RU2716006C2 - Method for remote detection and tracking of radio silent objects - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to radio engineering and can be used in control systems of ground, sea and air space using direct and scattered radio signals emitted by multiple uncontrolled and controlled transmitters of radioelectronic systems for various purposes. Higher sensitivity is achieved by using new operations of masking interference compensation and coherent generation at each expected frequency of Doppler shift elements of three-dimensional space-frequency-time image from signals of all antennas of the array and their combination into a resultant image, instead of operations of incoherent summation of a set of two-dimensional frequency-time images formed from signals of separate antennae.

EFFECT: technical result is high sensitivity when detecting and tracking radio silent objects.

1 cl, 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.

The technology of covert remote monitoring of moving objects, using natural radio illumination of targets created at multiple frequencies by radio emissions from transmitters for various purposes, has not yet received wide distribution, despite the fact that it can significantly increase the stealth and efficiency of detection, spatial localization and tracking of a wide class of radio-silent moving objects .

A known method for remote detection and tracking of radio-silent objects [1], which consists in selecting a transmitter emitting a spread spectrum radio signal, synchronously receiving an array of N antennas multi-beam radio signals, including a direct radio signal of the transmitter and scattered objects of the radio signal of this transmitter, synchronously transform the received antennas radio signals into digital signals, which are combined into a matrix digital signal, the matrix digital signal is stored and converted into a spatial signal a correlation matrix, which, together with the azimuthal elevation direction of the direct radio signal, wavelength and lattice geometry, the guidance vector signal is converted into an optimal weight vector signal, which, together with the matrix digital signal, is converted into a direct digital signal that is stored, generated and stored time-shift-dependent complex cross-correlation functions (CCFs) between the digital signal of an individual antenna and the direct digital signal determine the max the absolute value of the module of each complex VKF and fix the values of the complex VKF corresponding to these maxima, calculate the difference digital signals, form complex two-dimensional cross-correlation functions (DKKF) depending on the time and frequency shifts between each difference digital signal and the direct digital signal, average the modules of the complex DVKF, average determine the maximum of the number of compressed signals from the maxima of the averaged DKFF and fix the values of the time delay and absolute Doppler shift of each p-th compressed of the signal, identify the components of the complex DVKF corresponding to the individual maximum of the averaged DKFF as the pth signal compressed in time and frequency, extract and store the values of the components of the complex DKFF, the time delay and the absolute Doppler shift of each pth compressed signal, according to the selected values of p of the identified components of complex DCFs synthesize a complex two-dimensional angular spectrum, the maximum modulus of which determines the azimuth-elevation direction of arrival of the p-th compressed signal , based on the values of delay and absolute Doppler shift and azimuthal elevation direction of arrival, spatial coordinates of moving objects are detected and determined.

This method includes 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.

More effective is the method of remote detection and tracking of radio-silent objects [2], free from this drawback and selected as a prototype. According to this method:

selecting a transmitter emitting a spread spectrum radio signal;

at the same time, with the array of N antennas, multibeam radio signals are received, including the direct radio signal of the transmitter and the radio signals of this transmitter scattered by the objects;

из которого формируют цифровой прямой сигнал s',synchronously, the radio signals received by the antennas are converted into digital signals s _n , where n is the number of the antenna that is stored and combined into a digital matrix signal

from which form a digital direct signal s',

convert the direct signal s' into a multi-frequency matrix signal of the complex phasing function A, including hypothetical signals scattered by potential objects in the expected areas of Doppler frequencies and delays, store the matrix signal A;

где

- матрица, эрмитово сопряженная с А;convert the signal of an individual antenna s _n into a signal of a complex time-frequency image

Where

- a matrix Hermitian conjugate to A;

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

- z-й элемент вектора

k=1, 2, … - номер итерации, и сигнал очередного приближения комплексного частотно-временного изображения

где λ - множитель Лагранжа, до тех пор, пока номер текущей итерации не превысит заданный порог K;signal

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

is the zth element of the vector

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

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

then the modules of the current time-frequency images of individual antennas are averaged

z=1, ……, Z, где Z - число элементов изображения, определяют число рассеянных радиосигналов и фиксируют значения временной задержки и доплеровского сдвига каждого р-го рассеянного радиосигнала;by local maxima of the averaged time-frequency image

z = 1, ........ Z, where Z is the number of image elements, the number of scattered radio signals is determined and the values of the time delay and Doppler shift of each p-th scattered radio signal are fixed;

элементы

комплексных частотно-временных изображений

как составляющие р-го рассеянного радиосигнала;identify the corresponding individual maximum averaged image

the elements

integrated time-frequency images

as components of the p-th scattered radio signal;

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.identify and remember the values of the identified components

using which a complex angular spectrum is synthesized, the maximum modulus of which determines the azimuthal elevation direction of arrival of the pth scattered signal, and the spatial coordinates of moving objects are detected and determined by the values of time delay, Doppler shift and azimuthal elevation direction of arrival.

The prototype method provides for the detection and spatial localization of radio-silent objects with high resolution and increased dynamic range.

However, in the prototype method, incoherent summation of two-dimensional time-frequency image signals coherently formed from the signals of individual antenna arrays is used at the detection stage. In other words, the prototype method does not use spatial selectivity at the detection stage, which is typical for the case of coherent summation of the signals of all antennas in antenna arrays, which leads to the following disadvantages of the prototype method:

- loss of sensitivity by 3 dB when detecting, measuring spatial coordinates and tracking objects in conditions of uncorrelated noise and interference;

- an additional reduction in sensitivity in the presence of sources of correlated interference located in the surrounding space (for example, transmitter signals whose radio frequency coincides with the frequency of reception of signals scattered by objects).

In addition, the prototype method has no compensation operation for the direct backlight signal and signals scattered by stationary objects. As a result, the direct signal and the signals scattered by stationary objects mask the echo signals of small-sized low-speed objects, which further limits the sensitivity and, as a result, the range when they are detected and tracked.

Thus, the disadvantage of the prototype method is the limited sensitivity in the detection and tracking of radio-silent objects.

The technical result of the invention is to increase the sensitivity in the detection and tracking of radio-silent objects.

Increased sensitivity is achieved through the use of new operations:

- compensation of interference masking the echo signals of objects;

- coherent formation at each expected frequency of the Doppler shift of the elements of a three-dimensional spatial-frequency-time image from the signals of all the antennas of the array instead of forming from the signals of the individual antennas a combination of two-dimensional frequency-time images and their subsequent incoherent summation.

из которого формируют цифровой прямой сигнал s', согласно изобретению, преобразуют прямой сигнал s' в одночастотные матричные сигналы комплексной фазирующей функции А_ω, каждый из которых включает гипотетические сигналы, рассеиваемые потенциальными подвижными и стационарными объектами в ожидаемых областях задержек и угловых направлений на каждой ожидаемой частоте доплеровского сдвига ω, матричные сигналы А_ω запоминают, объединяют запомненные цифровые сигналы антенн s_n в векторный сигнал

векторный сигнал s запоминают и преобразуют всигнал элемента комплексного пространственно-частотно-временного изображения для нулевого значения ω=0 доплеровского сдвига частоты

где

-матрица, эрмитово сопряженная с А₀, с использованием сигнала

в качестве начального приближения итерационно формируют и запоминают зависящий от предыдущего решения вспомогательный матричный сигнал

где

- z-я компонента вектора элемента изображения

k=1, 2, … - номер итерации, а также сигнал очередного приближения элемента комплексного пространственно-частотно-временного зображения

где λ - множитель Лагранжа, и очищенный от прямого и рассеянных стационарными объектами сигналов векторный сигнал

до тех пор, пока номер текущей итерации не превысит заданный порог K, после этого из очищенного векторного сигнала

для каждого ожидаемого ненулевого значения доплеровского сдвига частоты ω формируют сигнал начального приближения

а затем итерационно получают и запоминают вспомогательный матричный сигнал

и сигнал очередного приближения

элемента комплексного пространственно-частотно-временного изображения до тех пор, пока номер текущей итерации не превысит заданный порог K, объединяют сформированные сигналы элементов изображения

в матричный сигнал результирующего комплексного пространственно-частотно-временного изображения Н, после чего по локальным максимумам квадрата модуля матричного сигнала результирующего изображения

где

компонента матричного сигнала Н, определяют число рассеянных радиосигналов, по параметрам которых - значениям доплеровского сдвига частоты со, временной задержки q и азимутально-угломестного направления приема

каждого рассеянного радиосигнала выполняют обнаружение, пространственную локализацию и сопровождение объектов. Операции способа поясняются чертежом.The technical result is achieved by the fact that in the method of remote detection and tracking of radio-silent objects, which consists in selecting a transmitter emitting a spread spectrum radio signal, synchronously receive an array of N antennas with multi-beam radio signals including a direct radio signal of the transmitter and the radio signals of this transmitter scattered by objects, synchronously convert the radio signals received by the antennas into digital signals s _n , where n is the number of the antenna that is stored and combined into a digital matrix signal

from which the digital direct signal s 'is formed, according to the invention, the direct signal s' is converted into single-frequency matrix signals of the complex phasing function A _ω , each of which includes hypothetical signals scattered by potential moving and stationary objects in the expected areas of delays and angular directions at each expected the frequency of the Doppler shift ω, the matrix signals A _{ω are} stored, the stored digital signals of the antennas s _n are combined into a vector signal

the vector signal s is stored and converted into the signal of an element of a complex spatial-frequency-time-image for a zero value of ω = 0 Doppler frequency shift

Where

matrix, Hermitian conjugate to A ₀ , using a signal

as an initial approximation, an auxiliary matrix signal depending on the previous solution is iteratively generated and stored

Where

- z-th component of the image element vector

k = 1, 2, ... is the iteration number, as well as the signal of the next approximation of the element of the complex spatial-frequency-temporal image

where λ is the Lagrange multiplier, and the vector signal purified from the direct and scattered by stationary objects signals

until the number of the current iteration exceeds the specified threshold K, then from the cleared vector signal

for each expected non-zero value of the Doppler frequency shift ω form an initial approximation signal

and then iteratively receive and store the auxiliary matrix signal

and the signal of the next approach

element of a complex spatial-frequency-temporal image until the current iteration number exceeds a predetermined threshold K, the generated image element signals are combined

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

Where

component of the matrix signal H, determine the number of scattered radio signals, the parameters of which are the values of the Doppler frequency shift ω, time delay q and azimuth-elevation direction of reception

each scattered radio signal performs the detection, spatial localization and tracking of 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 preprocessing 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 pre-processing system 1 includes an antenna array 1-1, a path for searching for illumination sources, including a frequency converter 1-2, an analog-to-digital converter (ADC) 1-3 and a detection device 1-4, as well as a direct path and scattered signals, including a frequency converter 1-5, ADC 1-6 and adaptive spatial filtering 1-7. 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), иметь антенные элементы с отличающимися векторными диаграммами направленности. Преобразователи частоты 1-2 и 1-5 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 являются N-канальными и синхронизированы 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, то вместо преобразователей частоты 1-2 и 1-5 могут использоваться частотно избирательные полосовые фильтры и усилители. Кроме этого, преобразователи частоты 1-2 и 1-5 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 1-7 представляют собой вычислительные устройства. Подсистема 2 является вычислительным устройством и предназначена для идентификации, отбора и периодического обновления рабочего списка 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 числа итераций с заданным порогом (блок 3-2) и синтеза пространственно-частотно-временного изображения (блок 3-1).Antenna array 1-1 consists of N antennas with numbers

The spatial configuration of the antenna array should provide the measurement of the azimuthal elevation direction of arrival of 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), have antenna elements with different vector radiation patterns. Frequency converters 1-2 and 1-5 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, then frequency selective bandpass filters and amplifiers can be used instead of frequency converters 1-2 and 1-5. In addition, frequency converters 1-2 and 1-5 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 channel calibration. The detection device 1-4 and the adaptive spatial filtering device 1-7 are computing devices. Subsystem 2 is a computing device and is intended for identification, selection, and periodic updating of the work list of spread spectrum radio transmitters used to highlight 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 the number of iterations with a given threshold (block 3-2), and synthesizing a spatio-frequency-temporal image (block 3-1).

The device operates as follows.

In system 2, based on data from the external base of the radio transmitters, as well as data on detected backlight transmitters from the device 1-4, using the modeling software, a working list 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 moving objects of various classes, which can be provided with different types of placement of transmitters relative to a detection-direction finding station, are estimated. 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, spectral width, its shape, synchronization parameters and emitted signal power, 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 the converters 1 -2 and 1-5. For simplicity, converter control circuits 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 radio signals with an extended spectrum on a discrete search frequency grid. The time-dependent radio signal 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 generated in the 1-2 converter are converted using ADC 1-3 into digital signals, which are fed to the detection device 1-4, in which, at each frequency of the discrete search frequency grid, the synchronization parameters of the backlight transmitters are detected and measured. 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 1-5 is tuned to a given reception frequency. The receiving path synchronously receives multipath radio signals at a given frequency, 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 with antenna array number 1-1 is filtered by frequency and transferred to a lower frequency in converter 1-5.

где

- номер временного отсчета сигнала, {}^T - означает транспонирование.The radio signals s _n (t) generated in the converter 1-5 are synchronously converted by digital converters 1-6 into digital signals

Where

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

The digital signals of the individual antennas s _n are supplied to the device 1-7 and to the unit 3-1, where they are stored.

In addition, in the device 1-7, the following actions are performed:

размером N×I;- the digital signals of the individual antennas s _n are combined into a matrix digital signal

size N × I;

- 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 the N × 1 signal of the optimal weight vector w = R ^_1 v, where VN × 1 is the guidance vector determined by the azimuthal elevation direction, the wavelength (frequency) of the direct radio signal and the geometry of the lattice;

- the matrix digital signal S is converted to a direct digital signal s' ^T = 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.

Formed in the device 1-7 direct digital signal s' is received and stored in block 3-4.

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

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

Where

учитывают фазовый сдвиг, вызванный различным пространственным расположением антенн решетки (определяемым их радиус-векторами r_n), ожидаемым направлением прихода сигнала

а также отличием диаграмм направленности антенн и их ориентацией. Для ненаправленных антенн справедливо следующее:

где

- волновой вектор, зависящий от частоты приема и направления прихода сигнала;- the matrix of the phasing function in the angular direction of size N × L. Multipliers

take into account the phase shift caused by the different spatial arrangement of the array antennas (determined by their radius vectors r _n ), the expected direction of arrival of the signal

as well as the difference in antenna patterns and their orientation. For omnidirectional antennas, the following applies:

Where

- wave vector, depending on the frequency of reception and direction of arrival of the signal;

обозначает прямое произведение матриц,

- векторы размером I×1, являющиеся задержанными по времени на qT_s версиями прямого сигнала s'; q=0, …, Q-1, Q - число временных задержек прямого сигнала; T_s - период выборки сигнала;symbol

denotes the direct product of matrices,

- vectors of size I × 1, which are time delayed by qT _s versions of the direct signal s'; q = 0, ..., Q-1, Q is the number of time delays of the direct signal; T _s - signal sampling period;

- Doppler shift matrices of size I × I, ω = 0, ± 1, ..., ± Ω, (2Ω + 1) - coordinate grid size by Doppler shift. The values of the Doppler frequency shift run through a discrete series of values of ω / (IT _s ).

Thus, the columns of the matrix A _ω are time-delayed, frequency-shifted Doppler shift and phased in the direction of the version of the direct signal s', and the size of this matrix IN × QL is determined by the number of samples I in the reconstructed signal (duration of the observation interval), the number of antennas N, the size of the coordinate grid for the time lag Q and the direction of arrival L.

и

для нулевого значения ω=0 доплеровского сдвига частоты, а также сигналы

для всех ненулевых значений ω=±1, …, ±Ω доплеровского сдвига частоты, которые поступают в блок 3-1, где также запоминаются.In addition, in the device 3-3 of the signal And _ω sequentially calculated signals

and

for zero value ω = 0 the Doppler frequency shift, as well as the signals

for all nonzero values ω = ± 1, ..., ± Ω of the Doppler frequency shift, which enter block 3-1, where they are also stored.

Векторный сигнал s запоминается, а также с использованием сигналов

поступивших от блока 3-3, преобразуется в сигнал элемента комплексного пространственно-частотно-временного изображения для нулевого значения ω=0 доплеровского сдвига частоты

(вектор с размером QL×1).In block 3-1, the stored digital antenna signals s _n are combined into a vector signal

The vector signal s is stored as well as using signals

received from block 3-3, is converted into a signal of an element of a complex spatial-frequency-time-image for a zero value of ω = 0 Doppler frequency shift

(vector with size QL × 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

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 зависящий от предыдущего решения вспомогательный матричный сигнал

где

- z-я компонента вектора элемента изображения

и взвешивающий сигнал

Значение множителя Лагранжа λ выбирают исходя из уровня шумов в каналах приема. Взвешивающий сигнал

поступает в блок 3-1.In the device 3-3 using the signal of the image element obtained in the previous iteration, that is

at k = 1, an auxiliary matrix signal depending on the previous solution is formed

Where

- z-th component of the image element vector

and weighting signal

The value of the Lagrange multiplier λ is selected based on the noise level in the reception channels. Weighting signal

enters block 3-1.

и запомненного векторного сигнала s синтезируется сигнал очередного приближения элемента комплексного пространственно-частотно-временного изображения для нулевого значения ω=0 доплеровского сдвига частоты

и очищенный от прямого и рассеянных стационарными объектами сигналов векторный сигнал

In block 3-1 using a signal

and the stored vector signal s, the next approximation signal of the complex spatial-frequency-time-image element is synthesized for a zero value ω = 0 of the Doppler frequency shift

and the vector signal purified from direct and scattered by stationary objects signals

запоминается в блоке 3-1. Сигнал

поступает в блок 3-2, где также запоминается для использования на следующей итерации. Кроме того сигнал

поступает в устройство 3-3 для запоминания и инициализации очередной итерации синтеза элемента пространственно-частотно-временного изображения для нулевого значения со = 0 доплеровского сдвига частоты и очищенного сигнала.Signal

memorized in block 3-1. Signal

enters block 3-2, where it is also remembered for use in the next iteration. In addition, the signal

enters the device 3-3 for storing and initializing the next iteration of the synthesis of the element of the space-time-frequency image for the zero value co = 0 of the Doppler frequency shift and the cleaned signal.

запоминанию сигналов

а также сравнению номера текущей итерации с заданным порогом K.Then, in the device 3-3, blocks 3-1 and 3-2, the previously described sequence of operations for generating signals is performed

signal storage

as well as comparing the current iteration number with a given threshold K.

для каждого ожидаемого ненулевого значения доплеровского сдвига частоты ω формируется сигнал начального приближения

а затем итерационно получаются и запоминаются вспомогательный матричный сигнал

где

- z-я компонента вектора элемента изображения

и сигнал очередного приближения

элемента очищенного комплексного частотно-временного изображения до тех пор, пока номер текущей итерации не превысит заданный порог K.When the number of the current iteration exceeds the threshold K in the device 3-3, blocks 3-1 and 3-2 of the stored signals

for each expected nonzero value of the Doppler frequency shift ω, an initial approximation signal is generated

and then the auxiliary matrix signal is iteratively obtained and stored

Where

- z-th component of the image element vector

and the signal of the next approach

element of the cleared complex time-frequency image until the current iteration number exceeds a predetermined threshold K.

объединяются в матричный сигнал результирующего комплексного пространственно-частотно-временного изображения Н.When the number of the current iteration exceeds the specified threshold K in block 3-1, the generated signals of the elements of the cleared image

are combined into a matrix signal of the resulting complex spatial-frequency-temporal image N.

Note that the signal of the resulting complex spatial-frequency-time-image H can be three-dimensional when synthesizing an image in the coordinates "azimuth-Doppler frequency shift-delay" or four-dimensional when synthesizing an image in the coordinates "azimuth-elevation-elevation-Doppler frequency-delay".

в матричный сигнал Н осуществляется путем присоединения элементов очищенного изображения

друг к другу в порядке убывания или возрастания трех или четырех координат.Combining the signals of the elements of the cleared image

in the matrix signal H is carried out by attaching the elements of the cleaned image

to each other in descending or ascending order of three or four coordinates.

рассеянного радиосигнала матричный сигнал части результирующего комплексного пространственно-частотно-временного изображения

формируется в соответствии со следующей формулой:For example, with a fixed azimuthal elevation direction

scattered radio signal, a matrix signal of a part of the resulting complex spatial-frequency-time image

formed in accordance with the following formula:

The matrix signal of the resulting complex spatial-frequency-time-image H is supplied to block 4.

матричного сигнала результирующего комплексного частотно-временного изображения Н. По локальным максимумам квадратов модулей

определяется число рассеянных радиосигналов, по параметрам которых - значениям доплеровского сдвига частоты со, временной задержки q и азимутально-угломестного направления приема

каждого рассеянного радиосигнала выполняют обнаружение, пространственную локализацию и сопровождение объектов.In block 4, the squares of the modules are calculated

matrix signal of the resulting complex time-frequency image N. By the local maximums of the squares of the modules

the number of scattered radio signals is determined, the parameters of which are the values of the Doppler frequency shift ω, time delay q and azimuth-elevation direction of reception

each scattered radio signal performs the detection, spatial localization and tracking of objects.

Detection, spatial localization and tracking of objects is carried out by known methods, for example, [3].

In addition, to increase the information content in block 4, the results of detection, spatial localization and tracking of objects are displayed.

From the above description, it follows that the device that implements the proposed method, when forming spatio-frequency-time images of the echo signals of objects, compensates for masking interference and multidimensional processing of signals of all the antennas of the array, which in terms of spatial signal processing is equivalent to coherent formation of the total spatial antenna pattern lattice.

This, in comparison with the incoherent signal processing of individual array antennas implemented in the prototype method, increases the sensitivity by at least 3 dB in conditions of uncorrelated noise and interference and improves noise immunity and noise immunity in the presence of sources of correlated interference located in the surrounding space. As a result, the detection range and tracking accuracy of a wide class of manned and unmanned small-sized low-speed radio-silent objects are increased.

Thus, due to the application of new operations of coherent formation at each expected frequency of the Doppler shift of elements of a three-dimensional (four-dimensional) spatio-frequency-temporal image of echo signals of objects from signals of all antenna arrays cleared of masking interference, instead of the operations of generating a set of two-dimensional frequency-time images of the signals of individual antennas and their subsequent incoherent summation, it is possible to solve the problem with the achievement of the specified technical re result.

Sources of information:

1. RU, patent, 2444754, IPC G01S 13/02, 2012

2. RU, patent, 2524401, IPC G01S 13/02, 2014

3. Reference radar. Ed. M. Skolnik. New York, 1970. Transl. from English (in four volumes) under the general ed. K.N. Trofimova. Volume 4

Radar stations and systems. Ed. M.M. Weisbane, M., Sov.radio. 1978. 376 p.

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

Claims (1)

A method for remote detection and tracking of radio-silent objects, which consists in selecting a transmitter emitting a spread spectrum radio signal, synchronously receiving a multi-beam radio signal from the N antenna, including a direct radio signal of the transmitter and scattered objects from this transmitter, synchronously converts the received radio signals into digital signals s _n , where n is the number of antennas that are stored and combined into a digital matrix signal S = {s ₁ , ..., s _n , ..., s _N } ^T , from which the digital a direct direct signal s ', characterized in that they convert a direct signal s' into single-frequency matrix signals of the complex phasing function A _ω , each of which includes hypothetical signals scattered by potential moving and stationary objects in the expected areas of delays and angular directions at each expected Doppler frequency shift ω, the matrix signals A _{ω are} stored, the stored digital signals of the antennas s _n are combined into a vector signal

, the vector signal s is stored and converted into a signal of an element of a complex spatial-frequency-time-image for a zero value of ω = 0 Doppler frequency shift

where

- a Hermitian conjugate matrix with A ₀ using a signal

as an initial approximation, an auxiliary matrix signal depending on the previous solution is iteratively generated and stored

where

- z-th component of the image element vector

, k = 1, 2, ... is the iteration number, as well as the signal of the next approximation of the element of the complex spatial-frequency-temporal image

, where λ is the Lagrange multiplier, and the vector signal purified from the direct and scattered by stationary objects signals

until the number of the current iteration exceeds the specified threshold K, then from the cleared vector signal

for each expected non-zero value of the Doppler frequency shift ω form an initial approximation signal

, and then iteratively receive and store the auxiliary matrix signal

and the signal of the next approach

element of a complex spatio-frequency-temporal image until the current iteration number exceeds a predetermined threshold K, the generated image element signals are combined

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

where

-

component of the matrix signal H, determine the number of scattered radio signals, the parameters of which are the values of the Doppler frequency shift ω, time delay q and azimuth-elevation direction of reception

each scattered radio signal - perform detection, spatial localization and tracking of objects.

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