CN109188387B - Estimation Method of Distributed Coherent Radar Target Parameters Based on Interpolation Compensation - Google Patents

Abstract

The invention discloses a distributed coherent radar target parameter estimation method based on interpolation compensation, which mainly solves the problems of poor estimation precision and low real-time processing efficiency of ground slow-speed moving target parameters in the prior art. The method comprises the following implementation steps: generating a baseband echo matrix; (2) filtering the baseband echo matrix; (3) Estimating rough position parameters of the ground slow moving target; (4) Estimating fine position parameters of the ground slow moving target by using an interpolation compensation method; (5) And finding out the abscissa value and the ordinate value of the ground slow motion target. Compared with the prior art, the method improves the estimation precision of the distributed coherent system on the parameters of the ground slow-speed moving target, and simultaneously improves the real-time processing efficiency of the distributed coherent system.

Description

Estimation Method of Distributed Coherent Radar Target Parameters Based on Interpolation Compensation

technical field

The invention belongs to the technical field of radar, and further relates to a distributed coherent radar target parameter estimation method based on interpolation compensation in the technical field of moving platform radar. The invention can utilize the distributed coherent system to estimate the position coordinates of the ground slow moving target.

Background technique

The clutter is relatively weak when the distributed coherent system is working on the sea or detecting high-altitude targets. At this time, the estimation of the target parameters by the distributed coherent system in the weak clutter background can be regarded as the estimation of the target parameters in the noise background. The distributed coherent system has the advantages of long detection distance and high coherence performance, so it is widely used in detection scenarios that require high parameter accuracy.

Song Jing, Zhang Jianyun, Zheng Zhidong and others proposed a phase synchronization based distributed radar target Parameter Estimation Method. In the multiple-input multiple-output (MIMO) mode, the method first derives the hybrid Cramer-Rao bound (HCRB) closed-form solution for the delay difference estimation, and then in the fully coherent mode, the distributed system receives the target After energy accumulation of the echoes, the analytical formula of the accumulated target output signal-to-noise ratio gain is given, and the configuration criteria of the number of transmitting and receiving antennas are studied. Finally, it is concluded that the phase synchronization-based processing The method can obtain the conclusion of higher delay difference estimation accuracy and output signal-to-noise ratio gain. The disadvantage of this method is that since the energy accumulation is realized by registering the phase, this will bring an additional phase to the target echo, which will cause the estimated target position coordinates to deviate from the real target position coordinates.

The University of Electronic Science and Technology of China proposed an improved ML method based on the maximum likelihood function in its patent document "An Improved ML Sky Wave Radar Maneuvering Target Parameter Estimation Method" (application number: CN201610190528.9, application publication number: CN105676217A). (Maximum Likelihood) sky-wave radar maneuvering target parameter estimation method. In this method, the maneuvering target signal of sky-wave radar is modeled as a generalized phase polynomial, and then the likelihood function maximization problem is transformed into an optimization problem of 'overdetermined' nonlinear least squares estimation. A multidimensional search is performed to achieve parameter estimation of the maneuvering target. The disadvantage of this method is that this method introduces the optimization problem of 'overdetermined' nonlinear least squares estimation, which will bring the least squares fitting error to the subsequent maneuvering target parameter estimation, resulting in the maneuvering target parameter Estimation accuracy deteriorates.

Beijing University of Aeronautics and Astronautics proposed a method for estimating moving target parameters based on correlation functions in its patent document "A Method for Estimating Moving Target Parameters Based on Correlation Functions" (Application No.: CN201510256088.8 Application Publication No.: CN104898119A) . The method includes the following steps: step 1: read in the original moving target echo data and related imaging parameters; step 2: azimuth Fourier transform processing; step 3: multiply the azimuth with the CS (CompressiveSensing) factor Compensation; Step 4: Range to Fourier Transform processing; Step 5: Range to the same distance compensation factor multiplied to perform distance compression processing; Step 6: Range to Inverse Fourier Transform processing; Step 7: Distance to Doppler Carry out correlation function processing in Le domain; Step 8: Azimuth to Fourier inverse transform processing; Step 9: Fill zero in frequency domain, up-sample in time domain to perform interpolation processing on correlation processing results to obtain the maximum value; Step 10: Process by correlation The maximum value estimates the target speed. The disadvantage of this method is that in the frequency domain zero padding step, the time domain upsampling to interpolate the correlation results will increase the amount of system calculation, resulting in low real-time performance of the system.

Contents of the invention

The purpose of the present invention is to provide a method for estimating parameters of distributed coherent radar targets based on interpolation compensation in view of the deficiencies of the above-mentioned prior art.

The idea of realizing the object of the present invention is: inside the distributed coherent system, multiple transmitting unit radars transmit signals simultaneously, and all receiving unit radars receive echoes scattered by ground slow-moving targets. Considering the operability in real life, each unit radar in the distributed coherent system has the functions of transmitting unit radar and receiving unit radar. And in order to achieve receiving coherence, all receiving unit radars should be guaranteed to fly in formation. In receiving coherent processing, firstly, system error correction is performed on the three-dimensional echo matrix (number of range gates*transmission pulse processing cycles*number of receiving array elements) of the radars of each receiving unit to eliminate the local error caused by the radars of the receiving units. The impact of the inconsistency between vibration phase and time synchronization phase. After that, the system error corrected echo matrix is down-converted, that is, the frequency center of all elements of the matrix is moved to the baseband position, and the baseband echo matrix of each receiving unit radar is obtained. In order to separate the target-scattered echoes of different transmitting unit radars through multiple baseband matched filters in the receiver of each receiving unit radar, it is necessary to select mutually orthogonal transmitting waveforms for each transmitting unit radar, so that each The echo components contributed by each transmitting unit radar are matched in the receiving unit radar. In each receiving unit radar, use the peak extraction method to find out the rough position parameters of the ground slow-moving target, including the range gate of the ground slow-moving target, Doppler channel number and beam number, and then use the interpolation compensation method to obtain the fine position parameters of the slow moving target on the ground. Finally, each transmitting unit radar transmits and each receiving unit radar receives, and the ground slow moving target The fine position parameters are used as the element values of the matrix index of the three-dimensional matrix after interpolation and compensation, and form the target echo column vector in the order of the radar serial number of the receiving unit from small to large. Use this column vector to match the gain value of each point in the earth observation area of the distributed coherent system, find out the position point corresponding to the maximum gain value, and use the abscissa value and ordinate value corresponding to the position point as The abscissa and ordinate values of the ground slow-moving target realize the estimation of the position coordinates of the ground slow-moving target by using the distributed coherent system. In order to improve the real-time processing efficiency of the system and reduce the amount of calculation, the rough position parameters of the target obtained by the peak extraction method are used, and only the part near the rough position parameters is selected, and the three-dimensional echo matrix is compensated by local interpolation, so that the parameter estimation accuracy can not be reduced. Under the premise of the system, the real-time processing efficiency of the system is significantly improved and the calculation amount is reduced.

Concrete steps of the present invention include as follows:

(1) Generate baseband echo matrix:

(1a) In the distributed coherent system, the echo matrix composed of the echo data scattered by the ground slow-moving target received by each receiving unit radar is subjected to systematic error correction, and the echo matrix after the systematic error correction is obtained;

(1b) Move the frequency center of the element at each position of the echo matrix after systematic error correction to the baseband frequency position to obtain the baseband echo matrix of each receiving unit radar;

(2) Filtering the baseband echo matrix:

(2a) Using the range-domain matched filter formula, calculate the echo value corresponding to each transmitting unit radar after each element in the baseband echo matrix has been processed by the range-domain matched filter. Sorting to form a three-dimensional echo matrix after matched filtering in the range domain;

(2b) Use the Doppler filter formula to calculate the value of each element in the three-dimensional echo matrix after the range domain matched filter after Doppler filter processing, and sort all the values according to the Doppler channel number where they are located from small to large , forming a three-dimensional echo matrix after Doppler filtering;

(2c) Use the digital beamforming formula to calculate the value of each element in the three-dimensional echo matrix after Doppler filtering after digital beamforming processing, and sort all the values according to the number of their beams from small to large to form a digital beamforming The final three-dimensional echo matrix;

(3) Estimate the rough position parameters of the slow moving target on the ground;

(4) Use the interpolation compensation method to estimate the fine position parameters of the slow moving target on the ground:

(4a) using interpolation compensation method to obtain a three-dimensional echo matrix after interpolation compensation;

(4b) Using the peak extraction method, find out the fine position parameters of the ground slow-moving target from the three-dimensional echo matrix after interpolation compensation;

(5) Find out the abscissa and ordinate values of the ground slow-moving target:

(5a) Utilize the assignment method to obtain the search interval of the abscissa value and the ordinate value of the ground slow-moving target;

(5b) Find the abscissa value and ordinate value of the ground slow-moving target respectively from the rectangular area formed by the search interval of the abscissa value and the ordinate value.

Compared with the prior art, the present invention has the following advantages:

First, since the present invention utilizes the interpolation compensation method, the extra phase brought to the target echo by energy accumulation is compensated, which overcomes the problem of the prior art that the energy accumulation brings extra phase to the target echo, causing The fact that the estimated target position coordinates deviates from the real target position coordinates makes the present invention less susceptible to the influence of additional phases in engineering practice, and improves the estimation accuracy of the distributed coherent system for the position parameters of slow moving targets on the ground.

Second, because the present invention utilizes the peak value extraction method, the position parameters of the ground slow-moving target are obtained by extracting the index corresponding to the maximum value, which improves the real-time performance of the system and overcomes the problem of using time-domain up-sampling to correlate As a result, interpolation processing increases the calculation amount of the system, resulting in the problem that the real-time performance of the system is not high, so that the present invention can improve the real-time processing efficiency of the distributed coherent system.

Description of drawings

Fig. 1 is a flow chart of the present invention;

Fig. 2 is a simulation diagram of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

With reference to Fig. 1, the steps of the present invention are further described.

Step 1, generate a baseband echo matrix.

In the distributed coherent system, the system error correction is performed on the echo matrix composed of the echo data scattered by the ground slow-moving target received by each receiving unit radar, and the echo matrix after the system error correction is obtained.

The specific steps of the system error correction are as follows:

The first step is to use the system error estimation module inside the distributed coherent system to estimate the system error matrix caused by the difference between the local oscillator phase and the time synchronization phase between the radars of each receiving unit.

Step 2: Divide the elements at each position in the echo matrix formed by the echo data scattered by the ground slow-moving target received by the radars of each receiving unit by the elements at the same position in the system error matrix to obtain the system Echo matrix after error correction.

The frequency center of the element at each position of the echo matrix after systematic error correction is moved to the baseband frequency position to obtain the baseband echo matrix of each receiving unit radar.

Step 2, performing filtering processing on the baseband echo matrix.

Using the distance domain matched filter formula, calculate the echo value corresponding to each transmitting unit radar after each element in the baseband echo matrix is processed by the distance domain matched filter, sort all the values according to the range gate where they are located from small to large, and form The 3D echo matrix after matched filtering in the range domain.

The distance domain matched filtering formula is as follows:

Among them, y _p,q (l,k,n) represents the baseband echo matrix after the range-domain matched filter processing, the p-th transmitting unit radar transmits, the q-th receiving unit radar receives the l-th range gate, the k-th transmission pulse processing cycle, the value of the nth receiving array element, p=1,2,...,m _T , m _T represents the total number of transmitting unit radars in the distributed coherent system, q=1,2, ...,m _R , m _R represents the total number of receiving unit radars in the distributed coherent system, l=1,2,...,L, L represents the total number of range gates, k=1,2,... .., K, K represents the total number of all transmit pulse processing cycles, n=1, 2,..., N, N represents the total number of receiving array elements in each receiving unit radar of the distributed coherent system, ∑ represents the sum Operation, x _q (r,k,n) represents the r-th range-frequency domain sampling point received by the q-th receiving unit radar, the k-th transmit pulse processing cycle, and the range-frequency domain echo data of the n-th receiving element , sp (r) represents the range-frequency domain matched filter data at the r-th range-frequency domain sampling point of the _p -th transmitting unit radar, * represents the conjugate operation, exp represents the exponential operation with the natural logarithm as the base, j Represents the imaginary unit symbol, and π represents pi.

Use the Doppler filter formula to calculate the value of each element in the three-dimensional echo matrix after the matched filter in the range domain after Doppler filter processing, and sort all the values according to the Doppler channel number where they are located, from small to large, forming a multi-dimensional The three-dimensional echo matrix after Puler filtering.

The Doppler filter formula is as follows:

Among them, z _{p, q} (l, a, n) represents the three-dimensional echo matrix after the range domain matching filter and the lth echo matrix received by the pth transmitting unit radar and the qth receiving unit radar after Doppler filtering processing. The value of the range gate, the a-th Doppler channel, and the n-th receiving array element, a=1,2,...,K, b represents the sequence number of the transmit pulse processing cycle.

Use the digital beamforming formula to calculate the value of each element in the Doppler filtered three-dimensional echo matrix after digital beamforming processing, and sort all the values according to the number of their beams from small to large to form a three-dimensional image after digital beamforming echo matrix.

The digital beamforming formula is as follows:

Among them, f _p,q (l,a,c) represent the three-dimensional echo matrix after Doppler filtering, the pth transmitting unit radar transmits and the qth receiving unit radar receives the first Values of the l range gate, the a-th Doppler channel, and the c-th beam, c=1, 2,..., N, and g represents the serial number of the receiving array element.

Step 3, estimate the rough location parameters of the slow moving target on the ground.

The specific steps of estimating the rough position parameters of the ground slow-moving target are as follows:

Step 1, from the 3D echo matrix after digital beamforming, find the maximum value of all elements.

Step 2, use the matrix index of the maximum value to replace the rough location parameters of the ground slow-moving target.

Step 4, using the interpolation compensation method to estimate the fine position parameters of the ground slow moving target.

Using the interpolation compensation method, the three-dimensional echo matrix after interpolation compensation is obtained.

The specific steps of the interpolation compensation method are as follows:

In the first step, in the three-dimensional echo matrix after digital beamforming, inverse fast Fourier transform is performed on each dimension to obtain the three-dimensional echo matrix after inverse fast Fourier transform.

和αN为止，α表示补零倍数，α∈[1,10]内的正整数，∈表示属于符号，得到补零后的三维回波矩阵。In the second step, the tails of each dimension of the three-dimensional echo matrix after the inverse fast Fourier transform are filled with zeros until the three dimensions respectively reach αL,

Up to αN, α represents the multiple of zero padding, a positive integer in α∈[1,10], ∈ represents a symbol, and the three-dimensional echo matrix after zero padding is obtained.

点和αN点的快速傅里叶变换，得到插值补偿后的三维回波矩阵。Step 3, for each dimension of the three-dimensional echo matrix after zero padding, respectively make αL points,

The fast Fourier transform of the points and αN points is used to obtain the three-dimensional echo matrix after interpolation and compensation.

Using the peak extraction method, the fine position parameters of the ground slow-moving target are found from the three-dimensional echo matrix after interpolation and compensation.

The concrete steps of described peak extraction method are as follows:

The first step is to find the maximum value of all elements from the three-dimensional echo matrix after interpolation compensation.

Step 2, use the matrix index of the maximum value to replace the fine position parameters of the ground slow moving target.

Step 5, find out the abscissa value and ordinate value of the slow moving target on the ground.

Using the assignment method, the search interval of the abscissa and ordinate values of the ground slow-moving target is obtained.

The specific steps of the assignment method are as follows:

The first step is to replace the search interval of the abscissa value of the ground slow-moving target with the value interval of the abscissa value of the earth observation area of the distributed coherent system.

The second step is to replace the search interval of the ordinate value of the ground slow-moving target with the value interval of the ordinate value of the earth observation area of the distributed coherent system.

Find the abscissa value and ordinate value of the ground slow-moving target from the rectangular area formed by the search interval of the abscissa value and the ordinate value respectively.

The specific steps of finding out the abscissa value and the ordinate value of the ground slow-moving target respectively are as follows:

Step 1: From the three-dimensional echo matrix after interpolation compensation, find out the element values whose matrix index is the fine position parameter of the slow moving target on the ground, and combine these element values according to the order of the radar serial number of the receiving unit from small to large to form Target echo column vector.

Step 2, according to the following formula, calculate the search guide vector corresponding to each location point in the rectangular area:

Among them, s _w represents the search steering vector corresponding to the wth position point in the rectangular area, λ represents the emission wavelength, T _w1 represents the distance from the wth position point in the rectangular area to the radar of the first transmitting unit, and R _w1 represents the rectangular area The distance from the wth position point in the rectangular area to the first receiving unit radar, T _w2 represents the distance from the wth position point in the rectangular area to the second transmitting unit radar, and T _wp represents the wth position point in the rectangular area to the first The distance from the radar of the p transmitting unit, R _wq represents the distance from the wth position point in the rectangular area to the qth receiving unit radar, and T represents the transpose operation.

Step 3, according to the following formula, calculate the gain value at each position point in the rectangular area:

Y _w =s _w ^H z

Among them, Y _w represents the gain value at the wth position point in the rectangular area, H represents the conjugate transpose operation, and z represents the target echo column vector.

Step 4: Find the position point corresponding to the maximum gain value from all the position points in the rectangular area, and use the abscissa value and ordinate value corresponding to the position point as the abscissa value and ordinate value of the slow moving target on the ground respectively coordinate value.

The effects of the present invention will be further described below in combination with simulation experiments.

1. Simulation conditions:

The environment of the simulation experiment of the present invention is: MATLAB 2017b, Intel (R) Xeon (R) CPU 2.20GHz, Window7 professional edition.

2. Simulation content and result analysis:

The simulation experiment of the present invention uses the method of the present invention to estimate the abscissa and ordinate values of the slow moving target on the ground according to the echoes of the slow moving target on the ground received by the distributed coherent system. Each unit radar in the distributed coherent system has the integration of sending and receiving, that is, each unit radar is both a transmitting unit radar and a receiving unit radar. The total number of unit radars is 4, the total number of range gates is 200, the total number of all transmitting pulse processing cycles is 128, the number of receiving array elements of each receiving unit radar is 8, and the multiple of zero padding is 10 times. The transmission power of the unit radar is 200kw, the transmission carrier frequency is 300MHz, the transmission signal bandwidth is 1MHz, the pulse repetition frequency is 5KHz, and the signal-to-noise ratio of the echo of the slow moving target on the ground is 30dB.

Fig. 2 is a simulation diagram of the present invention. Figure 2(a) is a phase comparison diagram of the echo vector under ideal conditions, interpolation compensation and no interpolation compensation for slow moving targets on the ground when the distance between the receiving unit radars is 100 meters. The abscissa in Fig. 2(a) represents the transmit-receive pair, and the ordinate represents the phase of the echo vector. The unmarked curve in Figure 2(a) represents the simulation result curve of the echo vector phase under ideal conditions, the curve marked with a square represents the simulation result curve of the echo vector phase under interpolation compensation, and the curve marked with a triangle represents The simulation result curve of echo vector phase without interpolation compensation.

It can be seen from Figure 2(a) that when the signal-to-noise ratio is 30dB and the distance between the receiving unit radars is 100 meters, compared with the echo vector phase curve without interpolation compensation, the echo vector phase curve under the interpolation compensation condition is The phase curve of the wave vector agrees better with most points of the phase curve of the echo vector under ideal conditions. Only at the position where the abscissa is 11, the phase of this point is different from that of the corresponding point under ideal conditions due to the ambiguity of the space angle. It can be seen that when the spacing between the receiving unit radars is uniform, the abscissa and ordinate values of the target can be estimated more accurately by using the echo vector in the case of interpolation compensation. Ideally, the echo vector phase is only related to the transmitting distance and receiving distance. The launch distance refers to the distance from each launch unit radar to the slow moving target on the ground. The receiving distance refers to the distance from each receiving unit radar to the slow moving target on the ground.

Figure 2(b) is for the slow moving target on the ground, when the distance between the four receiving unit radars is 100 meters, 200 meters and 300 meters, the ideal situation, interpolation compensation and no interpolation compensation Phase comparison plot of wave vectors. The abscissa in Figure 2(b) represents the transmit-receive pair, and the ordinate represents the phase of the echo vector. The unmarked curve in Figure 2(b) represents the simulation result curve of the echo vector phase under ideal conditions, the curve marked with a diamond represents the simulation result curve of the echo vector phase under interpolation compensation, and the curve marked with a circle A simulation result curve representing the echo vector phase without interpolation compensation.

It can be seen from Figure 2(b) that when the radar spacing parameters of the receiving unit are adjusted so that the spacing between the radars of the four receiving units is 100 meters, 200 meters and 300 meters respectively, compared with the situation without interpolation compensation The phase curve of the echo vector, the phase curve of the echo vector under the interpolation compensation condition and the phase curve of the echo vector under the ideal condition have a better coincidence degree. It can be seen that when the spacing between the receiving unit radars is non-uniform, the abscissa and ordinate values of the target can be accurately estimated by using the echo vector in the case of interpolation compensation.

Claims (10)

1. A distributed coherent radar target parameter estimation method based on interpolation compensation, it is characterized in that, to the echo matrix formed by the echo data after receiving the ground slow moving target scattering by each receiving unit radar, utilize the interpolation compensation method Estimate the fine position parameters of the ground slow-moving target, find out the abscissa value and the ordinate value of the ground slow-moving target; the specific steps of the method include as follows: (1) Generate baseband echo matrix: (1a) In the distributed coherent system, the echo matrix composed of the echo data scattered by the ground slow-moving target received by each receiving unit radar is subjected to systematic error correction, and the echo matrix after the systematic error correction is obtained; (1b) Move the frequency center of the element at each position of the echo matrix after systematic error correction to the baseband frequency position to obtain the baseband echo matrix of each receiving unit radar; (2) Filtering the baseband echo matrix: (2a) Using the range-domain matched filter formula, calculate the echo value corresponding to each transmitting unit radar after each element in the baseband echo matrix has been processed by the range-domain matched filter. Sorting to form a three-dimensional echo matrix after matched filtering in the range domain; (2b) Use the Doppler filter formula to calculate the value of each element in the three-dimensional echo matrix after the range domain matched filter after Doppler filter processing, and sort all the values according to the Doppler channel number where they are located from small to large , forming a three-dimensional echo matrix after Doppler filtering; (2c) Use the digital beamforming formula to calculate the value of each element in the three-dimensional echo matrix after Doppler filtering after digital beamforming processing, and sort all the values according to the number of their beams from small to large to form a digital beamforming The final three-dimensional echo matrix; (3) Estimate the rough position parameters of the slow moving target on the ground; (4) Use the interpolation compensation method to estimate the fine position parameters of the slow moving target on the ground: (4a) using interpolation compensation method to obtain a three-dimensional echo matrix after interpolation compensation; (4b) Using the peak extraction method, find out the fine position parameters of the ground slow-moving target from the three-dimensional echo matrix after interpolation compensation; (5) Find out the abscissa and ordinate values of the ground slow-moving target: (5a) Utilize the assignment method to obtain the search interval of the abscissa value and the ordinate value of the ground slow-moving target; (5b) Find the abscissa value and ordinate value of the ground slow-moving target respectively from the rectangular area formed by the search interval of the abscissa value and the ordinate value. 2. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, the specific steps of systematic error correction described in step (1a) are as follows: The first step is to use the system error estimation module inside the distributed coherent system to estimate the system error matrix caused by the difference between the local oscillator phase and the time synchronization phase between the radars of each receiving unit; The second step is to divide the elements at each position in the echo matrix formed by the echo data scattered by the ground slow moving target received by the radar of each receiving unit by the elements at the same position in the system error matrix to obtain the system Echo matrix after error correction. 3. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, the distance domain matched filtering formula described in step (2a) is as follows:

Among them, y _p,q (l,k,n) represents the baseband echo matrix after the range-domain matched filter processing, the p-th transmitting unit radar transmits, the q-th receiving unit radar receives the l-th range gate, the k-th transmission pulse processing cycle, the value of the nth receiving array element, p=1,2,...,m _T , m _T represents the total number of transmitting unit radars in the distributed coherent system, q=1,2, ...,m _R , m _R represents the total number of receiving unit radars in the distributed coherent system, l=1,2,...,L, L represents the total number of range gates, k=1,2,... ., K, K represents the total number of all transmit pulse processing cycles, n=1,2,...,N, N represents the total number of receiving array elements in each receiving unit radar of the distributed coherent system, ∑ represents the summation operation , x _q (r,k,n) represents the r-th range-frequency domain sampling point received by the q-th receiving unit radar, the k-th transmit pulse processing cycle, and the range-frequency domain echo data of the n-th receiving element, sp (r) represents the range-frequency domain matched filter data at the r-th range-frequency domain sampling point of the _p -th transmitter radar, * represents the conjugate operation, exp represents the exponential operation with the natural logarithm as the base, and j represents The imaginary unit symbol, π means pi. 4. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, the Doppler filtering formula described in step (2b) is as follows:

Among them, z _{p, q} (l, a, n) represents the three-dimensional echo matrix after the range domain matching filter and the lth echo matrix received by the pth transmitting unit radar and the qth receiving unit radar after Doppler filtering processing. The value of the range gate, the a-th Doppler channel, and the n-th receiving array element, a=1,2,...,K, b represents the sequence number of the transmit pulse processing cycle. 5. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, the digital beam forming formula described in step (2c) is as follows:

Among them, f _p,q (l,a,c) represent the three-dimensional echo matrix after Doppler filtering, the pth transmitting unit radar transmits and the qth receiving unit radar receives the first Values of the l range gate, the a-th Doppler channel, and the c-th beam, c=1, 2,..., N, and g represents the serial number of the receiving array element. 6. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, the concrete steps of the rough position parameter of the estimation ground slow moving target described in step (3) are as follows: The first step is to find the maximum value of all elements from the three-dimensional echo matrix after digital beamforming; In the second step, the matrix index of the maximum value is used to replace the rough location parameters of the ground slow-moving target. 7. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, the concrete steps of interpolation compensation method described in step (4a) are as follows: In the first step, in the three-dimensional echo matrix after digital beamforming, inverse fast Fourier transform is performed on each dimension to obtain the three-dimensional echo matrix after inverse fast Fourier transform; In the second step, the tails of each dimension of the three-dimensional echo matrix after the inverse fast Fourier transform are filled with zeros until the three dimensions respectively reach αL,

Up to αN, α represents the multiple of zero padding, a positive integer in α∈[1,10], ∈ represents a symbol, and the three-dimensional echo matrix after zero padding is obtained; In the third step, for each dimension of the three-dimensional echo matrix after zero padding, respectively make αL points,

The fast Fourier transform of the points and αN points is used to obtain the three-dimensional echo matrix after interpolation and compensation. 8. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, the concrete steps of peak extraction method described in step (4b) are as follows: The first step is to find the maximum value of all elements from the three-dimensional echo matrix after interpolation compensation; In the second step, the matrix index of the maximum value is used to replace the fine position parameters of the ground slow-moving target. 9. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, the specific steps of assignment method described in step (5a) are as follows: The first step is to replace the search interval of the abscissa value of the ground slow-moving target with the value interval of the abscissa value of the earth observation area of the distributed coherent system; The second step is to replace the search interval of the ordinate value of the ground slow-moving target with the value interval of the ordinate value of the earth observation area of the distributed coherent system. 10. the distributed coherent radar target parameter estimation method based on interpolation compensation according to claim 1, is characterized in that, described in the step (5b) respectively finds out the abscissa value and the ordinate value of ground slow moving target The specific steps are as follows: In the first step, from the three-dimensional echo matrix after interpolation and compensation, find out the element values whose matrix index is based on the fine position parameters of the ground slow-moving targets, and combine these element values in the order of the receiving unit radar serial number from small to large to form echo vector; In the second step, calculate the search guide vector corresponding to each location point in the rectangular area according to the following formula:

Among them, s _w represents the search steering vector corresponding to the wth position point in the rectangular area, λ represents the emission wavelength, T _w1 represents the distance from the wth position point in the rectangular area to the radar of the first transmitting unit, and R _w1 represents the rectangular area The distance from the wth position point in the rectangular area to the first receiving unit radar, T _w2 represents the distance from the wth position point in the rectangular area to the second transmitting unit radar, and T _wp represents the wth position point in the rectangular area to the first The distance from the radar of the p transmitting unit, R _wq represents the distance from the wth location point in the rectangular area to the qth receiving unit radar, and T represents the transpose operation; The third step is to calculate the gain value at each position point in the rectangular area according to the following formula: Y _w =s _w ^H z Among them, Y _w represents the gain value at the wth position point in the rectangular area, H represents the conjugate transpose operation, and z represents the echo vector; The fourth step is to find the position point corresponding to the maximum gain value from all the position points in the rectangular area, and use the abscissa value and ordinate value corresponding to the position point as the abscissa value and ordinate value of the slow moving target on the ground, respectively. coordinate value.

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