Monopulse Angle Measurement Method and Electronic Device Based on Coherent Synthesis of Distributed Arrays

Abstract

The present invention discloses a monopulse angle measurement method and an electronic device based on distributed array coherent synthesis, including: mixing the echo data received by multiple sub-arrays of each platform, and shifting the frequency to the intermediate frequency to obtain the mixed data; forming the sum channel, elevation difference channel and azimuth difference channel data by using the mixed data, and performing channel separation to obtain the corresponding superimposed echo data; sequentially performing filtering and decimation, pulse compression, and MTD coherent accumulation processing on the corresponding superimposed echo data of each platform; sequentially performing non-coherent accumulation, CFAR detection, and centroid condensation processing on the processed data; detecting the target according to the processed data, performing MISO coherent parameter estimation and MISO coherent synthesis by using the data after MTD coherent accumulation processing of the sum channel, and performing MIMO coherent parameter estimation and MIMO coherent synthesis by using the data after MISO coherent synthesis to perform monopulse angle measurement estimation. The present invention can achieve high-precision monopulse angle measurement.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar processing, and particularly relates to a monopulse angle measurement method and an electronic device based on distributed array coherent synthesis. Background Art

[0002] The distributed radar system solves the contradiction between the requirements of traditional radar for high-precision positioning and poor maneuverability. The collaborative application between multiple platforms will be the mainstream trend of future radar development. Applying the distributed coherent radar technology to multiple platforms forms a multi-platform distributed coherent system. The multi-platform distributed coherent system can achieve collaborative illumination and energy synthesis between multiple platforms, obtain a greater energy gain compared to the independent illumination of a single radar, improve the action range, detection power, anti-destruction ability and anti-interference ability of the target, and improve the tracking accuracy through multi-radar beam synthesis.

[0003] At present, a small number of domestic scholars have started to research multi-platform distributed radars. For example, in the aspect of airborne distributed radars, Wang Zhilei et al. from the University of Electronic Science and Technology applied distributed MIMO radars to airborne platforms, proposed a target parameter estimation algorithm for airborne distributed MIMO radars, studied the coherent transmission performance in the full coherent transceiver mode, analyzed the influence of radar operating frequency and transmitter interval on coherent transmission performance, and the influence of phase synchronization error on the coherent processing performance of the radar system; Song Hongbo et al. studied the target positioning, velocity estimation, waveform design and coherent parameter estimation of airborne distributed MIMO radars; in the aspect of shipborne distributed radars, Cheng Guangxia et al. from Harbin Institute of Technology studied and analyzed how to rationally sparse array elements and how to reduce the high sidelobe problem caused by safety distance limitations during the combination of distributed shipborne high-frequency ground wave radar MIMO array technology; Jiang Ou et al. studied the DOA estimation algorithm for distributed multi-shipborne radars with virtual arrays.

[0004] However, most of the existing research realizes estimations such as distance and speed in the plane dimension, lacking key technologies around distributed angle measurement and related aspects in the multi-platform distributed coherent synthesis system. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a monopulse angle measurement method and an electronic device based on distributed array coherent synthesis. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a monopulse angle measurement method based on distributed array coherent synthesis, which is applied to a multi-platform distributed coherent system composed of multiple platforms, and each platform includes multiple sub-arrays. The method includes:

[0007] Mix the echo data received by multiple sub-arrays of each platform, and shift the frequency to the intermediate frequency to obtain mixed data;

[0008] Use the mixed data to form data for the sum channel, elevation difference channel, and azimuth difference channel, and perform channel separation on the data of the sum channel, elevation difference channel, and azimuth difference channel to obtain the superimposed echo data corresponding to each platform; wherein, the superimposed echo data includes monostatic echo data and multistatic echo data;

[0009] Perform filtering and decimation, pulse compression, and MTD coherent accumulation processing on the superimposed echo data corresponding to each platform in sequence to obtain first processed data;

[0010] Perform non-coherent accumulation, CFAR detection, and centroid condensation processing on the first processed data in sequence to obtain second processed data;

[0011] Judge whether a target is detected according to the second processed data. If found, use the data after MTD coherent accumulation processing in the sum channel of the first processed data to perform MISO coherent parameter estimation;

[0012] Perform MISO coherent synthesis on the sum channel, elevation difference channel, and azimuth difference channel using the estimated MISO coherent parameters;

[0013] Perform monopulse angle measurement estimation using the data after MISO coherent synthesis;

[0014] In an embodiment of the present invention, the formula of the mixed data is expressed as:

[0015]

[0016] Wherein, A l (t) represents the mixed data corresponding to the echo data received by the l-th platform, N represents the number of platforms in the system, and a lm represents the scatterer response on the receiving path of the signal transmitted by the m-th platform after being reflected by the target and reaching the l-th platform, and s m (t - τ lm ) represents the signal transmitted by the m-th platform, w0 represents the carrier frequency, represents the initial phase of the signal transmitted by the m-th platform, represents the initial phase of the signal received by the l-th platform, τ lm = τ l + τ m represents the time delay of the signal transmitted by the m-th platform after being reflected by the target and reaching the l-th platform, τ m represents the time delay of the signal transmitted by the m-th platform to the target, and τ l represents the time delay of the signal reflected from the target and received by the l-th platform.

[0017] In one embodiment of the present invention, the data for forming the sum channel, the elevation difference channel, and the azimuth difference channel by using the mixed-frequency data includes:

[0018] Using the mixed-frequency data corresponding to the conical scanning beams formed by multiple sub-arrays of each platform to form the data of the sum channel, the elevation difference channel, and the azimuth difference channel.

[0019] In one embodiment of the present invention, the data formula after MISO coherent synthesis is expressed as:

[0020]

[0021] where A(t) represents the data after MISO coherent synthesis, represents the data after the MISO coherent parameter estimation results of the signal transmitted by the m-th platform and received by the l-th platform after passing through the target are aligned in time and phase, represents the MISO delay coherent parameter of the signal transmitted by the m-th platform and received by the l-th platform after passing through the target, represents the MISO delay coherent parameter of the signal transmitted by the m-th platform to the target, represents the MISO delay coherent parameter of the signal reflected from the target and received by the l-th platform, represents the MISO phase coherent parameter of the signal transmitted by the m-th platform and received by the l-th platform after passing through the target, α = a lm represents the scatterer response on the path, β(t - ε lm ) represents the main lobe response in MISO coherent synthesis, w0 represents the carrier frequency, represents the MISO phase coherent parameter of the signal transmitted by the m-th platform, represents the MISO phase coherent parameter of the signal received by the l-th platform, n lm (t) represents the noise on the path of the signal transmitted by the m-th platform and received by the l-th platform after passing through the target in MISO coherent synthesis.

[0022] In one embodiment of the present invention, the method further includes:

[0023] Using the data after MISO coherent synthesis of the sum channel to estimate the MIMO coherent parameters;

[0024] Using the estimated MIMO coherent parameters to perform MIMO coherent synthesis on the sum channel, the azimuth difference channel, and the elevation difference channel;

[0025] Correspondingly, the single-pulse angle measurement estimation using the data after MISO coherent synthesis includes:

[0026] Performing single-pulse angle measurement estimation using the data after MIMO coherent synthesis.

[0027] In an embodiment of the present invention, the result formula of the MIMO coherent synthesis is expressed as:

[0028]

[0029] wherein, A'(t) represents the data after MIMO coherent synthesis, represents the data after alignment in time and phase of the MIMO coherent parameter estimation result that the signal transmitted by the m-th platform reaches the l-th platform after being reflected by the target, represents the MIMO delay coherent parameter that the signal transmitted by the m-th platform reaches the l-th platform after being reflected by the target, represents the MIMO delay coherent parameter of the signal transmitted by the m-th platform to the target, represents the MIMO delay coherent parameter of the signal reaching the l-th platform after being reflected from the target, represents the MIMO phase coherent parameter that the signal transmitted by the m-th platform reaches the l-th platform after being reflected by the target, α = a lm represents the scatterer response on the path, β'(t - ε′ lm ) represents the main lobe response in the MIMO coherent synthesis, w0 represents the carrier frequency, represents the MIMO phase coherent parameter of the signal transmitted by the m-th platform, represents the MIMO phase coherent parameter of the signal received by the l-th platform, n′ lm (t) represents the noise on the path that the signal transmitted by the m-th platform reaches the l-th platform after being reflected by the target in the MIMO coherent synthesis.

[0030] In an embodiment of the present invention, the process of the single-pulse angle measurement estimation includes:

[0031] Calculating the synthesized data of the sum channel, azimuth difference channel, and elevation difference channel respectively according to the data after coherent synthesis; wherein, the data after coherent synthesis includes the data after MISO coherent synthesis and the data after MIMO coherent synthesis;

[0032] Calculating the normalized error data of the data after coherent synthesis in the azimuth dimension and elevation dimension respectively according to the synthesized data of the sum channel, azimuth difference channel, and elevation difference channel;

[0033] The corresponding error angle is found from a preset error angle table according to the normalized error data of the azimuth dimension and the elevation dimension; wherein, the error angle table is calculated in advance according to the multi-platform distributed coherent system;

[0034] The antenna boresight angle corresponding to each sub-array of each platform is corrected according to the error angle to realize monopulse angle measurement estimation.

[0035] In an embodiment of the present invention, the multi-platform distributed coherent system further includes a phased array phase shifter, and the corresponding method further includes:

[0036] The estimated monopulse angle measurement is transmitted to the phased array phase shifter to track the target.

[0037] In a second aspect, an embodiment of the present invention provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory complete mutual communication through the communication bus;

[0038] The memory is used to store a computer program;

[0039] When the processor is used to execute the program stored on the memory, the steps of any of the above-mentioned monopulse angle measurement methods based on distributed array coherent synthesis are realized.

[0040] The beneficial effects of the present invention:

[0041] The monopulse angle measurement method based on distributed array coherent synthesis proposed by the present invention combines the advantages of distributed array coherent synthesis and monopulse angle measurement, designs a set of signal processing flow schemes, and can realize monopulse angle measurement estimation in the single-base and MISO modes respectively. Specifically: Mix the echo data received by multiple sub-arrays of each platform, shift the frequency to the intermediate frequency to obtain the mixed data, use the mixed data to form the data of the sum channel, azimuth difference channel, and elevation difference channel, and then perform channel separation, filtering and decimation, pulse compression, and MTD coherent accumulation on the data of the sum channel, azimuth difference channel, and elevation difference channel respectively to obtain the first processed data. Perform non-coherent accumulation, CFAR detection, and centroid condensation processing on the first processed data in sequence to obtain the second processed data, use the second processed data for target detection, and for the case of detecting a target, estimate the MISO coherent parameters using the data after MTD coherent accumulation processing in the sum channel, and perform MISO coherent synthesis on the sum channel, azimuth difference channel, and elevation difference channel, and perform monopulse angle measurement estimation according to the data after MISO coherent synthesis. The present invention utilizes the characteristic that the sum channel has higher signal energy, uses the data of the sum channel for CFAR target detection and MISO coherent parameter estimation to improve the signal-to-noise ratio and the accuracy of MISO coherent parameter estimation, and then uses the relatively high-precision coherent parameters estimated by the sum channel for coherent synthesis of the difference channel, which can improve the accuracy of coherent synthesis of the difference channel, thereby realizing high-precision monopulse angle measurement estimation. For example, by using the method of MISO coherent parameter estimation, the angle measurement accuracy can be improved by N 1 / 2 times, and finally the target detection probability is improved, making the target detection more stable. It can be seen that the present invention greatly improves the monopulse angle measurement accuracy and provides a new idea for the research of improving the conventional monopulse angle measurement method.

[0042] The following will further elaborate on the present invention in conjunction with the accompanying drawings and embodiments. Description of the Drawings

[0043] Figure 1 is a schematic flow chart of a monopulse angle measurement method based on distributed array coherent synthesis provided by an embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of the system space three-dimensional geometric model provided by an embodiment of the present invention;

[0045] Figure 3 is a schematic diagram of the planar sub-array layout structure corresponding to each platform provided by an embodiment of the present invention;

[0046] Figure 4 is a schematic flow chart of the monopulse angle measurement estimation process provided by an embodiment of the present invention;

[0047] Figure 5 It is a schematic flow chart of another monopulse angle measurement method based on distributed array coherent synthesis provided by an embodiment of the present invention;

[0048] Figure 6 It is a schematic flow chart of another monopulse angle measurement estimation process provided by an embodiment of the present invention;

[0049] Figure 7 It is a schematic flow chart of a target tracking method provided by an embodiment of the present invention;

[0050] Figure 8 It is a schematic diagram of the simulation result of estimating the direction of arrival angle of a target provided by an embodiment of the present invention;

[0051] Figure 9 It is a schematic diagram of the simulation result of the root mean square error of the angle measurement accuracy varying with the signal-to-noise ratio provided by an embodiment of the present invention;

[0052] Figure 10 It is a schematic diagram of the simulation result of the root mean square error of the angle measurement accuracy varying with the signal-to-noise ratio after the coherent synthesis is performed on each channel using the coherent parameters estimated by the sum channel and the coherent synthesis is performed on each channel using the coherent parameters estimated by itself respectively to estimate the direction of arrival of the target.

[0053] Figure 11 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. Detailed implementation manners

[0054] The following further describes the present invention in detail with specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0055] In order to achieve high-precision monopulse angle measurement estimation for a distributed array coherent synthesis system, an embodiment of the present invention designs a set of signal processing flow schemes. Please refer to Figure 1 , an embodiment of the present invention provides a monopulse angle measurement method based on distributed array coherent synthesis, which is applied to a multi-platform distributed coherent system composed of multiple platforms as shown in Figure 2 . Each platform includes multiple sub-arrays as shown in Figure 3 . This set of flow schemes can achieve monopulse angle measurement estimation in the single-base and MISO modes respectively. The method specifically includes the following steps:

[0056] S10. Mix the echo data received by multiple sub-arrays of each platform, and shift the frequency to the intermediate frequency to obtain the mixed data.

[0057] In the multi-platform distributed coherent system according to the embodiments of the present invention, a three-dimensional rectangular coordinate system in space is first established. A target corresponds to a spatial point position information, its velocity information, elevation angle information, and azimuth angle information in the three-dimensional rectangular coordinate system in space. Each platform corresponds to a spatial point position information, its velocity information, elevation angle information, and azimuth angle information in the three-dimensional rectangular coordinate system in space. In the case of a fixed platform, the velocities of multiple platforms are all 0; in the case of a moving platform, the velocities of multiple platforms are determined according to specific situations.

[0058] In the above three-dimensional rectangular coordinate system in space, a received signal model is constructed: Assume that N platforms constitute a multi-platform distributed coherent system. Each platform can independently transmit signals and also receive signals. Let m represent the serial number of the platform when transmitting signals, and l represent the serial number of the platform when receiving signals. Then the signal transmitted by the m-th platform is where, w0, are the carrier frequency and the initial phase of the signal transmitted by the m-th platform respectively. The echo data corresponding to the signal transmitted by the m-th platform received by the l-th platform is where, τ lm =τ l +τ m represents the time delay of the signal transmitted by the m-th platform reaching the l-th platform after being reflected by the target. a lm is the scatterer response on this path.

[0059] Taking the signal received by the l-th platform as an example, the superimposed signal of the N waveforms received by the l-th platform is:

[0060]

[0061] Correspondingly, the mixing data formula for mixing the echo data received by multiple sub-arrays of each platform and shifting it to the intermediate frequency is expressed as:

[0062]

[0063] where, A l (t) represents the mixing data corresponding to the echo data received by the l-th platform. N represents the number of platforms in the system. a lm represents the scatterer response on the receiving path of the signal transmitted by the m-th platform and reaching the l-th platform after being reflected by the target. s m (t - τ lm ) represents the signal transmitted by the m-th platform. w0 represents the carrier frequency, represents the initial phase of the signal transmitted by the m-th platform, represents the initial phase of the signal received by the l-th platform, τ lm =τ l +τ mDenote the time delay when the signal transmitted by the m-th platform reaches the l-th platform after being reflected by the target as τ m Denote the time delay when the signal transmitted by the m-th platform reaches the target as τ l Denote the time delay when the signal reflected from the target reaches the l-th platform for reception. Among them, w0 indicates that the carrier frequency is mixed and shifted to the intermediate frequency.

[0064] The following takes the case of two moving platforms transmitting frequency-modulated pulse signals as an example for further introduction:

[0065] As Figure 2 shown, assume that platform A is located at the spatial point (x A , y A , z A ), platform B is located at the spatial point (x B , y B , z B ), and the target C is located at the spatial point (x C , y C , z C ); the speed of platform A is V A (V Ax , V Ay , V Az ), the pitch angle is and the azimuth angle is θ A ; the speed of platform B is V B (V Bx , V By , V Bz ), the pitch angle is and the azimuth angle is θ B ; the speed of the target C is V C (V Cx , V Cy , V Cz ), the pitch angle is and the azimuth angle is θ C .

[0066] The signal formula transmitted by platform A is expressed as:

[0067] x1(t) = cos(2πF1t + πμt 2 ) (3)

[0068] The signal formula transmitted by platform B is:

[0069] x2(t) = cos(2πF2t + πμt 2 ) (4)

[0070] Among them, F1 represents the transmission signal frequency of platform A, F2 represents the transmission signal frequency of platform B, and μ = B m / T e represents the frequency modulation slope, Bm denotes the bandwidth of the signal transmitted by the m-th platform, T e denotes the pulse width, and t is the transmission time series.

[0071] Taking platform A as an example, the echo data received by platform A is the result of the superposition of the monostatic echo and the bistatic echo. Then the real echo signal received can be expressed as:

[0072]

[0073] where τ 11 denotes the delay of the signal transmitted by platform A after being reflected by the target and reaching platform A to receive the echo data, and τ 12 denotes the delay of the signal transmitted by platform B after being reflected by the target and reaching platform A to receive the echo data, and N(t) represents the receiver noise.

[0074] Since the receiving channel of the signal processor requires the intermediate frequency signal to be f0, the receiver needs to mix the echo data to the signal with an intermediate frequency of f0. The formula of the mixed signal is expressed as:

[0075] x'(t) = cos[2πf1t + πμ(t - τ 11 ) 2 - 2πF1τ 11 + cos[2πf2t + πμ(t - τ 12 ) 2 - 2πF2τ 12 + N'(t)(6)

[0076] where f1 denotes the intermediate frequency of the monostatic signal after mixing the echo data received by platform A, f2 denotes the frequency of the bistatic signal after mixing the echo data received by platform A, and f0 is between f1 and f2.

[0077] S20. Use the mixed data to form the data of the sum channel, the elevation difference channel, and the azimuth difference channel, and perform channel separation on the data of the sum channel, the elevation difference channel, and the azimuth difference channel to obtain the superimposed echo data corresponding to each platform; among them, the superimposed echo data includes monostatic echo data and multi-static echo data.

[0078] Before forming the data of the sum channel, the elevation difference channel, and the azimuth difference channel in the embodiments of the present invention, the mixed data can be first sampled by an analog-to-digital converter (ADC), and then the sampled data is used to form the data of the sum channel, the elevation difference channel, and the azimuth difference channel. That is, using the mixed data to form the data of the sum channel, the elevation difference channel, and the azimuth difference channel includes: sampling the mixed data by ADC, and using the sampled data to form the data of the sum channel, the elevation difference channel, and the azimuth difference channel.

[0079] Since monopulse processing includes synthesis and beam Σ, azimuth difference beam Δ az , elevation difference beam Δ el , that is, the data corresponding to the sum channel, elevation dimension difference channel, and azimuth dimension difference channel respectively. The normalized error signals in the elevation dimension and azimuth dimension can be obtained by dividing the signals of the elevation dimension difference channel and azimuth dimension difference channel by the signal of the sum channel respectively, so as to determine the angle measurement of the target. A specific optional solution provided by the embodiment of the present invention is to form the data of the sum channel, elevation dimension difference channel, and azimuth dimension difference channel by using the sampled data corresponding to the conical scanning beams formed by multiple sub-arrays of each platform.

[0080] Taking the example that multiple sub-arrays of each platform form 4 conical scanning beams, the 4 conical scanning beams are respectively denoted as A, B, C, and D. By first forming the sum (A + B) and (C + D), and then calculating the difference between (A + B) and (C + D), a larger elevation angle difference signal Δ el is obtained; similarly, by first forming the sum (A + D) and (B + C), and then calculating the difference between (A + D) and (B + C), a larger azimuth angle difference signal Δ az can be obtained;

[0081] Next, channel separation is performed on the data of the sum channel, azimuth dimension difference channel, and elevation dimension difference channel to obtain the superimposed echo data corresponding to each platform; among them, the superimposed echo data includes monostatic echo data and multistatic echo data. It can be seen that the superimposed echo data corresponding to the data of the sum channel, azimuth dimension difference channel, and elevation dimension difference channel includes monostatic echo data and multistatic echo data.

[0082] S30. Perform filtering decimation, pulse compression, and MTD coherent accumulation processing on the superimposed echo data corresponding to each platform in sequence to obtain the first processed data.

[0083] In the embodiment of the present invention, filtering decimation processing is first performed on the superimposed echo data corresponding to each platform, which can reduce the amount of data in the processing process to reduce the difficulty of hardware processing implementation. For example, in the embodiment of the present invention, the filtering decimation is 8 times, and the decimated signal is the result of extracting 1 point every 8 points of the original superimposed echo signal.

[0084] For convenience, it is assumed that the scatterer responses on all paths are the same, let α = a in formula (2) lm , and perform pulse compression on A l (t). Then the output formula of the mixed-frequency data transmitted by the mth platform and reflected by the target and reaching the lth platform after pulse compression is expressed as:

[0085]

[0086] wherein, β(t - τ lm ) represents the main lobe response after filtering and decimation, n lm (t) is the noise on the receiving path of the m-th platform's transmission reaching the l-th platform after being reflected by the target, (·) * represents taking the conjugate, represents the convolution operation. Perform Doppler-dimensional FFT on the result after pulse compression to achieve MTD coherent accumulation and obtain the first processed signal. The first processed signal has a relatively high signal-to-noise ratio and prepares for the next signal processing step.

[0087] S40. Perform non-coherent accumulation, CFAR detection, and centroid condensation processing on the first processed data in sequence to obtain the second processed data.

[0088] In the embodiment of the present invention, non-coherent accumulation is performed on the first processed data to improve the signal-to-noise ratio for better subsequent CFAR detection.

[0089] Then, perform CFAR detection on the result of non-coherent accumulation processing. The purpose of CFAR constant false alarm processing is to keep the false alarm rate of signal detection constant under interference so that the computer will not be overloaded due to too many false alarms during data processing. Generally, a certain combination of adjacent reference units in the range or Doppler dimension is used for averaging to further estimate the level. The CFAR detection here is actually a sliding window detection in the range and Doppler dimensions, which involves the selection of several parameters: the guard cell is to prevent the appearance of targets in the reference cells, and its selection needs to refer to the target size and the size of the resolution cell; the reference cells are centered on the detection cell, and a total of M reference cells are selected on the left and right for averaging to obtain the estimated level value Z of the background interference noise, and the detection threshold is K·Z. In the case of a single target, the more reference cells, the more accurate the estimation, but in the presence of multiple targets, there will be interference.

[0090] Finally, perform centroid condensation processing on the result of CFAR constant false alarm processing to obtain the second processed data. A single target may split into multiple targets after CAFR sliding window detection: the target occupies multiple range cells due to sidelobe interference, the target has multiple scattering points in azimuth / range, and the sliding window detection causes target splitting, etc. Centroid condensation processing can re-condense the split targets into one target, so that the target can be effectively detected from the obtained second processed data. Among them, the range cell is determined by the target size and the range resolution cell, and the selection of the velocity cell is related to the target mobility.

[0091] S50. Determine whether a target is detected according to the second processed data. If a target is found, use the data after MTD coherent accumulation processing in the sum channel of the first processed data for MISO coherent parameter estimation.

[0092] As can be seen from the above, the second processed data obtained through S40 can better detect the target. When the target is found based on the second processed data, the next step is to continue, that is, to use the data after the coherent accumulation processing of the sum channel MTD in the first processed data for MISO coherent parameter estimation. The MISO coherent parameter estimation results include the estimation of MISO delay coherent parameters and MISO phase coherent parameters. The estimated value of the MISO delay coherent parameter is denoted as which represents the MISO delay coherent parameter of the signal transmitted by the m-th platform to the target, which represents the MISO delay coherent parameter of the signal reflected from the target and received by the l-th platform. The estimated value of the MISO phase coherent parameter is denoted as where w0 represents the carrier frequency, which represents the MISO phase coherent parameter of the signal transmitted by the m-th platform, which represents the MISO phase coherent parameter of the signal received by the l-th platform.

[0093] It should be noted that for the case where the target is not detected based on the second processed data, it is possible to return to S10 to continue the calculation of a new round of mixing data until the target is detected, and then execute the subsequent signal processing process.

[0094] S60: Use the estimated MISO coherent parameters to perform MISO coherent synthesis on the sum channel, elevation difference channel, and azimuth difference channel.

[0095] In the embodiment of the present invention, the MISO parameter estimation result is obtained through S50. After aligning the N-channel echo data in time and phase, the signal formula is expressed as:

[0096]

[0097] After variable substitution The above formula (8) can be simplified to:

[0098]

[0099] Finally, the superimposed signal of the N waveforms received by the l-th platform, that is, the data formula after MISO coherent synthesis, is expressed as:

[0100]

[0101] where A(t) represents the data after MISO coherent synthesis, represents the data after aligning the MISO coherent parameter estimation results of the signal transmitted by the m-th platform and reflected by the target and received by the l-th platform in time and phase, It represents the MISO delay coherence parameter for the signal transmitted by the m-th platform and received by the l-th platform after reflection from the target. It represents the MISO delay coherence parameter for the signal transmitted by the m-th platform to the target. It represents the MISO delay coherence parameter for the signal received by the l-th platform after reflection from the target. It represents the MISO phase coherence parameter for the signal transmitted by the m-th platform and received by the l-th platform after reflection from the target, α = a lm It represents the response of the scatterer on the path, β(t - ε lm ) represents the main lobe response in MISO coherent synthesis. w0 represents the carrier frequency. It represents the MISO phase coherence parameter for the signal transmitted by the m-th platform. It represents the MISO phase coherence parameter for the signal received by the l-th platform. n lm (t) represents the noise on the path from the signal transmitted by the m-th platform and received by the l-th platform after reflection from the target in MISO coherent synthesis.

[0102] S70. Use the data after MISO coherent synthesis for monopulse angle measurement estimation.

[0103] Through the research of the inventor, it is found that: Let be the direction of the incoming wave from the target, be the direction of the antenna boresight, and be two partially overlapping beams formed on the left and right of the direction of the incoming wave from the target, represents the angle between the antenna boresight and the beam. Only when , that is, when the direction of the incoming wave from the target coincides with the direction of the antenna boresight, the intensities of the amplitudes of the two beams are the same, and the ratio of the amplitudes is 1; while when , that is, when the direction of the incoming wave from the target deviates from the direction of the antenna boresight, the intensities of the amplitudes of the two beams are different, and the ratio of the amplitudes is not 1. The radar forms the receiving pattern through Digital Beam Forming (DBF for short), and its transmitting pattern is obtained through pulse synthesis. When forming the sum and difference beams, the receiving DBF and pulse synthesis processing can be carried out simultaneously in the and directions to obtain the beams and Then subtract and add these two beams to obtain the sum and difference beams, and the error angle can be obtained by comparing the sum and difference beams.

[0104] If the angle between the target incoming wave direction and the antenna boresight direction is called the error angle, then there is a definite one-to-one correspondence between the ratio of the amplitudes of the two beams and the error angle. According to the ratio of the received beam amplitudes, the corresponding error angle can be obtained, and by correcting the antenna boresight angle with the error angle, an accurate estimate of the target incoming wave direction may be obtained. Therefore, based on the above analysis, the embodiments of the present invention propose to calculate an error angle table in advance according to a multi-platform distributed coherent system and store it in a computer. The error angle table includes an azimuth dimension error angle table and an elevation dimension error angle table for monopulse angle measurement estimation. Please refer to Figure 4 , and the specific process of monopulse angle measurement estimation includes:

[0105] S701. Calculate the synthesized data of the sum channel, azimuth difference channel, and elevation difference channel respectively according to the data after MISO coherent synthesis; since the signal forms after MISO coherent synthesis of the sum channel, elevation difference channel, and azimuth difference channel are the same, only the signal amplitudes are different. Calculate the synthesized data of the sum channel, azimuth difference channel, and elevation difference channel after MISO coherent synthesis respectively according to formula (10), which are ∑, Δ az , Δ el .

[0106] S702. Calculate the normalized error data of the data after MISO coherent synthesis in the azimuth dimension and elevation dimension respectively according to the synthesized data of the sum channel, azimuth difference channel, and elevation difference channel; among them, the formula for the normalized error data of the data after MISO coherent synthesis in the azimuth dimension is expressed as:

[0107]

[0108] Similarly, the formula for the normalized error data of the data after MISO coherent synthesis in the elevation dimension is expressed as:

[0109]

[0110] Among them, MRC az represents the normalized error data in the azimuth dimension, MRC el represents the normalized error data in the elevation dimension, (·) * represents taking the conjugate, and Real(·) represents taking the real part.

[0111] S703. Look up the corresponding error angle from the preset error angle table according to the normalized error data in the azimuth dimension and elevation dimension; there is an error angle table corresponding to the azimuth dimension and elevation dimension respectively, and look up the corresponding error angle from the preset error angle table according to the normalized error data in the azimuth dimension and elevation dimension.

[0112] S704. Correct the antenna boresight angle corresponding to each subarray of each platform according to the error angle to achieve monopulse angle measurement estimation.

[0113] Referring to the conventional monopulse radar, the digital monopulse angle measurement accuracy formula is expressed as:

[0114]

[0115] where δ Δθ represents the digital monopulse angle measurement accuracy, θ 3dB represents the half-power beam width, SNR represents the signal-to-noise ratio of the signal received by the unit antenna, and M·N represents the gain of the entire array DBF processing. It can be seen that the performance of digital monopulse angle measurement is greatly affected by SNR. Moreover, after the parameters of a single-platform radar are fixed, its monopulse angle measurement accuracy is already close to the Cramer-Rao lower bound, so the room for improvement is relatively small. And the MISO coherent parameter estimation method proposed in the embodiments of the present invention can theoretically increase the energy of the platform by N times in distributed angle measurement, so theoretically the angle measurement accuracy can be improved by N 1 / 2 times.

[0116] Furthermore, in order to further improve the accuracy of monopulse angle measurement, the embodiments of the present invention design another set of signal processing flow schemes. This set of flow schemes realizes monopulse angle measurement estimation in the single-base, MISO mode, and MIMO mode respectively. On the basis of the above Figure 1 , please refer to Figure 5 , the method of the embodiments of the present invention further includes:

[0117] S80. Perform MIMO coherent parameter estimation using the data after MISO coherent synthesis of the sum channel.

[0118] MIMO coherent synthesis is based on MISO coherent synthesis. MISO processing is performed once on each platform, and then the results of MISO processing on all platforms are fused. MISO coherent synthesis is the superposition of N waveforms received by the l-th platform. The MIMO mode is the superposition of the signals of a total of N 2 echoes received by all N platforms.

[0119] Performing MIMO coherent parameter estimation on the data after MISO coherent synthesis of the sum channel is similar to MISO coherent parameter estimation. The MIMO coherent parameter estimation results include MIMO coherent parameter estimation. The MIMO coherent parameter estimation results include the estimation of MIMO delay coherent parameters and MIMO phase coherent parameters. The estimated value of the MIMO delay coherent parameter is denoted as representing the MIMO delay coherent parameter from the signal transmitted by the m-th platform to the target, representing the MIMO delay coherent parameter from the signal reflected by the target and received by the l-th platform. The estimated value of the MIMO phase coherent parameter is denoted as w0 represents the carrier frequency, represents the MIMO phase coherence parameter of the signal transmitted by the m-th platform, represents the MIMO phase coherence parameter of the signal received by the l-th platform.

[0120] S90. Use the estimated MIMO coherence parameters to perform MIMO coherent synthesis on the sum channel, azimuth difference channel, and elevation difference channel;

[0121] In the embodiment of the present invention, the MIMO parameter estimation result is obtained through S80, and the N 2 echoes received by all N platforms are aligned in time and phase, and finally the N 2 signals received by N platforms are superimposed. The result formula of MIMO coherent synthesis is expressed as:

[0122]

[0123] where A'(t) represents the data after MIMO coherent synthesis, represents the data after the MIMO coherence parameter estimation result of the signal transmitted by the m-th platform and reflected by the target and received by the l-th platform is aligned in time and phase, represents the MIMO delay coherence parameter of the signal transmitted by the m-th platform and reflected by the target and received by the l-th platform, represents the MIMO delay coherence parameter of the signal transmitted by the m-th platform to the target, represents the MIMO delay coherence parameter of the signal reflected from the target and received by the l-th platform, represents the MIMO phase coherence parameter of the signal transmitted by the m-th platform and reflected by the target and received by the l-th platform, α = a lm represents the scatterer response on the path, β'(t - ε′ lm ) represents the main lobe response in MIMO coherent synthesis, w0 represents the carrier frequency, represents the MIMO phase coherence parameter of the signal transmitted by the m-th platform, represents the MIMO phase coherence parameter of the signal received by the l-th platform, n′ lm (t) represents the noise on the path of the signal transmitted by the m-th platform and reflected by the target and received by the l-th platform in MIMO coherent synthesis.

[0124] Correspondingly, S70. Use the data after MISO coherent synthesis to perform monopulse angle measurement estimation, updated as:

[0125] S100. Use the data after MIMO coherent synthesis to perform monopulse angle measurement estimation.

[0126] S100 is implemented similarly to S70. The difference is that during the monopulse angle measurement estimation process, the data used is the data after MIMO coherent synthesis. Please refer to Figure 6 , specifically:

[0127] S1001. Calculate the synthesized data of the sum channel, azimuth difference channel, and elevation difference channel respectively according to the data after MIMO coherent synthesis;

[0128] S1002. Calculate the normalized error data of the data after MIMO coherent synthesis in the azimuth dimension and elevation dimension respectively according to the synthesized data of the sum channel, azimuth difference channel, and elevation difference channel;

[0129] S1003. Look up the corresponding error angle from a preset error angle table according to the normalized error data in the azimuth dimension and elevation dimension; among them, the error angle table is calculated and stored in advance according to a multi-platform distributed coherent system;

[0130] S1004. Correct the antenna boresight angle corresponding to each subarray of each platform according to the error angle to achieve monopulse angle measurement estimation.

[0131] The specific implementation of S1001 - S1004 will not be elaborated here. Please refer to S701 - S704.

[0132] Similar to the MISO coherent parameter estimation method, based on the combination of MISO coherent parameter estimation and MIMO coherent parameter estimation methods, the distributed angle measurement can theoretically increase the energy of the platform by N 2 times. Therefore, theoretically, the angle measurement accuracy can be increased by N times.

[0133] Furthermore, the multi-platform distributed coherent system of the embodiment of the present invention further includes a phased array phase shifter. Please refer to Figure 7 , and the corresponding method further includes:

[0134] S110. Transmit the estimated monopulse angle measurement to the phased array phase shifter to track the target. It can be seen that the monopulse angle measurement estimation of the embodiment of the present invention can be applied to target tracking, but is not limited to target tracking. After the monopulse angle measurement estimation is completed, the estimated monopulse angle measurement is transmitted to the phased array phase shifter, and by adjusting the antenna axis direction corresponding to each subarray of each platform in the multi-platform distributed coherent system, more accurate target tracking can be achieved.

[0135] In order to verify the effectiveness of the monopulse angle measurement method based on distributed array coherent synthesis provided by the embodiment of the present invention, the following experiments are carried out for verification.

[0136] 1. Simulation conditions:

[0137] Environmental configuration: In the simulation experiment of the embodiment of the present invention, the configuration environment of the computer is an Intel(R) Core (i5-3470) 3.20GHZ central processing unit, 4G of memory, and the WINDOWS 10 operating system. The computer simulation software uses MATLAB R2017b software;

[0138] System modeling and simulation parameters: A three-dimensional rectangular coordinate system in space is established. Platform A is located at the spatial point (x A , y A , z A ), where x A = 5000, y A = -5000, z A = 5000; Platform B is located at the spatial point (x B , y B , z B ), and satisfies x A = -x B , y A = -y B , z A = z B ; The target C is located at the spatial point (x C , y C , z C ), where x C = 15000, y C = -15000, z C = 10000; The speed of platform A is V A (V Ax , V Ay , V Az ), where V A = 800m / s, the initial pitch angle is The initial azimuth angle is θ A = 0°, the speed of platform B is V B (V Bx , V By , V Bz ), where V B = 800m / s, the initial pitch angle is The initial azimuth angle is θ B = θ A , the target speed is V C (V Cx , V Cy , V Cz ), where V C = 300m / s, the initial pitch angle is The initial azimuth angle is θ C= -135°. The positions and velocities of the platform and the target are updated once per pulse repetition period;

[0139] Simulation parameters of the antenna array: A uniform planar array is arranged for each platform, with the element spacing D = λ / 2 and the number of elements P = 12;

[0140] Simulation parameters required for various signal processing procedures involved: The sampling rate f required for ADC sampling s = 200 MHz, the number of sampling points nTr corresponding to the pulse repetition period = 40000; The decimation factor C for filtering and decimation = 8, and the order N of the decimation filter l = 64; The number of points for pulse compression nTr3 = 4096; The number of pulses K accumulated by MTD coherent integration = 256; The guard cell N required for CFAR constant false alarm detection p = 4, and the reference cell N r = 10, the detection signal-to-noise ratio DSNR = 20 dB; The range window N1 = 6 and the Doppler window N2 = 5 required for centroid condensation; The time delay difference τ for MISO coherent parameter estimation miso , and the phase difference φ miso ; The time delay difference τ for MIMO coherent parameter estimation mimo , and the phase difference φ mimo ; The number of Monte Carlo experiments N m = 200;

[0141] Simulation parameters of the target signal: The target signal is a chirp signal, and its spatial angles in the elevation and azimuth dimensions are respectively

[0142] 2. Contents of the simulation experiment:

[0143] Simulation 1: Under the above simulation parameter conditions, when the signal-to-noise ratio SNR = 0 dB, the method proposed in the embodiment of the present invention is used to estimate the direction of arrival (DOA) of the target, and the discrete point distribution of the target position estimation value and the target true position is obtained. The results are as Figure 8 shown, Figure 8 where the x-axis and y-axis in Figure 8 respectively represent the azimuth angle and elevation angle of the target, with the unit of degree. It can be seen from Figure 8 that the actual value of the target direction of arrival coincides with the estimated value of the target direction of arrival, indicating that the method proposed in the embodiment of the present invention can accurately estimate the two-dimensional direction of arrival angle information of the azimuth angle and elevation angle of the target.

[0144] Simulation 2: Under the above simulation parameter conditions, when the number of Monte Carlo experiments N m = 200 and the signal-to-noise ratio SNR takes different values, the method proposed in the embodiment of the present invention is used to simulate the variation of the root mean square error of estimating the azimuth angle and elevation angle of the target direction with the signal-to-noise ratio. The results are as Figure 9 shown. It can be seen fromFigure 9 It can be seen that the method proposed in the embodiment of the present invention has better target direction-of-arrival estimation performance, smaller root mean square error for two-dimensional target direction-of-arrival estimation, and more accurate estimation values.

[0145] Simulation 3: Under the above simulation parameter conditions, when the number of Monte Carlo experiments N m = 200 and the signal-to-noise ratio SNR takes different values, the present invention is adopted. The coherent parameters estimated by the sum channel are used for coherent synthesis in the sum channel, the elevation difference channel, and the azimuth difference channel, and then the direction-of-arrival of the target direction is estimated; the coherent parameters estimated by their own channels are used for coherent synthesis in the sum channel, the elevation difference channel, and the azimuth difference channel, and then the direction-of-arrival of the target direction is estimated. The variation of the root mean square error with the signal-to-noise ratio in both cases is simulated, and the results are as Figure 10 shown; It can be seen from Figure 10 that the method proposed in the embodiment of the present invention has better target direction-of-arrival estimation performance and more accurate estimation of coherent parameters. Using the coherent parameters with higher estimation accuracy estimated by the sum channel for coherent synthesis in the difference channel can improve the coherent synthesis effect of the difference channel, thereby making the root mean square error of the two-dimensional target direction-of-arrival estimation smaller and the estimation value more accurate.

[0146] In summary, the monopulse angle measurement method based on distributed array coherent synthesis proposed in the embodiments of the present invention combines the advantages of distributed array coherent synthesis and monopulse angle measurement, designs a set of signal processing flow schemes, and this set of flow schemes can achieve monopulse angle measurement estimation in the monostatic and MISO modes respectively. Specifically: the echo data received by multiple sub-arrays of each platform are mixed, and the frequency is shifted to the intermediate frequency to obtain the mixed data. The data of the sum channel, azimuth difference channel, and elevation difference channel are formed by using the mixed data. Then, channel separation, filtering and decimation, pulse compression, and MTD coherent accumulation are performed on the data of the sum channel, azimuth difference channel, and elevation difference channel respectively to obtain the first processed data. Non-coherent accumulation, CFAR detection, and centroid condensation processing are sequentially performed on the first processed data to obtain the second processed data. The second processed data is used for target detection. In the case of detecting a target, the MISO coherent parameters are estimated by using the data after MTD coherent accumulation processing in the sum channel of the first processed data, and MISO coherent synthesis is performed on the sum channel, azimuth difference channel, and elevation difference channel. Monopulse angle measurement estimation is performed according to the data after MISO coherent synthesis. The embodiments of the present invention utilize the characteristic that the sum channel has higher signal energy, and adopt the data of the sum channel for CFAR target detection and MISO coherent parameter estimation to improve the signal-to-noise ratio and the accuracy of MISO coherent parameter estimation. Furthermore, the coherent synthesis accuracy of the difference channel can be improved by using the relatively high-precision coherent parameters estimated by the sum channel, so as to achieve high-precision monopulse angle measurement estimation. For example, by using the method of MISO coherent parameter estimation, the angle measurement accuracy can be improved by N 1 / 2 times, and finally the target detection probability is increased, making the target detection more stable. It can be seen that the embodiments of the present invention greatly improve the monopulse angle measurement accuracy and provide a new idea for the research of improving the conventional monopulse angle measurement method.

[0147] Meanwhile, the embodiment of the present invention designs another set of signal processing flow schemes. This set of flow schemes can achieve monopulse angle measurement estimation in the MIMO mode. Based on the data after MISO coherent synthesis above, MIMO coherent parameter estimation is performed using the data after MISO coherent synthesis in the sum channel. The estimated MIMO coherent parameters are used to perform MIMO coherent synthesis on the sum channel, the azimuth difference channel, and the elevation difference channel. Finally, monopulse angle measurement estimation is performed using the data after MIMO coherent synthesis. Another set of signal processing flow schemes proposed by the embodiment of the present invention, based on the data after MISO coherent synthesis above, simultaneously uses the data in the sum channel for MIMO coherent parameter estimation, which can improve the accuracy of MIMO coherent parameter estimation. By combining MISO coherent parameters with MIMO coherent parameter estimation, the angle measurement accuracy can be further increased by N times. It can be seen that the embodiment of the present invention further greatly improves the monopulse angle measurement accuracy, providing another new idea for the research on improving the conventional monopulse angle measurement method.

[0148] Please refer to Figure 11 , the embodiment of the present invention provides an electronic device, including a processor 1101, a communication interface 1102, a memory 1103, and a communication bus 1104. Among them, the processor 1101, the communication interface 1102, and the memory 1103 complete mutual communication through the communication bus 1104;

[0149] The memory 1103 is used to store computer programs;

[0150] The processor 1101 is used to implement the steps of the above monopulse angle measurement method based on distributed array coherent synthesis when executing the program stored on the memory 1103.

[0151] The embodiment of the present invention provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above monopulse angle measurement method based on distributed array coherent synthesis are implemented.

[0152] For the device / electronic device / storage medium embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For related parts, please refer to the partial description of the method embodiment.

[0153] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0154] Although the present application has been described in connection with various embodiments, it will be understood by those skilled in the art that other variations of the disclosed embodiments can be understood and effected while practicing the claimed application. Looking at the drawings, the disclosure, and the appended claims, in the claims, the word "comprising" does not exclude other elements or steps, and the singular "a" or "one" does not exclude a plurality. A single processor or other unit may implement several functions recited in the claims. Certain measures are recited in mutually different dependent claims, but this does not mean that these measures cannot be combined to good effect.

[0155] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A monopulse angle measurement method based on distributed array coherent synthesis, characterized in that, Applied to a multi-platform distributed coherent system composed of multiple platforms, each platform including multiple sub-arrays, the method comprises: Mix the echo data received by multiple sub-arrays of each platform, and move the frequency to the intermediate frequency to obtain mixed data; The mixed data is used to form data of a sum channel, a pitch dimension difference channel and an azimuth dimension difference channel, and the sum channel, the pitch dimension difference channel and the azimuth dimension difference channel are subjected to channel separation to obtain superimposed echo data corresponding to each platform; wherein the superimposed echo data includes single-base echo data and multi-base echo data; The superimposed echo data corresponding to each platform is sequentially subjected to filtering extraction, pulse compression, and MTD coherent accumulation processing to obtain the first processed data; Performing non-coherent accumulation, CFAR detection and centroid aggregation processing on the first processed data in sequence to obtain second processed data; Determine whether the target is detected according to the second processed data, and if found, estimate the MISO coherent parameters using the data processed by the first processed data and the channel MTD coherent accumulation; The estimated MISO coherent parameters are used to perform MISO coherent synthesis on the sum channel, the elevation dimension difference channel and the azimuth dimension difference channel; The single pulse angle estimation is performed using the data synthesized by MISO coherent synthesis.

2. The monopulse angle measurement method based on distributed array coherent synthesis according to claim 1, wherein The mixing data formula is expressed as: Among them, A l (t) represents the mixed-frequency data corresponding to the echo data received by the l-th platform, N represents the number of platforms in the system, a lm represents the scatterer response on the receiving path of the l-th platform after the signal transmitted by the m-th platform is reflected by the target, s m (t - τ lm ) represents the signal transmitted by the m-th platform, w0 represents the carrier frequency, represents the initial phase of the signal transmitted by the m-th platform, represents the initial phase of the signal received by the l-th platform, τ lm = τ l + τ m represents the time delay of the signal transmitted by the m-th platform after being reflected by the target and reaching the l-th platform, τ m represents the time delay of the signal transmitted by the m-th platform to the target, τ l represents the time delay of the signal reflected from the target and received by the l-th platform.

3. The monopulse angle measurement method based on distributed array coherent synthesis according to claim 2, wherein The method of using the mixed frequency data to form the data of the sum channel, the pitch dimension difference channel and the azimuth dimension difference channel comprises: The mixed data corresponding to the conical scanning beam formed by multiple sub-arrays of each platform is used to form data of a sum channel, a pitch dimension difference channel and an azimuth dimension difference channel.

4. The monopulse angle measurement method based on distributed array coherent synthesis according to claim 2, characterized in that, The data formula after the MISO coherent synthesis is expressed as: Among them, A(t) represents the data after MISO coherent synthesis, represents the data after alignment in time and phase of the MISO coherent parameter estimation result of the signal transmitted by the m-th platform and received by the l-th platform after reflection by the target, represents the MISO delay coherent parameter of the signal transmitted by the m-th platform and received by the l-th platform after reflection by the target, represents the MISO delay coherent parameter of the signal transmitted by the m-th platform to the target, represents the MISO delay coherent parameter of the signal reflected by the target and received by the l-th platform, represents the MISO phase coherent parameter of the signal transmitted by the m-th platform and received by the l-th platform after reflection by the target, α = a lm represents the scatterer response on the path, β(t - ε lm ) represents the main lobe response in MISO coherent synthesis, w0 represents the carrier frequency, represents the MISO phase coherent parameter of the signal transmitted by the m-th platform, represents the MISO phase coherent parameter of the signal received by the l-th platform, n lm (t) represents the noise on the path of the signal transmitted by the m-th platform and received by the l-th platform after reflection by the target in MISO coherent synthesis.

5. The monopulse angle measurement method based on distributed array coherent synthesis according to claim 2, wherein, The method further comprises: MIMO coherent parameter estimation is performed using the data synthesized by coherent synthesis with channel MISO; The estimated MIMO coherent parameters are used to perform MIMO coherent synthesis on the sum channel, azimuth dimension difference channel and elevation dimension difference channel; Correspondingly, the single pulse angle estimation using the data after MISO coherent synthesis includes: The single pulse angle estimation is performed using the data after MIMO coherent synthesis.

6. The monopulse angle measurement method based on distributed array coherent synthesis according to claim 5, characterized in that The result formula of the MIMO coherent synthesis is expressed as: Among them, A'(t) represents the data after MIMO coherent synthesis. It represents the data after the MIMO coherent parameter estimation results of the signals transmitted by the m-th platform and received by the l-th platform after being reflected by the target are aligned in time and phase. It represents the MIMO delay coherent parameter of the signals transmitted by the m-th platform and received by the l-th platform after being reflected by the target. It represents the MIMO delay coherent parameter of the signals transmitted by the m-th platform to the target. It represents the MIMO delay coherent parameter of the signals reflected by the target and received by the l-th platform. It represents the MIMO phase coherent parameter of the signals transmitted by the m-th platform and received by the l-th platform after being reflected by the target, α = a lm It represents the scatterer response on the path, β'(t - ε l ' m ) represents the main lobe response in MIMO coherent synthesis. w0 represents the carrier frequency. It represents the MIMO phase coherent parameter of the signals transmitted by the m-th platform. It represents the MIMO phase coherent parameter of the signals received by the l-th platform. n l ' m (t) represents the noise on the path of the signals transmitted by the m-th platform and received by the l-th platform after being reflected by the target in MIMO coherent synthesis.

7. The monopulse angle measurement method based on distributed array coherent synthesis according to claim 1 or 5, characterized in that The process of single pulse angle measurement and estimation includes: Calculate the synthesized data of the sum channel, the azimuth dimension difference channel, and the elevation dimension difference channel respectively according to the coherently synthesized data; wherein the coherently synthesized data includes the MISO coherently synthesized data and the MIMO coherently synthesized data; According to the synthesized data of the azimuth dimension difference channel and the elevation dimension difference channel of the sum channel, respectively, normalized error data of the data after coherent synthesis in the azimuth dimension and the elevation dimension are calculated; According to the normalized error data of the azimuth dimension and the pitch dimension, a corresponding error angle is obtained by searching from a preset error angle table; wherein the error angle table is calculated in advance according to the multi-platform distributed coherent system; The antenna boresight angle corresponding to each subarray of each platform is corrected according to the error angle to achieve single pulse angle estimation.

8. The monopulse angle measurement method based on distributed array coherent synthesis according to claim 1 or 5, characterized in that The multi-platform distributed coherent system further includes a phased array phase shifter, and the corresponding method further includes: The estimated monopulse angle measurement is transmitted to the phased array phase shifter to track the target.

9. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete mutual communication through the communication bus; The memory is used to store computer programs; When the processor executes the programs stored on the memory, it realizes the steps of the monopulse angle measurement method based on distributed array coherent synthesis according to any one of claims 1 to 8.

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