A Radar Signal Processing Method Based on Polarization Weighted Combining Technology for External Radiation Sources

Abstract

This invention proposes a radar signal processing method for external radiation sources based on polarization-weighted combining technology. The method involves acquiring monitoring signals using an orthogonally polarized antenna; correcting for array errors using polarization calibration; obtaining a clean reference signal through signal reconstruction; suppressing interference and clutter signals using spatial and temporal filtering methods to obtain filtered horizontal and vertical channel data; performing matched filtering on the filtered horizontal and vertical channel data with the clean reference signal to obtain the range-Doppler spectra of the horizontal and vertical channels, respectively; combining the two channel data using a polarization-weighted combining method to achieve a target signal-to-noise ratio superior to either single-polarized channel; and obtaining continuous target detection points using a constant false alarm rate (CFAR) detection method.

Description

Technical Field

[0001] This invention relates to the field of signal processing technology, and specifically to a method for processing external radiation source radar signals based on polarization weighted combining technology. Background Technology

[0002] External radiation source radar, as a novel radar system, has become a research hotspot in recent years due to its non-radiating and low-cost characteristics. As the name suggests, external radiation source radar utilizes external radiation sources such as civilian broadcast television signals, and its emission source is uncontrollable. External radiation source radar processing methods typically employ coherent processing techniques, requiring at least two channels in the receiving system: a reference channel and a monitoring channel, used to receive the reference signal and target echo signal respectively. Therefore, external radiation source radar is a special type of bistatic / multistatic radar system. The polarization scattering characteristics of a target are multi-parameter variables related to factors such as signal frequency, incident angle, reflection angle, target structure, material, and flight attitude. Changes in these parameters cause fluctuations in the signal strength of different polarization receiving channels in the radar system, which is highly detrimental to target detection in traditional single-polarization external radiation source radar. This invention proposes a novel signal processing method based on polarization weighted merging technology. Experiments have verified that this method effectively utilizes the polarization fluctuation characteristics of the two polarization channels, improving the target signal detection performance of external radiation source radar.

[0003] Polarization-weighted combining technology combines signals from different polarization channels in a weighted manner, effectively improving the signal-to-noise ratio (SNR) of the target signal. This invention combines polarization-weighted combining technology with external radiation source radar correlation technology to enhance the target signal and reduce the impact of noise and residual clutter signals on the target SNR. The method proposed in this invention can serve as a supplement to existing detection methods and is of research significance.

[0004] Improving the detection performance of external radiation source radar has always been a research hotspot and challenge in the field. Traditional single-polarization external radiation source radar systems cannot acquire target polarization information, and their detection performance is significantly affected by the scintillation of target scattered echoes from different polarization channels. Polarized external radiation source radar uses polarized receiving antennas, which can effectively receive multi-polarization scattered echo signals from targets. Traditional polarization incoherent accumulation methods can enhance target signals and improve target detection performance; however, due to the imbalance of the signal-to-noise ratio of targets in different polarization channels, the final detection performance may even be worse than that of a single-polarization radar system. Therefore, finding an effective and robust target signal enhancement method for polarized external radiation source radar is essential. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a method for processing radar signals from external radiation sources based on polarization-weighted merging.

[0006] The technical solution of this invention is a method for processing radar signals from external radiation sources based on polarization-weighted merging, specifically including the following steps:

[0007] Step 1: Acquire polarization monitoring signals using a polarization antenna array, and correct polarization array errors using array calibration technology;

[0008] Step 2: Acquire the reference signal using the reference antenna, and refine the reference signal using a signal reconstruction method;

[0009] Step 3: Perform spatial filtering on the vertical and horizontal channel monitoring signals after calibration in Step 1. Then, perform time-domain filtering on the clean reference signal and the spatially filtered vertical and horizontal channel data described in Step 2 to suppress direct waves and multipath clutter in the monitoring signals, and obtain the filtered vertical and horizontal channel data.

[0010] Step 4: Perform matched filtering on the filtered horizontal channel data from Step 3 and the clean reference signal from Step 2 to obtain the range Doppler spectrum of the horizontal channel signal; perform matched filtering on the filtered vertical channel data from Step 3 and the clean reference signal from Step 2 to obtain the range Doppler spectrum of the vertical channel signal.

[0011] Step 5: Based on the differences in target signal-to-noise ratios in different polarization channels, construct a polarization merging weighted value, and then weight and merge the horizontal and vertical channel data.

[0012] Step 6: Perform target detection on the merged signal using a constant false alarm rate (CFAR) detection method. Preferably, the original polarized antenna array signal mentioned in Step 1 is:

[0013]

[0014] in, This represents the amplitude gain of the k polarization channels; , The initial phase is represented by k, the number of array channels is represented by h, and the number of polarized antennas is represented by h. Representing polarization vectors, γ, φ and These represent the polarization angle, azimuth angle, and polarization phase difference of the emitted polarized wave, respectively. Let d represent the array spatial steering vector matrix, λ be the array spacing, and λ be the polarization wavelength; n(t) be white noise.

[0015] Using active calibration technology, a reference channel is first established, and the relative amplitude and phase errors of other channels compared to the reference channel are obtained using the ratio method. After subtracting the known spatial phase difference, if the reference channel is channel 1, i.e., the vertical channel of the first polarized antenna, the array received signal is:

[0016]

[0017] By accurately measuring the angle between the active calibration transmitting antenna and the array normal, as well as the transmitting polarization angle, the actual error matrix can be obtained; by subtracting the error value from the original array signal data, the data after eliminating amplitude and phase errors can be obtained.

[0018] As a preferred embodiment, the OFDM signal reconstruction flowchart in step 2 is as follows: Figure 2 As shown.

[0019] The basic principle of reference signal reconstruction is to first obtain a clean code stream using demodulation, decoding, and error correction techniques employed in communication, and then repeat the encoding and modulation process performed at the transmitting end to reconstruct the transmitted signal, which is then used as the reference signal for the radar system. Essentially, the reconstruction method only requires that the signal-to-noise ratio of the signal to be reconstructed in the received signal meets certain requirements.

[0020] Preferably, the spatial filtering technique in step 3 is as follows:

[0021] After spatial filtering and interference suppression of the calibrated vertical and horizontal channel monitoring signals described in step 1, the output signal of the vertical antenna array can be expressed as:

[0022]

[0023] The output vector of a horizontal antenna array can be expressed as:

[0024]

[0025] Wherein, "H" is the conjugate transpose symbol; "v" represents vertical polarization and "h" represents horizontal polarization.

[0026] The optimal weight vector for the beamformer vertical array is:

[0027]

[0028] The optimal weight vector for the horizontal array of the beamformer is:

[0029]

[0030] in, The desired direction of signal wave arrival; For guide vector symbols; Here, μ represents the covariance matrix of the array input signal; μ is a scaling constant that can be expressed as:

[0031]

[0032] The time-domain filtering technique described in step 3 is as follows:

[0033] After spatial filtering, further processing of remaining interference and clutter signals is required. The clean reference signal extracted in step 2 is used to perform time-domain cancellation processing on the spatially filtered vertical and horizontal channel monitoring signals. Taking the vertical channel signal as an example, if the power of the remaining signal after interference cancellation is minimized:

[0034]

[0035] in, , This is a clean reference signal;

[0036] Matrix B is a selection matrix, used to select the last N rows of the rightmost adjacent matrix. Matrix B can be represented as:

[0037]

[0038] This is a diagonal matrix, corresponding to the p-th Doppler unit:

[0039]

[0040] Constructing a zero-Doppler delay sequence of the reference signal for:

[0041]

[0042] Where D is the unit delay matrix, which is defined as:

[0043]

[0044] From the formula You can obtain:

[0045]

[0046] Therefore, the vertical channel monitoring signal becomes after clutter suppression:

[0047]

[0048] Matrix P is an orthogonal projection matrix that projects the vertical channel monitoring signal into the orthogonal subspace of the interference signal subspace. In this way, the remaining signal will no longer contain interference signal components, and the interference is suppressed.

[0049] Preferably, the matched filtering technique in step 4 is:

[0050] The pure reference signal described in step 2 is cross-correlated with the filtered data from the vertical and horizontal channels in two dimensions. The matched filtering process for the vertical and horizontal channels is represented as follows:

[0051]

[0052]

[0053] in, Indicates a pure reference signal; and These represent the data after filtering in the vertical channel and the horizontal channel of the monitoring antenna, respectively. ; υ represents the distance-Doppler spectrum, and υ represents the Doppler frequency shift unit.

[0054] As a preferred embodiment, the polarization-weighted merging method described in step 5 is implemented as follows:

[0055] (1) After clutter suppression, the horizontal and vertical channel data are subjected to two-dimensional cross-correlation processing to obtain matched filter data;

[0056] (2) Perform square-law detection on the matched filter data of the horizontal and vertical channels respectively;

[0057] (3) Using the average value of the reference unit as the average noise base of the unit to be detected, calculate the signal-to-noise ratio of the unit to be detected at the same position in the horizontal and vertical polarization channels, and obtain the weight vector in this way;

[0058] (4) Weighted merging of different polarization channels, and inputting the output results into the constant false alarm rate detector;

[0059] (5) Repeat steps 4 to 6 until all data on the distance Doppler are merged and detected;

[0060] See the detailed implementation flowchart. Figure 3 .

[0061] The vertical channel signal range-Doppler spectrum and the horizontal channel signal range-Doppler spectrum described in step 4 are respectively processed by square-law detection. Taking the vertical channel range-Doppler spectrum as an example, the first... k The first channel, the... m The units to be detected are Define the PWC output signal as:

[0062]

[0063] in, , Indicates the first l The first channel, the... m The average value of the reference cell samples for each cell to be tested.

[0064] The specific implementation principle diagram of the polarization weighted merging method is as follows: Figure 4 As shown.

[0065] As a preferred option, the constant false alarm rate (CFAR) detection technique described in step 6 is:

[0066] Taking the Constant False Alarm Rate (CA-CFAR) detector as an example, the detection threshold is determined based on the actual average value of the reference cell samples and the set false alarm probability. If the value of the cell to be detected exceeds the detection threshold, the cell is considered to contain a target; otherwise, the target is considered not to exist. The CA-CFAR processing is as follows: Figure 5 As shown.

[0067] The external radiation source radar signal processing method proposed in this invention combines polarization weighted merging technology with external radiation source radar processing methods. The new signal processing method utilizes the scintillation characteristics between polarization channels, effectively improving the target detection effect.

[0068] This invention employs a variable-weight vector approach, flexibly constructing weighting values ​​based on the varying signal-to-noise ratios of targets in different polarization channels. This effectively avoids the drawback of traditional incoherent accumulation methods, which are susceptible to channel imbalances, resulting in improved robustness in target detection. Compared to single-polarization detection methods and polarization-incoherent accumulation methods, this method achieves superior target detection performance (see...). Figure 6 , 7 8). Attached Figure Description

[0069] Figure 1 This is the process flow of the present invention.

[0070] Figure 2 This is a flowchart of OFDM signal reconstruction.

[0071] Figure 3 This is a flowchart illustrating the specific implementation of the polarization weighted merging method.

[0072] Figure 4 This is a schematic diagram illustrating the specific implementation principle of the polarization weighted merging method.

[0073] Figure 5 This is a schematic diagram of the CA-CFAR processing principle.

[0074] Figure 6 This invention compares the detection results of the external radiation source radar signal processing method based on polarization weighted merging technology and the single-polarization external radiation source radar signal processing method in the vertical channel with the PWC detection results. ADS-B is a broadcast automatic correlation surveillance system.

[0075] Figure 7 This invention compares the detection results of the external radiation source radar signal processing method based on polarization weighted merging technology and the single-polarization external radiation source radar signal processing method in the horizontal channel with the PWC detection results. ADS-B is a broadcast automatic correlation surveillance system.

[0076] Figure 8 This invention compares the detection results of the external radiation source radar signal processing method based on polarization weighted merging technology with those after polarization incoherent accumulation processing. ADS-B is a broadcast automatic correlation surveillance system. Specific implementation methods

[0077] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0078] In this embodiment of the invention, a polarization diversity external radiation source radar is used. The radiation source used in this embodiment of the invention is China Digital Multimedia Broadcasting, which has a transmission frequency of 714MHz and uses an orthogonal polarization antenna to receive signals.

[0079] The following is combined with Figures 1 to 4 The embodiments of the present invention are described below, and the embodiments of the present invention include the following steps:

[0080] Step 1: Acquire polarization monitoring signals using a polarization antenna array, and correct polarization array errors using array calibration technology;

[0081] Step 2: Acquire the reference signal using the reference antenna, and refine the reference signal using a signal reconstruction method;

[0082] Step 3: Perform spatial filtering on the vertical and horizontal channel monitoring signals after calibration in Step 1. Then, perform time-domain filtering on the clean reference signal and the spatially filtered vertical and horizontal channel data described in Step 2 to suppress direct waves and multipath clutter in the monitoring signals, and obtain the filtered vertical and horizontal channel data.

[0083] Step 4: Perform matched filtering on the filtered horizontal channel data from Step 3 and the clean reference signal from Step 2 to obtain the range Doppler spectrum of the horizontal channel signal; perform matched filtering on the filtered vertical channel data from Step 3 and the clean reference signal from Step 2 to obtain the range Doppler spectrum of the vertical channel signal.

[0084] Step 5: Based on the differences in target signal-to-noise ratios in different polarization channels, construct a polarization merging weighted value, and then weight and merge the horizontal and vertical channel data.

[0085] Step 6: Perform target detection on the merged signal using a constant false alarm rate (CFAR) detection method. Preferably, the original polarized antenna array signal mentioned in Step 1 is:

[0086]

[0087] in, This represents the amplitude gain of the k polarization channels; , The initial phase is represented by k, the number of array channels is represented by h, and the number of polarized antennas is represented by h. Representing polarization vectors, γ, φ and These represent the polarization angle, azimuth angle, and polarization phase difference of the emitted polarized wave, respectively. Let d represent the array spatial steering vector matrix, λ be the array spacing, and λ be the polarization wavelength; n(t) be white noise.

[0088] Using active calibration technology, a reference channel is first established, and the relative amplitude and phase errors of other channels compared to the reference channel are obtained using the ratio method. After subtracting the known spatial phase difference, if the reference channel is channel 1, i.e., the vertical channel of the first polarized antenna, the array received signal is:

[0089]

[0090] By accurately measuring the angle between the active calibration transmitting antenna and the array normal, as well as the transmitting polarization angle, the actual error matrix can be obtained; by subtracting the error value from the original array signal data, the data after eliminating amplitude and phase errors can be obtained.

[0091] As a preferred embodiment, the OFDM signal reconstruction flowchart in step 2 is as follows: Figure 2 As shown:

[0092] The basic principle of reference signal reconstruction is to first obtain a clean code stream using demodulation, decoding, and error correction techniques employed in communication, and then repeat the encoding and modulation process performed at the transmitting end to reconstruct the transmitted signal, which is then used as the reference signal for the radar system. Essentially, the reconstruction method only requires that the signal-to-noise ratio of the signal to be reconstructed in the received signal meets certain requirements.

[0093] Preferably, the spatial filtering technique in step 3 is as follows:

[0094] After spatial filtering and interference suppression of the calibrated vertical and horizontal channel monitoring signals described in step 1, the output signal of the vertical antenna array can be expressed as:

[0095]

[0096] The output vector of a horizontal antenna array can be expressed as:

[0097]

[0098] Wherein, "H" is the conjugate transpose symbol; "v" represents vertical polarization and "h" represents horizontal polarization.

[0099] The optimal weight vector for the beamformer vertical array is:

[0100]

[0101] The optimal weight vector for the horizontal array of the beamformer is:

[0102]

[0103] in, The desired direction of signal wave arrival; For guide vector symbols; Here, μ represents the covariance matrix of the array input signal; μ is a scaling constant that can be expressed as:

[0104]

[0105] The time-domain filtering technique described in step 3 is as follows:

[0106] After spatial filtering, further processing of remaining interference and clutter signals is required. The clean reference signal extracted in step 2 is used to perform time-domain cancellation processing on the spatially filtered vertical and horizontal channel monitoring signals. Taking the vertical channel signal as an example, if the power of the remaining signal after interference cancellation is minimized:

[0107]

[0108] in, , This is a clean reference signal;

[0109] Matrix B is a selection matrix, used to select the last N rows of the rightmost adjacent matrix. Matrix B can be represented as:

[0110]

[0111] This is a diagonal matrix, corresponding to the p-th Doppler unit:

[0112]

[0113] Constructing a zero-Doppler delay sequence of the reference signal for:

[0114]

[0115] Where D is the unit delay matrix, which is defined as:

[0116]

[0117] From the formula You can obtain:

[0118]

[0119] Therefore, the vertical channel monitoring signal becomes after clutter suppression:

[0120]

[0121] Matrix P is an orthogonal projection matrix that projects the vertical channel monitoring signal into the orthogonal subspace of the interference signal subspace. In this way, the remaining signal will no longer contain interference signal components, and the interference is suppressed.

[0122] Preferably, the matched filtering technique in step 4 is:

[0123] The pure reference signal described in step 2 is cross-correlated with the filtered data from the vertical and horizontal channels in two dimensions. The matched filtering process for the vertical and horizontal channels is represented as follows:

[0124]

[0125]

[0126] in, Indicates a pure reference signal; and These represent the data after filtering in the vertical channel and the horizontal channel of the monitoring antenna, respectively. ; υ represents the distance-Doppler spectrum, and υ represents the Doppler frequency shift unit.

[0127] As a preferred embodiment, the polarization-weighted merging method described in step 5 is implemented as follows:

[0128] (1) After clutter suppression, the horizontal and vertical channel data are subjected to two-dimensional cross-correlation processing to obtain matched filter data;

[0129] (2) Perform square-law detection on the matched filter data of the horizontal and vertical channels respectively;

[0130] (3) Using the average value of the reference unit as the average noise base of the unit to be detected, calculate the signal-to-noise ratio of the unit to be detected at the same position in the horizontal and vertical polarization channels, and obtain the weight vector in this way;

[0131] (4) Weighted merging of different polarization channels, and inputting the output results into the constant false alarm rate detector;

[0132] (5) Repeat steps 4 to 6 until all data on the distance Doppler are merged and detected;

[0133] See the detailed implementation flowchart. Figure 3 .

[0134] The vertical channel signal range-Doppler spectrum and the horizontal channel signal range-Doppler spectrum described in step 4 are respectively processed by square-law detection. Taking the vertical channel range-Doppler spectrum as an example, the first... k The first channel, the... m The units to be detected are Define the PWC output signal as:

[0135]

[0136] in, , Indicates the first l The first channel, the... m The average value of the reference cell samples for each cell to be tested.

[0137] The specific implementation principle diagram of the polarization weighted merging method is as follows: Figure 4 As shown:

[0138] As a preferred option, the constant false alarm rate (CFAR) detection technique described in step 6 is:

[0139] Taking the Constant False Alarm Rate (CA-CFAR) detector as an example, the detection threshold is determined based on the actual average value of the reference cell samples and the set false alarm probability. If the value of the cell to be detected exceeds the detection threshold, the cell is considered to contain a target; otherwise, the target is considered not to exist. The CA-CFAR processing is as follows: Figure 5 As shown.

[0140] The experimental results obtained through the above steps in the embodiments of the present invention are as follows: Figure 6 , 7 As shown in Figure 8. Figure 6 , 7 The results show that, compared with traditional single-polarization external radiation source radar, the detection performance of the method of the present invention is improved by 8.2% (vertical single-polarization reception) and 14.5% (horizontal single-polarization reception); compared with the polarization incoherent accumulation method, the detection performance is improved by 9.7%.

[0141] It should be understood that the above description of the preferred embodiments is quite detailed, but it should not be considered as a limitation on the scope of protection of this invention. Those skilled in the art, under the guidance of this invention, can make substitutions or modifications without departing from the scope of protection of the claims of this invention, and all such substitutions or modifications fall within the scope of protection of this invention. The scope of protection of this invention should be determined by the appended claims.

Claims

1. A method for processing radar signals from external radiation sources based on polarization-weighted combining technology, characterized in that, Includes the following steps: Step 1: Acquire polarization monitoring signals using a polarization antenna array, and correct polarization array errors using array calibration technology; Step 2: Acquire the reference signal using the reference antenna, and refine the reference signal using the signal reconstruction method to obtain a clean reference signal; Step 3: Perform spatial filtering on the vertical and horizontal channel monitoring signals after calibration in Step 1. Then, perform time-domain filtering on the clean reference signal from Step 2 and the spatially filtered vertical and horizontal channel data to suppress direct waves and multipath clutter in the monitoring signals, and obtain the filtered vertical and horizontal channel data. Step 4: Perform matched filtering on the horizontal channel data after spatial filtering in Step 3 and the clean reference signal in Step 2 to obtain the range Doppler spectrum of the horizontal channel signal; perform matched filtering on the vertical channel data after spatial filtering in Step 3 and the clean reference signal in Step 2 to obtain the range Doppler spectrum of the vertical channel signal. Step 5: Based on the differences in target signal-to-noise ratios in different polarization channels, construct a polarization merging weighted value, and then weight and merge the horizontal and vertical channel data. Step 6: Use the constant false alarm rate (CFAR) detection method to perform target detection on the merged signal.

2. The method for processing external radiation source radar signals based on polarization weighted combining technology according to claim 1, characterized in that: The polarization monitoring signal in step 1 is: in, This represents the amplitude gain of the k polarization channels; , This represents the initial phase, and k represents the number of array channels. h represents the number of polarized antennas; Represents the polarization vector. , , These represent the polarization angle, azimuth angle, and polarization phase difference of the emitted polarized wave, respectively. The array spatial steering vector matrix is ​​represented by d, where d is the array spacing and λ is the polarization wavelength; n(t) represents white noise. Using active calibration technology, a reference channel is first established, and the relative amplitude and phase errors of other channels compared to the reference channel are obtained using the ratio method. After subtracting the known spatial phase difference, if the reference channel is channel 1, i.e., the vertical channel of the first polarized antenna, the array received signal is: By accurately measuring the angle between the active calibration transmitting antenna and the array normal, as well as the transmitting polarization angle, the actual error matrix can be obtained; by subtracting the error value from the original array signal data, the data after eliminating amplitude and phase errors can be obtained.

3. The method for processing external radiation source radar signals based on polarization weighted merging technology according to claim 1, characterized in that: The signal reconstruction method in step 2 is as follows: Sampling: OFDM signal – reference antenna – analog front end – ADC – DDC; Demodulation: Synchronization and OFDM demodulation – Channel estimation and equalization – Constellation inverse mapping – Channel decoding; Modulation: Channel coding – constellation mapping – pilot insertion – OFDM modulation – reference signal reconstruction; The basic principle of reference signal reconstruction is to first obtain a clean code stream using demodulation, decoding, and error correction techniques employed in communication, and then repeat the encoding and modulation process performed at the transmitting end to reconstruct the transmitted signal and use it as the reference signal for the radar system. The reconstruction method essentially only requires that the signal-to-noise ratio of the signal to be reconstructed in the received signal meets certain requirements.

4. The method for processing external radiation source radar signals based on polarization weighted combining technology according to claim 1, characterized in that: The spatial filtering process described in step 3 is as follows: After spatial filtering and interference suppression of the vertical and horizontal channel monitoring signals calibrated in step 1, the output signal of the vertical antenna array is expressed as follows: The output vector of the horizontal antenna array is represented as: Wherein, "H" is the conjugate transpose symbol; "v" represents vertical polarization and "h" represents horizontal polarization; The optimal weight vector for the beamformer vertical array is: The optimal weight vector for the horizontal array of the beamformer is: in, The desired direction of signal wave arrival; For guiding vector symbols; The input signal covariance matrix of the array; A proportionality constant is expressed as: The time-domain filtering process described in step 3 is as follows: After spatial filtering, further processing of remaining interference and clutter signals is required. The clean reference signal extracted in step 2 is used to perform time-domain cancellation processing on the spatially filtered vertical and horizontal channel monitoring signals. Taking the vertical channel signal as an example, if the power of the remaining signal after interference cancellation is minimized: in, , A clean reference signal; Matrix B is a selection matrix, used to select the last N rows of the rightmost adjacent matrix; matrix B is represented as: This is a diagonal matrix, corresponding to the p-th Doppler unit: Constructing a zero-Doppler delay sequence of the reference signal for: Where D is the unit delay matrix, which is defined as: From the formula You can obtain: Therefore, the vertical channel monitoring signal becomes after clutter suppression: Matrix P is an orthogonal projection matrix that projects the vertical channel monitoring signal into the orthogonal subspace of the interference signal subspace. In this way, the remaining signal will no longer contain interference signal components, and the interference is suppressed.

5. The method for processing external radiation source radar signals based on polarization weighted combining technology according to claim 1, characterized in that: The matched filtering technique mentioned in step 4 is as follows: The pure reference signal described in step 2 is cross-correlated with the filtered data from the vertical and horizontal channels in two dimensions. The matched filtering process for the vertical and horizontal channels is represented as follows: in, Indicates a pure reference signal; and These represent the data after filtering in the vertical channel and the horizontal channel of the monitoring antenna, respectively. ; Indicates the distance Doppler spectrum. This represents the Doppler frequency shift unit.

6. The method for processing external radiation source radar signals based on polarization weighted combining technology according to claim 1, characterized in that: The implementation process of the polarization merging weighting value in step 5 is as follows: (1) After clutter suppression, the horizontal and vertical channel data are subjected to two-dimensional cross-correlation processing to obtain matched filter data; (2) Perform square-law detection on the matched filter data of the horizontal and vertical channels respectively; (3) Using the average value of the reference unit as the average noise base of the unit to be detected, calculate the signal-to-noise ratio of the unit to be detected at the same position in the horizontal and vertical polarization channels, and obtain the weight vector accordingly. (4) Weighted merging of different polarization channels, and inputting the output results into the constant false alarm rate detector; (5) Repeat steps 4 to 6 until all data on the distance Doppler are merged and detected; The specific implementation process is as follows: Start – Output after matched filtering – Square-law detection – SNR estimation for H and V channels – Calculation of weighted value W H and W V - Weighted merging of H and V channels - Constant false alarm rate detection - End; The vertical channel signal range-Doppler spectrum and the horizontal channel signal range-Doppler spectrum described in step 4 are respectively processed by square-law detection. Taking the vertical channel range-Doppler spectrum as an example, the first... k The first channel, the... m The units to be detected are The polarization-weighted merged output signal is defined as: in, , Indicates the first l The first channel, the... m The average value of the reference cell samples for each cell to be tested.

7. The method for processing external radiation source radar signals based on polarization weighted combining technology according to claim 1, characterized in that: The constant false alarm rate detection method described in step 6 is as follows: taking the unit average constant false alarm rate detector as an example, the detection threshold is determined based on the actual average value of the reference unit samples and the set false alarm probability. If the unit to be detected is greater than the detection threshold, it is considered that the unit has a target; otherwise, it is considered that the target does not exist.

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