RU2410707C2 - Method of polarisation-independent detection and localisation of wideband radio signals - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: invention relates to measurement equipment and may be used in radio equipment for detection and frequency-space localisation of radio radiation sources under conditions of a priori uncertainty. Technical result is achieved due to additional information extracted by usage of polarisation parameters of signals as additional criterion of identification of localised signals field components, application of operations of forming double-component complex AFR, including vertical and horizontal polarised components of received signals field, and also application of operations of estimating polarisation-angular proximity of identified components of localised signals field.

EFFECT: improved efficiency of detection and frequency-space localisation of wideband signals of sources of radio radiation under conditions of a priori uncertainty relative to type of polarisation, angles of arrival, width of spectrum and position of spectrum on axis of frequencies of received signals.

2 cl, 1 dwg

Description

The invention relates to measuring equipment and can be used in radio engineering for the detection and frequency-spatial localization of radio emission sources under conditions of a priori uncertainty.

Achieving the theoretically maximum efficiency of detection and localization of signals from radio emission sources is limited by significant a priori uncertainty regarding the parameters of controlled radio signals and the imperfection of their processing methods.

The use of methods of polarization-independent detection and localization of signals is one of the main ways to increase the efficiency of a wide class of measurement systems under conditions of a priori uncertainty.

A known method of polarization-independent detection and localization of broadband signals [1], which consists in the fact that:

receive radio signals of unknown polarization by an antenna array consisting of magnetic antennas with combined phase centers,

form an ensemble of radio signals depending on the time and antenna number,

synchronously transform the ensemble of received radio signals into digital signals,

convert digital signals of pairs of opposite antennas into complex quadrature components of the dipole and quadrupole output signals,

receive information about the direction of arrival of the radio signals according to the phase difference of the signals of the quadrature components of the dipole and quadrupole output signals.

This method provides increased stability of the spatial localization of signals to polarization errors. However, this method under conditions close to maximum a priori uncertainty, that is, when the polarization parameters are a priori unknown, the direction of arrival and the position of the spectrum of the localized signal in the analyzed time-frequency domain loses its effectiveness.

More effective is the method of polarization-independent detection and localization of broadband signals [2], free from this drawback and selected as a prototype. According to this method:

receive radio signals N vertically polarized antennas in a given frequency band,

synchronously transform the ensemble of received signals into digital signals,

частоте полосы приема формируют сигнал вертикально поляризованной компоненты

комплексного амплитудно-фазового распределения (АФР),of digital signals on each

the frequency of the receiving band generates a signal of vertically polarized components

complex amplitude-phase distribution (AFR),

на частоте

с вертикально поляризованной компонентой комплексного АФР

на всех остальных частотах

полосы приема,form the squares of the modules of the mutual correlation coefficients of the vertically polarized components of complex AFR

on frequency

with vertically polarized complex AFR component

at all other frequencies

reception bands

с порогом,comparing the squares of the modules of the cross-correlation coefficients

with a threshold

radio signals with frequencies at which the threshold is exceeded are combined into a signal that

identify as the i-th detected radio signal belonging to one transmitter,

fix the frequency band localization of the i-th radio signal,

в найденной полосе частот локализации, формируют сигнал вертикально поляризованной компоненты комплексного АФР⁽ⁱ⁾ i-го радиосигнала,averaging the signals of vertically polarized components of complex AFR

in the found localization frequency band, the signal of the vertically polarized component of the complex AFR ^{(i) of the} i-th radio signal is formed,

the obtained AFR ⁽ⁱ⁾ form a two-dimensional complex angular spectrum, which determine the azimuth and elevation of the transmitter of the i-th detected radio signal.

The prototype method effectively solves the problem of detection and frequency-spatial localization of broadband signals of known polarization. However, according to signals of unknown polarization, that is, in those cases where the polarization characteristics of the receiving array antennas are not consistent with the polarization of the incident waves or the array antennas are located near reflectors that can change the polarization, this method loses its effectiveness.

The technical result of the invention is to increase the detection efficiency and the spatial frequency localization of broadband signals of radio sources under conditions of a priori uncertainty regarding the type of polarization, arrival angles, spectral width and spectrum position on the frequency axis of the received signals.

Improving the efficiency of detection and localization of signals is achieved due to additional information extracted by:

- the use of polarization parameters of the signals as an additional sign of identification of the components of the field of localized signals;

- the application of the operations of forming a two-component complex AFR, including vertically and horizontally polarized field components of the received signals, instead of forming a one-component vertically polarized AFR;

- application of operations for assessing the polarization-angular proximity of identifiable field components of localized signals instead of operations for evaluating their angular proximity.

частоте полосы приема формируют сигнал вертикально поляризованной компоненты

комплексного амплитудно-фазового распределения (АФР), согласно изобретению дополнительно принимают радиосигналы N горизонтально поляризованными антеннами, синхронно преобразуют ансамбль принятых сигналов в цифровые сигналы, из которых на каждой

частоте полосы приема формируют сигнал горизонтально поляризованной компоненты

комплексного АФР, объединяют сигналы вертикально поляризованной

и горизонтально поляризованной

компонент в сигнал двухкомпонентного комплексного АФР

по сигналам двухкомпонентного комплексного АФР

выполняют обнаружение и частотно-пространственную локализацию радиосигналов.The technical result is achieved by the fact that in the method of polarization-independent detection and localization of broadband signals, which consists in receiving radio signals N by vertically polarized antennas in a given frequency band, synchronously convert the ensemble of received signals into digital signals from digital signals on each

the frequency of the receiving band generates a signal of vertically polarized components

complex amplitude-phase distribution (AFR), according to the invention, additionally receive radio signals N horizontally polarized antennas, synchronously convert the ensemble of received signals into digital signals, of which each

the frequency of the receiving band generates a signal of horizontally polarized components

integrated AFR, combine vertically polarized signals

and horizontally polarized

component into the signal of a two-component complex AFR

by signals of a two-component complex AFR

perform detection and frequency-spatial localization of radio signals.

Particular cases of the method are possible:

на частоте

с сигналом двухкомпонентного АФР

на всех остальных частотах

полосы приема, сравнивают квадраты модулей коэффициентов взаимной корреляции

с порогом, радиосигналы с частотами, на которых превышен порог, объединяют в сигнал, который идентифицируют как i-й обнаруженный радиосигнал, принадлежащий одному передатчику, и фиксируют полосу частот его локализации.1. The detection and frequency localization of radio signals is carried out by forming the squares of the modules of the complex coefficients of cross-correlation of the signal of a two-component complex AFR

on frequency

with two-way AFR signal

at all other frequencies

reception bands, compare the squares of the modules of the cross-correlation coefficients

with a threshold, radio signals with frequencies at which the threshold is exceeded are combined into a signal that is identified as the i-th detected radio signal belonging to one transmitter and the frequency band of its localization is fixed.

This increases the efficiency of detection and frequency localization of broadband signals under conditions of a priori uncertainty regarding the type of polarization and angles of arrival of the received signals.

2. The spatial localization of radio signals is carried out by generating a signal of a two-component complex AFR ^{(i) of the} i-th detected radio signal, converting the signal of two-component AFR ⁽ⁱ⁾ into a two-dimensional complex angular spectrum and determining the azimuth and elevation of the transmitter of the i-th detected radio signal from the angular spectrum.

This increases the efficiency of spatial localization of signals of unknown polarization.

в полосе частот его локализации.3. The formation of the signal of a two-component complex AFR ^{(i) of the} i-th detected radio signal is carried out by averaging the signals of two-component complex AFR

in the frequency band of its localization.

This brings the sensitivity of spatial localization of signals with an unknown spectrum width and spectrum position on the frequency axis to potentially achievable.

The proposed method, in contrast to the prototype method, more fully uses the information contained in the received signals, which increases the efficiency of detection and localization of a priori unknown broadband signals.

Thus, due to the use of spatial and polarization parameters of signals as signs of identifying the field components of localized signals, in contrast to the prototype method using only spatial parameters of signals, the use of operations to form a two-component complex AFR that includes vertically and horizontally polarized field components of the received signals, instead of the formation of a single-component vertically polarized AFR, as well as the application of operations to assess the polar isation-angular proximity of the identifiable components of the field of localized signals, instead of evaluating their angular proximity, it is possible to solve the problem with the achievement of the specified technical result.

The operation of the method is illustrated in the drawing, which shows a structural diagram of a device that implements the proposed method of polarization-independent detection and localization of broadband signals.

Consider the operation of a device that implements the method.

A device that implements the proposed method comprises a series-connected antenna system 1, a multi-channel frequency converter 2, a multi-channel analog-to-digital converter (ADC) 3, a computer 4, a correlation and frequency localization device 5 and a spatial localization device 6. The output of the device 6 is used for connections to external systems. In turn, the calculator 4 contains parallel to the output of the ADC 3 fast Fourier transform processors (FFT) 7 (1) ... 7 (2N), the outputs of which through the shapers of the AFR components 8 (1) and 8 (2) are connected to the inputs of the device 5.

Antenna system 1 contains N antennas, each of which consists of vertically polarized antenna elements with numbers n = 1 (v), ... N (v) and horizontally polarized antenna elements with numbers n = 1 (h), ... N (h). All antenna elements have independent outputs. As antenna elements, for example, vibrator or loop antennas can be used. The multi-channel frequency converter 2 includes 2N channels and is made with a common local oscillator and with a channel bandwidth of each channel many times greater than the spectrum width of a single transmitter signal. A common local oscillator provides multi-channel coherent signal reception, which is the main condition for coherent signal registration. A wide bandwidth of the channels of the converter 2 is necessary for the simultaneous registration of the signals of several transmitters. Multichannel ADC 3 also contains 2N channels. If the resolution and speed of the ADC 3 are sufficient for direct analog-to-digital conversion of the input signals, as, for example, in the KB range of radio waves, then instead of converter 2, a set of 2N frequency-selective bandpass filters and amplifiers can be used. The calculator 4 provides parallel processing of the signals received by each of the 2N antenna elements of the antenna system 1, and the formation of vertically polarized and horizontally polarized components of complex AFR at discrete frequencies in the reception band.

The device operates as follows.

Multi-frequency time signals x _vn (t) from outputs of antenna elements with numbers n = 1 (ν), ... N (ν) and signals x _hn (t) from outputs of antenna elements with numbers n = 1 (h), ... N (h ) of the antenna system 1 are fed to the inputs of the converter 2, where they are coherently transferred to a lower frequency in the reception band many times the spectrum width of a single radio signal from the transmitter.

Using ADC 3, the signals x _vn (t) and x _hn (t) are synchronously converted to digital signals x _vn (z) and x _hn (z), where z is the number of the time reference of the signal, and fed to the input of calculator 4.

частоте полосы приема формируются сигналы вертикально поляризованной компоненты

и горизонтально поляризованной компоненты

комплексного АФР, где L - число дискретных частот в полосе приема.In the calculator 4 of the digital signals on each

the frequency of the reception band are formed signals vertically polarized components

and horizontally polarized components

complex AFR, where L is the number of discrete frequencies in the reception band.

и горизонтально поляризованной

компонент комплексного АФР могут быть сформированы различными способами [3].Note that the signals are vertically polarized

and horizontally polarized

component of complex AFR can be formed in various ways [3].

и

где F_t{…} - оператор дискретного Фурье-преобразования по времени,

- номер дискреты по частоте,

Consider the method according to which in the FFT processors 7 (1) ... 7 (2N) of calculator 4, signals of complex spectral densities are formed from digital signals x _vn (z) and x _hn (z)

and

where F _t {...} is the discrete Fourier transform operator in time,

- number of discrete frequency

поступают в формирователь 8(1), а сигналы

- в формирователь 8(2).Signals of complex spectral densities

come in shaper 8 (1), and the signals

- into the shaper 8 (2).

где ()* - означает комплексное сопряжение. Из сигнала пространственной корреляционной матрицы

формируются сигнал максимального собственного значения и соответствующий сигнал собственного вектора, который используется в качестве сигнала вертикально поляризованной

компоненты комплексного АФР. Формирование сигналов максимального собственного значения и максимального собственного вектора осуществляется известными способами [4, стр.170].In the shaper 8 (1) of spectral densities by multiplication and averaging of complex conjugate spectral densities, an N × N spatial correlation matrix is formed in the form

where () * - means complex conjugation. From a spatial correlation matrix signal

the maximum eigenvalue signal and the corresponding eigenvector signal are generated, which is used as a signal of vertically polarized

components of complex AFR. The formation of signals of maximum eigenvalue and maximum eigenvector is carried out by known methods [4, p. 170].

аналогичным способом формируются сигналы горизонтально поляризованных

компонент комплексного АФР.At the same time in the shaper 8 (2) of spectral densities

in a similar way, horizontally polarized signals are formed

component of complex AFR.

и горизонтально поляризованной

компонент комплексного АФР поступают в устройство 5.Signals Vertically Polarized

and horizontally polarized

component of complex AFR enter device 5.

The device 5 performs the following actions:

и горизонтально поляризованной

компонент в сигнал двухкомпонентного комплексного АФР

.- signals of vertically polarized are combined

and horizontally polarized

component into the signal of a two-component complex AFR

.

частоте представляет собой 2N×1 матричный сигнал

с элементами в виде вектор-столбцов

и

;Note that the signal of a two-component complex AFR on

frequency is a 2N × 1 matrix signal

with elements in the form of vector columns

and

;

выполняют обнаружение и частотно-пространственную локализацию радиосигналов.- based on signals from a two-component complex AFR

perform detection and frequency-spatial localization of radio signals.

Moreover, to increase the detection efficiency and frequency-spatial localization of broadband radio signals under conditions of a priori uncertainty in the device 5, the following actions are performed:

на частоте

с сигналом двухкомпонентного АФР

на всех остальных частотах

полосы приема,

по формуле

где ()⁺ обозначает эрмитово сопряжение, которая в развернутой форме имеет следующий вид:- squares of the modules of the complex coefficients of cross-correlation of the signal of the two-component complex AFR are formed

on frequency

with two-way AFR signal

at all other frequencies

reception bands

according to the formula

where () ⁺ denotes Hermitian conjugation, which in expanded form has the following form:

которая предусматривает формирование квадратов модулей коэффициентов взаимной корреляции только сигналов вертикально поляризованных компонент

и

идентифицируемых составляющих поля локализуемых сигналов.Note that this formula is more general than the formula used in the prototype method

which provides for the formation of squared modules of cross-correlation coefficients of only signals of vertically polarized components

and

identifiable field components of localized signals.

Thus, this operation, being one of the main when achieving a technical result, provides polarization independence for the identification of the field components of localized broadband radio signals and, as a result, increases the efficiency of their detection and localization.

, принятых решеткой антенн на разных частотах полосы приема. Это означает, что сигналы частотных составляющих полосы приема, имеющие одинаковые двухкомпонентные АФР или, что эквивалентно, имеющие одинаковые поляризации и углы прихода, будут идентифицированы как радиосигнал, принадлежащий одному передатчику;Physically, at this stage, the magnitude of the complex cross-correlation of the signals of two-component complex AFRs is checked

received by the antenna array at different frequencies of the reception band. This means that the signals of the frequency components of the reception band having the same two-component AFR or, equivalently, having the same polarization and angles of arrival, will be identified as a radio signal belonging to one transmitter;

с порогом.- compares the squares of the modules of the cross-correlation coefficients

with a threshold.

The threshold is selected based on the condition of minimizing the probability of false alarm;

- radio signals with frequencies at which the threshold is exceeded are combined into a signal that is identified as the i-th detected radio signal belonging to one transmitter;

- the localization band of the i-th radio signal is fixed.

и полоса частот локализации в виде двоичных чисел

отличных от нуля в полосе частот локализации i-го радиосигнала, поступают в устройство 6.Obtained in the device 5 two-component complex AFR

and localization frequency band in the form of binary numbers

non-zero in the frequency band localization of the i-th radio signal, enter the device 6.

The device 6 performs the following actions:

в найденной полосе частот локализации формируется сигнал двухкомпонентного комплексного АФР⁽ⁱ⁾ i-го радиосигнала

где

- двоичные числа (0,1), отличные от нуля в полосе частот локализации i-го радиосигнала,

- индекс, соответствующий средней частоте спектра i-го радиосигнала;- averaging of two-component complex AFR

in the found localization frequency band, a signal of a two-component complex AFR ^{(i) of the} i-th radio signal is formed

Where

- binary numbers (0,1), nonzero in the localization frequency band of the i-th radio signal,

- index corresponding to the average frequency of the spectrum of the i-th radio signal;

формируется двумерный комплексный угловой спектр, по которому определяется азимут и угол места передатчика i-го обнаруженного радиосигнала.- according to received AFR ⁽ⁱ⁾

a two-dimensional complex angular spectrum is formed, which determines the azimuth and elevation angle of the transmitter of the i-th detected radio signal.

The formation of a two-dimensional complex angular spectrum can be carried out in various ways, for example, the classical method of beam formation or high resolution methods described in [5].

в сигнал двумерного комплексного углового спектра путем его умножения на фазирующую функцию, представляющую собой взвешенную комплексными коэффициентами поляризации сумму двух ортогонально поляризованных векторов наведения.When using the classical method of beam forming, the signal is converted from a two-component complex AFR ^{(i) of the} i-th radio signal

into a signal of a two-dimensional complex angular spectrum by multiplying it by a phasing function, which is the sum of two orthogonally polarized guidance vectors weighted by complex polarization coefficients.

и фазирующей функции по азимуту, углу места и поляризации, идентифицируется как азимутально-угломестное направление на передатчик i-го обнаруженного радиосигнала.Direction corresponding to the maximum approval of the PRA ⁽ⁱ⁾

and the phasing function in azimuth, elevation and polarization, is identified as the azimuthal elevation direction to the transmitter of the i-th detected radio signal.

The obtained azimuth and elevation angle of the transmitter of the i-th detected radio signal are transmitted to external systems.

From the above description, it follows that as a result of using the operations of assessing the polarization-angular proximity of identifiable components of the field of localized signals, a device containing an antenna system of N antenna elements, a multichannel frequency converter, a multichannel ADC and a multiprocessor calculator provides effective detection and frequency-spatial localization of unknown signals .

So, for example, the described device with an antenna system containing N antennas, each of which consists of a vertically polarized and horizontally polarized antenna element with an independent output, provides an increase in detection sensitivity and frequency-spatial localization of signals in comparison with a device that implements a prototype method with linear oblique polarization close to horizontal by 5 dB.

Thus, the proposed method of polarization-independent detection and localization of broadband signals due to additional information extracted by

the use of polarization parameters of the signals as an additional sign of identification of the components of the field of localized signals,

the application of the operations of generating signals of a two-component complex AFR, including vertically and horizontally polarized field components of the received signals,

application of operations for assessing the polarization-angular proximity of identifiable field components of localized signals,

provides an increase in the efficiency of detection and frequency-spatial localization of broadband signals from radio sources under conditions of a priori uncertainty regarding the type of polarization, arrival angles, spectral width and spectrum position on the frequency axis of the received signals.

Information sources

1. US patent 5032844, CL G01S 5/04, 1991

2. RU, patent, 2190236, IPC G01S 5/04, 2002

3. Johnson D.H. Application of spectral estimation methods to problems of determining the angular coordinates of radiation sources // TIIER. - 1982. - T. 70. No. 9. - S.126.

4. Beklemishev D.V. Additional chapters of linear algebra. M .: Science. 1983.

5. Ferrara E.R., Parks T.M. Direction Finding with an Array of Antennas Having Diverse Polarizations // IEEE Trans. Antennas Propagation, vol. AR - 31, p.231-236, March 1983.

Claims (2)

1. The method of polarization-independent detection and localization of broadband radio signals, which consists in receiving radio signals N by vertically polarized antennas in a given frequency band, synchronously converting the ensemble of received signals into digital signals, generating a signal from digital signals at each i-th frequency of the reception band vertically polarized components

complex amplitude-phase distribution (AFR), characterized in that they additionally receive radio signals N with horizontally polarized antennas, synchronously transform the ensemble of received signals into digital signals, from which a signal of horizontally polarized component is formed at each l-th frequency of the reception band

integrated AFR, combine vertically polarized signals

and horizontally polarized

component into the signal of a two-component complex AFR

, based on the signals of a two-component complex AFR

detect and frequency-spatial localization of radio signals, while the detection and frequency localization of radio signals is carried out by forming the squares of the modules of the complex coefficients of cross-correlation of the signal of a two-component complex AFR

at frequency l with a two-component AFR signal

at all other frequencies of the reception band l ', compare the squared modules of the cross-correlation coefficients K (l, l') with the threshold, radio signals with frequencies at which the threshold is exceeded, are combined into a signal that is identified as the i-th detected radio signal belonging to one transmitter and the fixed frequency band localization and spatial localization of radio signals is carried out by forming a complex binary signal PRA ^{(i) i-th} detected radio signal, converting binary signal PRA ⁽ⁱ⁾ at dd dimensional complex angular spectrum and determining the angular range and azimuth angle of the transmitter i-th place of the detected radio signal. 2. The method according to claim 1, characterized in that the signal formation of a two-component complex AFR ^{(i) of the} i-th detected radio signal is carried out by averaging the signals of two-component complex AFR

in the frequency band of its localization.

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