RU2524401C1 - Method for detection and spatial localisation of mobile objects - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: high quality of detection and spatial localisation of nearly invisible objects is achieved by employing, in each channel of an N-element antenna array, new adaptive and nonlinear processing operations which increase resolution and dynamic range of synthesis of a frequency-time image of radio signals scattered by the controlled objects.

EFFECT: high quality of detection and spatial localisation of nearly invisible objects.

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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.

A known method for detecting and spatial localization of objects [1], which consists in the fact that they select a transmitter emitting a spread spectrum radio signal, synchronously receive an array of multipath radio signals including the direct radio signal of the transmitter and the radio signals of this transmitter scattered from objects, synchronously transform the ensemble of radio signals received by the antennas into digital signals, direct and compressed scattered signals are formed from digital signals, the selected direct and scattered signals are compared and determined time delays, Doppler shifts and directions of arrival of scattered signals are divided, according to time delays, Doppler shifts and directions of arrival, detection and spatial localization of air objects are performed.

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 detection and spatial localization of objects [2], free from this drawback and selected as a prototype. According to this method:

selecting a transmitter emitting a spread spectrum radio signal;

synchronously receive a multi-beam radio signal including a direct radio signal of the transmitter and the radio signals of this transmitter scattered by objects from an array of N antennas;

synchronously, the radio signals received by the antennas are converted into digital signals s _n , where n is the antenna number, which are combined into a matrix digital signal S = {s ₁ , ..., s _n , ..., s _N } ^T and stored;

a signal of the spatial correlation matrix R is formed from a digital matrix signal S, which is converted into a signal of the optimal weight vector w = R ^-1 v, where v is the guidance vector determined by the azimuthal elevation direction of direct radio signal reception, wavelength and lattice geometry;

transform the matrix digital signal S into a direct digital signal s = w ^H S, which is stored, where (·) ^H is the symbol of Hermitian conjugation;

forming and storing time-shift-dependent complex cross-correlation functions (CCFs) between the digital signal of an individual antenna s _n and the direct digital signal s;

determine the maximum module value of each complex VKF and fix the corresponding values of the complex VKF corresponding to these maxima;

calculating differential digital signals;

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

averaging the modules of complex DKFV;

determine by the maxima of the averaged DKFV the number of compressed signals and fix the delay values in time and the absolute Doppler shift of each p-th compressed signal;

the components of complex DKFV corresponding to a separate maximum of the averaged DKFV are identified as the pth signal compressed in time and frequency;

isolate and remember the values of the constituents of complex DKFV, time delay and absolute Doppler shift of each p-th compressed signal;

from the selected values of the p-x identified components of the complex DKFV, a complex two-dimensional angular spectrum is synthesized, the maximum modulus of which determines the azimuth-elevation direction of arrival of the p-th compressed signal;

the values of the delay and the absolute Doppler shift and the azimuthal elevation direction of arrival detect and determine the spatial coordinates of moving objects.

The prototype method due to the presence of adaptive spatial filtering operations and operations of electronic compensation of coherent interference in the form of a powerful direct radio signal of the backlight transmitter provides detection of a wider class of moving objects. However, the prototype method contains the operation of forming a classical two-dimensional cross-correlation function, which, in addition to the main lobe, the width of which limits the resolution of detection, contains high side lobes masking the signals of distant and weakly scattering objects.

Thus, the disadvantage of the prototype method is the low quality of detection and spatial localization of subtle objects.

The technical result of the invention is to improve the quality of detection and spatial localization of subtle objects.

Improving the quality of detection and spatial localization of subtle objects is achieved through the use of new adaptive and nonlinear processing operations in each channel of the N-element antenna array, which increase the resolution and dynamic range of synthesis of the time-frequency image of radio signals scattered by controlled objects.

, где А^H - матрица, эрмитово сопряженная с А, сигнал $$h_n^{(0)}$$

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

$$h_{n_z}^{\left(k-1\right)}$$

- z-й элемент вектора $$h_{n_{}}^{\left(k-1\right)}$$

, k=1,2,… - номер итерации, и сигнал очередного приближения комплексного частотно-временного изображения $$h_n^{(k)}={\left[A^{H}A+\lambda Л\left(h_n^{(k-1)}\right)\right]}^{-1}{A}^H{S}_n^{},$$

где λ - множитель Лагранжа, до тех пор, пока номер текущей итерации не превысит заданный порог, после чего усредняют модули текущих частотно-временных изображений отдельных антенн - $$\overline{h_z^{(k)}=}{\displaystyle \sum _n\left|h_{nz}^{(k)}\right|,}$$

по локальным максимумам усредненного частотно-временного изображения $$\overline{h_z^{(k)}}$$

определяют число рассеянных радиосигналов и фиксируют значения временной задержки и доплеровского сдвига каждого р-го рассеянного радиосигнала, идентифицируют соответствующие отдельному максимуму усредненного изображения $$\overline{h_z^{(k)}}$$

элементы $$h_{nz/p}^{(k)}$$

комплексных частотно-временных изображений $$h_{nz}^{(k)}$$

как составляющие р-го рассеянного радиосигнала, выделяют и запоминают значения идентифицированных составляющих $$h_{nz/p}^{(k)}$$

, по которым синтезируют комплексный угловой спектр, по максимумам модуля которого определяют азимутально-угломестное направление прихода р-го рассеянного сигнала, по значениям временной задержки, доплеровского сдвига и азимутально-угломестного направления прихода обнаруживают и определяют пространственные координаты подвижных объектов. Операции способа поясняются чертежом.The technical result is achieved by the fact that in the method for detecting and spatial localization of objects, which consists in choosing a transmitter emitting a spread spectrum radio signal, synchronously receive an array of N antennas with multi-beam radio signals, including a direct transmitter radio signal and scattered objects from this transmitter, synchronously transform received antenna signals into digital signals s _n, where n - number of antennas, which combine in the digital signal matrix S = {s _{1, ..., s n, ...,} s N} T and memorize , A matrix formed of a digital signal S signal spatial correlation matrix R, which is converted into a signal of an optimal weight vector w = R ^-1 v, where v - pointing vector, determined by the elevation direction azimuthally receiving direct radio signal wavelength and grating geometry transform matrix digital signal S into a direct digital signal s = w ^H S, which is stored where (·) ^H is a Hermitian conjugation symbol, according to the invention, the digital direct signal s is converted into a matrix signal of a complex phasing function A, radiant hypothetical signals scattered by each potential object, store the matrix signal A, convert the digital signal of an individual antenna s _n into a signal of a complex time-frequency image $$h_n^{(0)}={\left(A^H{A}^{}\right)}^{-\mathrm{one}}{A}^H{S}_n^{},$$

where A ^H is a Hermitian conjugate matrix with A, the signal $$h_n^{(0)}$$

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

$$h_{n_z}^{\left(k-\mathrm{one}\right)}$$

is the zth element of the vector $$h_{n_{}}^{\left(k-\mathrm{one}\right)}$$

, k = 1,2, ... is the iteration number, and the signal of the next approximation of the complex time-frequency image $$h_n^{(k)}={\left[A^{H}A+\lambda L\left(h_n^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}^H{S}_n^{},$$

where λ is the Lagrange multiplier, until the current iteration number exceeds a predetermined threshold, after which the modules of the current frequency-time images of individual antennas are averaged - $$\overline{h_z^{(k)}=}{\displaystyle \sum _n|\; |\; |h_{nz}^{(k)}|\; |\; |,}$$

by local maxima of the averaged time-frequency image $$\overline{h_z^{(k)}}$$

determine the number of scattered radio signals and fix the values of the time delay and Doppler shift of each p-th scattered radio signal, identify the corresponding individual maximum of the averaged image $$\overline{h_z^{(k)}}$$

the elements $$h_{nz/p}^{(k)}$$

integrated time-frequency images $$h_{nz}^{(k)}$$

as components of the nth scattered radio signal, isolate and store the values of the identified components $$h_{nz/p}^{(k)}$$

using which the complex angular spectrum is synthesized, the azimuth-elevation direction of arrival of the p-th scattered signal is determined from the maxima of the module, the spatial coordinates of moving objects are detected and determined from the values of time delay, Doppler shift and azimuth-elevation direction of arrival. 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 and measure the synchronization parameters of backlight transmitters for objects emitting spread-spectrum radio signals, as well as for adaptive spatial filtering of useful direct and scattered radio signals. Note that after the synchronization parameters of the direct radio signal of the selected backlight transmitter are measured or when they are a priori known, the direct radio signal of the transmitter can be generated by modeling in system 2.

. Пространственная конфигурация антенной решетки должна обеспечивать измерение азимутально-угломестного направления прихода радиосигналов и может быть произвольной пространственной конфигурации: плоской прямоугольной, плоской кольцевой или объемной, в частности конформной. Для улучшения различения сигналов не только по пространству, но и по поляризации требуется существенное различие поляризационных откликов антенн решетки, то есть антенная решетка должна быть неоднородной (гетерогенной), то есть иметь антенные элементы с отличающимися векторными диаграммами направленности. Преобразователи частоты 1-2 и 1-7 являются N-канальными, выполнены с общим гетеродином и с полосой пропускания каждого канала, изменяемой в соответствии с шириной спектра принимаемого радиосигнала. Общий гетеродин обеспечивает многоканальный когерентный прием сигналов. АЦП 1-3 и 1-6 также является N-канальным и синхронизирован сигналом одного опорного генератора (для упрощения опорный генератор на схеме не показан). Если разрядность и быстродействие АЦП достаточны для непосредственного аналого-цифрового преобразования входных сигналов, как, например, в KB диапазоне, то вместо преобразователей частоты 1-2 и 1-7 могут использоваться частотно избирательные полосовые фильтры и усилители. Кроме того, преобразователи частоты 1-2 и 1-7 обеспечивают подключение одной из антенн вместо всех антенн решетки для периодической калибровки приемных каналов по внешнему источнику сигнала. Возможна калибровка с использованием внутреннего генератора, выход которого также подключается вместо всех антенн для периодической калибровки каналов. Устройство обнаружения 1-4 и устройство адаптивной пространственной фильтрации 1-5 представляют собой вычислительные устройства. Подсистема 2 является вычислительным устройством и предназначена для идентификации, отбора и периодического обновления передатчиков радиосигналов с расширенным спектром, используемых для подсвета заданной области контролируемого пространства, а также для формирования модельных сигналов выбранных передатчиков. Вычислительная система 3 предназначена для формирования сигнала фазирующей функции (блок 3-4), формирования вспомогательного и взвешивающего сигналов (устройство 3-3), сравнения сигналов частотно-временных изображений, формируемых на смежных итерациях (блок 3-2) и синтеза частотно-временного изображения (блок 3-1).Antenna array 1-1 consists of N antennas with numbers $$n=\overline{\mathrm{one,}N}$$

. The spatial configuration of the antenna array should provide measurements of the azimuthal elevation direction of arrival of the radio signals and can be of any spatial configuration: flat rectangular, flat circular or surround, in particular conformal. To improve the distinction of signals not only in space but also in polarization, a significant difference in the polarization responses of the array antennas is required, that is, the antenna array must be heterogeneous (heterogeneous), that is, have antenna elements with different vector radiation patterns. 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. The ADC 1-3 and 1-6 is also N-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, as, for example, in the KB 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. 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 the monitored space, as well as to generate model signals of selected transmitters. Computing system 3 is intended for generating a signal of a phasing function (block 3-4), generating auxiliary and weighting signals (device 3-3), comparing signals of time-frequency images generated at adjacent iterations (block 3-2), and synthesizing a time-frequency images (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. In addition, in system 2, received direct radio signals are regenerated or model transmitter signals are generated with the required synchronization parameters.

The parameters of the selected set of transmitters (number, carrier frequency, spectrum width, shape, synchronization parameters and 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 are 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. At the same time, the search path searches and measures the synchronization parameters of the backlight transmitters emitting spread-spectrum radio signals at frequencies f _{k of the} discrete search frequency grid. In this case, the time-dependent radio signal s _kn (t) received by each antenna element 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 _kn (t) formed in the converter 1-2 are converted using ADC 1-3 into digital signals, which are fed to the detection device 1-4, in which the transmitter synchronization parameters are detected and measured at each frequency f _{k of the} discrete search frequency grid backlight. The operation of the detection device 1-4 is based on widely 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 f _k . The receiving path synchronously receives multipath radio signals at a frequency f _k , 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 element number n of the antenna array 1-1 is filtered by frequency and transferred to a lower frequency in converter 1-7.

- номер временного отсчета сигнала.The radio signals s _n (t) generated in the converter 1-7 are synchronously converted by means of the ADC 1-6 into digital signals s _n = {s _n (1), ..., s _n (z), ..., s _n (Z)}, Where $$z=\overline{\mathrm{one,}Z}$$

- number of the time reference signal.

The digital signals of the individual antennas s _n are received in the device 1-5, where they are combined into a matrix signal S = {s ₁ , ..., s _n , ..., s _N } ^T and stored. The matrix signal S has the dimension N × Z.

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

- from the matrix digital signal S, an N × N signal of the spatial correlation matrix R is formed;

- the signal of the correlation matrix R is converted to N × 1 signal

the optimal weight vector w = R ^-1 v, where v is N × 1 guidance vector, determined by the azimuthal elevation direction of direct radio signal reception, wavelength (frequency f _k ) and lattice geometry;

- the matrix digital signal S is converted to 1 × Z direct digital signal s = w ^H S.

The physically described adaptive spatial filtering operations provide directional reception of a useful direct radio signal of a selected backlight transmitter from a given direction while simultaneously 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 direct digital signal s formed in the device 1-5 is supplied and stored in block 3-4, and the stored digital signals of the individual antennas s _n are supplied to the device 3-1, where they are also stored.

After that, in block 3-4, the digital direct signal s is converted into a matrix signal of the complex phasing function A, which is supplied to the device 3-3, where it is stored.

The direct signal s is converted into matrix signal A according to the following formula: A = [Ds ₀ , ..., Ds _j , ..., Ds _j-1 ], where s _j = [s _(1-j) , ..., s _(zj) ] ^T are vectors of size Z × 1, which are time shifted by jTs versions of the reference signal s, j = 0, ..., J-1, J is the number of time delays of the direct signal, T _s is the signal sampling period;

$$D=\left[D_{-L},...,D_{-\ell },...,D_0,...,D_{+\ell },...,D_{+L}\right],D\ell =\left[\begin{array}{cccc}\mathrm{one}& 0& ...& 0\\ 0& e^{j2\pi \ell /Z}& ...& 0\\ ...& ...& ...& ...\\ 0& 0& ...& e^{j2\pi \ell (Z-\mathrm{one})/Z}\end{array}\right]$$

are the Doppler shift matrices, ℓ = 0, ..., ± L, L is the size of the grid along the Doppler shift.

Thus, the columns of matrix A are time-delayed and frequency-shifted Doppler shift versions of the direct signal S, and the size of this matrix Z × J (2L + 1) is determined by the number of samples in the reconnaissance signal (the length of the observation interval) and the size of the coordinate grid on time lag and Doppler frequency shift.

In addition, in the device 3-3, from the signal a, the signals A ^H , A _H A and (A ^H A) ^-1 are sequentially calculated, which enter block 3-1, where they are stored.

In block 3-1, using the digital signal of a separate antenna s _n received from device 1-5 and the signals A ^H and (A ^H A) ^-1 received from block 3-3, the initial approximation signal of the complex time-frequency image is calculated $$h_n^{(0)}={\left(A^H{A}^{}\right)}^{-\mathrm{one}}{A}^H{s}_n^{}.$$

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

the initial approximation is stored in block 3-2 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 $$Л\left(h_n^{\left(1\right)}\right)\equiv diag\left\{{\left|h_{n_z}^{(1)}\right|}^{-1}/2\right\},$$

$$h_{n_z}^{\left(1\right)}$$

z-й элемент вектора $$h_{n_z}^{\left(1\right)}$$

, и взвешивающий сигнал $${\left[A^H{A}^{}+\lambda Л\left(h_n^{(1)}\right)\right]}^{-1}{A}^H.$$

Значение множителя Лагранжа λ выбирают исходя из уровня шумов в каналах приема. Взвешивающий сигнал $${\left[A^H{A}^{}+\lambda Л\left(h_n^{(1)}\right)\right]}^{-1}{A}^H$$

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

at k-1, an auxiliary matrix signal is formed $$L\left(h_n^{\left(\mathrm{one}\right)}\right)\equiv diag\left\{{|\; |\; |h_{n_z}^{(\mathrm{one})}|\; |\; |}^{-\mathrm{one}}/2\right\},$$

$$h_{n_z}^{\left(\mathrm{one}\right)}$$

zth element of the vector $$h_{n_z}^{\left(\mathrm{one}\right)}$$

, and weighting signal $${\left[A^H{A}^{}+\lambda L\left(h_n^{(\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}^H.$$

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

enters block 3-1.

и запомненного цифрового сигнала отдельной антенны s_n синтезируется сигнал текущего приближения комплексного частотно-временного изображения $$h_n^{(1)}={\left[A^{H}A+\lambda Л\left(h_n^{(1)}\right)\right]}^{-1}{A}^H{S}_n^{}.$$

Полученный сигнал $$h_n^{\left(1\right)}$$

поступает в блок 3-2.In block 3-1 using the signal $${\left[A^H{A}^{}+\lambda L\left(h_n^{(\mathrm{one}}\right)\right]}^{-\mathrm{one}}{A}^H$$

and a stored digital signal of an individual antenna s _n , the current approximation signal of a complex time-frequency image is synthesized $$h_n^{(\mathrm{one})}={\left[A^{H}A+\lambda L\left(h_n^{(\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}^H{S}_n^{}.$$

Received signal $$h_n^{\left(\mathrm{one}\right)}$$

enters block 3-2.

запоминается для использования на следующей итерации. Кроме того, в блоке 3-2 номер текущей итерации k сравнивается с заранее установленным фиксированным порогом k₀. Экспериментально установленное значение порога равно k₀=10.In block 3-2, the signal $$h_n^{\left(\mathrm{one}\right)}$$

remembered for use in the next iteration. In addition, in block 3-2, the current iteration number k is compared with a predetermined fixed threshold k ₀ . The experimentally set threshold value is k ₀ = 10.

поступает в устройство 3-3 для запоминания и инициализации очередной итерации синтеза частотно-временного изображения.When the condition k≤k _{0 is} fulfilled, the signal $$h_n^{\left(\mathrm{one}\right)}$$

enters the device 3-3 for storing and initializing the next iteration of the synthesis of the time-frequency image.

$${\left[A^H{A}^{}+\lambda Л\left(h_n^{(k-1)}\right)\right]}^{-1}{A}^H,$$

$$h_n^{(k)}={\left[A^{H}A+\lambda Л\left(h_n^{(k-1)}\right)\right]}^{-1}{A}^H{s}_n^{},$$

запоминанию сигнала $$h_n^{\left(k\right)}$$

и проверке выполнения условия k≤k₀.Then, in the device 3-3, blocks 3-1 and 3-2, the previously described sequence of operations for generating signals is performed $$L\left(h_n^{(k-\mathrm{one})}\right),$$

$${\left[A^H{A}^{}+\lambda L\left(h_n^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}^H,$$

$$h_n^{(k)}={\left[A^{H}A+\lambda L\left(h_n^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}^H{s}_n^{},$$

signal storage $$h_n^{\left(k\right)}$$

and verification of the condition k≤k ₀ .

из блока 3-2 поступает в блок 4. Сигнал $$h_n^{\left(k\right)}$$

является векторным сигналом и описывает сформированное из цифрового сигнала отдельной антенны s_n текущее частотно-временное изображения с элементами $$h_{nz}^{\left(k\right)}.$$

If the condition k≤k _{0 is} not fulfilled, the signal $$h_n^{\left(k\right)}$$

from block 3-2 goes to block 4. The signal $$h_n^{\left(k\right)}$$

is a vector signal and describes the current time-frequency image with elements generated from the digital signal of a separate antenna s _n $$h_{nz}^{\left(k\right)}.$$

зависит от предыдущего решения $$h_n^{\left(k-1\right)}$$

, предложенный способ реализует адаптацию с обратной связью по полезному сигналу в каждом канале N-элементной антенной решетки, что повышает чувствительность и динамический диапазон формирования изображения. Кроме того, новые операции нелинейной обработки сигналов повышают в каждом канале N - элементной антенной решетки разрешающую способность формирования изображения радиосигналов, рассеянных объектами. Это в совокупности повышает качество выполняемых на последующих этапах операций обнаружения и пространственной локализации малозаметных объектов.Given that the signal of the current complex time-frequency image $$h_n^{\left(k\right)}$$

depends on previous decision $$h_n^{\left(k-\mathrm{one}\right)}$$

, the proposed method implements adaptation with feedback on the useful signal in each channel of the N-element antenna array, which increases the sensitivity and dynamic range of image formation. In addition, new non-linear signal processing operations increase the resolution of imaging of radio signals scattered by objects in each channel of the N - element antenna array. This together improves the quality of the detection and spatial localization of obscure objects performed at subsequent stages.

In block 4, the following actions are performed:

- modules of the current time-frequency images of individual antennas are averaged $$\overline{h_z^{(k)}=}{\displaystyle \sum _n|\; |\; |h_{nz}^{(k)}|\; |\; |;}$$

определяется число рассеянных радиосигналов и фиксируются значения временной задержки τ_р и доплеровского сдвига F_р каждого р-го рассеянного радиосигнала;- by local maxima of the averaged time-frequency image $$\overline{h_z^{(k)}}$$

the number of scattered radio signals is determined and the values of the time delay τ _p and the Doppler shift F _{p of} each p-th scattered radio signal are fixed;

элементы $$h_{nz/p}^{\left(k\right)}$$

комплексных частотно-временных изображений как составляющие р-го рассеянного радиосигнала;- identified corresponding to a separate maximum averaged image $$\overline{h_z^{(k)}}$$

the elements $$h_{nz/p}^{\left(k\right)}$$

complex time-frequency images as components of the p-th scattered radio signal;

, по которым синтезируется комплексный угловой спектр. Комплексный угловой спектр синтезируется известными способами, например, [3];- the values of the identified components are highlighted and stored $$h_{nz/p}^{\left(k\right)}$$

by which the complex angular spectrum is synthesized. The complex angular spectrum is synthesized by known methods, for example, [3];

- the azimuthal elevation direction of arrival (α _p , β _p ) of the nth scattered signal is determined from the maxima of the modulus of the synthesized complex angular spectrum;

- the values of the delay τ _s , the Doppler shift F _p and the azimuthal elevation direction of arrival (α _p , β _p ) are detected and determined by the spatial coordinates 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 detection and spatial localization are displayed to increase information content.

From the above description it follows that the device that implements the proposed method provides improved detection and spatial localization of subtle objects due to the use of new adaptive and non-linear processing of radio signals in each channel of the N-element antenna array.

Thus, due to the use of an N-element antenna array in each channel, instead of the classical two-dimensional cross-correlation, adaptive processing operations with feedback on the useful radio signal and non-linear processing operations of the received radio signals provide an increase in the sensitivity, dynamic range and resolution of the synthesis of the time-frequency image of radio signals goals, 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, 2444754, 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 communication. 2003 year

Claims (1)

A method for detecting and spatial localization of objects, which consists in selecting a transmitter emitting a spread spectrum radio signal, synchronously receiving a multipath radio signal from an array of N antennas, including a direct transmitter radio signal and scattered objects from this transmitter, simultaneously synchronizing the received radio signals into digital signals s _n, where n - number of antennas, which combine in the digital signal matrix s = {s _{1, ..., s n, ...,} s N} T and stored, a matrix formed of a digital signal s Igna spatial correlation matrix R, which is converted into a signal of an optimal weight vector w = R ^-1 v, where v - pointing vector, determined by the elevation direction azimuthally receiving direct radio signal wavelength and the geometry of the lattice, the matrix is converted into a digital signal S direct digital signal s = w ^H S, which is stored, where (·) ^H - symbol Hermitian conjugation, characterized in that the converted digital signal to direct signal s in the matrix a of complex phasing function comprising hypothetical signals dissipated each potential object stored matrix signal A is converted into a digital signal s _n individual antenna signal in a complex frequency-time image $$h_n^{(0)}={\left(A^H{A}^{}\right)}^{-\mathrm{one}}{A}^H{S}_n^{}$$

where A ^H is a Hermitian conjugate matrix with A, the signal $$h_n^{(0)}$$

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

$$h_{nz}^{\left(k-\mathrm{one}\right)}$$

is the zth element of the vector $$h_{n_{}}^{\left(k-\mathrm{one}\right)}$$

, k = 1,2, ... is the iteration number, and the signal of the next approximation of the complex time-frequency image $$h_n^{(k)}={\left[A^{H}A+\lambda L\left(h_n^{(k-\mathrm{one})}\right)\right]}^{-\mathrm{one}}{A}^H{s}_n$$

, where λ is the Lagrange multiplier until the current iteration number exceeds a given threshold, after which the modules of the current time-frequency images of individual antennas are averaged $$\overline{h_z^{(k)}=}{\displaystyle \sum _n|\; |\; |h_{nz}^{(k)}|\; |\; |}$$

, according to the local maxima of the averaged time-frequency image $$\overline{h_z^{(k)}}$$

determine the number of scattered radio signals and fix the values of the time delay and Doppler shift of each p-th scattered radio signal, identify the corresponding individual maximum of the averaged image $$\overline{h_z^{(k)}}$$

the elements $$h_{nz/p}^{(k)}$$

integrated time-frequency images $$h_{nz}^{(k)}$$

as components of the nth scattered radio signal, isolate and store the values of the identified components $$h_{nz/p}^{(k)}$$

using which the complex angular spectrum is synthesized, the azimuth-elevation direction of arrival of the p-th scattered signal is determined from the maxima of the module, the spatial coordinates of moving objects are detected and determined from the values of time delay, Doppler shift and azimuth-elevation direction of arrival.