RU2168740C1 - Device for determination of parameters of target motion - Google Patents

Abstract

FIELD: radio detection and range finding, in particular, methods for recovery of target trajectory in spaced radar tracking. SUBSTANCE: the device taken as a prototype has a transmitting position and a receiving position being in a point that is remote from it, consisting of an antenna connected to the receiving device having N partial channels containing receivers, whose outputs are connected to the respective inputs of the Doppler frequency measuring unit and of the interference signal arrival direction measuring unit, unit for extrapolation of the measured parameters, unit for computation of the time moment of intersection of the base line by the target, and a unit for determining the position surface, whose output is connected to one of the inputs of the trajectory parameters computing unit, the other input of the trajectory parameters computing unit is connected to the output of the unit for measurement the direction of arrival of interference signal, and the output serves as the output of the whole device, one of the inputs of the unit for extrapolation of the measured parameters is connected to the output of the unit for measurement of the direction of arrival of the interference signal, and the output - to the input of the computing unit of the time moment of inter-section of the base line by the target, and to one of the inputs of the unit for determining the position surface, whose other input is connected to the output of the computing unit of the time moment of intersection of the base line by the target, the central partial channel comprises the reference voltage division unit, whose input serves as one of the inputs of the receiving device, and one of the outputs is connected directly to the respective receiver. The other N-I partial channels comprise summers, whose one of the inputs serves as the input of the receiving device, and the other is connected to the respective input of the reference voltage division unit. The output of each summer is connected to the respective receiver. Besides, the device comprises a unit for identification of signals by frequency and subtraction of false signals, whose input is connected to the output of the Doppler frequency measuring unit, and the output - to one of the inputs of the unit for extrapolation of measured parameters. EFFECT: enhanced accuracy of determination of the bearing in case of expansion of the bearing zone due to the increase of the number of partial channels. 1 dwg

Description

 The invention relates to the field of radar, in particular to methods for restoring the path of a target in a spaced radar.

 Various devices are known for determining the motion parameters of an object in diversity radar. A device that implements a method for determining the motion parameters of a target (see: Patent No. 2133480 according to application 98101955/9), claimed 02.02.98; IPC G 01 S 3/72. The radar method for determining the parameters of the object’s movement contains a transmitting position emitting a monochromatic signal, and at a point remote from it, a receiving position containing a receiving device, a unit for measuring the direction of arrival of the interference signal, a unit for measuring the Doppler frequency, a unit for determining the position surface, and a unit for calculating path parameters.

 The main disadvantage of this device is the inability to determine the location of the target before it crosses the base line. This is due to the impossibility of measuring the moment in time when the frequency of the interference signal of the beats is zero until the target crosses the base line, since this moment of time corresponds to the direct location of the target on the base line, the frequency of the interference signal of the beats when the target is on this line is zero.

 The specified drawback is devoid of the device (see RF patent N 2124220, application 97117868 from 10.29.97, G 01 S 13/06). A device for determining the motion parameters of the target, which contains a transmitting position and at a point remote from it, a receiving position consisting of an antenna connected to a receiving device having two or more partial channels, each of which consists of a serial connection of the receiver, detector and low-pass filter (LPF), the outputs of the latter are connected to the corresponding inputs of the unit for measuring the direction of arrival of the interference signal and the unit for measuring the Doppler frequency, the extrapolation unit for the measured param moat unit calculating intersection points in time order and base line determination unit surface position, the output of which is connected to one input calculation unit trajectory parameters, the other input of which is connected to the output measure signal arrival directions of the interference block and the output is the output of the entire device. One of the inputs of the extrapolation unit of the measured parameters is connected to the output of the unit for measuring the direction of arrival of the interference signal, and the output is connected to the input of the unit for calculating the instant of crossing the target of the base line and one of the inputs of the unit for determining the position surface, the other input of which is connected to the output of the unit for calculating the moment of intersection target line base.

 The disadvantage of this device is the deterioration in the accuracy of determining the bearing of the target in the case of an increase in the number of partial channels and a narrowing of their radiation pattern to expand the direction finding zone, since with an increase in the number of partial channels and the narrowing of their radiation pattern, the reference voltage in the channels decreases in proportion to their distance from the central channel, which it is maximum. A drop in the reference voltage leads to distortion of the amplitude information in the detector and, consequently, to errors in determining the bearing of the target.

 The proposed device eliminates this drawback. This is achieved by the fact that in the device, taken as a prototype and containing a transmitting position and located at a remote point of the receiving position, consisting of an antenna connected to a receiving device having N (N> 2) partial channels containing receivers consisting of linear part, detector and low-pass filter, the outputs of which are connected to the corresponding inputs of the unit for measuring the direction of arrival of the interference signal and the unit for measuring the Doppler frequency, the unit for extrapolation of the measured parameters, the unit in calculating the time moment when the target intersects the base line and the position surface determining unit, the output of which is connected to one of the inputs of the trajectory parameter calculation unit, the other input of which is connected to the output of the interference signal arrival direction measuring unit, and the output is the output of the entire device, one of the inputs of the extrapolation unit of the measured parameters is connected to the output of the unit for measuring the direction of arrival of the interference signal, and the output is connected to the input of the unit for calculating the instant of crossing the target the base line and one of the inputs of the position surface determining unit, the other input of which is connected to the output of the unit for calculating the time the base line intersects the target, a reference voltage division unit is introduced into the central partial channel of the receiving device, the input of which is one of the inputs of the receiving device, and one of The outputs are directly connected to the input of the corresponding receiver. In the remaining N-1 partial channels, summing devices are introduced, one of the inputs of which is the input of the receiving device, and the other is connected to the corresponding output of the reference voltage division unit. The outputs of the summing devices are connected to the respective receivers. In addition, a unit for identifying signals by frequency and subtracting false signals is introduced into the device, the input of which is connected to the output of the Doppler frequency measurement unit, and the output is connected to one of the inputs of the extrapolation unit of the measured parameters.

 The expansion of the bearing area by increasing the number of partial channels leads to a sharp deterioration in the accuracy of determining the bearing of the target, and the introduction of new blocks and relationships allows to increase this accuracy. This is achieved by distributing the reference voltage received by the central partial channel over the channels where this voltage is small or absent altogether. Target signals received by the central channel and being false for other channels are eliminated during further processing after determining their Doppler frequency.

The drawing shows a functional diagram of the inventive device with N partial channels and the following notation:
1 - transmitting position;
2 - antenna receiving position;
3 - block division of the reference voltage;
4 - summing device;
5 - receiver;
6 - block measuring the direction of arrival of the interference signal;
7 - unit for measuring Doppler frequency;
8 - a unit for identifying signals by frequency and subtracting false signals;
9 - block extrapolation of the measured parameters;
10 - unit for calculating the instant of time when the target intersects the base line;
11 - block determining the position surface;
12 is a block calculating the trajectory parameters.

 The proposed device consists of a transmitting position 1 and, at a point remote from the radiation source, a receiving position, which in turn consists of an antenna 2 of a receiving position having N outputs, each of which, except for the central one, is connected to one of the inputs of the corresponding summing device 4 the output of which is connected to the receiver 5. The central output of the antenna 2 is connected to the unit 3 for dividing the reference voltage, one of the outputs of which is connected directly to the input of the receiver 5, and the remaining N-1 outputs are connected to the inputs ing devices 4 corresponding to the partial channels. The outputs of the receiver 5 are separately connected to the corresponding inputs of the unit 6 for measuring the direction of arrival of the interference signal and the unit 7 for measuring the Doppler frequency, the output of which is connected to the input of the unit 8 for identifying signals by frequency and calculating false signals, the output of which is in turn connected to one of the inputs of unit 9 extrapolation of the measured parameters. The second input of the unit 9 for extrapolation of the measured parameters is connected to the output of the unit 6 for measuring the direction of arrival of the interference signal, and the output is connected to the input of the unit 10 for calculating the time moment when the target intersects the base line and one of the inputs of the position surface determining unit 11, the second input of which is connected to the output of unit 10 calculating the instant of crossing the target line base. The output of block 10 is connected to one of the inputs of the block 12 for calculating the path parameters, the second input of which is connected to the output of the block 6 for measuring the direction of arrival of the interference signal, and the output of the block 12 for calculating the path parameters is the output of the entire device.

 The inventive device operates as follows.

 A probing continuous (unmodulated) signal is emitted by the transmitting position 1. The radiation pattern of the antenna of the transmitter has a sufficiently large width in azimuth. The antenna 2 of the receiving position receives the direct signal of the transmitting position 1 and the signals reflected from the target. In the receiving position, N partial channels are formed, overlapped at half power level. The direct transmitter signal received by the central partial channel is divided in the reference voltage division unit 3 and, in accordance with the radiation pattern, is proportionally supplied to the remaining N-1 partial channels to the summing devices 4, where it is added to the signal received by the corresponding channel. From the output of the summing devices 4 and the reference direction division unit 3, the signal is sent to the corresponding receiver 5, where low-frequency oscillations are detected and extracted from the total signal generated by interference of the direct signal of the transmitter and the signal reflected from the target.

 Further, from the outputs of the parallel channels, the low-frequency oscillation enters the Doppler frequency measurement unit 7, where the Doppler frequency is measured by the beat frequency generated by adding the signal reflected from the target and the direct signal of the transmitter, and into the unit 6 for measuring the arrival direction of the interference signal, in which the angular the target coordinate by comparing the amplitudes of the low-frequency signal in each of the partial channels.

 Consider the possibility of determining the location of the target from the measured values of the Doppler frequency and the angular coordinate of the target.

где R_Σ(t) - суммарное расстояние передатчик - цель - приемник.It is known (see Chernyak BC, Zaslavsky L.P., Osipov L.V. Foreign Radio Electronics, 1987, N 1, pp. 29-30) that the Doppler frequency shift (i.e., the frequency of the interference signal of the beats) of the echo signal on the path is the transmitting position - goal - the transmitting position is described by the equation

where R _Σ (t) is the total distance of the transmitter - target - receiver.

The value of R _Σ defines the position surface in space (see the Guide to Radar, vol. 4, edited by M. Skolnik, M., Sov. Radio, 1978), which is an ellipsoid of revolution with foci located at the location points of the receiving and transmitting antennas;
λ is the radiation wavelength;
f _d (t) is the Doppler frequency shift.

где R₀ - начальное (в момент времени t₀ начальных траекторных измерений) значение R_Σ(t₀).
Если учесть, что в момент времени пересечения целью линии базы (t_п) значение R_Σ(t) известно точно и равно длине линии базы L, то для R₀ из (2) получим следующее значение:

Подставив (3) в (2), получим

Согласно выражениям (4), (5) при t ≥ t_п (после пересечения целью линии базы) оценку

суммарной дальности можно найти, интегрируя на интервале (t_п, t) оценку

доплеровской частоты принимаемого сигнала. При t < t_п оценка

на интервале (t, t_п) неизвестна.Integrating (1) on the interval (t ₀ , t), we obtain

where R ₀ is the initial (at time t ₀ initial trajectory measurements) value of R _Σ (t ₀ ).
If we take into account that at the time when the target intersects the base line (t _p ), the value of R _Σ (t) is known exactly and equal to the length of the base line L, then for R ₀ from (2) we obtain the following value:

Substituting (3) into (2), we obtain

According to expressions (4), (5) for t ≥ t _p (after the target crosses the base line), the estimate

total range can be found by integrating on the interval (t _p , t) estimate

Doppler frequency of the received signal. For t <t _{p, the} estimate

on the interval (t, t _p ) is unknown.

с использованием выражений (4), (5) момент t_п пересечения целью линии базы точно не известен, так как при α = 0 доплеровский сдвиг частоты f_д = 0 [это непосредственно следует из выражения (1)] и сигналы целей не наблюдаются в некоторой области малых значений f_д (зоны режекции), в которой значения доплеровской частоты не превосходят ширины зоны режекции доплеровских частот приемного устройства. Зона режекции необходима для устранения отраженного сигнала от подстилающей поверхности и прямого сигнала передатчика.When determining the grade

using expressions (4), (5), the moment t _n of the target’s intersection of the base line is not exactly known, since at α = 0 the Doppler frequency shift f _d = 0 [this follows directly from expression (1)] and the target signals are not observed in a certain region of small values of f _d (notch zone), in which the values of the Doppler frequency do not exceed the width of the notch zone of the Doppler frequencies of the receiving device. The notch zone is necessary to eliminate the reflected signal from the underlying surface and the direct signal of the transmitter.

момента пересечения целью линии базы, которую можно найти как решение одного из уравнений

(t) = 0 или

(t) = 0, где

(t) и

(t) - экстраполированные на зону режекции оценки измеряемых координат.Therefore, instead of t _p in expressions (4), (5), it is necessary to use the estimate

the moment the target crosses the base line, which can be found as a solution to one of the equations

(t) = 0 or

(t) = 0, where

(t) and

(t) - extrapolated to the notch zone estimates of the measured coordinates.

оценки суммарной дальности

из (4), (5), вычисленной с помощью экстраполированных оценок

и оценки угловой координаты

дает искомую оценку дальности до цели из приемной позиции

С блока 7 измерения доплеровской частоты сигнал поступает в блок 8 идентификации сигналов по частоте и вычисления ложных сигналов, где происходит сравнение доплеровских частот сигналов, принятых центральным каналом, с частотами сигналов, принятых остальными парциальными каналами. Сигналы, частоты которых совпадают с частотой центрального канала, удаляются из дальнейшей обработки.Substitution in the equation

total range estimates

from (4), (5) calculated using extrapolated estimates

and estimates of the angular coordinate

gives the desired estimate of the range to the target from the receiving position

From the unit 7 for measuring the Doppler frequency, the signal enters the unit 8 for identifying signals by frequency and calculating false signals, where the Doppler frequencies of the signals received by the central channel are compared with the frequencies of the signals received by the other partial channels. Signals whose frequencies coincide with the frequency of the central channel are removed from further processing.

 Based on the data obtained from the unit 6 for measuring the direction of arrival of the interference signal and the unit 8 for identifying signals by frequency and subtracting false signals, in the unit 9 for extrapolating the measured parameters, the functional dependences of the Doppler frequency and the direction of arrival of the interference signal on time are extrapolated.

Let us consider briefly the possible extrapolation algorithms that underlie the block 9 for extrapolating the measured parameters. We assume that the measurement data f _d and α come from the outputs of the unit 8 for identifying signals by frequency and subtracting false signals and unit 6 for measuring the direction of arrival of the interference signal discretely. Measurement errors will be considered independent.

= c_k•t^k + c_k-1•t^k-1 + ... + c₀. (7)
Из уравнений (6), (7) видно, что для получения функциональных зависимостей частоты Доплера

и направления прихода интерференционного сигнала

от времени необходимо вычислить по нескольким измерениям α и f_д коэффициенты a_k и c_k.In the case of a polynomial measurement model of the described parameters, the extrapolated dependencies will be presented in the form:

= c _k • t ^k + c _k-1 • t ^k-1 + ... + c ₀ . (7)
From equations (6), (7) it can be seen that to obtain the functional dependences of the Doppler frequency

and directions of arrival of the interference signal

from time to time, it is necessary to calculate the coefficients a _k and c _k from several measurements of α and f _d .

где

k - порядок полиномиальной модели;
α₀ (t₀), α₁ (t₁), ..., α_k (t_k) - величины измеряемых угловых коэффициентов в моменты времени t₀, t₁, ..., t_k.For example, let us dwell on the calculation of a _k coefficients. In matrix form, equation (6) for several measured values of α can be written as

Where

k is the order of the polynomial model;
α ₀ (t ₀ ), α ₁ (t ₁ ), ..., α _k (t _k ) - the measured angular coefficients at time t ₀ , t ₁ , ..., t _k .

в этой модели по критерию наименьших квадратов сводится к решению матричного уравнения

Подобное вычисление оптимальных по критерию наименьших квадратов оценок коэффициентов полиномиальной модели для любого порядка "k" подробно описано в книге Сейдж Э., Меле Дж. "Теория оценивания и ее применение в связи и управлении", Связь, 1976.Calculation of optimal coefficients

in this model by the least squares criterion is reduced to solving the matrix equation

A similar calculation of the least-squares optimal estimates of the coefficients of the polynomial model for any order of "k" is described in detail in the book by Sage E., Mele J. "The theory of estimation and its application in communication and control", Communication, 1976.

(t) и

(t) на интервал времени, следующий за моментом времени последнего измерения входных данных.Substituting the obtained values of the coefficients in equations (6) and (7), we obtain functional dependencies

(t) and

(t) for the time interval following the point in time of the last measurement of the input data.

(t) и

(t) приближенно определяется экстраполированный момент времени пересечения целью линии базы до пролета целью этой линии.From block 9, the information goes to block 10 for calculating the time moment when the target intersects the base line, where based on the dependencies

(t) and

(t) the extrapolated moment of time the target crosses the base line to the span of the target line is approximately determined.

(t) = a_k•t_n,э ^k + a_k-1t_n,э ^k-1 +...+ a₀ = 0, (10)

(t) = c_k•t_n,э ^k + c_k-1t_n,э ^k-1 +...+ c₀ = 0. (11)
Информация, полученная в блоке 9 экстраполяции измеряемых параметров и блоке 10 вычисления момента времени пересечения целью линии базы, поступает в блок 11 определения поверхности положения, где происходит определение поверхности положения.When finding the target on the base line, the angular coordinate α and the Doppler frequency f _d are equal to zero (see the Guide to Radar, vol. 4, edited by Skolnik, M., Sov. Radio, 1978), therefore, the sought time according to (6) , (7) can be found from the equations

(t) = a _k • t _{n, e} ^k + a _k-1 t _{n, e} ^k-1 + ... + a ₀ = 0, (10)

(t) = c _k • t _{n, e} ^k + c _k-1 t _{n, e} ^k-1 + ... + c ₀ = 0. (11)
Information obtained in block 9 for extrapolation of the measured parameters and block 10 for calculating the time moment when the target intersects the base line is sent to block 11 for determining the position surface, where the determination of the position surface takes place.

где n-й дискретный момент времени соответствует текущему значению времени t = i_n, в котором и производится оценка R_Σn; m-й дискретный момент времени соответствует моменту времени пересечения целью линии базы t_п = i_m. Таким образом, основной операцией данного блока в случае дискретных, измерений является суммирование входного напряжения.As can be seen from formulas (4) and (5), the position surface determining unit 11 integrates the input voltage with subsequent scaling. If the measurement data of the Doppler frequency f _d arrive discretely at equal time intervals Δ, then formulas (4), (5) can be represented as

where the n-th discrete moment of time corresponds to the current value of time t = i _n , at which R _{Σn is} estimated; The m-th discrete time instant corresponds to the time instant when the target intersects the base line t _p = i _m . Thus, the main operation of this unit in the case of discrete measurements is the summation of the input voltage.

 Further, based on the data obtained from the position surface determining unit 11 and the interference signal arrival direction measuring unit 6, in the block 12 for calculating the path parameters, the path parameters of the target are determined. The spatial coordinates of the target are uniquely determined as the coordinates of the point of intersection of the position surface and the direction line to the target from the receiving position (bearing line).

 The proposed invention formed the basis of the technical design of a new product, which was successfully protected in front of the customer.

Literature
1. Patent 2133480 of the Russian Federation, IPC 6 G 01 S 3/72. The radar method for determining the parameters of the movement of an object / Blyakhman A.B., Samarin A.V. (RF). - N 98101955/09; Application 02/02/98; Publ. 07/20/99, Bull. N 20.

 2. Patent 2124220 of the Russian Federation, IPC 6 G 01 S 13/06. A device for determining the parameters of the target’s movement / Blyakhman A.B., Ryndyk A.G., Kovalev F.N. (RF). - N 97117868/09; Claim 12/27/97; Publ. 12/27/98, Bull. N 36. (prototype).

 3. V.S. Chernyak, L.P. Zaslavsky, L.V. Osipov. Foreign Radio Electronics, 1987, N 1, p. 29-30.

 4. Handbook of Radar, vol. 4, Ed. M. Skolnik, M., Sov. Radio, 1978.

 5. Sage E., Mele J. The theory of evaluation and its application in communication and management. Communication, 1976.

Claims (1)

 A device for determining the motion parameters of a target, comprising a transmitting position and a receiving position located at a point remote from it, consisting of an antenna connected to a receiving device having N partial channels, the outputs of which are connected to the corresponding inputs of the Doppler frequency measuring unit and the interference arrival direction measuring unit signal, each of the N partial channels consists of a receiver, and also containing an extrapolation unit for the measured parameters, a unit for calculating the time instant the goal is the base line and the position surface determining unit, the output of which is connected to one of the inputs of the trajectory parameter calculation unit, the other input of the trajectory parameter calculation unit is connected to the output of the measuring unit for the direction of arrival of the interference signal, and the output is the output of the entire device, one of the inputs of the extrapolation unit the measured parameters is connected to the output of the unit for measuring the direction of arrival of the interference signal, and the output is connected to the input of the unit for calculating the instant of crossing the target of the base and one of the inputs of the position surface determining unit, the other input of which is connected to the output of the unit for calculating the instant of crossing the base line with the target, characterized in that a reference voltage division unit is introduced into the central partial channel of the receiving device, the input of which is one of the inputs of the receiving device and one of the outputs is connected directly to the input of the corresponding receiver, summing devices are introduced into the remaining N-1 partial channels, one of the inputs of which is the inputs of a device, and the other is connected to the corresponding output of the reference voltage division unit, the output of each summing device is connected to the corresponding receiver, in addition, a signal identification and false signal subtraction unit is introduced into the device, the input of which is connected to the output of the Doppler frequency measurement unit, and output - with one of the inputs of the extrapolation unit of the measured parameters.