RU2366079C1 - Panoramic receiver - Google Patents

Abstract

FIELD: radio electronics.

SUBSTANCE: invention relates to radio electronics and can be used for determination of carrier frequency and type of modulation of signals received in preset frequency range. Proposed panoramic receiver comprises receiving antenna, input circuit, scan unit, HF amplifier, heterodyne, mixer, IF amplifier, three amplitude detectors, video amplifier, frequency sweep shaper, five CRTs, key, factor-2-phase multiplier, factor-4-phase multiplier, factor-8-phase multiplier, factor-2-phase splitter, factor-4-phase-splitter, factor-8-phase-splitter, three bandpass filters, switch and frequency detector.

EFFECT: expanded performances due to received signal modulation type determination.

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Description

The proposed receiver relates to the field of electronics and can be used to determine the carrier frequency and the type of modulation of signals received in a given frequency range.

Panoramic receivers are known (author's certificate of the USSR No. 1.290.192, 1.012.152, 1.180.804, 1.187.095, 1.272.266, 1.290.192, 1.354.124; RF patents No. 2.001.407, 2.010.244 , 2.025.737, 2.030.750, 2.124.216, 2.230.330; US patent No. 4.443.801; Valin S.A., Shustov L.N. Fundamentals of radio countermeasures and electronic intelligence. M: Sov. Radio, 1968, p. 386-396, fig. 10.3 and others).

Of the known panoramic receivers, the closest to the proposed one is the “Panoramic receiver” (Valin SA, Shustov LN Fundamentals of radio countermeasures and electronic intelligence. M: Sov. Radio, 1968, p. 386-396, Fig. 10.3) , which is selected as a prototype.

The specified panoramic receiver provides a visual determination of only the carrier frequency of the received signal and does not allow to determine the type of modulation.

One of the characteristic features of modern and promising electronic equipment (RES) is the widespread use of simple and complex signals, which are characterized by a wide variety of modulations.

The type of modulation is an important characteristic of radio emissions, providing a solution to a number of problems of reception and analysis of RES signals. The task of determining the type of modulation is also important in assessing the parameters of the modulating function of the received signals. Typically, parameter analyzers for each type of signal are constructed according to different principles and provide false information for signals with other modulation laws. Selection of signals by type of modulation makes it possible to eliminate this drawback.

An object of the invention is to expand the functionality of a panoramic receiver by determining the type of modulation of the received signal.

The problem is solved in that the panoramic receiver contains a receiving antenna, an input circuit, a high-frequency amplifier, a mixer, the second input of which is connected to the local oscillator output, an intermediate-frequency amplifier, a first amplitude detector, a video amplifier and vertically-deflecting plates of the first cathode ray tube the horizontal deflecting plates of which are connected to the output of the frequency sweep forming device, while the control inputs of the input circuit of the high-frequency amplifier , a local oscillator and frequency sweep forming devices are connected to the corresponding outputs of the search unit, equipped with a key, a switch, a frequency detector, a fifth cathode ray tube and three processing channels, each of which contains a phase multiplier, a phase divider, a bandpass filter, an amplitude detector, and vertically deflecting plates of an additional cathode ray tube, the horizontally deflecting plates of which are connected to the output of the frequency hands, and to the output of the intermediate frequency amplifier, a key is connected in series, the second input of which is connected to the output of the video amplifier, a switch, a frequency detector and vertically-deflecting plates of the fifth cathode ray tube, the horizontally-deflecting plates of which are connected to the output of the frequency-shaping device, three channels the processing is connected to the key output, in the first channel the phase of the received signal is multiplied and divided by two, in the second - by four, in the third - by eight.

The structural diagram of a panoramic receiver is presented in figure 1. The possible waveforms are shown in FIGS. 2 and 3.

The panoramic receiver contains a receiving antenna 1 connected in series, an input circuit 2, a high-frequency amplifier 4, a mixer 6, the second input of which is connected to the output of the local oscillator 5, an intermediate-frequency amplifier 7, a first amplitude detector 8, a video amplifier 9, and CRT 11 vertically-deflecting plates, the horizontal deflecting plate which is connected to the output of the device 10 forming a frequency sweep. The control inputs of the input circuit 2, the high-frequency amplifier 4, the local oscillator 5 and the frequency sweep forming device 10 are connected to the corresponding outputs of the search unit 3, for which a sawtooth voltage generator can be used. To the output of the intermediate frequency amplifier 7, a key 12 is connected in series, the second input of which is connected to the output of the video amplifier 9, and three processing channels, each of which consists of a phase multiplier 13.1 (13.2, 13.3), a phase divider 14.1 (14.2, 14.3), connected in series ), a band-pass filter 15.1 (15.2, 15.3), an amplitude detector 16.1 (16.2, 16.3) and vertically-deflecting plates of an additional CRT 17.1 (17.2, 17.3), the horizontally-deflecting plates of which are connected to the output of the frequency sweep forming device 10.

The proposed panoramic receiver operates as follows.

The search for signals in a given frequency range is carried out using a search unit 3, which, according to a sawtooth law, consistently changes the settings of the input circuit 2, high-frequency amplifier 4 and local oscillator 5. At the same time, the search unit 3 controls the frequency sweep generation device 10 on the CRT screens 11, 17.1, 17.2 , 17.3 and 20. As a result, a pulse (frequency mark) is generated on the screen of the CRT 11, the position of which on the frequency sweep determines the carrier frequency of the received signal (figure 2).

The voltage from the output of the video amplifier 9 is simultaneously supplied to the control input of the key 12, opening it. In the initial state, the key 12 is always closed.

In this case, the received signal, for example, with binary phase shift keying (FMN-2) at an intermediate frequency

U _pr (t) = U _pr · cos [ω _pr t + φ _k (t) + φ _pr ], 0≤t≤T _c ,

;Where

;

k is the transfer coefficient of the mixer;

ω _CR (t) = ω _C -ω _G - intermediate frequency;

φ _ol (t) = φ _C -φ _G ;

φ _k (t) = {0; π} is the manipulated component of the phase, which displays the law of phase manipulation in accordance with the modulating code M (t), and φ _k (t) = const for kτ _E <t <(k + 1) τ _E and can change stepwise at t = kτ _E , i.e. at the borders between elementary premises (k = 1, 2, 3 ... 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 );

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

U _Г , ω _Г , φ _Г - amplitude, frequency and initial phase of the local oscillator voltage;

from the output of the amplifier 7 of the intermediate frequency through the public key 12 is supplied to the outputs of the phase multipliers by two 13.1, by four 13.2 and by eight 13.3, at the outputs of which harmonic voltages are formed:

U ₁ (t) = U ₁ · cos [2ω _pr t + 2φ _pr ];

U ₂ (t) = U ₂ · cos [4ω _pr t + 4φ _pr ];

U ₃ (t) = U ₃ · cos [8ω _pr t + 8φ _pr ], 0≤t≤T _c .

Since 2φ _k (t) = {0; 2π}, 4φ _k (t) = {0; 4π}, 8φ _k (t) = {0; 8π}, then the phase manipulation is already absent in the indicated voltages.

The spectral width Δf _C-2 PSK signal of duration τ is determined by its chip _E

,

,

while the width of the spectrum of the second Δf ₂ , fourth Δf ₄ and eighth harmonic Δf ₈ is determined by the signal duration

.

.

Therefore, when the phase is multiplied by two, four, and eight, the spectrum of the FMN-2 signal is collapsed N times

and transforms into single spectral components. This circumstance is a sign of recognition of FMN-2 signal.

Harmonic voltages U ₁ (t), U ₂ (t), U ₃ (t) are supplied to the inputs of the phase dividers into two 14.1, four 14.2 and eight 14.3, respectively, at the outputs of which the following harmonic voltages are formed:

U ₄ (t) = U ₄ · cos [ω _pr t + φ _pr ];

U ₅ (t) = U ₅ · cos [ω _pr t + φ _pr ];

₆ U (t) = U ₆ · cos [ω t + φ _{etc. etc.],} 0≤t≤T _c.

These voltages are distinguished by band-pass filters 15.1, 15.2 and 15.3 respectively, are detected by amplitude detectors 16.1, 16.2, 16.3 and applied to vertically-deflecting plates of CRT 17.1, 17.2 and 17.3. The frequency sweep of the CRT 17.1, 17.2 and 17.3 are formed using the device 10, the voltage of which is supplied to the horizontally deflecting plates. On the CRT screens 17.1, 17.2 and 17.3, pulses are formed that are visually observed and serve as a sign of recognition of the FMN-2 signal (Fig. 3, a).

, то на выходе полосового фильтра 15.1 образуется ФМн-2 сигнал [φ_k(t)={0, π, 2π, 3π}], а на выходе полосовых фильтров 15.2 и 15.3 образуются соответствующие гармонические напряжения. В этом случае на экране ЭЛТ 17.1 визуально наблюдается спектр ФМн-2 сигнала, а на экранах ЭЛТ 17.2 и 17.3 наблюдаются одиночные спектральные составляющие (фиг.3, б).If an FMN-4 signal is input to the panoramic receiver

then, at the output of the bandpass filter 15.1, an FMN-2 signal [φ _k (t) = {0, π, 2π, 3π}] is generated, and the corresponding harmonic voltages are formed at the output of the bandpass filters 15.2 and 15.3. In this case, the spectrum of FMN-2 signal is visually observed on the CRT screen 17.1, and single spectral components are observed on the CRT screens 17.2 and 17.3 (Fig. 3, b).

, то на выходе полосового фильтра 15.1 образуется ФМн-2 сигнал [φ_k, (t)={0, π, 2π, 3π}], а гармоническое напряжение образуется только на выходе полосового фильтра 15.3 (фиг.3, в).If an FMN-8 signal is input to the panoramic receiver

, then at the output of the band-pass filter 15.1, an FMN-2 signal [φ _k , (t) = {0, π, 2π, 3π}] is generated, and harmonic voltage is generated only at the output of the band-pass filter 15.3 (Fig. 3, c).

In the general case, messages can be transmitted from n sources simultaneously on one carrier frequency using m-fold phase shift keying. However, one- (FMn-2), two- (FMn-4) and three-time (FMn-8) phase manipulations, which have found wide application in practice, are advisable. A further increase in the multiplicity of phase manipulation is limited by the fact that the distance between the elementary signals is reduced and the noise immunity of the communication channel is substantially reduced.

Among complex signals with frequency shift keying (FSK), signals with minimal frequency shift keying (FSK-2), with binary frequency shift keying (FSK-3) and with rounded frequency-shift keying (FSK-5) are widely used.

If the input of the panoramic receiver receives the FSK-2 signal, then the output of the bandpass filters 15.1, 15.2 and 15.3 form frequency-manipulated signals with the frequency manipulation index m _f = 1. In this case, the spectrum of the FSK-2 signal is transformed into two spectral components (Fig. 3, d), which is a sign of recognition of the FSK-2 signal.

If the input of the panoramic receiver receives the ChMn-3 or ChMn-5 signal, then its continuous spectrum is transformed into three (Fig. 3, e) or five (Fig. 3, e) spectral components, respectively.

If a frequency modulated (FM) signal is input to the panoramic receiver

U _c (t) = U _c · cos [ω _c t + πγtj + φ _c ], 0≤t≤T _c ,

- скорость изменения частоты внутри импульса;Where

- rate of change of frequency inside the pulse;

Δf _∂ - frequency deviation;

j = 2, 3, ...,

then after the frequency conversion in the mixer 6 through the public key 12, it enters the inputs of the phase multipliers by two 13.1, four by 13.2 and eight by 13.3, at the output of which voltages are respectively generated:

U ₇ (t) = U ₇ · cos [2ω _pr t + 2πγtj + 2φ _pr ],

U ₈ (t) = U ₈ · cos [4ω _pr t + 4πγtj + 4φ _pr ],

U ₉ (t) = U ₉ · cos [8ω _pr t + 8πγtj + 8φ _pr ], 0≤t≤T _s .

Since the duration of T _{with the} FM signal and its harmonics remains constant, an increase in γ by two, four, and eight times occurs due to an increase in the number of times the frequency deviation Δf _∂ and the spectrum width of the received FM signal.

Therefore, on the CRT screen 17.1, 17.2 and 17.3, spectra of FM signals are visually observed, the width of which is two, four and eight times the width of the spectrum of the original signal (Fig. 3, g). This circumstance is a sign of recognition of FM signals.

To recognize the type and law of frequency modulation, the operator closes the switch 18. At the same time, the received FM signal converted in frequency through the public key 12 and the closed switch 18 is fed to the input of the frequency detector 19. An oscillogram is formed on the screen of the CRT 20, the nature of which determines the type frequency modulation.

For signals with linear frequency modulation (LFM) j = 2, the oscillogram has the form shown in Fig. 3, h.

One of the modifications of the chirp signal is a signal with symmetric linear frequency modulation (UHFM) (figure 3, and).

For signals with quadrature frequency modulation (MFC) j = 3, the waveform has the form shown in figure 3, K.

Thus, the proposed receiver in comparison with the prototype provides a definition of not only the carrier frequency of the received signal, but also the type of modulation. Thus, the functionality of the panoramic receiver is expanded.

Claims (1)

A panoramic receiver comprising a receiving antenna in series, an input circuit, a high-frequency amplifier, a mixer, the second input of which is connected to the local oscillator output, an intermediate-frequency amplifier, a first amplitude detector, a video amplifier and vertically-deflecting plates of the first cathode ray tube, horizontally-deflecting plates which are connected to the output of the frequency sweep shaping device, while the control inputs of the input circuit of the high-frequency amplifier, local oscillator, and device Frequency sweeps are connected to the corresponding outputs of the search unit, characterized in that it is equipped with a key, a switch, a frequency detector, a fifth cathode ray tube and three processing channels, each of which contains a phase multiplier, a phase divider, a bandpass filter, an amplitude detector, and a vertical detector - deflecting plates of an additional cathode ray tube, the horizontally deflecting plates of which are connected to the output of the frequency sweep forming device, and to the output of the intermediate frequency amplifier is connected in series with a key, the second input of which is connected to the output of the video amplifier, a switch, a frequency detector and vertically-deflecting plates of the fifth cathode ray tube, the horizontally-deflecting plates of which are connected to the output of the frequency sweep forming device, three processing channels are connected to the output of the key, in the first channel, the phase of the received signal is multiplied and divided by two, in the second - by four, in the third - by eight.

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