RU2546329C1 - Method for polarisation-sensitive detection of mobile objects - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: high probability of detection is achieved using novel operations for polarisation-sensitive nonlinear iteration processing of radio signals, which increase sensitivity and the dynamic range when forming horizontal and vertical polarisation components of a two-component complex frequency-time image of radio signals scattered by objects in the analysed region of Doppler frequencies and time delays.

EFFECT: high probability of detecting remote and weakly scattering objects.

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Description

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

The technology of secretive detection and tracking of objects using natural radio illumination of targets created at a variety of frequencies by radio emissions from transmitters for various purposes: broadcast (VHF FM broadcasting, UHF digital television), information (communication) and measuring (control, navigation), have not yet received sufficient distribution, despite the fact that it can significantly increase the efficiency of detection, spatial localization and identification of a wide class of moving objects.

The received radio signal, as a rule, includes powerful direct radio signals and the signal components of the selected target radio illumination transmitter scattered from the earth's infrastructure. In addition, it contains time-delayed and shifted by the frequency of the Doppler shift signals scattered by objects, as well as signals of other uncontrolled sources operating at a frequency that matches the frequency of reception. For effective detection and accurate spatial localization of a wide class of objects (cars, ships, planes and unmanned aerial vehicles, helicopters, rockets, descent vehicles), high-quality selection of weak radio signals scattered from objects against the background of a powerful direct signal of the selected radio backlight transmitter, as well as against the background of signals other unwanted sources. In most typical situations, the noise level is 40-60 dB higher than the level of scattered signals.

Covert radar systems include a direct signal reception channel for the backlight transmitter and a reconnaissance channel.

Traditionally, in stealth radar systems, partial suppression of interference in the form of a direct signal from the backlight transmitter is achieved by minimizing side lobes, generating zero in the antenna radiation pattern, or adaptive spatial filtering of useful signals in the reconnaissance channel.

Additional suppression of the direct signal can be achieved by using an antenna with a polarization orthogonal to the polarization of the radio signal of the backlight transmitter in the reconnaissance channel.

However, the best characteristics of stealth radar systems can be achieved by using two reconnaissance channels with orthogonal polarizations. This is due to the fact that the signal scattered by the target, as a rule, has random polarization. As a result, incoherent summation of images in the coordinates “time delay (range) - Doppler frequency (speed)”, formed using radio signals of two orthogonal polarizations, provides an increase in the average signal-to-noise ratio compared to using a single fixed polarization.

A known method of polarization-sensitive detection of moving objects [1], including the reception of radio signals scattered by moving objects of unknown polarization by a low-base antenna array consisting of orthogonally located antennas with combined phase centers, the formation of an ensemble of radio signals depending on the time and antenna number, synchronous conversion of the ensemble of received radio signals into digital signals, the conversion of digital signals of pairs of opposite antennas into complex quadrature components guides dipole and quadrupole output signals, detect moving objects scattered radio signals and their arrival directions of signals of the quadrature components of the dipole and quadrupole output signals.

This method provides increased detection stability and spatial localization to polarization errors. However, this method belongs to the class of low-base direction finding methods, which is a fundamental limitation on the path to achieving the potential accuracy of spatial localization of moving objects.

A known method of polarization-sensitive detection of moving objects [2], free from these shortcomings and adopted 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 components of horizontal and vertical polarization of the vector multipath electromagnetic field of direct and scattered radio signals;

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

и рассеянные $$s_{\ell }=\left[\begin{array}{c}{s}_{\ell }^h\\ s_{\ell }^{\nu }\end{array}\right]$$

сигналы для выбранных азимутально-угломестных направлений приема ℓ, где h и ν - индексы, обозначающие компоненты горизонтальной и вертикальной поляризации, которые совместно со значением азимутально-угломестного направления приема запоминают;digital signals are converted into two-component direct $$\tilde{s}=\left[\begin{array}{c}{\tilde{s}}^h\\ {\tilde{s}}^{\nu }\end{array}\right]$$

and scattered $$s_{\ell }=\left[\begin{array}{c}{s}_{\ell }^h\\ s_{\ell }^{\nu }\end{array}\right]$$

signals for the selected azimuthal elevation directions of reception ℓ, where h and ν are indices denoting the components of horizontal and vertical polarization, which together with the value of the azimuthal elevation direction of reception are stored;

и $${\Vert {\tilde{s}}^{\nu }\Vert }^2$$

прямого сигнала;calculate and compare component energy $${\Vert {\tilde{s}}^h\Vert }^2$$

and $${\Vert {\tilde{s}}^{\nu }\Vert }^2$$

direct signal;

;choose the component of the direct signal with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

;

в матричный сигнал комплексной фазирующей функции A, включающий гипотетические сигналы, рассеиваемые каждым потенциальным объектом;convert the direct signal component with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

in the matrix signal of the complex phasing function A, including hypothetical signals scattered by each potential object;

, где A^H - матрица, эрмитово сопряженная с A;for each selected azimuthal elevation direction, the scattered signal s _ℓ is converted into the signals of the components of the complex time-frequency image

where A ^H is the Hermitian conjugate matrix with A;

, где $$h_{\ell z}^h$$

и $$h_{\ell z}^{\nu }$$

- z-е элементы сигналов компонент $$h_{\ell }^h$$

и $$h_{\ell }^{\nu }$$

, определяют число рассеянных радиосигналов, по параметрам которых - значениям временной задержки, доплеровского сдвига и азимутально-угломестного направления приема - выполняют обнаружение и пространственную локализацию подвижных объектов.after which, according to local maxima of the sum of the squares of the modules of the elements of the components of the complex time-frequency image $${\left|h_{\ell z}^h\right|}^2+{\left|h_{\ell z}^{\nu }\right|}^2$$

where $$h_{\ell z}^h$$

and $$h_{\ell z}^{\nu }$$

- z-elements of the component signals $$h_{\ell }^h$$

and $$h_{\ell }^{\nu }$$

, determine the number of scattered radio signals, according to the parameters of which - the values of time delay, Doppler shift and azimuth-elevation direction of reception - carry out the detection and spatial localization of moving objects.

The prototype method implements a fairly effective detection of moving objects in an unknown polarization of the scattered objects signals.

However, the prototype method, when generating the signals of the horizontal and vertical polarization components of a complex time-frequency image, uses operations based on the formation of a normalized classical two-dimensional cross-correlation function, which, in addition to the main lobe, contains high side lobes masking the signals of distant and weakly scattering objects.

Thus, the disadvantage of the prototype method is the low probability of detecting distant and poorly scattering objects.

The technical result of the invention is to increase the likelihood of detecting distant and poorly scattering objects.

An increase in the probability of detection is achieved through the use of new operations of polarization-sensitive nonlinear iterative processing of radio signals, which increase the sensitivity and dynamic range when forming components of horizontal and vertical polarization of a two-component complex time-frequency image of radio signals scattered by objects in the analyzed region of Doppler frequencies and time delays.

и рассеянные $$s_{\ell }=\left[\begin{array}{c}{s}_{\ell }^h\\ s_{\ell }^{\nu }\end{array}\right]$$

сигналы для выбранных азимутально-угломестных направлений приема ℓ, где h и ν - индексы компонент горизонтальной и вертикальной поляризации, которые совместно со значением азимутально-угломестного направления приема запоминают, вычисляют и сравнивают энергию компонент $${\Vert {\tilde{s}}^h\Vert }^2$$

и $${\Vert {\tilde{s}}^{\nu }\Vert }^2$$

прямого сигнала, выбирают компоненту прямого сигнала с максимальной энергией $${\tilde{s}}_{\max }^{h,\nu }$$

, согласно изобретению, для каждого ожидаемого значения доплеровского сдвига частоты ω преобразуют компоненту прямого сигнала с максимальной энергией $${\tilde{s}}_{\max }^{h,\nu }$$

в матричный сигнал комплексной фазирующей функции A_ω, включающий гипотетические сигналы, рассеиваемые в ожидаемой области задержек каждым потенциальным подвижным и стационарным объектом, матричный сигнал A_ω запоминают, для каждого выбранного азимутально-угломестного направления приема и каждого ожидаемого значения доплеровского сдвига частоты преобразуют рассеянный сигнал каждой компоненты $$s_{\ell }^h$$

и $$s_{\ell }^{\nu }$$

в сигнал элемента компоненты комплексного частотно-временного изображения

и

, где $$A_{\omega }^H$$

- матрица, эрмитово сопряженная с A_ω, сигналы элементов компонент изображения $$h_{\ell \omega }^{(0),h}$$

и $$h_{\ell \omega }^{(0),\nu }$$

запоминают и используют в качестве начального приближения, а также итерационно формируют зависящий от предыдущего решения вспомогательный матричный сигнал

, где $$h_{\ell \omega z}^{(k-1),h}$$

и $$h_{\ell \omega z}^{(k-1),\nu }$$

- z-е составляющие векторов элементов компонент изображения $$h_{\ell \omega }^{(k-1),h}$$

и $$h_{\ell \omega }^{(k-1),\nu }$$

, k=1, 2, … - номер итерации, и сигналы очередного приближения элементов компонент изображения

и

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

и $$h_{\ell \omega }^{(k),\nu }$$

в результирующие матричные сигналы компонент изображения $$H_{\ell }^h$$

и $$H_{\ell }^{\nu }$$

, после чего по локальным максимумам суммы квадратов модулей составляющих результирующих матричных сигналов компонент комплексных частотно-временных изображений $${\left|H_{\ell \omega q}^h\right|}^2+{\left|H_{\ell \omega q}^{\nu }\right|}^2$$

, где $$H_{\ell \omega q}^h$$

и $$H_{\ell \omega q}^{\nu }$$

- ωq-е составляющие матричных сигналов $$H_{\ell }^h$$

и $$H_{\ell }^{\nu }$$

, определяют число рассеянных радиосигналов, по параметрам которых - значениям временной задержки, доплеровского сдвига частоты и азимутально-угломестного направления приема - выполняют обнаружение и пространственную локализацию подвижных объектов.The technical result is achieved by the fact that in the method of polarization-sensitive detection 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 horizontal and vertical polarization components of the vector multi-beam electromagnetic field is received from N antennas direct and scattered radio signals, synchronously transform the ensemble of radio signals received by the antennas into qi front-end signals, digital signals are converted into two-component direct $$\tilde{s}=\left[\begin{array}{c}{\tilde{s}}_{}^h\\ {\tilde{s}}_{}^{\nu }\end{array}\right]$$

and scattered $$s_{\ell }=\left[\begin{array}{c}{s}_{\ell }^h\\ s_{\ell }^{\nu }\end{array}\right]$$

signals for the selected azimuthal elevation directions of reception ℓ, where h and ν are the indices of the components of horizontal and vertical polarization, which, together with the azimuthal elevation direction of reception, memorize, calculate and compare the energy of the components $${\Vert {\tilde{s}}^h\Vert }^2$$

and $${\Vert {\tilde{s}}^{\nu }\Vert }^2$$

direct signal, select the component of the direct signal with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

, according to the invention, for each expected value of the Doppler frequency shift ω transform the component of the direct signal with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

into a matrix signal of the complex phasing function A _ω , including hypothetical signals scattered in the expected delay region by each potential moving and stationary object, the matrix signal A _{ω is} stored, for each selected azimuth-elevation direction of reception and each expected value of the Doppler frequency shift, the scattered signal of each Components $$s_{\ell }^h$$

and $$s_{\ell }^{\nu }$$

into the signal element of the component of the integrated time-frequency image

and

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

- a Hermitian conjugate matrix with A _ω , signals of image component elements $$h_{\ell \omega }^{(0),h}$$

and $$h_{\ell \omega }^{(0),\nu }$$

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

where $$h_{\ell \omega z}^{(k-\mathrm{one}),h}$$

and $$h_{\ell \omega z}^{(k-\mathrm{one}),\nu }$$

- z-component of the vectors of the elements of the image component $$h_{\ell \omega }^{(k-\mathrm{one}),h}$$

and $$h_{\ell \omega }^{(k-\mathrm{one}),\nu }$$

, k = 1, 2, ... is the iteration number, and signals of the next approximation of the elements of the image components

and

, where λ is the Lagrange multiplier, until the current iteration number exceeds a predetermined threshold, the generated signals of the component elements are combined $$h_{\ell \omega }^{(k),h}$$

and $$h_{\ell \omega }^{(k),\nu }$$

into the resulting matrix signals of the image component $$H_{\ell }^h$$

and $$H_{\ell }^{\nu }$$

after which, according to local maxima of the sum of the squares of the modules of the components of the resulting matrix signals of the components of the complex time-frequency images $${\left|H_{\ell \omega q}^h\right|}^2+{\left|H_{\ell \omega q}^{\nu }\right|}^2$$

where $$H_{\ell \omega q}^h$$

and $$H_{\ell \omega q}^{\nu }$$

- ωq components of matrix signals $$H_{\ell }^h$$

and $$H_{\ell }^{\nu }$$

, determine the number of scattered radio signals, the parameters of which are the values of time delay, Doppler frequency shift and azimuth-elevation direction of reception — the detection and spatial localization of moving objects is performed.

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 preprocessing system 1 and computer system 2.

In turn, the reception and pretreatment system 1 includes an antenna array 1-1, a direct and scattered signal receiving path, including a frequency converter 1-2, ADC 1-3 and an adaptive spatial filtering device 1-4.

At the same time, system 2 has an output intended for connection to external systems.

System 1 is an analog-to-digital device and is designed for adaptive spatial filtering of useful direct and scattered radio signals by objects.

. Каждая антенна обеспечивает одновременный ненаправленный или направленный прием двух скалярных полей - ортогональных составляющих поляризованной волны в точке приема и имеет два отдельных выхода для радиосигналов горизонтальной (h) и вертикальной (ν) поляризаций.Antenna array 1-1 consists of N antennas with numbers $$n=\overline{\mathrm{one,}N}$$

. Each antenna provides simultaneous non-directional or directional reception of two scalar fields - the orthogonal components of the polarized wave at the receiving point and has two separate outputs for horizontal (h) and vertical (ν) polarization radio signals.

The spatial configuration of the antenna array can be arbitrary: flat rectangular, flat annular or three-dimensional, in particular conformal.

The frequency converter 1-2 is a 2N-channel, made with a common local oscillator and with the bandwidth of each channel, variable 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 is also 2N-channel and is 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 the input signals, then frequency selective bandpass filters and amplifiers can be used instead of the frequency converter 1-2. In addition, the frequency converter 1-2 provides 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 (to simplify, the internal generator is not shown in the diagram).

Device 1-4 is a computing device that provides adaptive spatial filtering.

Computing system 2 is intended for iterative formation of a two-component signal of a complex time-frequency image of radio signals scattered by objects in the analyzed region of Doppler frequencies and time delays, as well as for the detection and spatial localization of moving objects.

The device operates as follows.

In system 2, based on data from external systems, a set of transmitters emitting spread-spectrum radio signals is identified, selected, and periodically updated.

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 system 2 and are also used to configure the converter 1-2. In order to simplify the control circuit of the converter are not shown.

The frequency converter 1-2 according to the signals of system 2 is tuned to a given frequency of reception.

и вертикальной $$x_n^{\nu }\left(t\right)$$

поляризаций поступает на входы преобразователя частоты 1-2.The vector multipath electromagnetic field of the direct and scattered radio signals received by each antenna with the number n of the array 1-1 is in the form of horizontal time-dependent radio signals $$x_n^h\left(t\right)$$

and vertical $$x_n^{\nu }\left(t\right)$$

polarization goes to the inputs of the frequency converter 1-2.

и $$x_n^{\nu }\left(t\right)$$

фильтруется по частоте и переносится на более низкую частоту.In the 1-2 frequency converter, each received radio signal $$x_n^h\left(t\right)$$

and $$x_n^{\nu }\left(t\right)$$

filtered by frequency and transferred to a lower frequency.

и $$x_n^{\nu }\left(t\right)$$

синхронно преобразуется с помощью АЦП 1-3 в цифровые сигналы $$x_1^h\left(i\right),\dots ,x_N^h\left(i\right)$$

и $$x_1^{\nu }\left(i\right),\dots ,x_N^{\nu }\left(i\right)$$

, где i - номер временного отсчета сигнала, которые поступают в устройство 1-4, где запоминаются.1-2 radio signal ensemble formed in the converter $$x_n^h\left(t\right)$$

and $$x_n^{\nu }\left(t\right)$$

synchronously converted using ADC 1-3 to digital signals $$x_{\mathrm{one}}^h\left(i\right),...,x_N^h\left(i\right)$$

and $$x_{\mathrm{one}}^{\nu }\left(i\right),...,x_N^{\nu }\left(i\right)$$

, where i is the number of time counts of the signal that enter the device 1-4, where they are stored.

и рассеянные $$s_{\ell }=\left[\begin{array}{c}{s}_{\ell }^h\\ s_{\ell }^{\nu }\end{array}\right]$$

сигналы для выбранных азимутально-угломестных направлений приема ℓ.In device 1-4, digital signals are converted into two-component direct $$\tilde{s}=\left[\begin{array}{c}{\tilde{s}}^h\\ {\tilde{s}}^{\nu }\end{array}\right]$$

and scattered $$s_{\ell }=\left[\begin{array}{c}{s}_{\ell }^h\\ s_{\ell }^{\nu }\end{array}\right]$$

signals for the selected azimuth-elevation directions of reception ℓ.

и двухкомпонентные рассеянные сигналы s_ℓ для выбранных азимутально-угломестных направлений приема осуществляется известными способами адаптивной пространственной фильтрации [3].Converting digital signals to a two-component direct signal $$\tilde{s}$$

and two-component scattered signals s _ℓ for the selected azimuthal elevation directions of reception is carried out by known methods of adaptive spatial filtering [3].

формируется сигнал пространственной корреляционной матрицы входных сигналов R. Сигнал корреляционной матрицы R преобразуется в сигнал оптимального весового вектора w=R^-1η для формирования прямого сигнала, где η - вектор наведения, определяемый азимутально-угломестным направлением приема прямого радиосигнала, длиной волны (частотой) и геометрией решетки.In this case, for example, from digital signals of horizontal polarization $$x_{\mathrm{one}}^h\left(i\right),...,x_N^h\left(i\right)$$

the signal of the spatial correlation matrix of the input signals R is generated. The signal of the correlation matrix R is converted to the signal of the optimal weight vector w = R ^-1 η to form a direct signal, where η is the guidance vector determined by the azimuth-elevation direction of direct radio signal reception, wavelength (frequency) and lattice geometry.

объединяются в матричный цифровой сигнал X, преобразованием которого формируется сигнал $${\tilde{s}}^h=w^{H}X$$

, являющийся векторным сигналом компоненты горизонтальной поляризации прямого сигнала $${\tilde{s}}^h={\left\{s^h\left(1\right),\dots ,s^h\left(i\right),\dots ,s^h\left(I\right)\right\}}^T$$

, где I - число временных отсчетов сигнала, принятого в выбранном азимутально-угломестном направлении.After that, digital signals $$x_{\mathrm{one}}^h\left(i\right),...,x_N^h\left(i\right)$$

combined into a matrix digital signal X, the conversion of which forms a signal $${\tilde{s}}^h=w^{H}X$$

being a vector signal of the horizontal polarization component of the direct signal $${\tilde{s}}^h={\left\{s^h\left(\mathrm{one}\right),...,s^h\left(i\right),...,s^h\left(I\right)\right\}}^T$$

where I is the number of time samples of the signal received in the selected azimuth-elevation direction.

, а также компонент $$s_{\ell }^h$$

и $$s_{\ell }^{\nu }$$

рассеянных сигналов для выбранных азимутально-угломестных направлений приема ℓ.Similarly, the formation of the component of the vertical polarization of the direct signal $${\tilde{s}}^{\nu }$$

as well as the component $$s_{\ell }^h$$

and $$s_{\ell }^{\nu }$$

scattered signals for the selected azimuth-elevation directions of reception ℓ.

The physically described adaptive spatial filtering operations provide simultaneous directional reception from given directions of two components of the useful direct signal of the selected backlight transmitter and two components of the useful scattered signal in the receiving direction ℓ while suppressing a wide class of interference coming from other directions.

The received two-component signals together with the value of the azimuthal elevation direction of reception ℓ enter the computing system 2, where they are stored.

In computing system 2, the following actions are performed:

и $${\Vert {\tilde{s}}^{\nu }\Vert }^2$$

прямого сигнала;- component energy is calculated and compared $${\Vert {\tilde{s}}^h\Vert }^2$$

and $${\Vert {\tilde{s}}^{\nu }\Vert }^2$$

direct signal;

;- selects the component of the direct signal with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

;

преобразуется в матричный сигнал комплексной фазирующей функции A_ω, включающий гипотетические сигналы, рассеиваемые в ожидаемой области задержек каждым потенциальным подвижным и стационарным объектом.- for each expected value of the Doppler frequency shift ω of the component of the direct signal with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

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.

в матричный сигнал A_ω осуществляется по следующей формуле:Convert direct-signal components with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

in the matrix signal A _{ω is} carried out according to the following formula:

,

,

- векторы размером I×1, являющиеся сдвинутыми по времени на qT_s версиями прямого сигнала $${\tilde{s}}_{\max }^{h,\nu }$$

, q=0, …, Q-1, Q - число временных задержек прямого сигнала, T_s - период выборки сигнала;Where $${\tilde{s}}_{\max ,q}^{h,\nu }={\left[{\tilde{s}}_{\max ,q(\mathrm{one}-q)}^{h,\nu },...,{\tilde{s}}_{\max ,(I-q)}^{h,\nu }\right]}^T$$

- vectors of size I × 1, which are time-shifted qT _s versions of the direct signal $${\tilde{s}}_{\max }^{h,\nu }$$

, 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 sizes of the matrices D _ω and A _ω , respectively, are equal to I × I and I × 2Q.

, а размер этой матрицы I×2Q определяется числом отсчетов в разведываемом сигнале (длительностью интервала наблюдения) и размерами координатной сетки по временному запаздыванию;Thus, the columns of the matrix A _ω are time-delayed and frequency-shifted Doppler shift versions of the direct signal $${\tilde{s}}_{\max }^{h,\nu }$$

, and the size of this matrix I × 2Q is determined by the number of samples in the reconnaissance signal (the duration of the observation interval) and the size of the coordinate grid by time delay;

- the matrix signal of the complex phasing function A _{ω is} stored.

After that, in computing system 2, for each selected azimuth-elevation direction of reception and each expected value of the Doppler frequency shift running through a discrete series of values of ω / (IT _s ) (ω = 0, ± 1, ..., ± Ω), the following actions are performed:

и $$s_{\ell }^{\nu }$$

в сигнал элемента компоненты комплексного частотно-временного изображения

;- scattered signal of each component is converted $$s_{\ell }^h$$

and $$s_{\ell }^{\nu }$$

into the signal element of the component of the integrated time-frequency image

;

и $$h_{\ell \omega }^{(0),\nu }$$

запоминаются и используются в качестве начального приближения;- signals of the components of the image component $$h_{\ell \omega }^{(0),h}$$

and $$h_{\ell \omega }^{(0),\nu }$$

remembered and used as an initial approximation;

, где $$h_{\ell \omega z}^{(k-1),h}$$

и $$h_{\ell \omega z}^{(k-1),\nu }$$

- z-е составляющие компонент $$h_{\ell \omega }^{(k-1),h}$$

и $$h_{\ell \omega }^{(k-1),\nu }$$

, k=1, 2, … - номер итерации, и сигналы очередного приближения элементов компонент изображения

и

, где λ - множитель Лагранжа, до тех пор, пока номер текущей итерации не превысит заданный порог;- an auxiliary matrix signal depending on the previous solution is iteratively formed

where $$h_{\ell \omega z}^{(k-\mathrm{one}),h}$$

and $$h_{\ell \omega z}^{(k-\mathrm{one}),\nu }$$

- z-component components $$h_{\ell \omega }^{(k-\mathrm{one}),h}$$

and $$h_{\ell \omega }^{(k-\mathrm{one}),\nu }$$

, k = 1, 2, ... is the iteration number, and signals of the next approximation of the elements of the image components

and

where λ is the Lagrange multiplier until the current iteration number exceeds a given threshold;

объединяются в результирующий матричный сигнал горизонтальной компоненты изображения $$H_{\ell }^h$$

, а сигналы элементов вертикальной компоненты изображения $$h_{\ell \omega }^{(k),\nu }$$

объединяются в результирующий матричный сигнал вертикальной компоненты изображения $$H_{\ell }^{\nu }$$

по формулам:- after performing a given number of iterations, the generated signals of the elements of the horizontal image component $$h_{\ell \omega }^{(k),h}$$

combined into the resulting matrix signal of the horizontal image component $$H_{\ell }^h$$

, and the signals of the elements of the vertical image component $$h_{\ell \omega }^{(k),\nu }$$

combined into the resulting matrix signal of the vertical image component $$H_{\ell }^{\nu }$$

according to the formulas:

,

,

;

;

, где $$H_{\ell \omega q}^h$$

и $$H_{\ell \omega q}^{\nu }$$

- ωq-е составляющие матричных сигналов $$H_{\ell }^h$$

и $$H_{\ell }^{\nu }$$

, определяют число рассеянных радиосигналов, по параметрам которых - значениям временной задержки, доплеровского сдвига частоты и азимутально-угломестного направления приема - выполняют обнаружение и пространственную локализацию подвижных объектов.- for local maxima of the sum of the squares of the modules of the components of the resulting matrix signals of the components of the complex frequency-time images $${\left|H_{\ell \omega q}^h\right|}^2+{\left|H_{\ell \omega q}^{\nu }\right|}^2$$

where $$H_{\ell \omega q}^h$$

and $$H_{\ell \omega q}^{\nu }$$

- ωq components of matrix signals $$H_{\ell }^h$$

and $$H_{\ell }^{\nu }$$

, determine the number of scattered radio signals, the parameters of which are the values of time delay, Doppler frequency shift and azimuth-elevation direction of reception — the detection and spatial localization of moving objects is performed.

The following actions are performed:

- the values of the Doppler shift of each scattered signal are compared with the threshold, and when the threshold is exceeded, a decision is made to detect a moving object in the analyzed azimuth-elevation direction of reception.

The threshold is selected based on minimizing the probability of missing an object;

- from the value of the time delay of the signal τ, the apparent distance to the object is determined D = τc, where c is the speed of light;

- the spatial coordinates of the detected object are determined by the apparent range D and the azimuth and elevation angles of the reception of scattered signals, for example, in accordance with [4].

Moreover, for the pair “detection device - transmitter”, an ellipsoid of equal apparent distances corresponding to the geometrical place of points in space is built, the sum of the distances to which (from the transmitter to the object and from the object to the detection device) is equal to the found value of the apparent distance D. At the intersection of the ellipsoid and direction values (azimuth and elevation angle) of scattered signal reception are determined by the geographical coordinates of the detected object.

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

и $$h_{\ell \omega }^{(k),\nu }$$

(для каждого ℓ-го азимутально-угломестного направления приема и для каждого ожидаемого значения доплеровского сдвига частоты ω принятых сигналов) и последующего их объединения в результирующие матричные сигналы компонент изображения $$H_{\ell }^h$$

и $$H_{\ell }^{\nu }$$

.From the above description it follows that the device that implements the proposed method provides an increase in the probability of detection of distant and weakly scattering objects due to the use of new operations of nonlinear signal generation of elements of polarizing image components $$h_{\ell \omega }^{(k),h}$$

and $$h_{\ell \omega }^{(k),\nu }$$

(for each ℓth azimuthal elevation direction of reception and for each expected value of the Doppler frequency shift ω of the received signals) and their subsequent combination into the resulting matrix signals of the image component $$H_{\ell }^h$$

and $$H_{\ell }^{\nu }$$

.

Thus, due to the use in each azimuthal-elevation direction of searching for objects instead of polarization-sensitive classical two-dimensional cross-correlation of operations of polarization-sensitive nonlinear iterative processing of radio signals, which provides increased sensitivity and dynamic range when forming components of horizontal and vertical polarization of a two-component time-frequency image of radio signals scattered by objects in the analyzed area of the Doppler hour by (velocity) and time delays (ranges), it is possible to solve the problem with achieving said technical result.

Information sources

1. RU, patent, 2158002, cl. G01S 13/14, 2000

2. US patent 7304603 B2, cl. G01S 13/02, 2007

3. Ratynsky M.V. Adaptation and superresolution in antenna arrays. M .: Radio and communication. 2003 year

4. RU, patent, 2444754 C15, cl. G01S 13/02, 2012

Claims (1)

The method of polarization-sensitive detection 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, receive by a lattice of N antennas the components of horizontal and vertical polarization of the vector 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 two-straight $$\tilde{s}=\left[\begin{array}{c}{\tilde{s}}^h\\ {\tilde{s}}^{\nu }\end{array}\right]$$

and scattered $$s_l=\left[\begin{array}{c}{s}_l^h\\ s_l^{\nu }\end{array}\right]$$

signals for the selected azimuthal elevation directions of reception l, where h and ν are the indices of the components of horizontal and vertical polarization, which together with the azimuthal elevation direction of the reception memorize, calculate and compare the energy of the components $${\Vert {\tilde{s}}^h\Vert }^2$$

and $${\Vert {\tilde{s}}^{\nu }\Vert }^2$$

direct signal, select the component of the direct signal with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

, characterized in that for each expected value of the Doppler frequency shift ω transform the component of the direct signal with maximum energy $${\tilde{s}}_{\max }^{h,\nu }$$

into a matrix signal of the complex phasing function A _ω , including hypothetical signals scattered in the expected delay region by each potential moving and stationary object, the matrix signal A _{ω is} stored, for each selected azimuth-elevation direction of reception and each expected value of the Doppler frequency shift, the scattered signal of each Components $$s_l^h$$

and $$s_l^{\nu }$$

into the signal element of the component of the integrated time-frequency image

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

- a Hermitian conjugate matrix with A _ω , signals of image component elements $$h_{l\omega }^{(0),h}$$

and $$h_{l\omega }^{(0),\nu }$$

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

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

and $$h_{l\omega z}^{(k-\mathrm{one}),\nu }$$

- z-component of the vectors of the elements of the image component $$h_{l\omega }^{(k-\mathrm{one}),h}$$

and $$h_{l\omega }^{(k-\mathrm{one}),\nu }$$

, k = 1,2, ... is the iteration number, and signals of the next approximation of the elements of the image components

and

, where λ is the Lagrange multiplier, until the current iteration number exceeds a predetermined threshold, the generated signals of the component elements are combined $$h_{l\omega }^{(k),h}$$

and $$h_{l\omega }^{(k),\nu }$$

into the resulting matrix signals of the image component $$H_l^h$$

and $$H_l^{\nu }$$

after which, according to local maxima of the sum of the squares of the modules of the components of the resulting matrix signals of the components of the complex time-frequency images $${\left|H_{l\omega q}^h\right|}^2+{\left|H_{l\omega q}^{\nu }\right|}^2$$

where $$H_{l\omega q}^h$$

and $$H_{l\omega q}^{\nu }$$

- ωq components of matrix signals $$H_l^h$$

and $$H_l^{\nu }$$

, determine the number of scattered radio signals, the parameters of which are the values of time delay, Doppler frequency shift and azimuth-elevation direction of reception — the detection and spatial localization of moving objects is performed.