

φ _up3 = φ _g1 -φ _z11 ; φ _up4 = φ _r2 -φ _z12;,

The voltage u _up4 (t) from the output of the amplifier 43 tripled intermediate frequency is supplied to the input of the amplitude detector 48, where it is detected. About the detected signal is fed to the control input of the key 47, opening it. In this case, the voltage u _up3 (t) from the output of the intermediate frequency amplifier 42 through the public key 47 is supplied to the first inputs of the multipliers 50, 58, 59, 64, 65 and to the piezoelectric transducers of the Bragg cells 82, 85, and 86.

The second input of the multiplier 50 is supplied with voltage u _up4 (t) from the output of the amplifier 43 triple the intermediate frequency. At the output of the multiplier 50, harmonic oscillation is generated

u ₅ (t) = U ₅ · cos (2w _up t + Δφ + Δφ _{1 g),} 0≤t≤T _P1,

;Where

;

Δφ = φ ₁ -φ _{z12 z11} - phase shift defines the direction (azimuth), the radiation source PSK signals.

This oscillation is distinguished by a narrow-band filter 51 and is fed to the first input of the phase detector 52, to the second input of which a harmonic oscillation u ₄ (t) is supplied from the output of the narrow-band filter 13. A constant voltage is generated at the output of the phase detector 52

u _n4 (γ ₁ ) = U _n4 · cosΔφ ₁ ,

;Where

;

,

,

γ ₁ - direction (azimuth) to the radiation source of the PSK signals.

This voltage is detected by the registration unit 53.

Multipliers 58, 59, 64 and 65, narrow-band filters 60 and 66, low-pass filters 61 and 67, phase inverters 68 and 69, and a subtractor 62 form a two-channel demodulator of FMN signals received through the first mirror channel at a frequency w _s1 . The specified demodulator also provides attenuation of narrow-band interference due to their antiphase interaction, its operation is similar to that described above.

The Bragg cell 82, the lens 83, and the photodetector array 84 form an acousto-optic spectrum analyzer that provides spectral analysis of the PSK signals received on the first mirror channel at a frequency w _s1 .

Bragg cells 85 and 86, lens 87 and photodetector array 88 form an acousto-optic demodulator of FMN signals received via the first mirror channel at a frequency w _s1 . It can be used if the duration τ _{e of} elementary premises is a priori known.

If the QPSK signals:

u _z21 (t) = U _z2 · cos [w _z2 t + φ _k2 (t) + φ _z21 ],

_z22 u (t) = U _s2 · cos [w _{s2 h2} t + φ (t) + φ _z22], 0≤t≤T _s2,

taken through the second mirror channel at a frequency w _s2 , then the amplifiers 41 tripled intermediate frequency and 9 intermediate frequency the following voltages are allocated:

u _up5 (t) = U _pr5 · cos [3w _up t + φ _к2 (t) + φ _pr5 ],

u _up6 (t) = U _pr6 · cos [w _up t + φ _k2 (1) + φ _up6], 0≤t≤T _s2,

;Where

;

3w _up = w _z2 -w _g1 - triple intermediate frequency;

w _up = w _z2 -w _g2 - intermediate frequency

φ _up5 = φ _z21 -φ _g1 ; φ _up6 = φ _z22 -φ _r2.

The voltage u _up5 (t) from the output of the amplifier 41 tripled intermediate frequency is supplied to the input of the amplitude detector 46, where it is detected. The detected signal is fed to the control input of the key 49, opening it. In this case, the voltage u _up6 (t) from the output of the intermediate frequency amplifier 9 through the public key 49 is supplied to the first inputs of the multipliers 54, 70, 71, 76, 77 and to the piezoelectric transducers of the Bragg cells 89, 92, and 93.

The second input of the multiplier 54 is supplied with voltage u _up5 (t) from the output of the amplifier 41 triple the intermediate frequency. At the output of the multiplier 54, harmonic oscillation is generated

₆ u (t) = U ₆ · cos (2w _up t + Δφ + Δφ _{2 g),} 0≤t≤T _P1,

;Where

;

Δφ ₂ = φ _z22 -φ _z21 is the phase shift that determines the direction (azimuth) to the radiation source of the PSK signals.

This oscillation is distinguished by a narrow-band filter 55 and is fed to the first input of the phase detector 56, to the second input of which a harmonic oscillation u ₄ (t) is supplied from the output of the narrow-band filter 13. A constant voltage is generated at the output of the phase detector 56

u _n5 (γ ₂ ) = U _n5 · cosΔφ ₂ ,

;Where

;

,

,

γ ₂ - direction (azimuth) to the radiation source of the PSK signals.

This voltage is detected by the registration unit 57.

Multipliers 70, 71, 76 and 77, narrow-band filters 72 and 78, filters 73 and 79, and a subtractor 74 form a two-channel demodulator of FMN signals received via the second mirror channel at a frequency _wz2 . The detected signal is fixed by the registration unit 57. The specified demodulator also provides attenuation of narrow-band interference due to their antiphase interaction, its operation is similar to that described above.

The Bragg cell 89, the lens 90, and the photodetector array 91 form an acousto-optic spectrum analyzer that provides spectral analysis of the QPSK signals received on the second mirror channel at a frequency w _s2 .

The Bragg cells 92 and 93, the lens 94 and the photodetector array 95 form an acousto-optic demodulator of FMN signals received on the second mirror channel at a frequency w _s2 . It can be used if the duration τ _{e of} elementary premises is a priori known.

If the PSK signals are simultaneously received on the first _wz1 and second _wz2 mirror channels, then a situation arises similar to the reception of PSK signals on the main channel at a frequency w _c , i.e. ambiguity arises. The elimination of this ambiguity is achieved by correlation processing of channel stresses.

If the PSK signals are simultaneously received through the first _wz1 and second _wz2 mirror channels, then the second and third demodulators of the PSK signals, Bragg cells 82, 85, 86 and 89, 92, 93 come into operation. In this case, the voltages u _up3 (t ) and u _up6 (t) from the outputs of amplifiers 8 and 9 of an intermediate frequency are fed to two inputs of correlator 14. Since these voltages are formed by different PSK signals received at different frequencies w _s1 and w _s2 , therefore there is a weak correlation between them. The output voltage of the correlator 14 does not reach the maximum value and does not exceed the threshold level U _then in the threshold block 15, the key 16 does not open. This eliminates the above ambiguity.

If PSK signals are simultaneously received through the main channel at frequency w _c, w _P1 of the first and second channels w mirror _s2, the work involved in all blocks acousto-optic receiver.

Thus, the proposed acousto-optical receiver in comparison with the prototype provides an extension of the range of operating frequencies without expanding the range of frequency tuning of local oscillators. This is achieved by using FMN signals received on two mirror channels at frequencies w _z1 and w _z2 .

Conversion on the mirror channels of the reception occurs with the same conversion coefficient K _ol as on the main channel. Therefore, they are the most significant among the additional reception channels.

For direction finding of radiation sources of QPSK signals received via mirror channels, the phase method is also used, which is characterized by a contradiction between the requirements of measurement accuracy and the uniqueness of reading angular coordinates.

An increase in the accuracy of direction finding of radiation sources of QPSK signals received via mirror channels is also achieved by increasing the measurement base d, and the resulting ambiguity in reading the angular coordinates is eliminated by the correlation method, which uses the remarkable correlation properties of QPSK signals.

The proposed two-channel demodulators of FMN signals received via mirror channels are also free from the phenomenon of “reverse operation” and provide significant attenuation of narrow-band interference due to their antiphase interaction.

To implement acousto-optical spectrum analyzers and acousto-optic demodulators of QPSK signals received via mirror channels, a single laser beam is used, on the optical axis of which nine Bragg cells are placed.

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 each other by Δх = V · τ _e , where V is the propagation velocity of acoustic waves; τ _e is the duration of the elementary premises, a second lens is installed on the propagation path of the second and third Bragg cells of the light beam diffracted by the second lens, 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 one connected in series mixer, a 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 and a key, a second antenna 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, a first narrow-band filter, a first phase detector and a first recording unit, connected in series to the output of the first local oscillator, a second multiplier, the second input of which is connected to the output of the second local oscillator, and the second narrow-band filter, connected in series to the output of the first intermediate frequency amplifier, the second key, sec the 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, 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 which is connected to the output of the second key, the first low-pass filter, a first subtractor, the second input of which is connected to the output of the second low-pass filter, and a second registration unit, sequentially connected to the output of the second key, the fifth multiplier, the second input of which is connected to the output of the second phase inverter, 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, and the second low-pass filter, the output of which is connected to the input of the second phase inverter, characterized in that it is equipped with a third intermediate frequency amplifier, two triplicate intermediate frequency amplifiers, three amplitude detectors, a third, fourth and fifth to filters, the seventh, the eighth, the ninth, the tenth, the eleventh, the twelfth, the thirteenth, the fourteenth, the fifteenth and the sixteenth multipliers, the fifth, the sixth, the seventh, the eighth, the ninth and the tenth narrow-band filters, the second and third phase detectors, the fifth and the fourth registration units, six phase inverters, fourth, fifth, sixth, seventh, eighth and ninth Bragg cells, third, fourth, fifth and sixth lenses, third, fourth, fifth and sixth photodetector arrays, the second input of the first alternating current the resident is connected to the output of the first key, the second input of the first phase detector is connected to the output of the second narrow-band filter, the first amplitude detector and the third key are connected in series to the output of the second intermediate-frequency amplifier, the second input of which is connected to the output of the first intermediate-frequency amplifier, and the output is connected to the second the input of the first key, the third amplifier of the intermediate frequency, the fourth key, the seventh multiplier, the second input of which dinene with the output of the second amplifier tripled intermediate frequency, the fifth narrow-band filter, the second phase detector, the second input of which is connected to the output of the second narrow-band filter, and the third recording unit, the first amplifier of the triple intermediate frequency, the second amplitude detector, the fifth key are connected in series to the output of the first mixer the second input of which is connected to the output of the second intermediate frequency amplifier, the eighth multiplier, the second input of which is connected to the output of the first amplifier tripled the intermediate frequency, the sixth narrow-band filter, the third phase detector, the second input of which is connected to the output of the second narrow-band filter, and the fourth recording unit, the ninth multiplier is connected to the output of the fourth key, the second input of which is connected to the output of the third low-pass filter, the seventh narrow-band filter, the tenth multiplier, the second input of which is connected to the output of the fourth key, the third low-pass filter, the second subtractor, the second input of which is connected to the output of the fourth of a low-pass filter, and a fifth registration unit, to the fourth key output, a twelfth multiplier is connected in series, the second input of which is connected to the output of the third phase inverter, the fourth low-pass filter, the eleventh multiplier, the second input of which is connected to the fourth key output, and the eighth narrow-band filter, the output of which is connected to the input of the third phase inverter, the thirteenth multiplier is connected in series to the output of the fifth key, the second input of which is connected to the output of the fifth filter frequencies, the ninth narrow-band filter, the fourteenth multiplier, the second input of which is connected to the output of the fifth key, the fifth low-pass filter, the third subtractor, the second input of which is connected to the output of the sixth low-pass filter, and the sixth recording unit, connected to the output of the fifth key the fifteenth multiplier, the second input of which is connected to the output of the sixth phase inverter, the tenth narrow-band filter, the fifth phase inverter, sixteenth multiplier, the second input of which is connected to the output of the fifth the fourth key, and the sixth low-pass filter, the output of which is connected to the input of the sixth phase inverter, the fourth, fifth, sixth, seventh, eighth and ninth Bragg cells are sequentially installed in the path of the laser beam, while part of the beam is diffracted by the fourth Bragg cell a third lens is installed, in the focal plane of which a third photodetector array is located, the fifth and sixth Bragg cells are located on the optical axis of the device closely to one another with identical directions by the propagation directions of acoustic waves in them, are shifted relative to each other by Δх, the fourth lens is installed on the path of propagation of the fifth and sixth Bragg cells of the light beam, the fourth photodetector array is located in the focal plane of the part of the light beam, diffracted by the seventh Bragg cell a fifth lens is installed, in the focal plane of which the fifth photodetector array is located, the eighth and ninth Bragg cells are located on the optical axis of the device one to the other with the same directions of propagation of acoustic waves in them, shifted relative to each other by Δx, along the path of the diffracted eighth and ninth Bragg cells of the light beam, a sixth lens is installed, in the focal plane of which there is a sixth photodetector array, fourth piezoelectric transducers, the fifth and sixth Bragg cells are connected to the output of the fourth key, the piezoelectric transducers of the seventh, eighth and ninth Bragg cells are connected to the output of the fifth the key.

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