RU2557250C1 - Method for stealth radar detection of mobile objects - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention can be used in systems for monitoring ground, marine and air space using forward radio signals and radio signals scattered by objects, said signals being emitted by multiple uncontrolled and controlled transmitters of radio electronic systems for various purposes. The result is achieved by using new nonlinear iterative radio signal processing procedures.

EFFECT: high efficiency of detection and spatial localisation of a wide range of objects.

1 dwg

Description

The invention relates to radio engineering and can be used in monitoring systems of land, sea and air space using direct and scattered objects of radio signals emitted by many uncontrolled and monitored transmitters of electronic systems for various purposes.

Achieving high detection efficiency, localization and identification of land, sea and air objects is limited by significant a priori uncertainty in size, spatial orientation, reflecting properties and parameters of the movement of objects, as well as the imperfection of known methods for detecting and tracking moving objects.

The technology of covert detection and tracking of moving objects, using natural radio illumination of targets, created at a variety of frequencies by radio emissions from transmitters for various purposes in the short, meter, decimeter and centimeter wavelengths: broadcast (commercial FM broadcasting, high-definition television), information (communication) and measuring (control, navigation), has not yet received sufficient distribution, despite the fact that it can significantly increase the secrecy and effectiveness of detection, spatial localization and identification of a wide class of moving objects.

The known method of covert radar of moving objects [1], which consists in the fact that they select a transmitter emitting a spread spectrum radio signal, synchronously receive a multipath radio signal from N antennas, including a direct transmitter radio signal and scattered objects from this transmitter, synchronously transform the ensemble of received antennas into digital signals, direct and compressed scattered signals are formed from digital signals, direct and scattered signals are compared and time delays are determined Alarms, Doppler shifts and directions of arrival of scattered signals, based on time delays, Doppler shifts and directions of arrival, perform detection and spatial localization of airborne objects.

This method does not contain operations to suppress coherent interference in the form of a direct radio signal from the transmitter and, as a result, provides effective detection of only very large closely spaced objects.

More effective is the method of covert radar of moving objects [2], free from this drawback and selected as a prototype. According to this method:

use direct and scattered by mobile objects radio signals emitted by broadband transmitters of various electronic systems;

receive a lattice of N antennas signals of a multipath electromagnetic field of direct and scattered radio signals;

synchronously transform the ensemble of radio signals received by the antennas into digital signals;

digital signals are converted into direct s and scattered s _l signals for the selected azimuth-elevation directions of reception l, which are stored together with the value of the azimuth-elevation direction of reception;

for each selected azimuthal elevation direction of reception, a complex cross-correlation function (WKF), depending on the time shift, between the direct s and s _l scattered signals is generated and stored;

determine the maximum value of the module of the integrated VKF and fix the value of the integrated VKF corresponding to this maximum;

calculating a differential scattered digital signal;

forming a complex two-dimensional cross-correlation function (DKKF) depending on the time and frequency shifts between the difference scattered digital signal and the digital direct signal;

modulo complex DVKF determine the number of compressed scattered signals, as well as the values of time delay and absolute Doppler shift of each compressed scattered signal;

the values of the delay and the absolute Doppler shift and the azimuthal elevation direction of the reception of compressed scattered signals detect and determine the spatial coordinates of the object.

The prototype method due to the presence of adaptive spatial filtering operations and operations to compensate for coherent interference in the form of a powerful direct radio signal of the backlight transmitter provides detection of a wider class of objects.

However, this prototype method contains the operation of forming a classical two-dimensional cross-correlation function, which, in addition to the main lobe, limiting the resolution and accuracy of spatial localization of targets, contains high side lobes limiting the detection sensitivity due to masking signals of distant and weakly scattering targets.

Thus, the disadvantage of the prototype method is the low detection efficiency and spatial localization of a wide class of objects.

The technical result of the invention is to increase the detection efficiency and spatial localization of a wide class of objects.

Improving the detection efficiency and spatial localization of a wide class of objects is achieved through the use of new nonlinear iterative processing of radio signals.

, где $$A_{\omega }^H$$

- матрица, эрмитово сопряженная с A_ω, сигнал $$h_{l\omega }^{(0)}$$

запоминают и используют в качестве начального приближения, а также итерационно формируют зависящий от предыдущего решения вспомогательный матричный сигнал $$\Lambda \left(h_{l\omega }^{(k-1)}\right)\equiv diag\left\{{\left|h_{l\omega z}^{(k-1)}\right|}^{-1}/2\right\}$$

, где $$h_{l\omega z}^{(k-1)}$$

- z-я компонента вектора элемента изображения $$h_{l\omega }^{(k-1)}$$

, k=1, 2, … - номер итерации, и сигнал очередного приближения элемента комплексного частотно-временного изображения $$h_{l\omega }^{(k)}={\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda (h_{l\omega }^{(k-1)})\right]}^{-1}{A}_{\omega }^H{s}_l$$

, где λ - множитель Лагранжа, до тех пор, пока номер текущей итерации не превысит заданный порог, объединяют сформированные сигналы элементов изображения $$h_{l\omega }^{(k)}$$

в матричный сигнал результирующего комплексного частотно-временного изображения H_l, после чего по локальным максимумам квадрата модуля компонент матричного сигнала результирующего изображения $${\left|H_{l\omega q}\right|}^2$$

, где H_lωq - ωq-я компонента матрицы результирующего изображения H_l, определяют число рассеянных радиосигналов в выбранном азимутально-угломестном направлении, по параметрам которых - значениям временной задержки, доплеровского сдвига частоты каждого рассеянного радиосигнала и азимутально-угломестного направления приема рассеянных радиосигналов - выполняют обнаружение и пространственную локализацию подвижных объектов.The technical result is achieved by the fact that in the method of covert radar of moving objects, which consists in the use of direct and scattered by moving objects radio signals emitted by broadband transmitters of electronic systems for various purposes, the array of N antennas receives signals of the multipath electromagnetic field of direct and scattered radio signals, synchronously converts ensemble received radio antennas into digital signals, digital signals are converted into s direct and scattered signals s _l d I selected azimuthally elevation reception directions l, which together with the value azimuthally approach elevation direction of reception is stored, according to the invention, for each expected Doppler frequency ω converted direct signal s to the matrix signal complex phasing function A _ω, comprising hypothetical signals scattered in the expected field delays each potential mobile and stationary objects, the matrix signal A _ω storing, for each of the selected directions azimuthally approach elevation reception and each expected value of the Doppler frequency shift of the scattered signal is converted into a signal s _l element integrated time-frequency picture $$h_{l\omega }^{(0)}={\left(A_{\omega }^H{A}_{\omega }\right)}^{-\mathrm{one}}{A}_{\omega }^H{s}_l$$

where $$A_{\omega }^H$$

- matrix Hermitian conjugate to A _ω , signal $$h_{l\omega }^{(0)}$$

remember and use as an initial approximation, and also iteratively form an auxiliary matrix signal depending on the previous solution $$\Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)\equiv diag\left\{{\left|h_{l\omega z}^{(k-\mathrm{one})}\right|}^{-\mathrm{one}}/2\right\}$$

where $$h_{l\omega z}^{(k-\mathrm{one})}$$

- z-th component of the image element vector $$h_{l\omega }^{(k-\mathrm{one})}$$

, k = 1, 2, ... is the iteration number, and the signal of the next approximation of the element of the complex time-frequency image $$h_{l\omega }^{(k)}={\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda (h_{l\omega }^{(k-\mathrm{one})})\right]}^{-\mathrm{one}}{A}_{\omega }^H{s}_l$$

, where λ is the Lagrange multiplier, until the current iteration number exceeds a given threshold, the generated image element signals are combined $$h_{l\omega }^{(k)}$$

into the matrix signal of the resulting complex time-frequency image H _l , after which, according to the local maxima of the module square, the components of the matrix signal of the resulting image $${\left|H_{l\omega q}\right|}^2$$

where H _lωq is the ωqth component of the matrix of the resulting image H _l , the number of scattered radio signals is determined in the selected azimuth-elevation direction, the parameters of which are the values of the time delay, Doppler frequency shift of each scattered radio signal and the azimuth-elevation direction of the scattered radio signals reception detection and spatial localization of moving objects.

The operation of the method is illustrated in the drawing.

A device in which the proposed method is implemented includes a series-connected reception and pre-processing system 1, a radio transmitter modeling and selection system (RPD) 2, a computer system 3, and a control and indication unit 4.

In turn, the reception and preprocessing system 1 includes an antenna array 1-1, a path for searching for illumination sources, including a frequency converter 1-2, ADC 1-3 and a detection device 1-4, as well as a path for receiving direct and scattered signals, including a converter frequencies 1-7, ADC 1-6 and adaptive spatial filtering device 1-5.

Computing system 3 includes a time-frequency image synthesis unit 3-1, a comparison unit 3-2, a device for generating an auxiliary and weighting signal 3-3, and a signal generating unit for the phasing function 3-4. In this case, system 2 is connected to the input of block 4, and also has an interface for connecting to an external RPD base. In addition, block 4 has an output intended for connection to external systems.

Subsystem 1 is an analog-to-digital device and is designed to search for backlight transmitters for objects emitting spread-spectrum radio signals, as well as for adaptive spatial filtering of useful direct and scattered radio signals.

. Пространственная конфигурация антенной решетки должна обеспечивать прием с заданного азимутально-угломестного направления прихода радиосигналов и может быть произвольной пространственной конфигурации: плоской прямоугольной, плоской кольцевой или объемной, в частности, конформной.Antenna array 1-1 consists of N antennas with numbers $$n=\overline{\mathrm{one,}N}$$

. The spatial configuration of the antenna array should provide reception from a given azimuthal elevation direction of arrival of radio signals and may be of any spatial configuration: flat rectangular, flat circular or surround, in particular conformal.

Frequency converters 1-2 and 1-7 are N-channels, made with a common local oscillator and with the bandwidth of each channel, which is changed in accordance with the width of the spectrum of the received radio signal. A common local oscillator provides multi-channel coherent signal reception.

ADC 1-3 and 1-6 are also N-channel and are synchronized by the signal of one reference oscillator (for simplicity, the reference oscillator is not shown in the diagram). If the resolution and speed of the ADC are sufficient for direct analog-to-digital conversion of input signals, such as in the HF range, then frequency selective bandpass filters and amplifiers can be used instead of frequency converters 1-2 and 1-7. In addition, frequency converters 1-2 and 1-7 provide the connection of one of the antennas instead of all the antennas of the array for periodic calibration of the receiving channels using an external signal source. Calibration is possible using an internal generator, the output of which is also connected instead of all antennas for periodic calibration of channels. For simplicity, the internal generator is not shown.

The detection device 1-4 and the adaptive spatial filtering device 1-5 are computing devices.

Subsystem 2 is a computing device and is designed to identify, select, and periodically update spread spectrum radio transmitters used to illuminate a given area of airspace.

Computing system 3 is designed to generate a phasing function signal (block 3-4), generate an auxiliary and weighting signal (device 3-3), compare the number of iterations with a given threshold (block 3-2), and synthesize a time-frequency image of radio signals scattered by objects ( block 3-1).

The device operates as follows.

In system 2, based on the data of the external base of the radio transmitters, as well as data on the detected backlight transmitters from the device 1-4, using the modeling software, a set of transmitters emitting spread-spectrum radio signals is identified, selected and periodically updated. During the simulation, possible coverage areas, detection probabilities, and achievable localization and identification accuracy of airborne objects of various classes are estimated, which can be provided with different types of placement of transmitters relative to a detection-direction finding station.

The parameters of the selected set of transmitters (number, carrier frequency, spectrum width, shape, power of the emitted signal, coordinates or distance and angular position relative to the receiving point) are stored in subsystem 2, received in block 4, and also used to configure converters 1-2 and 1 -7. In order to simplify the control circuit of the converter are not shown.

According to the signals of system 2, the frequency converter 1-2 begins to be tuned at a given pace in a given frequency range of the search for radio signals, for example, in the range of 10-1000 MHz. In this case, the search path searches for backlight transmitters emitting spread-spectrum radio signals at frequencies of a discrete search frequency grid. At the same time, the time-dependent radio signal s _n (t) received by each antenna with the number n of the antenna array 1-1 is filtered by frequency and transferred to a lower frequency in converter 1-2. The radio signals s _n (t) formed in the converter 1-2 are converted using ADC 1-3 into digital signals, which enter the detection device 1-4, in which the backlight transmitters are detected at each frequency of the discrete search frequency grid. The operation of the detection device 1-4 is based on well-known methods of radio monitoring, for example, [3].

At the same time, according to the signals of system 2, the frequency converter 1-7 is tuned to a given reception frequency. The receiving path synchronously receives at the receiving frequency multipath radio signals, including the direct radio signal of the selected spread spectrum transmitter and the radio signals of this transmitter scattered by the objects.

The time-dependent radio signal s _n (t) received by each antenna with array number n of the array 1-1 is filtered by frequency and transferred to a lower frequency in converter 1-7.

, где $$i=\overline{\mathrm{1,}I}$$

- номер временного отсчета сигнала, {}^T - означает транспонирование.The radio signals s _n (t) generated in the converter 1-7 are synchronously converted using digital converters 1-6 into digital signals $$s_n={\left\{s_n(\mathrm{one}),...,s_n(i),...,s_n(I)\right\}}^T$$

where $$i=\overline{\mathrm{one,}I}$$

- time reference number of the signal, {} ^T - means transpose.

и запоминаются. Матричный сигнал S имеет размерность N×I.The digital signals of individual antennas s _n enter the device 1-5, where they are combined into a matrix digital signal $$S={\left\{s_{\mathrm{one}},...,s_n,...,s_N\right\}}^T$$

and are remembered. The matrix signal S has the dimension N × I.

In addition, in the device 1-5, the following actions are performed:

- a signal of a spatial correlation matrix R of size N × N is formed from a digital matrix signal S;

и рассеянных $$w_l=R^{-1}{v}_l$$

радиосигналов размером N×1, где v - вектор наведения размером N×1, определяемый азимутально-угломестным направлением приема радиосигнала, длиной волны (частотой) и геометрией решетки, l - азимутально-угломестное направление приема рассеянного радиосигнала,- the signal of the correlation matrix R is converted into signals of optimal weight vectors to form a direct $$w=R^{-\mathrm{one}}v$$

and scattered $$w_l=R^{-\mathrm{one}}{v}_l$$

radio signals of size N × 1, where v is the guidance vector of size N × 1, determined by the azimuthal elevation direction of receiving the radio signal, wavelength (frequency) and lattice geometry, l is the azimuthal elevation direction of receiving the scattered radio signal,

и рассеянные $$s_l=w_l^{H}S$$

сигналы, где (·)^H - символ эрмитова сопряжения.- matrix digital signal S is converted to direct $$s=w^{H}S$$

and scattered $$s_l=w_l^{H}S$$

signals, where (·) ^H is the symbol of Hermitian conjugation.

The physically described adaptive spatial filtering operations provide simultaneous directional reception from a given direction of the useful direct signal of the selected backlight transmitter and the useful scattered signal while suppressing a wide class of interference coming from other directions. Note that the technically feasible interference suppression depth reaches 40 dB [4].

This provides a gain in sensitivity in the formation of weak scattered signals in subsequent processing steps.

The scattered signals s _l formed in the device 1-5 together with the value of the selected azimuthal elevation direction of their reception are sent to block 3-1, and the direct signal s is sent to block 3-4, where they are stored.

After that, in block 3-4, for each expected value of the Doppler frequency shift ω, the direct signal s is converted into a matrix signal of the complex phasing function A _ω , which includes hypothetical signals scattered in the expected delay region by each potential moving and stationary object. The matrix signal A _ω enters the device 3-3, where it is also stored.

The conversion of the direct signal s into a matrix signal A _{ω is} carried out according to the following formula:

- векторы размером I×1, являющиеся задержанными по времени на qT_s версиями опорного сигнала s, q=0, …, Q-1, Q - число временных задержек прямого сигнала, T_s - период выборки сигнала;Where $$s_q={\left[s_{(\mathrm{one}-q)},...,s_{(I-q)}\right]}^T$$

- vectors of size I × 1, which are time delayed versions of the reference signal s on qT _s , q = 0, ..., Q-1, Q is the number of time delays of the direct signal, T _s is the signal sampling period;

are Doppler shift matrices, ω = 0, ± 1, ..., ± Ω, (2Ω + 1) is the size of the grid along the Doppler shift. The values of the Doppler frequency shift run through a discrete series of values of ω / (IT _s ).

Thus, the columns of matrix A _ω are time-delayed and frequency-shifted Doppler shift versions of the direct signal s, and the size of this matrix, I × 2Q, is determined by the number of samples in the reconnoitered signal (duration of the observation interval) and the dimensions of the coordinate grid by time delay.

, $$A_{\omega }^H{A}_{\omega }$$

и $${\left(A_{\omega }^H{A}_{\omega }\right)}^{-1}$$

, которые поступают в блок 3-1, где запоминаются.In addition, in the device 3-3 from the signal A _ω signals are sequentially calculated $$A_{\omega }^H$$

, $$A_{\omega }^H{A}_{\omega }$$

and $${\left(A_{\omega }^H{A}_{\omega }\right)}^{-\mathrm{one}}$$

that go to block 3-1, where they are remembered.

и $${\left(A_{\omega }^H{A}_{\omega }\right)}^{-1}$$

, поступивших от блока 3-3, преобразуется в сигнал элемента комплексного частотно-временного изображения $$h_{l\omega }^{(0)}={\left(A_{\omega }^{H}A\right)}^{-1}{A}_{\omega }^H{s}_l$$

, (вектор с размером 2Q×1).In block 3-1, for each selected azimuthal elevation direction of reception l and each expected value of the Doppler frequency shift ω, the scattered signal s _l using signals $$A_{\omega }^H$$

and $${\left(A_{\omega }^H{A}_{\omega }\right)}^{-\mathrm{one}}$$

received from block 3-3, is converted into a signal element of a complex time-frequency image $$h_{l\omega }^{(0)}={\left(A_{\omega }^{H}A\right)}^{-\mathrm{one}}{A}_{\omega }^H{s}_l$$

, (vector with a size of 2Q × 1).

запоминается в блоке 3-2 в качестве начального приближения и транслируется в устройство 3-3 для запоминания и инициализации очередной итерации с номером k=1.The image element signal received in block 3-1 $$h_{l\omega }^{(0)}$$

stored in block 3-2 as an initial approximation and transmitted to the device 3-3 for storing and initializing the next iteration with the number k = 1.

при k=1, формируется вспомогательный матричный сигнал $$\Lambda \left(h_{l\omega }^{(k-1)}\right)\equiv diag\left\{{\left|h_{l\omega z}^{(k-1)}\right|}^{-1}/2\right\}$$

, где $$h_{l\omega z}^{(0)}$$

- z-я компонента вектора элемента изображения $$h_{l\omega }^{(k-1)}$$

, и взвешивающий сигнал $${\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-1)}\right)\right]}^{-1}{A}_{\omega }^H$$

. Значение множителя Лагранжа λ выбирают исходя из уровня шумов в каналах приема. Взвешивающий сигнал $${\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-1)}\right)\right]}^{-1}{A}_{\omega }^H$$

поступает в блок 3-1.In the device 3-3 using the signal of the image element obtained in the previous iteration, that is $$h_{l\omega }^{(k-\mathrm{one})}=h_{l\omega }^{(0)}$$

at k = 1, an auxiliary matrix signal is formed $$\Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)\equiv diag\left\{{\left|h_{l\omega z}^{(k-\mathrm{one})}\right|}^{-\mathrm{one}}/2\right\}$$

where $$h_{l\omega z}^{(0)}$$

- z-th component of the image element vector $$h_{l\omega }^{(k-\mathrm{one})}$$

, and weighting signal $${\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}_{\omega }^H$$

. The value of the Lagrange multiplier λ is selected based on the noise level in the reception channels. Weighting signal $${\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}_{\omega }^H$$

enters block 3-1.

и запомненного рассеянного сигнала s_l синтезируется сигнал очередного приближения элемента комплексного частотно-временного изображения $$h_{l\omega }^{(1)}={\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-1)}\right)\right]}^{-1}{A}_{\omega }^H{s}_l$$

. Полученный сигнал $$h_{l\omega }^{(1)}$$

поступает в блок 3-2.In block 3-1 using the signal $${\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}_{\omega }^H$$

and the stored scattered signal s _l , the next approximation signal of the complex time-frequency image element is synthesized $$h_{l\omega }^{(\mathrm{one})}={\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}_{\omega }^H{s}_l$$

. Received signal $$h_{l\omega }^{(\mathrm{one})}$$

enters block 3-2.

запоминается для использования на следующей итерации.In block 3-2, the signal $$h_{l\omega }^{(\mathrm{one})}$$

remembered for use in the next iteration.

поступает в устройство 3-3 для запоминания и инициализации очередной итерации синтеза элемента частотно-временного изображения. После чего в устройстве 3-3, блоках 3-1 и 3-2 выполняется описанная ранее последовательность операций по формированию сигналов $$\Lambda \left(h_{l\omega }^{(k-1)}\right)$$

, $${\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-1)}\right)\right]}^{-1}{A}_{\omega }^H$$

, $$h_{l\omega }^{(1)}={\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-1)}\right)\right]}^{-1}{A}_{\omega }^H{s}_l$$

, запоминанию сигнала $$h_{l\omega }^{(k)}$$

и сравнению номера текущей итерации с порогом.In this case, the signal $$h_{l\omega }^{(\mathrm{one})}$$

enters the device 3-3 for storing and initializing the next iteration of the synthesis of the element of the time-frequency image. Then, in the device 3-3, blocks 3-1 and 3-2, the previously described sequence of operations for generating signals is performed $$\Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)$$

, $${\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}_{\omega }^H$$

, $$h_{l\omega }^{(\mathrm{one})}={\left[A_{\omega }^H{A}_{\omega }+\lambda \Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}_{\omega }^H{s}_l$$

signal memorization $$h_{l\omega }^{(k)}$$

and comparing the current iteration number with a threshold.

объединяются в матричный сигнал результирующего комплексного частотно-временного изображения H_l. Объединение элементов изображения $$h_{l\omega }^{(k)}$$

в матричный сигнал результирующего комплексного изображения H_l осуществляется путем присоединения элементов изображения $$h_{l\omega }^{(k)}$$

друг к другу в порядке убывания доплеровского сдвига частоты ω в соответствии со следующей формулой:When the number of the current iteration exceeds the specified threshold in block 3-1, the generated image element signals $$h_{l\omega }^{(k)}$$

are combined into a matrix signal of the resulting complex time-frequency image H _l . Combining image elements $$h_{l\omega }^{(k)}$$

in the matrix signal of the resulting complex image H _{l is} carried out by attaching image elements $$h_{l\omega }^{(k)}$$

to each other in decreasing order of the Doppler frequency shift ω in accordance with the following formula:

The matrix signal of the resulting complex time-frequency image H _l enters block 4.

, где H_lωq - ωq-я компонента результирующего изображения H_l. По локальным максимумам квадратов модулей определяется число рассеянных радиосигналов в выбранном азимутально-угломестном направлении, по параметрам которых - значениям временной задержки, доплеровского сдвига частоты каждого рассеянного радиосигнала и азимутально-угломестного направления приема рассеянных радиосигналов - выполняют обнаружение и пространственную локализацию подвижных объектов.In block 4, the squares of the modules of the components of the matrix signal of the resulting complex time-frequency image are calculated $${\left|H_{l\omega q}\right|}^2$$

, where H _lωq is the ωqth component of the resulting image H _l . The local maximum squares of the modules determine the number of scattered radio signals in the selected azimuthal elevation direction, the parameters of which - the values of the time delay, Doppler frequency shift of each scattered radio signal and the azimuthal elevation direction of the reception of scattered radio signals - perform the detection and spatial localization of moving objects.

The detection and determination of the spatial coordinates of moving objects is carried out by known methods, for example, [2].

The results of the detection and spatial localization of airborne objects are displayed to increase information content.

выражается через полученный на предыдущей итерации сигнал элемента изображения $$h_{l\omega }^{(k-1)}$$

, сигнал очередного приближения элемента комплексного частотно-временного изображения $$h_{l\omega }^{(k)}$$

также зависит от предыдущего решения $$h_{l\omega }^{(k-1)}$$

. В связи с этим предложенный способ реализует итерационный процесс с обратной связью по полезному сигналу в каждом l-м азимутально-угломестном направлении поиска объектов. При этом компоненты, связанные с полезным сигналом, усиливаются, а компоненты, связанные с шумами, подавляются, что повышает чувствительность и динамический диапазон формирования изображения. Эта особенность, характерная для нелинейной обработки, приводит к повышению разрешающей способности формируемого радиоизображения.Thus, given that the auxiliary matrix signal $$\Lambda \left(h_{l\omega }^{(k-\mathrm{one})}\right)$$

expressed through the signal of the image element received at the previous iteration $$h_{l\omega }^{(k-\mathrm{one})}$$

, a signal of the next approximation of an element of a complex time-frequency image $$h_{l\omega }^{(k)}$$

also depends on previous decision $$h_{l\omega }^{(k-\mathrm{one})}$$

. In this regard, the proposed method implements an iterative process with feedback on the useful signal in each l-th azimuth-elevation direction of the search for objects. In this case, the components associated with the useful signal are amplified, and the components associated with noise are suppressed, which increases the sensitivity and dynamic range of image formation. This feature, characteristic of nonlinear processing, leads to an increase in the resolution of the generated radio image.

(для каждого l-го азимутально-угломестного направления приема и для каждого ожидаемого значения доплеровского сдвига частоты ω принятых сигналов) и последующего их объединения в матричный сигнал результирующего комплексного частотно-временного изображения H_l.From the above description it follows that the device that implements the proposed method provides an increase in the detection efficiency and spatial localization of a wide class of objects through the use of new operations of nonlinear generation of image element signals $$h_{l\omega }^{(k)}$$

(for each l-th azimuth-elevation direction of reception and for each expected value of the Doppler frequency shift ω of the received signals) and their subsequent combination into a matrix signal of the resulting complex time-frequency image H _l .

Thus, due to the use of non-linear iterative processing of radio signals instead of the classical two-dimensional cross-correlation, it is possible to solve the problem with the achievement of the specified technical result.

Information sources

1. US patent 6703968 B2, cl. G01S 13/87, 2004

2. RU, patent, 2444755, cl. G01S 13/02, 2012

3. RU, patent, 2190236, cl. G01S 5/04, 2002

4. Ratynsky M.V. Adaptation and superresolution in antenna arrays. M .: Radio and communications, 2003.

Claims (1)

The secretive radar method of moving objects, which consists in using direct and scattered by mobile objects radio signals emitted by broadband transmitters of electronic systems for various purposes, using a lattice of N antennas, accept the signals of the direct multi-beam electromagnetic field of direct and scattered radio signals, synchronously convert the ensemble of radio signals received by the antennas into digital signals , digital signals are converted into direct s and scattered s _l signals for the selected azimuthal elevation direction reception signals l, which together with the value of the azimuthal elevation direction of reception are stored, characterized in that for each expected Doppler frequency shift ω, the direct signal s is converted into a matrix signal of the complex phasing function A _ω , which includes hypothetical signals scattered in the expected delay region by each potential moving and stationary object, the matrix signal And _ω remember, for each selected azimuthal elevation direction of reception and each expected value of the Doppler the frequency shift transform the scattered signal s _l into the signal element of a complex time-frequency image

where

- matrix Hermitian conjugate to A _ω , signal

remember and use as an initial approximation, and also iteratively form an auxiliary matrix signal depending on the previous solution

Where

- z-th component of the image element vector

k = 1, 2, ... is the iteration number, and the signal of the next approximation of the element of the complex time-frequency image

, where λ is the Lagrange multiplier, until the current iteration number exceeds a given threshold, the generated image element signals are combined

into the matrix signal of the resulting complex time-frequency image H _l , after which, according to the local maxima of the module square, the components of the matrix signal of the resulting image

where H _lωq is the ωqth component of the matrix of the resulting image H _l , the number of scattered radio signals is determined in the selected azimuth-elevation direction, the parameters of which are the values of the time delay, Doppler frequency shift of each scattered radio signal and the azimuth-elevation direction of the scattered radio signals reception detection and spatial localization of moving objects.

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