RU2619454C2 - Acousto-optic receiver - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: acousto-optic receiver comprises a receiving antenna 1, a frequency converter 2, a mixer 3, a local oscillator 5, the first 6 and the second 12 multipliers, the first 7 and the second 13 narrow band filters, the first 8, the second 14, the third 15 and the fourth 16 amplitude detectors, the first 9, the second 17, the third 18 and the fourth 19 keys, an amplifier 10 of the first sum frequency, an amplifier 11of the second sum frequency, a laser 20, a collimator 21, the first 22, the second 23, the third 24 and the fourth 25 Bragg cells, the first 26, the second 27, the third 28 and the fourth lens 29, the first 30, the second 31, the third 32 and the fourth 33 matrix photodetectors.

EFFECT: expanding the operating frequency range of the acousto-optic receiver without expanding the frequency adjustment range of the local oscillator by using additional receiving channels.

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Description

The proposed receiver relates to electronics and can be used for receiving and spectral analysis of complex signals with phase modulation (PSK).

Acousto-optical receivers are known (ed. Certificate of the USSR No. 1.718.695, 1.758.883, 1.785.410, 1.799.226, 1.799.227, RF patents No. 2.001.533, 2.007.046, 2.234.808, 2.291.575 , 2.314.644, 2.325.761, 2.439.811; Dikarev V.I. Methods and technical solutions for receiving and processing radio signals (Textbook, St. Petersburg, 2000, pp. 413-462, etc.).

Of the known devices, the closest to the proposed one is the “Acousto-Optic Receiver” (ed. Certificate of the USSR No. 1,758.883, H04B 10/06, 1990), which is chosen as a prototype.

The specified receiver provides suppression of false signals (interference) received through the mirror and Raman channels.

But from the point of view of expanding the operating frequency range of an acousto-optic receiver without expanding the frequency range of the local oscillator, it is advisable not to suppress, but to use additional receive channels by marking them accordingly.

An object of the invention is to expand the operating frequency range of an acousto-optical receiver without expanding the frequency range of the local oscillator by using additional receive channels.

The problem is solved in that the acousto-optic receiver, containing, in accordance with the closest analogue, a laser, in which the collimator and the first Bragg cell are sequentially installed in the path of the light beam, the first lens is installed in the path of the diffracted part of the light beam, in the focal plane of which the first photodetector array, as well as a series-connected receiving antenna, a mixer, the second input of which is connected to the local oscillator output, and an intermediate frequency amplifier, The first multiplier, the first narrow-band filter, the first amplitude detector and the first switch, connected to the output of the receiving antenna, differs from the closest analogue in that it is equipped with an amplifier of the first total frequency, an amplifier of the second total frequency, a second multiplier, a second narrow-band filter, a second, third and fourth amplitude detectors, second, third and fourth keys, second, third and fourth Bragg cells, second, third and fourth lenses, second, third and fourth photodetector arrays tectors, and the second, third and fourth Bragg cells are sequentially installed on the propagation path of the laser light beam, the second, third and fourth lenses are respectively installed on the propagation path of the second, third and fourth Bragg cells of the light beam, respectively, in the focal plane of each of which the second , the third and fourth matrix of photodetectors, respectively, the amplifier of the first total frequency, the second amplitude detector and the second switch are connected in series to the mixer output whose swarm input is connected to the output of the intermediate frequency amplifier, and the output is connected to the piezoelectric transducer of the first Bragg cell, the second total frequency amplifier, the third amplitude detector and the third key, the second input of which is connected to the output of the intermediate frequency amplifier, are connected in series to the mixer output, and the output is connected to the piezoelectric transducer of the second Bragg cell, the second input of the first key is connected to the output of the intermediate frequency amplifier, and the output is connected to the piezoelectric To the transducer of the third Bragg cell, the second input of the first multiplier is connected to the output of the intermediate frequency amplifier, the second multiplier is connected to the output of the receiving antenna, the second input of which is connected to the output of the intermediate frequency amplifier, the second narrow-band filter, the fourth amplitude detector and the fourth key, the second input of which connected to the output of the intermediate frequency amplifier, and the output is connected to the fourth Bragg piezoelectric transducer.

The block diagram of an acousto-optical receiver is shown in FIG. 1. A frequency diagram illustrating frequency conversion of signals is shown in FIG. 2.

The acousto-optic receiver includes a receiving antenna 1 connected in series, a mixer 3, the second input of which is connected to the output of the local oscillator 4, an amplifier 10 of the first total frequency, a second amplitude detector 14 and a second switch 17, the second input of which is connected through the intermediate frequency amplifier 5 to the output of the mixer 3, and the output is connected to the piezoelectric transducer of the first Bragg cell 22. An amplifier 11 of the second total frequency, a third amplitude detector 15 and a third switch 18 are connected to the output of the mixer 3 the second input of which is connected to the output of the intermediate frequency amplifier 5, and the output is connected to the piezoelectric transducer of the second Bragg cell 23. The first multiplier 6 is connected in series to the output of the receiving antenna 1, the second input of which is connected to the output of the intermediate frequency amplifier 5, the first narrow-band filter 7, the first an amplitude detector 8 and a first switch 9, the second input of which is connected to the output of the intermediate frequency amplifier 5, and the input is connected to the piezoelectric transducer of the third Bragg cell 24. To the output the receiving antenna 1 is connected in series with a second multiplier 12, the second input of which is connected to the output of the intermediate frequency amplifier 5, the second narrow-band filter 13, the fourth amplitude detector 16 and the fourth key 19, the second input of which is connected to the output of the intermediate frequency amplifier 5, and the output is connected to the piezoelectric Bragg fourth cell converter 25.

A collimator 21, a first 22, a second 23, a third 24, and a fourth 25 Bragg cells are sequentially installed on the path of the light beam of the laser 20. On the propagation path of the light beam diffracted by the Bragg cell 22 (23, 24, 25), a lens 26 (27, 28, 29) is installed, in the focal plane of which a photodetector array 30 (31, 32, 33) is placed.

Serially connected local oscillator 4 and mixer 3 form a frequency converter 2.

Acousto-optic receiver operates as follows.

Received signal with phase shift keying (QPSK) at a frequency of ω _s

u _c (t) = U _c ⋅cos [(ω _c t + ϕ _k1 (t) + ϕ _c ], 0≤t≤T _c ,

where U _c , ω _c , ϕ _c , T _c - amplitude, carrier frequency, initial phase and signal duration;

ϕ _k1 (t) ≈ {0, π} is the manipulated component of the phase that displays the law of phase manipulation in accordance with the modulating code M ₁ (t), and ϕ _k1 (t) = const for kτ _e <t <(k + 1) τ _e and can change abruptly at t = kτ _e , i.e. at the borders between elementary premises (k = 1, 2, ..., N-1);

τ_uh, N is the duration and number of chips that make up a signal of duration T_from (T_from= N⋅τ_from),

from the output of the receiving antenna 1 simultaneously enters the first inputs of the mixer 3, the first 6 and second 12 multipliers. The second input of the mixer 3 from the output of the local oscillator 4 is supplied with voltage

u _g (t) = U _g ⋅cos [ω _g t + ϕ _g ],

where U _g , ω _g , ϕ _g - amplitude, frequency and initial phase of the local oscillator voltage.

The tuning frequency ω _{n1 of the} intermediate frequency amplifier 5 is chosen equal to the intermediate (difference) frequency (Fig. 2)

ω _n1 = ω _pr = ω _g -ω _s .

The tuning frequency ω _{n2 of the} amplifier 10 of the first total frequency is chosen equal to the first total frequency

ω _n2 = ω _Σ1 = ω _s + ω _g .

The tuning frequency ω _{n3 of the} amplifier 11 of the second total frequency is chosen equal to the second total frequency

ω _n3 = ω _Σ2 = ω _g + ω _s .

The tuning frequency ω _{n4 of the} first 6 and second 12 narrow-band filters is chosen equal to the second harmonic of the local oscillator frequency 4

ω _n4 = 2ω _g .

At the output of the mixer 3, voltages of combination frequencies are generated. Amplifiers 5 and 10 are allocated voltage intermediate (differential) and the first total frequency, respectively

u _pr1 (t) = U _pr1 ⋅cos [ω _pr t-ϕ _k1 (t) + ϕ _pr1 ],

u _Σ1 (t) = U _pr1 ⋅cos [ω _Σ1 t-ϕ _k1 (t) + ϕ _Σ1 ], 0≤t≤T _c ,

Where

ω _CR = ω _g -ω _with - intermediate (difference) frequency;

ω _Σ1 = ω _s + ω _g - the first total frequency;

ϕ _pr1 = ϕ _g -ϕ _s ; ϕ _Σ1 = ϕ _c + ϕ _g .

The voltage u _Σ1 (t) is supplied to the input of the amplitude detector 14, where its envelope is allocated, which is fed to the control input of the key 17, opening it. In the initial state, keys 9, 17, 18, and 19 are always closed.

In this case, the voltage u _pr1 (t) from the output of the intermediate frequency amplifier 5 through the public key 17 is supplied to the piezoelectric transducer of the first Bragg cell 22, where it is converted into acoustic vibration. Each Bragg cell 22 (23, 24, 25) 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.

The beam of light from the laser 20, collimated by the collimator 21, passes through the Bragg cell 22 and diffracts on acoustic vibrations excited by the voltage u _pr1 (t). It should be noted that only about a tenth of the light beam of the radiation source is diffracted on each Bragg cell.

On the propagation path of the diffracted part of the light beam, a lens 26 is installed, in the focal plane of which a photodetector array 30 is located.

Therefore, in the focal plane of the lens 30, a spatial spectrum of the received signal is formed. Moreover, each resolving element of the analyzed frequency range has its own photodetector.

The operation of the acousto-optic receiver described above corresponds to the case of receiving PSK signals along the main channel at a frequency ω _s (Fig. 2).

If the QPSK signal is received on the mirror channel at a frequency of ω _s

u _z (t) = U _z ⋅cos [ω _z t + ϕ _k2 (t) + ϕ _z ], 0≤t≤T _z ,

the amplifiers 5 and 11 are allocated the second voltage of the intermediate frequency and the voltage of the second total frequency, respectively

u _pr2 (t) = U _pr2 ⋅cos [ω _pr t-ϕ _k2 (t) + ϕ _pr2 ],

u _Σ2 (t) = U _pr2 ⋅cos [ω _Σ2 t-ϕ _k2 (t) + ϕ _Σ2 ], 0≤t≤T _s ,

Where

ω _CR = ω _s -ω _g - intermediate (difference) frequency;

ω _Σ2 = ω _g + ω _s - the second total frequency;

ϕ _ol = ϕ _s -ϕ _g ; ϕ _Σ2 = ϕ _g + ϕ _s

The voltage u _Σ2 (t) is supplied to the input of the amplitude detector 15, where its envelope is allocated, which is fed to the control input of the key 18, opening it.

In this case, the voltage u _pr2 (t) from the output of the intermediate frequency amplifier 5 through the public key 18 is supplied to the piezoelectric transducer of the second Bragg cell 23, where it is converted into acoustic vibration. The amplitude spectrum of the signal received through the mirror channel at a frequency of ω _s is analyzed in a matrix of 31 photodetectors.

If the PSK signal is received on the first combinational channel at a frequency ω _k1

u _k1 (t) = U _k1 ⋅cos [ω _k1 t + ϕ _k3 (t) + ϕ _k1 ], 0≤t≤T _k1 ,

the amplifier 5 emits the third voltage of the intermediate frequency

u _pr3 (t) = U _pr3 ⋅cos [ω _pr t + ϕ _k3 (t) + ϕ _k3 ], 0≤t≤T _k1 ,

Where

ω _ave = 2ω -ω _{r k1} - intermediate (difference) frequency;

ϕ _pr3 = ϕ _g -ϕ _k1 ,

which is fed to the second input of the first multiplier 6, the first input of which from the output of the receiving antenna 1 receives a signal u _k1 (t), received on the first combinational channel at a frequency ω _k1 . The output of the multiplier 6 are formed voltage of the Raman frequencies. The first narrow-band filter 7 distinguishes the harmonic voltage at the second harmonic of the frequency 2ω _g local oscillator 4

u ₁ (t) = U ₁ ⋅cos [2ω _g t + ϕ _g ], 0≤t≤T _k1 ,

которое поступает на вход первого амплитудного детектора 8, где выделяется его огибающая, которая поступает на управляющий вход первого ключа 9, открывая его.Where

which goes to the input of the first amplitude detector 8, where its envelope is highlighted, which goes to the control input of the first key 9, opening it.

In this case, the voltage u _pr (t) from the output of the intermediate frequency amplifier 5 through the public key 9 is supplied to the piezoelectric transducer of the third Bragg cell 24, where it is converted into acoustic vibration. The amplitude spectrum of the signal received through the first combination channel at a frequency ω _k1 is analyzed in a matrix of 32 photodetectors.

If the PSK signal is received on the second Raman channel at a frequency of ω _k2

u _k2 (t) = U _k2 ⋅cos [ω _k2 t + ϕ _k4 (t) + ϕ _k2 ], 0≤t≤T _k2 ,

then the intermediate frequency amplifier 5 produces a fourth intermediate frequency voltage

_WP4 u (t) = U _WP4 ⋅cos [ω _{ave t + φ k4 (t) +} φ _k4], 0≤t≤T _k2

Where

ω = ω _{ave k2} -2ω _g - intermediate (difference) frequency;

ϕ _pr4 = ϕ _k2 -ϕ _g ,

which is fed to the second input of the second multiplier 12, the first input of which from the output of the receiving antenna 1 receives a signal received via the second combination channel at a frequency ω _k2 . At the output of the multiplier 12, voltages of combination frequencies are generated. The second narrow-band filter 13 distinguishes the harmonic voltage at the second harmonic of the frequency 2ω _g local oscillator 4

u ₂ (t) = U ₂ ⋅СОs [2ω _g t + ϕ _g ], 0≤t≤T _k2 ,

которое поступает на вход четвертого амплитудного детектора 16, где выделяется его огибающая, которая поступает на управляющий вход четвертого ключа 19, открывая его.Where

which goes to the input of the fourth amplitude detector 16, where its envelope is highlighted, which goes to the control input of the fourth key 19, opening it.

The voltage u _CR4 (t) from the output of the intermediate frequency amplifier 5 through the public key 19 is supplied to the piezoelectric transducer of the fourth Bragg cell 33, where it is converted to acoustic vibration. The amplitude spectrum of the signal received through the second Raman channel at a frequency ω _k2 is analyzed in a matrix of 33 photodetectors.

Thus, the proposed acousto-optical receiver in comparison with the prototype and other technical solutions for a similar purpose provide an extension of the operating frequency range by four times. This is achieved by using additional reception channels: mirror, first and second combination.

Claims (1)

An acousto-optic receiver containing a laser, the collimator and the first Bragg cell are sequentially mounted on the path of the light beam, the first lens is installed on the path of the diffracted part of the light beam, in the focal plane of which the first photodetector array is located, as well as the receiving antenna, mixer, second the input of which is connected to the output of the local oscillator, and an intermediate frequency amplifier, connected in series to the output of the receiving antenna, the first multiplier, the first narrow-band filter, the first amplitude detector and the first key, characterized in that it is equipped with an amplifier of the first total frequency, an amplifier of the second total frequency, a second multiplier, a second narrow-band filter, a second, third and fourth amplitude detectors, a second, third and fourth keys, a second , the third and fourth Bragg cells, the second, third and fourth lenses, the second, third and fourth photodetector arrays, the second, three second and third Bragg cells, on the propagation path of the diffracted second, third, and fourth Bragg cells of the light beam, a second, third, and fourth lens, respectively, are installed in the focal plane of each of which the second, third, and fourth photodetector arrays are respectively connected to the output of the mixer an amplifier of the first total frequency, a second amplitude detector and a second switch, the second input of which is connected to the output of the intermediate frequency amplifier, and the output is connected to the piezoelectric the first Bragg cell, the second total frequency amplifier, the third amplitude detector and the third key are connected to the output of the mixer, the second input of which is connected to the output of the intermediate frequency amplifier, and the output is connected to the piezoelectric transducer of the second Bragg cell, the second input of the first key is connected to the output intermediate frequency amplifier, and the output is connected to the piezoelectric transducer of the third Bragg cell, the second input of the first multiplier is connected to the output of the amplifier frequency converter, the second multiplier is connected to the output of the receiving antenna, the second input of which is connected to the output of the intermediate frequency amplifier, the second narrow-band filter, the fourth amplitude detector and the fourth key, the second input of which is connected to the output of the intermediate frequency amplifier, and the output is connected to the piezoelectric transducer Bragg’s fourth cell.

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