RU170068U1 - ADAPTIVE DEVICE FOR SUPPRESSING INTERFERENCE - Google Patents

Abstract

The device relates to computer technology and can be used in automated coherent-pulse systems to isolate the signals of moving targets against the background of passive interference during the wobble of the repetition period of the probe pulses. Achievable technical result - improving the efficiency of the allocation of signals of moving targets. This result is achieved by the fact that the adaptive device for suppressing interference includes an auto-compensator, first and second delay units, a main unit for measuring the correlation coefficient, a unit for calculating weight coefficients, a main weight unit, a main adder, a clock generator, an additional unit for measuring the correlation coefficient, a digital delay line and additional weight unit, connected in a certain way and performing computational operations with the original samples. A particular embodiment of the calculator for adaptive interference suppression also includes a third delay unit and an additional adder. 18 ill.

Description

The device relates to computer technology and can be used in automated coherent-pulse systems to isolate the signals of moving targets against a background of passive interference with a priori unknown spectral-correlation properties during the wobble of the probe pulse repetition period.

A digital device for adaptive passive interference suppression [1] is known, which contains two channels, each of which contains three main multipliers, an adder, first and second memory blocks, first and second additional multipliers, as well as a phase measurement unit, a functional converter, a computing unit, a correlation coefficient measurement unit and a weight coefficient calculation unit. However, this device has a low efficiency of signal extraction of moving targets due to the narrowing of the interference delay band during the wobble of the repetition period, which is a consequence of the inability to adapt the weight coefficients of the device to non-stationary time intervals within the wobble period.

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. This device also has a number of drawbacks, among which the most significant are: low efficiency of signal extraction of moving targets due to narrowing of the passive jamming delay band during the wobble of the repetition period and poor suppression of extended interference edges, which is a consequence of the large time constant of the adaptive feedback circuit.

Closest to the proposed device is selected as a prototype digital adaptive device for suppressing interference [3], which contains an auto-compensator for the Doppler phase of passive interference, the first and second delay units for the repetition period, the main unit for measuring the correlation coefficient, the unit for calculating weight coefficients, the main weight block, main adder and clock. However, this device does not provide sufficient efficiency for distinguishing signals of moving targets against a background of passive interference with a priori unknown spectral correlation properties due to the narrowing of the passive interference retention band during the wobble of the repetition period and due to the lack of adaptation of filter weights to the interference properties during non-stationary time intervals .

The problem to be solved in the claimed device is to increase the efficiency of suppressing passive interference and highlighting signals of moving targets during a wobble period of repetition against a background of passive interference with a priori unknown spectral-correlation properties.

To solve the problem, an adaptive device for suppressing interference, containing an auto-compensator, first and second delay units, a main unit for measuring the correlation coefficient, a unit for calculating weight coefficients, a main weight unit, a main adder and a clock generator, while the outputs of the auto-compensator are connected to the inputs of the same unit delays, the first inputs of the main unit for measuring the correlation coefficient and the first inputs of the main adder; the outputs of the first delay unit are connected to the inputs of the second delay unit of the same name, the second inputs of the main unit for measuring the correlation coefficient and the first inputs of the main weight unit, the outputs of which are connected to the same inputs of the main adder; the output of the main unit for measuring the correlation coefficient is connected to the first input of the unit for calculating the weight coefficients, the first output of which is connected to the second input of the main weight unit; introduced an additional unit for measuring the correlation coefficient, a digital delay line and an additional weight unit, while the first inputs of the additional unit for measuring the correlation coefficient are connected to the first inputs of the same name for the main unit for measuring the correlation coefficient; the second inputs of the additional unit for measuring the correlation coefficient are connected to the same outputs of the second delay unit and the first inputs of the additional weight unit, the outputs of which are connected to the same third inputs of the main adder; the input of the digital delay line is connected to the output of the main unit for measuring the correlation coefficient; the output of the digital delay line is connected to the second input of the weighting unit, the third input of which is connected to the output of the additional unit for measuring the correlation coefficient, and the second output is connected to the second input of the additional weighting unit; moreover, the inputs of the adaptive device for suppressing interference are the inputs of the auto-compensator, and the outputs are the outputs of the main adder.

The technical result provided by the given set of features is to increase the efficiency of suppressing passive interference and highlighting signals of moving targets during a wobble period of repetition against a background of passive interference with a priori unknown spectral-correlation properties.

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

In FIG. 1 is a structural electrical diagram of an adaptive interference suppression device (AUDP); in FIG. 2 - a private embodiment of the AUDPP; in FIG. 3 - auto-compensator; in FIG. 4 - delay unit; in FIG. 5 - main and additional units for measuring the correlation coefficient; in FIG. 6 - weight block; in FIG. 7 - the main adder; in FIG. 8 - additional adder; in FIG. 9 - block retention; in FIG. 10 - phase measurement unit; in FIG. 11 - complex multiplier; in FIG. 12 - block complex conjugation; in FIG. 13 - integrated drive; in FIG. 14 - block combining quadratures; FIG. 15 - drive; in FIG. 16 - complex adder; in FIG. 17 - integrated inverter; in FIG. 18 shows the dependencies of the gain in the signal-to-noise ratio improvement of the proposed device averaged over the Doppler phase of the signal in comparison with the prototype.

The adaptive device for suppressing interference (Fig. 1) contains an auto-compensator 1, the first 2 and second 3 delay units, the main unit 4 for measuring the correlation coefficient, the unit 5 for calculating the weight coefficients, the main weight unit 6, the main adder 7, the clock 8, an additional unit 9 measuring the correlation coefficient, a digital delay line 10 and an additional weight unit 11.

A particular embodiment of an adaptive device for suppressing interference (FIG. 2) is characterized in that in the AUDP in FIG. 1, a third delay unit 12 and an additional adder 13 are additionally introduced.

The auto-compensator 1 (Fig. 3) comprises a delay unit 14, a first and second complex multiplier 15, a phase measurement unit 16, and a first and second delay unit 17; block 2, 3, 12, 17 delay (Fig. 4) contains two random access memory (RAM) 18; the main 4 and additional 9 blocks for measuring the correlation coefficient (Fig. 5) comprise a complex conjugation block 19, a complex multiplier 20, a complex storage 21, three quadrature combining units 22, two storage 23, two dividers 24 and a square root extraction unit 25; the weight unit 6, 11 (Fig. 6) contains two multipliers 26; the main adder 7 (Fig. 7) contains two complex adders 27; additional adder 13 (Fig. 8) contains a complex inverter 28 and a complex adder 29; block 14 detention (Fig. 9) contains two RAM 30; the phase measuring unit 16 (Fig. 10) comprises a complex conjugation unit 31, a complex multiplier 32, a complex drive 33, a quadrature combining unit 34, a square root extracting unit 35, and two dividers 36; complex multiplier 15, 20, 32 (Fig. 11) contains two channels (I and II), each of which consists of two multipliers 37 and the adder 38; block 19, 31 complex pairing (Fig. 12) contains an inverter 39; complex drive 21, 33 (Fig. 13) contains two drives 40; block 22, 34 combining quadratures (Fig. 14) contains two multipliers 41 and the adder 42; the drive 23, 40 (Fig. 15) contains a channel consisting of n delay elements 43 for the interval t _d and n adders 44; complex adder 27, 29 (Fig. 16) contains two adders 45; complex inverter 28 (Fig. 17) contains two inverters 46.

An adaptive device for suppressing interference works as follows.

A pack of coherent radio pulses, consisting of passive interference significantly exceeding the signal from the target, is fed to the input of the 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 (the corresponding blocks in Fig. 1 are not shown) .

The readings are received at time instants separated by p non-equidistant or unequal time intervals T ₁ , T ₂ , ..., T _i, ... T _p , and form the core of the wobble, repeating with a constant wobble period:

where p is the number of repetition periods in the core of the wobble.

Digital codes (x _kl , y _kl ) of both quadrature projections following through non-equidistant intervals T ₁ , T ₂ , ..., in each range resolution element (range ring) of each repetition period form a sequence of complex numbers

where k is the number of the current period, l is the number of the current range ring, θ _{kl is the} current phase (usually interference, due to its significant excess over the signal), and

where ϕ _0l is the initial phase; ϕ _jl is the Doppler phase shift of the interference over the period Tj equal to ϕ _jl = 2πf _jl T _j , here f _jl is the Doppler frequency of the interference.

Digital readings in the inventive device (Fig. 1) are fed to the inputs of the auto-compensator (AK) 1, in which adaptive compensation is performed directly for the Doppler shift of the interference spectrum. To realize this in the time domain, the total Doppler phase shift of the interference phase is measured over the incoming number of periods. This uses the current data of two adjacent repetition periods T _k-1 and T _k coming from n + 1 adjacent resolution elements in range and forming a training sample

The block diagram of AK is shown in FIG. 3. In the phase measurement block 16 (Fig. 10), according to the input samples U _kl and samples U _{k-1, l} delayed in the first delay block 17 _, estimates of the Doppler phase shift of the interference phase for the kth repetition period are calculated (k = 1, 2, ...) for each l-th element of range resolution (l = 1, 2, ...). At the same time, in block 31 of complex conjugation using inverter 39 (Fig. 12), the sign of imaginary projections is inverted. In the complex multiplier 32, the multiplication of the corresponding complex numbers occurs, realized by operations with the projections of these numbers in accordance with FIG. 11. Formed values

enter the complex drive 33 (Fig. 13), consisting of drives 40 (Fig. 15), which, using delay elements 43 and adders 44, summarize the products U _{k-1, j} U * _kj with n along the range in each repetition period +1 adjacent resolution elements in the range of the time strobe, except for the element with the number j = l, for which the output values of the delay element 43 with the number n / 2 are supplied only to the subsequent delay element 43 (Fig. 15). Thus at the outputs of the drive 33 (Fig. 13) values are formed

- оценка сдвига фазы помехи за период Т_k для l-го элемента разрешения по дальности, усредненная по n смежным элементам разрешения; n -объем обучающей выборки.Where

- an estimate of the phase shift of the interference for the period T _k for the l-th resolution element of range, averaged over n adjacent resolution elements; n is the volume of the training sample.

), поступающие на первые входы второго комплексного перемножителя 15 (фиг. 3). В результате их перемножения с выходными отсчетами второго блока 17 задержки образуются величиныIn block 34 combining quadratures (Fig. 14) determines the values | Y _kl | ² , in the square root extraction unit 35, the values | Y _kl |, and then at the outputs of the dividers 36 (Fig. 10), the values Y _kl / | Y _kl | = exp (-i

) arriving at the first inputs of the second complex multiplier 15 (Fig. 3). As a result of their multiplication with the output samples of the second delay unit 17, values are formed

In the first complex multiplier 15 (Fig. 3), these values are multiplied with the original samples U _kl = х _kl + iу _kl = | U _kl | exp (iθ _kl ) delayed by the delay unit 14 (Fig. 3) for the purpose of temporarily matching input and compensated phase shifts by the interval τ, equal to the delay in the estimates with respect to the middle element of the training sample.

The value of the interval τ is determined by the expression

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

Formed at the output of the auto-compensator 1 (Fig. 1, 3) values

с точностью до погрешностей измерения

accurate to measurement errors

не содержат доплеровского сдвига фазы помехи, что позволяет осуществлять последующее подавление помехи устройством с действительными весовыми коэффициентами..assessments

do not contain a Doppler phase shift of the interference, which allows subsequent suppression of interference by a device with actual weight coefficients ..

позволяет адаптироваться к аргументу реальной корреляционной функции помехи, что является необходимым условием ее эффективного подавления.Using current ratings

allows you to adapt to the argument of the real correlation function of the interference, which is a necessary condition for its effective suppression.

Basically 6 and an additional 11 weight blocks (Fig. 1), the projections are scalarly multiplied by the weighting coefficients g ₁ and g ₂ (Fig. 6), which come respectively from the first and second outputs of the weighting coefficient calculation unit 5 (Fig. 1). In the main adder 7 (Fig. 1) there is a separate summation (Fig. 7, 16) of the same name projections of the weighted sequence of processed samples and the formation of the output value of the device

In the case of a wobble of the repetition period, in order to eliminate the effect of reducing the suppression coefficient, the weight coefficients of the device should be determined according to new adaptive algorithms, in particular, for a second-order device (m = 2) having the form

^_ оценки коэффициентов межпериодной корреляции помехи.Where,

^_ estimates of inter-period correlation coefficients of interference.

вычисляется в основном блоке 4 измерения коэффициента корреляции (фиг. 1, 5). Цифровая линия 10 задержки оценки

позволяет получить оценку

, где k - номер текущего периода. Оценка

вычисляется в дополнительном блоке 9 измерения коэффициента корреляции (фиг. 1, 5). Блоки 4, 9 измерения коэффициента корреляции выполняются в соответствии с фиг. 5 и реализуют алгоритм оцениванияRating

calculated in the main unit 4 of the measurement of the correlation coefficient (Fig. 1, 5). Digital Line 10 Delay Evaluation

allows you to get an estimate

where k is the number of the current period. Rating

calculated in the additional unit 9 for measuring the correlation coefficient (Fig. 1, 5). The correlation coefficient measurement units 4, 9 are performed in accordance with FIG. 5 and implement the estimation algorithm

блок 5 вычисления весовых коэффициентов (фиг. 1) реализует алгоритмы (3). Данный блок представляет собой арифметико-логическое устройство или сигнальный процессор.Based on the obtained estimates of the inter-period interference correlation coefficients

block 5 calculation of weighting coefficients (Fig. 1) implements algorithms (3). This unit is an arithmetic logic device or signal processor.

Each of the delay blocks 2, 3, 12, 17 (Figs. 1, 2, 4) consists of RAM 18 connected in parallel. Moreover, each RAM 18 serves to store the values of the samples from the range rings of one quadrature channel for a period. Moreover, each RAM 18 of delay blocks 2, 3, 12, 17 is used to store only N first samples in each repetition period, where N = Т _min / t _d is the number of range rings corresponding to the minimum repetition period T _min = min (T ₁ , T ₂ , ...).

Block 14 delay (Fig. 3, 9) delays the input samples in real time by the interval m, determined from expression (2) and is equal to the delay estimates in relation to the middle element of the training sample, excluded in the drive 40 (Fig. 13, 15 ) in accordance with the expression (1). Then, in the case of a signal commensurate in magnitude with the interference, or discontinuous interference during the subsequent suppression of the interference samples from the resolution element containing the signal, the possibility of attenuation or suppression of the signal due to its influence on the estimates used is excluded. In this case, the RAM 30 are used for the "sliding" storage of τ / t _d samples.

The synchronization of an adaptive device for suppressing interference is carried out by applying to all the device blocks a sequence of synchronizing pulses generated by a sync generator 8 (Fig. 1), controlled by pulses of a radar synchronizer (not shown in Fig. 1), following alternately at intervals T ₁ , T ₂ , ... Period the repetition of the synchronizing pulses is equal to the time sampling interval t _d selected from the condition of the required range resolution.

In FIG. Figure 18 shows the dependences of the gain Δμ in the signal-to-noise ratio of the proposed device, averaged over the Doppler phase of the signal compared to the prototype, on the wobble depth mod (in percent) for two values of the normalized interference spectrum width β = ΔfT _min (β = 0.05 - curve 1 and β = 0.1 - curve 2). The curves are plotted for the case of a double wobble of the repetition period (p = 2) and the training sample size n = 5.

Thus, an adaptive device for suppressing interference increases the efficiency of suppressing passive interference and isolating signals of moving targets when a repetition period is wobbled against a background of passive interference with a priori unknown spectral correlation properties.

In FIG. 2 shows a particular embodiment of an adaptive device for suppressing interference. A third delay unit 12 and an additional adder 13 are introduced into it. It is known that these blocks are independently used to suppress passive interference. An additional inclusion of these blocks allows one to increase the efficiency of suppressing passive interference, to reduce the length of the discharge grid of digital arithmetic devices (multipliers, dividers, and adders) in subsequent blocks of an adaptive device for suppressing interference, without reducing the requirements for accuracy of calculations, or for the same length of the discharge grid increase the accuracy of calculations.

Bibliography

1. A. p. 809018 USSR, IPC G01S 7/36. Digital device for suppressing passive interference / D.I. Popov. - No. 2755228; declared 04/16/1979; publ. 02/28/1981, Bull. No. 8. - 5 sec.

2. Radio-electronic systems: fundamentals of construction and theory. Reference book / Ya.D. Shirman, S.T. Bagdasaryan, A.S. Malyarenko, D.I. Lekhovitsky [et al.]; edited by Y.D. Shirman. - 2nd ed., Revised. and additional.- M .: Radio engineering, 2007; from. 439, fig. 25.22.

3. A. p. 1098399 USSR, IPC G01S 7/36. Device adaptive rejection of passive interference / D.I. Popov. - No. 3299959; declared 06/12/1981; publ. 12/20/1998, Bull. Number 35. - 16 p.

Claims (1)

An adaptive device for suppressing interference, comprising an auto-compensator, first and second delay units, a main unit for measuring the correlation coefficient, a unit for calculating weight coefficients, a main weight unit, a main adder and a clock generator, while the outputs of the auto-compensator are connected to the inputs of the same delay unit, the first inputs of the main unit for measuring the correlation coefficient and the first inputs of the main adder, the outputs of the first delay unit are connected to the same inputs of the second delay unit, W by the inputs of the main unit for measuring the correlation coefficient and the first inputs of the main weight unit, the outputs of which are connected to the same second inputs of the main adder, the output of the main unit for measuring the correlation coefficient is connected to the first input of the unit for calculating the weight coefficients, the first output of which is connected to the second input of the main weight unit, the output of the sync generator is connected to the sync inputs of the auto-compensator, the first and second delay units, the main unit for measuring the correlation coefficient, b The calculation of the weighting coefficients, the main weight unit and the main adder, characterized in that an additional correlation coefficient measurement unit, a digital delay line and an additional weight unit are introduced, while the first inputs of the additional correlation coefficient measurement unit are connected to the first inputs of the main correlation coefficient measurement unit of the same name , the second inputs of the additional unit for measuring the correlation coefficient are connected with the same outputs of the second delay unit and the first the strokes of the additional weight unit, the outputs of which are connected to the third inputs of the main adder of the same name, the input of the digital delay line is connected to the output of the main unit for measuring the correlation coefficient, the output of the digital delay line is connected to the second input of the unit for calculating the weight coefficients, the third input of which is connected to the output of the additional measurement unit correlation coefficient, and the second output with the second input of the additional weight unit, the output of the clock is connected to the sync inputs a correlation coefficient measuring unit, a digital delay line and an additional weight unit, the inputs of the adaptive device for suppressing interference are the inputs of the auto-compensator, and the outputs are the outputs of the main adder.

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