RU2080655C1 - Device which recognizes information signals - Google Patents

Abstract

FIELD: automation and computer engineering, in particular, visual analysis of amplitude spectrum of information signals and detection of type of their modulation. SUBSTANCE: device has antenna 1, heterodyne 2, mixer 3, intermediate frequency amplifier 4, first, second and third signal phase doubling units 5, 6, 7, light-emitting source 8, collimator 9, first, second, third and fourth signal modulators 10, 11, 12 and 13, first, second, third and fourth lenses 14, 15, 16 and 17, first, second, third and fourth photodetectors 18, 19, 20 and 21, first, second, third and fourth indicators 21, 23, 24 and 25, signal receiver and amplifier 26, delay line 27, switch 28, fifth and sixth signal modulators 29 and 30, fifth lens 31, fifth photodetector 32 and fifth indicator 33. Laser is used as light- emitting source. Bragg cells are used as signal modulators 10-13, 29, 30. Oscilloscopes are used as indicators 22-25, 33. EFFECT: increased functional capabilities due possibility to detect frequency modulation of received signal. 5 dwg

Description

 The invention relates to the field of automation and computer technology and can be used for visual analysis of the amplitude spectrum of information signals and determine the type of modulation.

 Known devices for the recognition of information signals (ed. St. NN 1370594, 1536508, 1580569, 1765894, 1790031, 1789996 and others).

 Of the known devices closest to the proposed is a "Device for the recognition of information signals" (ed. St. N 1789996, CL G 06 K 9/00, 1990), which is selected as a prototype. The specified device provides a visual analysis of the amplitude spectrum of information signals and determine the type and modulation. Moreover, deformations of the amplitude spectrum of the received information signal when multiplying its phase by two, four, and eight are used as recognition signs. A sign of recognition of information signals with frequency modulation (FM) is an increase in the width of the amplitude spectrum of the received FM signal by two, four and eight times when its phase is multiplied by two, four and eight times. Among these signals, linear frequency modulation (LFM) signals with an increasing frequency law, a decreasing frequency law, a symmetric V-shaped frequency law, a symmetric Λ-shaped frequency law, and signals with non-linear frequency modulation laws are widespread. .

 However, the known device, selected as a prototype, does not provide the ability to visually determine the type of frequency modulation.

 The aim of the invention is to expand the functionality by visually determining the type of frequency modulation of the received information signal.

 This goal is achieved by the fact that in a device containing a series-connected unit for receiving and amplifying a signal, first to third signal phase doublers, as well as sequentially optically coupled radiation sources, a collimator, a first radiation modulator, the control input of which is connected to the output of the signal reception and amplification unit the second radiation modulator, the control input of which is connected to the output of the first signal phase doubler, the third radiation modulator, the control input of which is connected to the output of the second doubler phase of the signal, and a fourth radiation modulator, the control input of which is connected to the output of the third signal phase doubler, while the i-th radiation modulator (i = 1,2,3,4) is optically connected to the i-th lens, in the focal plane of which i -th photodetector, the output of which is the ith information output of the device, a delay line, a switch, a fifth and sixth radiation modulators, a fifth lens and a fifth photodetector are introduced, and a fifth radiation modulator is installed on the path of the light beam of the radiation source, controlling the input of which is connected to the output of the signal reception and amplification unit, the sixth radiation modulator is orthogonally installed on the propagation path of the fifth diffracted light beam emitter, the control input of which is connected through a series delay line and the switch is connected to the output of the signal reception and amplification unit, along the diffracted sixth a fifth lens is installed by a light beam radiation modulator, in the focal plane of which a fifth photodetector is placed, the output of which is the fifth and formational output device.

 In FIG. 1 presents a structural diagram of the proposed device; in FIG. 2, the law of displacement of the point M in the x, y plane for various FM signals; figure 3 diagram of the relative positioning of the symbolic frequencies of signals with multiple frequency manipulation; figure 4 the law of the phase change of the FSK signal; figure 5 view of the possible waveforms.

 A device for recognizing information signals contains an antenna 1, a local oscillator 2, a mixer 3, an intermediate frequency amplifier 4, a first 5, a second 6 and a third 7 signal phase doublers, a radiation source 8, a collimator 9, a first 10, a second 11, a third 12 and a fourth 13 , fifth and sixth 30 radiation modulators, first 14, second 15, third 16, fourth 17 and fifth 31 lenses, first 18, second 19, third 20, fourth 21 and fifth 32 photodetectors, first 22, second 23, third 24, fourth 25 and fifth 33 display units, signal receiving and amplification unit 26, delay line 27 and off ents 28. Moreover, to the output of antenna 1 is connected in series with the mixer 3, a second input coupled to an output of local oscillator 2, an intermediate frequency amplifier 4, the first 5 7 doublers third phase signal. On the propagation path of the light beam of the radiation source 8, a collimator 9 is installed in series, the first radiation modulator 10, the control input of which (piezoelectric transducer) is connected to the output of the signal receiving and amplification unit 26, the second radiation modulator 11, the control input of which is connected to the output of the first phase doubler 5 signal, the third radiation modulator 12, the control input of which is connected to the output of the second signal phase doubler 6, the fourth radiation modulator 13, the control input of which is connected to the output 7 doubler third phase signal, and a fifth radiation modulator 29, a control input coupled to receive the output unit 26, and signal amplification. On the propagation path of the part of the light beam diffracted by the i-th modulator 10 (11-13), a lens 14 (15-17) is installed, in the focal plane of which a photodetector 18 (19-21) is placed, to the output of which is connected a block 22 (23-25 ) indication. On the propagation path of the part of the light beam diffracted by the radiation modulator 29, a radiation modulator 30 is installed, the control input of which, through the delay line 27 connected in series and the switch 28, is connected to the output of the signal reception and amplification unit 26. On the propagation path of the part of the light beam diffracted by the radiation modulator 30, a lens 31 is mounted, in the focal plane of which a photodetector 32 is placed, to the output of which an indication unit 33 is connected. The antenna 1, the local oscillator 2, the mixer 3 and the amplifier 4 of the intermediate frequency form a block 26 of the reception and amplification of the signal. A laser is used as a radiation source 8. Bragg cells are used as modulators of radiation 10-13, 29, and 30. As the lenses 14-17, 31 are used lenses. Oscillographic indicators are used as display units 22-25, 33.

 Determining the type of frequency modulation is based on two-coordinate acousto-optical processing of the received FM signal.

 The device operates as follows.

где U_c, f_c, Φ_c, T_c амплитуда, начальная частота, начальная фаза и длительность сигнала;
Φ_к(t) манипулируемая составляющая фазы, отображающая закон фазовой манипуляции, причем Φ_к(t)=const при kτ_и < t < (k+1)τ_и и может изменяться скачком при t = kτ_и, т.е. на границах между элементарными посылками (K=1,2.N-1);
τ_и, N длительность и количество элементарных посылок, из которых составлен сигнал длительностью T_c(T_c=N•τ_и).If an information signal with phase shift keying (QPSK) arrives at the device input, then it can be analytically written as follows:

where U _c , f _c , Φ _c , T _c amplitude, initial frequency, initial phase and signal duration;
_To Φ (t) manipulated component phase DPSK mapping law, and _to Φ (t) = const at kτ _and <t <(k + 1) τ _u and may vary abruptly at t = kτ _and, i.e. at the borders between elementary premises (K = 1,2.N-1);
τ _and , N are the duration and number of chips that make up the signal of duration T _c (T _c = N • τ _and ).

. Причем от одного источника фаза манипулируется по закону O-n, а от другого по закону

. Для передачи сообщений от четырех источников используется трехкратная фазовая манипуляция

.If discrete information is transmitted from a single message source on a single carrier frequency, then it is advisable to use a single (binary) phase shift keying [FMN-2, Φ _to (t) = 0, π]. Two-phase phase shift keying is used to transmit messages from two sources.

. Moreover, from one source the phase is manipulated according to the law On, and from another source according to the law

. Three-phase phase shift keying is used to transmit messages from four sources.

.

 In the general case, at one carrier frequency, messages from η sources can be simultaneously transmitted using n-fold phase shift keying. However, it is advisable to single, double and triple phase manipulations, which are widely used in practice. A further increase in the multiplicity of phase manipulation is limited by the fact that the distance between the elementary signals decreases and the noise immunity of the communication channel is substantially reduced.

Received FMN-2 signal from the output of the antenna 1 is fed to the first input of the mixer 3, the second input of which is the voltage of the local oscillator 2:
U _g (t) = U _g • cos (2πf _g t + Φ _g ),
where U _r , f _r , Φ _g amplitude, frequency and initial phase of the local oscillator voltage.

 At the output of the mixer 3, voltages of combination frequencies are generated.

где

K коэффициент передачи смесителя;
f_пр f_c f_г промежуточная частота;
Φ_пр = Φ_с- Φ_г промежуточная начальная фаза;
которое последовательно поступает на входы умножителей 5, 6 и 7 фазы на два. На выходах последних образуются напряжения:

Так как

то в указанных колебаниях фазовая манипуляция уже отсутствует.Amplifier 4 is allocated voltage only intermediate (differential) frequency

Where

K transfer coefficient of the mixer;
f _CR f _c f _g intermediate frequency;
Φ _pr = Φ _s - Φ _g intermediate initial phase;
which sequentially arrives at the inputs of phase multipliers 5, 6 and 7 by two. The outputs of the latter are formed voltage:

Because

then in these oscillations phase manipulation is already absent.

,

,

осуществляется с помощью ячеек Брэгга 10-13, 29, 30 соответственно. Каждая ячейка Брэгга состоит из звукопровода и возбуждающей гиперзвук пьезоэлектрической пластины (пьезоэлектрического преобразователя), выполненной из кристалла ниобита лития соответственно X и Y-35^o среза. Это обеспечивает автоматическую подстройку по углу Брэгга и работу ячейки в широком диапазоне частот.The optical signal is generated using a laser 8 and a collimator 9. The spatial modulation of the optical signal with an information signal U _pr (t) and its harmonics

,

,

is carried out using Bragg cells 10-13, 29, 30, respectively. Each Bragg cell consists of a sound duct and a hypersonic exciting piezoelectric plate (piezoelectric transducer) made of lithium niobite crystal, respectively, X and Y-35 ^o cut. This provides automatic Bragg angle adjustment and cell operation in a wide frequency range.

,

и

с выхода усилителя 4 промежуточной частоты и умножителей 5, 6 и 7 фазы на два поступают на пьезоэлектрические преобразователи ячеек Брэгга 10-13. Ячейки Брэгга располагаются таким образом, чтобы сколлимированный оптический сигнал проходил через две ячейки Брэгга. Пьезоэлектрические преобразователи преобразуют информационный сигнал U_пр(t) и его гармоники

,

и

в ультразвуковые колебания.Stresses U _ol (t),

,

and

from the output of the intermediate-frequency amplifier 4 and phase multipliers 5, 6, and 7, two are supplied to the piezoelectric transducers of the Bragg cells 10-13. The Bragg cells are positioned so that the collimated optical signal passes through two Bragg cells. Piezoelectric transducers convert the information signal U _pr (t) and its harmonics

,

and

into ultrasonic vibrations.

,

,

. На пути распространения каждого дифрагированного пучка света установлена линза 14 (15, 16, 17), в фокальной плоскости которой размещен фотоприемник 18 (19, 20, 21), к выходу которого подключен осциллографический индикатор 22 (23, 24, 25).A collimated optical signal passing through the Bragg cells 10-13, 29 diffracts on acoustic vibrations excited by the signal U _pr (t) and its harmonics

,

,

. On the propagation path of each diffracted light beam, a lens 14 (15, 16, 17) is installed, in the focal plane of which a photodetector 18 (19, 20, 21) is placed, the oscilloscope indicator 22 (23, 24, 25) is connected to its output.

The width of the spectrum Δf _c FMN-2 signal is determined by the duration τ _and its elementary premises (Δf _c = 1 / τ _и ). Whereas the width of the spectrum of the second Δf ₂ , the fourth Δf ₄ and the eighth Δf ₈ harmonics of the signal is determined by the duration T of _the signal (Δf ₂ = Δf ₄ = Δf ₈ = 1 / T _c ).

и трансформируется в одиночные спектральные составляющие. Это обстоятельство и является признаком распознавания ФМн-2 сигнала. Амплитудные спектры принимаемого ФМн-2 сигнала и его гармонических составляющихся наблюдаются на экранах индикаторов 22-25 (фиг.5, а).Therefore, when the phase is multiplied by two, four, and eight, the spectrum of the FMN-2 signal “folds” N times

and transforms into single spectral components. This circumstance is a sign of recognition of the FMN-2 signal. The amplitude spectra of the received FMN-2 signal and its harmonic components are observed on the screens of indicators 22-25 (Fig. 5, a).

, то на выходе умножителя 5 фазы на два образуется ФМн-2 сигнал [Φ_к(t)=0,π,2π,3π], а на выходе умножителей 6 и 7 на два образуются соответствующие гармоники колебаний

и

. В этом случае на экранах индикаторов 22 и 23 наблюдаются амплитудные спектры ФМн-4 и ФМн-2 сигналов, а на экранах индикаторов 24 и 25 наблюдаются одиночные спектральные составляющие (фиг.5, б).If an information signal with double phase shift keying is input to the device

, then at the output of the phase 5 multiplier for two, an FMN-2 signal is generated [Φ _to (t) = 0, π, 2π, 3π], and at the output of multipliers 6 and 7 two corresponding harmonic oscillations are formed

and

. In this case, the amplitude spectra of FMN-4 and FMN-2 signals are observed on the screens of indicators 22 and 23, and single spectral components are observed on the screens of indicators 24 and 25 (Fig. 5, b).

, то на выходах умножителей 5 и 6 фазы на два образуются ФМн-4 и ФМн-2 сигналы, а на выходе умножителя 7 фазы на два образуется гармоническое колебание

. В этом случае на экранах индикаторов 22, 23 и 24 наблюдаются амплитудные спектры ФМн-8, ФМн-4 и ФМн-2 сигналов, а на экране индикатора 25 наблюдается одиночная спектральная составляющая (фиг.5, в). Именно такая ситуация характерна для ФМн-8 сигнала.If the device receives an FMN-8 signal

then, at the outputs of phase 5 and 6 multipliers by two, FMn-4 and FMn-2 signals are generated, and harmonic oscillation is generated at the output of phase 7 multiplier by two

. In this case, the amplitude spectra of FMN-8, FMN-4 and FMN-2 signals are observed on the screens of indicators 22, 23 and 24, and a single spectral component is observed on the screen of indicator 25 (Fig. 5, c). It is this situation that is characteristic of the FMN-8 signal.

 Among the information signals with frequency shift keying (FMN), signals with minimal frequency shift keying (CHMn-2), with binary frequency shift keying (FCMn-3) and with rounded frequency shift keying (CHMn-5) are widely used (Fig. 3).

,
где Φ(t) изменяющаяся во времени фазовая функция (фиг.4);

средняя частота сигнала;

частота сигнала, соответствующая символу "-1";

частота сигнала, соответствующая символу "+1";
Фазовая функция Φ(t) может быть представлена выражением

,
где b_k последовательность информационных символов-1, +1}
h 1/2 индекс девиации частоты;

Фазовая функция на каждом символьном интервале τ_и изменяется во времени линейно. За время одного символьного интервала набег фазы равен ± п/2.Complex Chmn-2 signal is analytically described by the expression:

,
where Φ (t) is a time-varying phase function (Fig. 4);

average signal frequency;

signal frequency corresponding to the symbol "-1";

signal frequency corresponding to the symbol "+1";
The phase function Φ (t) can be represented by the expression

,
where b _{k is a} sequence of information symbols -1, +1}
h 1/2 the index of the frequency deviation;

The phase function on each symbol interval τ _and varies linearly in time. During one symbol interval, the phase incursion is ± n / 2.

If an FMN-2 signal is input to the device, then an FMN signal with a frequency deviation index h 1 is generated at the output of a phase 5 multiplier by two. Moreover, its amplitude spectrum is transformed into two spectral components at frequencies 2f ₁ and 2f ₂ . At the outputs of multipliers of phase 6 and 7 by two, two spectral components are formed at frequencies 4f ₁ , 4f ₂ and 8f ₁ and 8f _2, respectively (Fig. 5d).

If an FMN-3 signal is input to the device, then at the outputs of multipliers of phase 6 and 7 two three spectral components are formed at frequencies 4f ₁ , 4f _cf , 4f ₂ and 8f ₁ , 8f _cf , 8f ₂ , i.e. the continuous spectrum is transformed into three spectral components (figure 2, e). At the output of the phase 5 multiplier by two amplitude spectrum of the FSK-3 signal is transformed into another continuous spectrum, since h <1.

 Thus, on the screens of indicators 22 and 23, continuous amplitude spectra will be observed (Fig. 5, e).

If the CMN-5 signal is input to the device, then at the output of the phase 7 multiplier by its two continuous spectrum, it transforms into five spectral lobes with peak values at frequencies 8f ₁ , 8f ₃ , 8f _cf , 8f ₄ and 8f ₂ . At the outputs of phase 5 and 6 multipliers by two, the continuous spectrum of the FSK-5 signal is transformed into other continuous amplitude spectra, since in this case h <1. Thus, on the screens of indicators 22, 23 and 24, continuous amplitude spectra will be observed, and on the screen of indicator 25, five continuous petals (Fig. 2, e). It is this situation that is a sign of recognition of the ChMn-5 signal.

,
где

скорость изменения частоты внутри импульса;
Δf_∂ девиация частоты;
то преобразователем частоты он переносится на промежуточную частоту

,
Напряжение U_пр(t) выделяется усилителем 4 промежуточной частоты и поступает на пьезоэлектрический преобразователь ячейки Брэгга 10 и на вход умножителя 5 фазы на два, на выходе которого образуется ЧМ сигнал:

,
который поступает на пьезоэлектрический преобразователь ячейки Брэгга 11. Так как длительность T_с ЧМ сигнала на основной и удвоенной промежуточной частоте одинакова, то увеличение γ в два раза происходит за счет увеличения в 2 раза девиации частоты Df_∂. Из этого следует, что ширина спектра ЧМ сигнала на удвоенной промежуточной частоте в два раза больше его ширины на основной промежуточной частоте (Δf₂= 2Δf₁).If a frequency modulated (FM) signal is input to the device

,
Where

rate of change of frequency within the pulse;
Δf _∂ frequency deviation;
then it is transferred to the intermediate frequency by the frequency converter

,
The voltage U _CR (t) is allocated by the intermediate-frequency amplifier 4 and supplied to the piezoelectric transducer of the Bragg cell 10 and to the input of the phase multiplier 5 by two, at the output of which an FM signal is generated:

,
which arrives at the piezoelectric transducer of the Bragg cell 11. Since the duration of T _{with the} FM signal at the fundamental and doubled intermediate frequencies is the same, a twofold increase in γ occurs due to a twofold increase in the frequency deviation Df _∂ . From this it follows that the width of the spectrum of the FM signal at twice the intermediate frequency is two times greater than its width at the main intermediate frequency (Δf ₂ = 2Δf ₁ ).

Similarly, at the outputs of phase 6 and 7 multipliers by two, the width of the FM signal spectrum increases by 4 and 8 times. Therefore, the spectrum of the FM signal is observed and analyzed, and on the screens of the indicators 23, 24 and 25, the amplitude spectra of the FM signals are observed, the width of which is two, four and eight times the width of the spectrum of the initial FM signal (Δf ₂ = 2Δf _c , Δf ₄ = 4Δf _c , Δf ₈ = 8Δf _c ) (Fig. 5, g). This circumstance is a sign of FM signal recognition.

где τ_з время задержки линии 27.To determine the type of frequency modulation, two-coordinate acousto-optical processing of the received signal is used. The essence of this processing is that the light beam passes through two orthogonally located Bragg cells 29 and 30, the piezoelectric transducers of which are supplied with voltage:

where τ _s the delay time of the line 27.

When the screens shown in FIG. 5g, the circuit breaker 28 is turned on by the operator. At the same time, the voltage U _pr (t-τ _s ) from the output of the delay line 27 is applied to the piezoelectric transducer of the Bragg cell 30.

При τ_з > 0 в уравнении траектории содержится полная информация о внутриимпульсной модуляции принимаемого сигнала в любой момент времени.In this case, the point M of the intersection of the twice diffracted light beam with the plane of the photodetector 32 (plane X, Y) simultaneously moves both in the X coordinate and in the Y coordinate. Moreover, the point M moves in the coordinate according to the law
x Af (t),
and according to the Y coordinate according to the law
y = B • f (t-τ _s ) ,,
where A and B are constants determined by the parameters of the acousto-optical paths along the X and Y coordinates, respectively;
f (t) = f _pr + γt.
Expanding f (t-τ _s ) in a Taylor series, the control of the trajectory of the point M will be determined as follows:

When τ _s > 0, the trajectory equation contains complete information about the intrapulse modulation of the received signal at any time.

При нелинейном изменении частоты внутри импульса (j ≠ 2) уравнение траектории точки М будет отличаться от прямой линии (фиг.2, б).If the input signal receives an information signal with a linear modulation frequency (LFM) (j = 2), then the equation of the trajectory of point M is a straight line (Fig. 2, a)

With a nonlinear change in the frequency inside the pulse (j ≠ 2), the equation of the trajectory of the point M will differ from the straight line (Fig. 2, b).

 Along with the classification of FM signals along the trajectory of the point M, a visual assessment of the main parameters of the intrapulse modulation of the received FM signal is also possible.

 Therefore, the two-coordinate acousto-optical processing of the received FM signal performs the function of a frequency demodulator. Moreover, by the nature of the waveforms on the screen 33, the law of frequency modulation is determined (Fig. 5, h).

 Thus, the proposed device in comparison with the prototype provides the ability to visually determine the type of frequency modulation. This is achieved by two-coordinate acoustic processing of the received FM signal. Thus, the functionality of the device is expanded.

Claims (1)

 A device for recognizing information signals, comprising serially connected signal reception and amplification unit and a first third signal phase doubler, as well as serially optically coupled radiation source, a collimator, a first radiation modulator, the control input of which is connected to the output of the signal reception and amplification unit, a second radiation modulator the control input of which is connected to the output of the first signal phase doubler, the third radiation modulator, the control input of which is connected to the output of the second double dividing the signal phases, and the fourth radiation modulator, the control input of which is connected to the output of the third signal phase doubler, while the i-th lens is optically coupled to the i-th radiation modulator (i 1, 2, 3, 4), in the focal plane of which is located i-th photodetector, the output of which is the i-th information output of the device, characterized in that a delay line, a switch, a fifth and sixth radiation modulators, a fifth lens and a fifth photodetector are introduced into it, and heels are installed on the path of the light beam of the radiation source the first radiation modulator, the control input of which is connected to the output of the signal reception and amplification unit, and the sixth radiation modulator is orthogonally installed on the propagation path of the light beam diaphragmed by the fifth radiation modulator, the control input of which is connected to the output of the signal reception and amplification unit through series-delayed switches , on the propagation path of the light beam diffracted by the sixth modulator of radiation, a fifth lens is mounted, in the focal plane of which the fifth photodetector is placed a receiver whose output is the fifth information output of the device.

Images