RU2332681C2 - Double-frequency coherent-correlation radio detector - Google Patents

Abstract

FIELD: radio technology.

SUBSTANCE: invention pertains to radio detector devices for detecting signals reflected by targets. The essence of the invention lies in the use of the form of the probing signal (impulses) based on double-frequency broad band noise discrete frequency-shift signals with a continuous phase, formed by a transmitter, use of coherent-correlation processing of broad band noise discrete frequency-shift signals with a continuous phase, with use of non-linear invariant shrinkage of the broad band signal spectrum in the narrow band (closer to the δ-function) and specific convolution during reflection of the signal. The probing signal (impulse) of the transmitter consists of two parts, each of which has a set of discrete units. The first part of the impulse consists of randomly changing combinations of discrete units (modulated by noise); the second part of the impulse is pseudo-random serial structure. The reflected signal is processed in the receiver in a binary way. In the regenerator there is shrinkage of the spectrum for the whole duration of the reflected signal i.e. becomes a perfect sinusoidal. Only the second part of the reflected signal is processed in the schematic of convolution on time.

EFFECT: increased ratio of signal/noise, increased range of action, increased noise protectiveness, increased accuracy of measuring coordinates, increased reflection surface of the target, reduced effect of active jamming.

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Description

The invention is a dual-frequency coherent correlation radar, relates to the field of electronics. The inventive radar device has a higher tactical and technical characteristics compared with known devices.

Analogs of the claimed invention are radar devices using wideband single-frequency discrete phase-shifted signals (DFM) and their standard conversion-convolution of the signal in time (L-1; L-2; L-4, etc.).

The essence of the claimed invention consists in the use of new, different from the known structures, the forms of the probing signal (sending) based on two-frequency broadband discrete frequency-manipulated signals with a continuous phase (ШП ДММНФ), formed by the transmitter, the use of through coherent-correlation processing of reflected signals, carried out by a new principle - non-linear invariant compression of the broadband spectrum of the signal into narrow-band (close to the δ-function) and its convolution in time.

The technical result of the use of the claimed device are:

- increasing the potential of the radar;

- increasing the ratio s / w;

- increase in range;

- improvement of noise immunity;

- phase sensitivity of the receiving device only to "their" signals;

- preventing the possibility of reconnaissance of the structure of the probe signal;

- improving the accuracy of measuring current coordinates and parameters;

- an increase in the effective reflective surface of the object being detected and a decrease in the influence of Stels technology;

- the exception of the unmasking sign of the spectrum of the DFM signals in the form of a dip at the carrier frequency.

Figure 1. The structure of the probe signal (package)

Figure 2. Block diagram of the transmitter.

Figure 3. Block diagram of the receiver.

The structures of synchronization nodes, AGC, detector-meter, aircraft, etc. are standard, not claiming to protect any novelty (L-4).

The general diagram of the radio engineering nodes of the radar and the connections between them includes: a transmitter (Fig. 2) that generates a sounding signal (Fig. 1), a receiver (Fig. 3) that processes broadband noise-like dhmnf signals and auxiliary means.

The radar transmitter of FIG. 2 contains a frequency and time standard (1) connected to a shaper of discrete carrier frequencies (LFD), a synchronizer (5), and auxiliary means. It differs from the analogue (L-3) in that it generates a SHF DCHMNF signals, consisting of two successive parts (A and B), Fig.1. The generator of the carrier frequencies of the samples, by dividing the reference frequency, generates continuous sinusoidal oscillations with frequencies f ₀ and f ₁ to fill the time samples of the probing package according to random or SRP laws for which the frequency manipulation index is D = 2 Δf T _d = 0.5, where 2Δf = f ₁ -f ₀ , and T _{d the} duration of one discrete.

In the first part of the probe package (A), of duration n T _d , the discrete pattern is random, changing from one package to another (modulated by noise) and performs a two-fold function: firstly, it masks the PSP combinations of the second part, and secondly, increases the potential of the radar due to the greater energy of the probe signal E _c = P _per (n + N) T _d without increasing the transmitter power. The number of “n” samples in the first part of the probe package may vary.

The second part of the premise (B) consists of N discrete and represents the SRP structure.

Two outputs of the generator of carrier frequencies of the discrete are connected to the input of the modulator - noise generator (3) and in series with it with the modulator-generator of the SRP (4). The third and fourth inputs of the modulator-generators are connected to the synchronizer (5), which controls the switching elements of the modulator-generators.

The probe signal thus formed is amplified (6) and emitted by the antenna.

The radar receiver of figure 3 includes: standard nodes for processing MSK signals: antenna, input nodes of the receiver, a linear amplifier (7) and a frequency doubler (8). The difference of the claimed receiver from the analogue (L-3) is that the output of the frequency doubler is connected to three channels:

- with a channel for regeneration of NPP;

- with a module-multiplier for the formation of the clock frequency,

- with a convolution diagram in time of the second part of the reflected signal (10).

The regenerator includes: two identical frequency channels 2f ₀ and 2f ₁ , each of which contains an input multiplier, a narrow-band filter, a second multiplier and a frequency divider connected in series. LFD recovery is performed by mutually cross heterodyning: signals with doubled LFFs of channel 2f ₀ are supplied to the second inputs of both channel multipliers 2f ₁ , and signals with doubled LFDs of channel 2f ₁ are fed to the second inputs of channel 2f ₀ multipliers. In addition, the outputs of the second multipliers are connected to the inputs of the convolution scheme in time and to the inputs of the fifth multiplier, the output of which is formed by a continuous oscillation at twice the average frequency 2f _cp = f ₀ + f ₁ .

The multiplier module | X |, which does not have an analogue, performs the basic operation of the nonlinear invariant compression of the spectrum of the BF of the DXMNF signal into a narrowband one. Its second input is connected to the output of the fifth regenerator multiplier, and the output is connected to a narrow-band filter, which generates an output harmonic signal with a duration of (n + N) T _d , providing the formation of an output signal with a maximum s / w ratio. The output of the filter is connected to the input of the detector-meter (11).

Based on this signal, the fact of signal detection is recorded in the detector-meter, the delay time of the reflected signal relative to the emitted signal is measured - range, the control voltage of the AGC is generated, the Doppler frequency offset is measured and other auxiliary operations are performed (L-4, p.229-265, 293-316 )

The convolution scheme of the BF DFMNF signals in time (10) converts the second part (B) of the reflected signal of duration NT _d into a signal of duration T _d . It differs from the standard one (L-4 p. 293) and is adapted for the time convolution of NF DFMF signals by including N multipliers between the delay cells and the adder, which are fed with continuous oscillations with doubled LF from the regenerator. Each multiplier chooses an alternative signal. The output signals of the adder are formed by a filter with a passband Δf _f = 1 / T _d , the output of which is connected to the detector-meter. Signals shortened by N times with amplitude increased by N times have a steeper leading edge and characterize the specified range compared to the regenerator.

The work of the radar. The transmitter emits sounding signals with a duration of (n + N) T _d with a noise first part and with a PSP combination of its second part through the antenna of the ШП ДММНФ antenna.

The reflected signal is received by the antenna, passes the linear amplifier (7) of the receiver and doubles in frequency (8). The analytical form of the reflected signal at the output of the frequency doubler

where k is the number of samples in the probing signal;

a = {+ 1, -1} according to random or PSP laws.

;

;

.

.

From the output of the frequency doubler, the signal branches into three directions:

- to the input of the regenerator;

- at the input of the multiplier module;

- the input of the convolution scheme in time.

In the regenerator, narrow-band filtering of signals on double carriers with a signal frequency memory is performed during the operation of an alternative discrete.

The conversion operation is implemented by cross heterodyning doubled LFD. Moreover, in the first two multipliers of the signal frequencies, 2 ω ₁ -2 ω ₀ are subtracted, and in the second multipliers in the channel “0”, 2 ω ₁ -4 Δω = 2 ω ₀ is subtracted, and in the channel “1”, the summation is 2 ω ₀ +4 Δω = 2 ω ₁ . Between the first and second multipliers of channel “0” and channel “1” narrow-band filters are included, tuned to a frequency of 2 Ω _m = 4 Δω. At the outputs of the multipliers of both channels, continuous oscillations are formed on double carriers, which then enter the convolution circuit in time and in two frequency dividers, forming oscillations with LFD, from which oscillation with a doubled average frequency ω ₀ + ω ₁ = 2 ω is formed in the fifth multiplier _cf supplied to the second input of the multiplier module.

The multiplier module (no analogue was found) performs the following operations: when a discrete with a frequency of 2 ω ₀ and a continuous oscillation with a frequency of 2 ω _cf arrives at the first signal input, an oscillation with a frequency of 2Δω = Ω _t is formed at the output, when a discrete with a frequency of 2 ω ₁ arrives at the signal input, then interacting with a vibration constantly acting on the second input with a frequency of 2 ω _cf , a continuous oscillation with a frequency of 2 Δω = Ω _t is formed again at the output. Moreover, with the described signal transformations, the coherence of the oscillations and the “stitching” of the phases of the oscillations between the discs are preserved. The output oscillation passes a narrow-band filter with a passband Δf _yf = 1 / (n + N) T _d , forming an output signal with a maximum s / w ratio, but with a relatively shallow leading edge.

The result of the multiplication of the frequency bandwidth of an HFMF signal with doubled LFB by a continuous signal with doubled average frequency is expressed

1 / 2cos 2Δω t + 1 / 2cos {4ω _cp t + a _k 2Δω [t- (k-1) T _d ]}.

The first term is a continuous sinusoidal oscillation over time (n + N) T _d with a clock frequency. The absence of the coefficient “a _k ” in it determines the invariance of the transformation with respect to the internal structure of the multiplied signals.

The second region with an oscillating frequency is suppressed by a narrow-band filter.

The reflected signal filtered in this way with a clock sampling frequency at the output of a narrow-band filter has a maximum s / w ratio.

A remarkable property of the nonlinear invariant spectrum compression (non-Fourier convolution) is manifested in the transfer module. i.e. a transformation independent of the internal structure of alternating discrete.

The output signal of the regenerator module multiplier is fed to the input of the detector-meter (11). According to it, delayed relative to the probe and exceeding the set threshold, the reflected signal is detected, the current coordinates and parameters of the target are measured, the AGC control voltage is generated, etc.

The convolution scheme of the reflected BF DFMNF signal in time, refines the range R by shortening the second part of the package from NT _d to the duration of one discrete. Its construction and operation differs from the usual ones and is adapted to the two-frequency structure of the DFMF signals.

In the time convolution scheme of the second part (B) of the reflected signal, there is a sequential delay of the samples, their conversion to double the clock frequency and summation of the amplitudes during the last sample of the package (noise - the first part of the package does not form a consistent response at the output of the convolution scheme). As a result, the duration of the second part of the package is reduced by N times and the amplitude also increases by N times. The output signal of the svetka circuit is formed by a filter with a passband Δf _f = 1 / T _d and enters the detector-meter.

This signal with a steep leading edge characterizes the specified value of the range R required in tracking radars.

As a result, ceteris paribus, the gains compared to the DFM signals are:

раз;- regarding s / w

time;

раз;- in range

time;

increased noise immunity due to phase and structural sensitivity only to "their" signals;

the influence of active interference is reduced due to the narrowing of the resulting receiver bandwidth;

the accuracy of measuring coordinates and motion parameters of the target is increased due to the greater potential;

the unmasking sign of the DFM signals in the form of a dip in the spectrum at the carrier frequency is excluded;

- increases the effective reflective surface of the target due to the use of a two-frequency signal, i.e. The impact of Stels technology is reduced.

The universality (as an option) of the proposed radar structure consists in the fact that it is advisable to use all of the nodes listed and described above in tracking radars, and the signal convolution node in time may not be used in surveillance radars.

Literature

L-1 Modern radar. Ed. “Owls. Radio ”, 1969, pp. 463-475, 589-613.

L-2 A.A. Korostelev. Spatio-temporal theory of radio systems. Ed. Radio and Communications, 1987, pp. 27-52.

L-3 Foreign electronics. M .: "Radio and communications", No. 4, 1982, pp. 58-72.

L-4 Radio-electronic systems. Ed. J.D. Shirman. M. ed. Radio Engineering, 2007, pp. 299-265, 293-316.

L-5 Av. St. No. 326750.

L-6 Aat. St. No. 1584079.

L-7 Patent No. 2045128.

L-8 Patent No. 2284658.

121069, Moscow, Khlebny per. 14, apt. 14, tel. 291-63-73.

Claims (1)

A two-frequency coherent correlation radar that uses wide-band noise-like discrete frequency-manipulated signals with a continuous phase (ШП ДММНФ), containing a transmitter consisting of a frequency and time standard, which is a master element of the transmitter, the first output of which is connected to the carrier frequency generator of samples (LFD) f ₀ and f ₁ , and the second output is connected to the synchronizer; the receiver, in which the reflected signal is received by the antenna, is amplified by a linear amplifier, the output of which is connected to the input of the frequency doubler, characterized in that the LFD driver generates sinusoidal oscillations with frequencies f ₀ and f ₁ from the reference frequency with a frequency manipulation index 2 Δf T _d = 0 5 where 2Δf = f ₁ -f _0, T _d - duration of one increment, two outputs NCHD generator coupled to the modulator input noise generator connected in series with the modulator-generator pseudorandom sequence (PRS), whose output oedinen the amplifier and the amplifier output is connected to the antenna, the second inputs of the modulator-generators are connected to respective outputs of the synchronizer, control signals from which provide the formation of the probe parcel length (n + N) T _d, where n - the number of discrete first portion of the probe parcels which may vary, N is the number of discretes of the second part of the premise; the output of the receiver frequency doubler is connected to the input of the regenerator and the input of the convolution circuit of the reflected signal of the DCHMNF signal in time, while the regenerator performs mutually cross heterodyning of continuous double LFDs 2 f ₀ and 2 f ₁ , their narrow-band filtering at the clock frequency and non-linear invariant compression the spectrum of the reflected BF DFMFF signal with a module multiplier followed by narrow-band filtering Δf _UV = 1 / (n + N) T _d ; the output of the regenerator is connected to the input of the detector-meter, and the outputs of the regenerator with double NPPs are connected to the corresponding inputs of the signal convolution circuit in time, the output signal of which characterizes the exact range, and the detector-detector detects the reflected signal, measures the current coordinates and parameters of the tracked object.

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