RU2642808C1 - Interference suppressor - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention is designed to isolate signals of moving targets against the background of passive interference during the group rearrangement of the carrier frequency of the probing pulses. Interference suppressor includes the first and the second delay units, a weighting coefficient unit, the first and the second complex multipliers, a weight block, a complex adder, a complex conjugation unit, a switching unit, an accuracy unit, a wiring unit and a two-channel switch interconnected in a certain way and carrying out a coherent processing of the original samples. The signal from the moving target and passive interference, significantly exceeding the useful signal in the quadrature phase detectors, is transferred to the video frequency and converted in such a way that the interference residues are compensated.

EFFECT: increasing the signal extraction efficiency of moving targets.

11 dwg

Description

The invention relates to computer technology and can be used in coherent-pulse radar systems to isolate the signals of moving targets against a background of passive interference during group tuning of the carrier frequency of the probe pulses.

Known radar device for detecting a moving target [1], containing sequentially included delay blocks, a complex number multiplier and a subtractor. However, this device has a low signal extraction efficiency for a moving target.

Another known device is the correlation auto-compensator [2], which contains a number of delay units, two multipliers, an adder and a unit for estimating the parameters of the correlated noise. The disadvantage of this device is the poor suppression of the edges of the extended interference due to the large time constant of the adaptive feedback circuit.

Closest to the present invention, a digital device for suppressing passive interference [3], selected as a prototype, contains two delay blocks, a block of weight coefficients, two complex multipliers, a weight block and a complex adder. However, this device due to the transient process upon receipt of the edge of the passive interference has a low efficiency of signal extraction of moving targets.

The problem to be solved in the invention is to increase the efficiency of suppressing passive interference and isolating signals of moving targets when processing a group of pulses against a background of passive interference with an a priori unknown Doppler speed.

To solve this problem, a third-party delay unit, a complex conjugation unit, a switching unit, an accuracy unit, switching unit and two-channel switch.

Additional blocks introduced into the proposed device are known. Thus, the first delay unit, the first complex multiplier, the weight unit, and the complex adder connected together are used to suppress passive interference, but their use together with the switching unit and a two-channel switch is not known for more accurate interference compensation. The links between the third delay unit and the weight unit, the weighting unit and the switching unit and the weight unit, the accuracy unit and the second complex multiplier, the second delay unit, the two-channel switch, the second complex multiplier and the switching unit, as well as the communication between the sync generator and input units are new devices that provide optimal and consistent processing of a group of pulses, which, taking into account more accurate compensation of interference, leads to an increase in the efficiency of signal isolation In the process of tuning the carrier frequency against the background of passive interference with an a priori unknown Doppler speed.

Comparison with technical solutions known from published sources of information shows that the claimed solution has novelty and has an inventive step.

The claimed solution is technical in nature, feasible, reproducible and, therefore, is industrially applicable.

In FIG. 1 shows a block diagram of a calculator for suppressing interference; in FIG. 2 - delay unit; in FIG. 3 - block complex conjugation; in FIG. 4 - complex multiplier; in FIG. 5 - weight block; in FIG. 6 - complex adder; in FIG. 7 - switching unit; in FIG. 8 - precision block; in FIG. 9 - drive; in FIG. 10 - unit calculation module; in FIG. 11 - two-channel switch.

The computer for suppressing interference (Fig. 1) contains a first delay unit 1, a weighting unit 2, a first complex multiplier 3, a weight unit 4, a complex adder 5, a second complex multiplier 6, a second delay unit 7, a clock 8, a third delay unit 9 , block 10 complex pairing, block 11 switching, block 12 accuracy, block 13 switching and two-channel switch 14.

Blocks 1, 7 and 9 of the delay (Fig. 2) contain two random access memory 15; block 10 complex interface (Fig. 3) contains an inverter 16; complex multiplier 3, 6 (Fig. 4) contains two channels (I, II), each of which contains multipliers 17, 18 and the adder 19; the weight unit 4 (Fig. 5) contains two multipliers 20; complex adder 5 (Fig. 6) contains two adders 21; block 11 switching (Fig. 7) contains a counter 22, a decoder 23, blocks 24 matches and the adder 25; the accuracy unit 12 (Fig. 8) contains a drive 26, a module calculation unit 27, and two dividers 28; drive 26 (Fig. 9) contains two channels (I, II), consisting of n delay elements 29 for the interval t _d and n adders 30; the module calculation unit 27 (FIG. 10) comprises two multipliers 31, an adder 32 and a square root extraction unit 33; two-channel switch 14 (Fig. 11) contains two switches 34.

The calculator for suppressing interference works as follows.

A group of coherent radio pulses, initially radiated with the same carrier frequency and consisting of a signal from a moving target and passive interference significantly exceeding the signal, is fed to the input of a receiving device, in which it is amplified, is transferred to the video frequency in quadrature phase detectors, and then subjected to analog-to-digital conversion (corresponding blocks in Fig. 1 are not shown).

The digital codes (x _kl , y _kl ) of both quadrature projections following through the repetition period T in each range resolution element (range ring) of each repetition period form complex numbers

where k is the number of the current period, l is the number of the current range ring, ϕ _l is the Doppler phase shift during the repetition period (usually interference, due to its significant excess over the signal), equal to ϕ _l = 2πƒ _l T, here ƒ _l is the Doppler interference frequency .

Digital readings in the inventive device (Fig. 1) are supplied to the inputs of the first delay unit 1 (Fig. 2) and to the inputs of the third delay unit 9 connected to them. Each of the delay units 1, 7, and 9 (Fig. 2) consists of parallel-connected random access memory (RAM) 15. RAM 15 of the delay units 1, 7 serve to store samples for one period T, and RAM 15 of the third delay unit 9 - during the interval τ.

In block 10 complex conjugation using an inverter 15 (Fig. 3), the sign of the imaginary projections of the samples delayed in block 1 is inverted. In the first complex multiplier 3, the multiplication of the corresponding complex numbers occurs, realized by operations with the projections of these numbers in accordance with FIG. 4. Formed values

с n+1 смежных элементов разрешения по дальности временного строба, кроме элемента с номером n/2+1, для чего выходные величины элемента 29 задержки с номером n/2 поступают только на последующий элемент 29 задержки (фиг. 9). На выходах накопителя 26 (фиг. 9) образуются величиныenter the accuracy block 12 (Fig. 8), in which the drive 26 (Fig. 9) performs, using delay elements 29 and adders 30, the products summed along the range in each repetition period

from n + 1 adjacent resolution elements according to the range of the temporary strobe, except for the element with the number n / 2 + 1, for which the output values of the delay element 29 with the number n / 2 go only to the subsequent delay element 29 (Fig. 9). At the outputs of the drive 26 (Fig. 9) values are formed

- оценка сдвига фазы помехи за период повторения, усредненная для повышения точности по n смежным элементам разрешения по дальности.Where

- an estimate of the phase shift of the interference over the repetition period, averaged to improve accuracy over n adjacent range resolution elements.

, а затем на выходах делителей 28 (фиг. 8) - величины

, поступающие на первые входы второго комплексного перемножителя 6.In block 27 calculation module (Fig. 10) are determined by

, and then at the outputs of the dividers 28 (Fig. 8) - values

entering the first inputs of the second complex multiplier 6.

The output samples of the delay unit 9 are received in the weight unit 4 (Fig. 5), in which the incoming samples are weighed by the weighting coefficients g _k , which are stored in the weighting unit 2. The number of weight coefficients g _k is determined by the implemented order of the computer to suppress noise m associated with the number of pulses in the group equal to m + 1. In particular, when m = 1, the weighting coefficients g ₀ = -g ₁ = 1; when m = 2 - g ₀ = g ₂ = 1, g ₁ = -2; when m = 3 - g ₀ = -g ₃ = 1, g ₂ = -g ₃ = -3. Weights are switched in each repetition period by the switching unit 11 (Fig. 7), which provides processing of a group of pulses (samples) with the same initial carrier frequency.

The pulse from the radar synchronizer (not shown in Fig. 1), corresponding to the radiation of the probe pulse in each period, is fed to the first control input (1) of the interference suppressor (Fig. 1), which is the first control input (1) of the switching unit 11, and then to the counting input of the counter 22 (Fig. 7). The counter readings corresponding to the pulse number in the group in the decoder 23 are converted into a single signal at the corresponding pulse number of the output of the decoder 23. This signal opens the coincidence cascade 24 connected to it, through which the corresponding weight coefficient passes through the adder 25 to the output of the switching unit 11 . Thus, each impulse in the group has its own weight coefficient.

весовыми суммами отсчетов всех предыдущих импульсов группы. В конечном счете, в результате весовой обработки отсчетов m+1 периодов образуется величинаThe samples weighted in the weight unit 4 are summed in the complex adder 5 with the delays delayed in the second block 7 for the repetition period T, passed through the two-channel switch 14 and multiplied in the second complex multiplier 6 by the amount

weighted sums of samples of all previous pulses of the group. Ultimately, as a result of weight processing of samples of m + 1 periods, the value

обеспечивает синфазность суммируемых отсчетов, а их взвешивание коэффициентами g_k - подавление (компенсацию) слагаемых отсчетов помехи. Сигнал от движущейся цели из-за сохранения доплеровских сдвигов фазы не подавляется.Two-dimensional rotation of delayed samples at an angle

provides the common mode of the summed samples, and their weighing by the coefficients g _k - suppression (compensation) of the summands of the interference samples. The signal from a moving target due to the conservation of Doppler phase shifts is not suppressed.

In the third delay block 9, the samples are delayed by the interval τ equal to the time delay of the estimates with respect to the middle element of the training sample, excluded in the drive 26 (Fig. 9) in accordance with expression (1). The value of τ is determined by the expression

τ = t + nt _{to d} / 2,

where t _at is the time of calculation of the estimation of the phase of interference, n is the number of elements of the training sample, t _d is the interval (period) of time sampling.

In this case, the correspondence of the 6 phase shifts introduced in the second complex multiplier to the middle element excluded from the training set is ensured. Then, in the case of a signal commensurate in magnitude with the interference, or discontinuous interference when suppressing the interference samples from the resolution element containing the signal, the possibility of attenuation or suppression of the signal due to its effect on the estimates used is excluded.

After the processing of data of m + 1 periods and the next tuning of the carrier frequency to the second control inputs (2) of the device (Fig. 1) and the switching unit 11 (Fig. 7) and the control input of the switching unit 13, a pulse arrives that resets the counter 22, and in block 13 switching switches the relaxation generator (multivibrator). At the command of the switching unit 13, the two-channel switch 14 switches the output of the second delay unit 7 to the output of the calculator, and during the repetition period T, the results of the suppression V are read. The data of the first period of the next group are received and processed at the input of the calculator.

The synchronization of the computer for suppressing interference is carried out by applying to all the blocks of the claimed device a sequence of synchronizing pulses from the synchronizer 8 (Fig. 1), controlled together with the pulse switching unit 11 of the radar synchronizer pulses (1) (not shown in Fig. 1), following with an interval T. The repetition period of the synchronizing pulses is equal to the time sampling interval t _d selected from the condition of the required range resolution.

The technical result achieved is as follows. Uncompensated residuals of noise in the transition mode, traditionally masking the signal from the target, do not arrive at the output of the device. In the proposed device, the output receives only compensated residual noise in the steady state, which eliminates the effect of the "edge" of the noise and increases the efficiency of signal extraction of moving targets.

Thus, the computer for suppressing interference increases the efficiency of compensating for passive interference and isolating the signals of moving targets against passive interference with an a priori unknown Doppler speed.

Bibliography

1. Patent No. 63-49193 (Japan), IPC G01S 13/52. Radar device for detecting a moving target / K.K. Toshiba. Publ. 10/03/1988. - Inventions of the countries of the world. - 1989. - Issue 109. - No. 15. - S. 52.

2. Radio-electronic systems: fundamentals of construction and theory. Reference book / Ya.D. Shirman, S.T. Baghdasaryan, A.S. Malyarenko, D.I. Lekhovitsky [et al.]; under the editorship of POISON. Shirman. - 2nd ed., Revised. and add. - M .: Radio engineering, 2007; from. 439, fig. 25.22.

3. AC 743208 USSR, IPC G01S 7/36. Digital device for suppressing passive interference / D.I. Popov. - No. 2540079/09; declared 11/03/1977; publ. 06/25/1980, Bull. Number 23. - 4 p.

Claims (2)

A noise suppressor comprising a first delay unit, a weighting unit, a first complex multiplier, a weight unit, a complex adder, a second complex multiplier, a second delay unit and a clock generator, wherein the inputs of the first delay unit are connected to the first inputs of the first complex multiplier, outputs of the weight blocks are connected to the first inputs of the complex adder, the second inputs of which are connected to the outputs of the second complex multiplier, the control input of the clock generator is connected with the first control input of the calculator for suppressing interference, the output of the sync generator is connected to the sync inputs of the first delay block, weight block, first complex multiplier, weight block, complex adder, second complex multiplier and second delay block, characterized in that the third delay block is introduced, block complex interface, switching unit, precision unit, switching unit and two-channel switch, while the inputs of the first delay unit are connected to the inputs of the third block Arms, the outputs of which are connected to the first inputs of the weight unit, the outputs of the first delay unit are connected to the inputs of the complex conjugation unit, the outputs of which are connected to the second inputs of the first complex multiplier, the outputs of the first complex multiplier are connected to the inputs of the precision unit, the outputs of which are connected to the first inputs of the second complex multiplier, the outputs of the weighting unit are connected to the main inputs of the switching unit, the output of which is connected to the second input of the weighting unit, the first ravlyaetsya input switching unit connected to a first control input calculator for suppressing interference, the complex adder outputs are connected to inputs of the second delay unit, which outputs are connected to the main inputs of the two-channel switch, the first outputs connected to two-channel switch the second inputs of the second complex multiplier, the control input of the two-channel switch is connected to the output of the switching unit, the second control input of the switching unit and the control input of the switching unit are connected to the second control input of the computer to suppress noise, the output of the clock generator is connected to the sync inputs of the third delay block, complex pairing unit, block switching, accuracy unit, switching unit and two-channel switch, the main inputs of the computer for suppressing interference is connected inputs of the first delay unit and the third delay unit of the weight unit, and the outputs are the second outputs of the two-channel switch.

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