A method and system for suppressing non-stationary clutter of space-based early warning radar

Abstract

The present invention relates to the field of radar signal processing technology, and discloses a non-stationary clutter suppression method and system for space-based early warning radar, including the following steps: S1. Array elements in all directions transmit signals, and encode them in the transmitted signals of different pulses and directions; S2. Incrementally increase the frequency of the transmitted signal of the antenna; S3. Perform down-conversion processing, then perform analog-to-digital conversion, and store the digitized echo data; S4. Perform pitch sub-array synthesis of the data of the digitized echo signal into a single-channel receiving channel, and at the same time perform sub-array synthesis of the data of the echo signal receiving azimuth into a multi-channel receiving channel; S5. Perform matched filtering on the receiving channel of each azimuth respectively, and decode the transmitted signal of each azimuth; S6. Design a pitch spatial domain filter, and perform space-time adaptive processing to filter out clutter. The present invention solves the problem that the prior art cannot effectively suppress non-stationary clutter under the condition of distance ambiguity, and has the characteristics of accuracy and stability.

Description

Technical Field

[0001] The present invention relates to the field of radar signal processing technology, and more specifically, to a method and system for suppressing non-stationary clutter of a space-based early warning radar. Background Art

[0002] Space-based early warning radar uses satellites as payload platforms, so it has many advantages over airborne radar in detecting moving targets, including: it can detect targets around the clock and in all weather conditions, it has a larger detection area, it is not restricted by national boundaries, and it can detect more types of targets, etc. Therefore, space-based early warning radar is an important means for countries to obtain information on moving targets on land, sea, air, and space in the future.

[0003] Similar to airborne early warning radar, space-based early warning radar works downward and moves at high speed, so it must detect targets under strong clutter background. Therefore, how to suppress clutter is a key problem that needs to be solved for target detection of space-based early warning radar. Space-time adaptive processing (STAP) technology uses joint adaptive processing in the spatial and temporal domains to effectively filter out clutter and achieve coherent accumulation of targets. Therefore, it is a key technology for suppressing clutter on moving radar platforms, and it has been widely used in a variety of airborne radars. However, compared with airborne radars, traditional STAP technology will suffer serious performance loss when directly applied to space-based early warning radars. First, the speed of satellites can reach several thousand meters per second, which is much greater than the speed of carrier aircraft, resulting in a much larger clutter distribution bandwidth than that of airborne radars; second, because satellites are located in space, their detectable distance is much greater than that of airborne radars, so the distance ambiguity they face is more serious; finally, due to the rotation of the earth, their clutter has serious non-stationary characteristics. The above three situations will lead to significant differences in the clutter Doppler frequency distribution of clutter in different range rings, which will cause the clutter to be severely broadened in the Doppler domain, resulting in a serious degradation of the performance of traditional STAP.

[0004] At present, relevant research has been conducted at home and abroad on the problem of non-stationary clutter suppression for space-based early warning radars. Among them, the pulse repetition rate optimization method reduces the influence of Doppler ambiguity and range ambiguity by optimizing the pulse repetition frequency, but it cannot fundamentally eliminate non-stationary clutter; the real-time dynamic adjustment of the antenna array axis can theoretically offset the adverse effects of the earth's rotation, but on the one hand, due to the large size of the satellite antenna, it is technically difficult to accurately adjust its axis, and on the other hand, the power consumed by it is difficult to meet on the satellite, so this idea is difficult to implement in actual engineering; the scheme of waveform modulation within the coherent pulse can suppress non-stationary clutter, but at the cost of being unable to resolve range ambiguity.

[0005] In addition to the above-mentioned non-stationary clutter suppression methods for space-based early warning radars, there are also many ideas for non-stationary clutter suppression for airborne early warning radars. Methods such as Doppler warping, Doppler-angle compensation, and space-time interpolation can solve the problem of inconsistent clutter distribution between different training data, but they are only applicable to scenes without range ambiguity, and therefore are not applicable to space-based early warning radars with severe range ambiguity. The array pitch pre-filtering method can pre-filter non-stationary clutter and stabilize the remaining clutter, but this method relies on the accurate acquisition of the simple non-stationary clutter component; the three-dimensional STAP method uses the azimuth-pitch-Doppler joint adaptive processing method to achieve effective decoupling of three-dimensional coupled clutter, but its huge computational burden and massive uniform sample requirements make it unsuitable for practical applications; in addition, the partial dimensionality reduction three-dimensional STAP method can alleviate its computational burden and sample requirement problems, but at the cost of certain performance loss; the frequency diversity array (FDA) implements different array element transmission frequency steps based on the multiple input multiple output (MIMO) system, so that the pitch frequency interval of clutter at different fuzzy distances becomes larger, and then uses pitch beamforming to extract a specific fuzzy distance. Under the condition of sufficient pitch freedom, it can effectively solve the non-stationary clutter problem of airborne radar. However, the range ambiguity of space-based early warning radar is several times more serious than that of airborne radar, and its array antenna has limited pitch freedom, so this method is not suitable for space-based early warning radar.

[0006] In summary, the existing technology has the problem of being unable to effectively suppress non-stationary clutter in the case of range ambiguity. Therefore, how to invent a method that can effectively suppress non-stationary clutter in the case of range ambiguity is a problem that urgently needs to be solved in this technical field. Summary of the invention

[0007] In order to solve the problem that the prior art cannot effectively suppress non-stationary clutter under range ambiguity, the present invention provides a method and system for suppressing non-stationary clutter of a space-based early warning radar, which has the characteristics of accuracy and stability.

[0008] In order to achieve the above-mentioned purpose of the present invention, the technical scheme adopted is as follows:

[0009] A method for suppressing non-stationary clutter of a space-based early warning radar comprises the following steps:

[0010] S1. Transmit signals through the transmitting elements of the antenna of the space-based early warning radar in all directions, and encode them in the transmitted signals of different pulses and directions;

[0011] S2. Incrementally increase the frequency of the signal transmitted by the antenna at each elevation element;

[0012] S3. The radar receives the echo signal, performs down-conversion processing, performs analog-to-digital conversion, and stores the digitized echo data;

[0013] S4. The digitized echo signal data is synthesized into a single-channel receiving channel by pitch sub-arrays, and the return signal receiving azimuth data is synthesized into a multi-channel receiving channel by sub-arrays;

[0014] S5. Perform matched filtering on the receiving channel of each azimuth respectively, and decode the transmission signal of each azimuth;

[0015] S6. Design an elevation spatial domain filter, extract the corresponding elevation main lobe echo in each receiving channel through the elevation spatial domain filter according to the decoded transmission signal, and perform space-time adaptive processing on the extracted elevation main lobe echo to filter out clutter.

[0016] Preferably, in step S1, the signals transmitted by the transmitting array elements in each orientation of the antenna are mutually orthogonal signals.

[0017] Furthermore, in the step S1, encoding is performed in the transmission signals of different pulses and orientations, specifically:

[0018]

[0019] Where n is the number of azimuths of the transmitting array element, k is the number of pulses, N is the maximum number of azimuths, K is the maximum number of pulses, and γ k is a parameter that varies with the pulse, C epc is the encoded transmission signal.

[0020] Furthermore, in step S2, the frequency of the signal transmitted by the antenna at each elevation element is increased incrementally, specifically:

[0021] f m =f 0 +(m-1)Δf,m=1,2,…,M

[0022] Where m is the number of pitch transmission array element signals, M is the maximum number of pitch transmission array element signals, and f 0 is the original reference frequency of the pitch transmitting array element signal, and Δf is the incremental frequency interval of the pitch transmitting array element signal.

[0023] Furthermore, in step S5, matched filtering is performed on the receiving channel of each orientation to decode the transmission signal of each orientation, specifically:

[0024]

[0025] Among them, g t =mod K (kp t ), p t is the range ring number corresponding to the elevation main lobe echo signal, Cdecode is the decoded transmission signal.

[0026] Furthermore, after step S6, CFAR detection is performed on the data after the space-time adaptive processing.

[0027] Furthermore, in the step S2, a stepped frequency method is adopted to gradually increase the frequency of the signal transmitted by the antenna at each elevation element.

[0028] Furthermore, in step S4, the subarray synthesis can be performed in three orders according to the type of radar:

[0029] The first sequence is a direct microwave-level synthetic cross-structure channel, which is suitable for traditional phased array radars;

[0030] The second sequence is to perform analog-to-digital conversion on the received data after microwave-level synthesis, and then perform digital-level synthesis of the cross-structure channel, which is suitable for sub-array-level digital radar;

[0031] The third sequence is to directly receive the data and then perform analog-to-digital conversion, and then perform digital-level synthesis of the cross-structure channel, which is suitable for all-digital array radars.

[0032] Furthermore, in step S6, the space-time adaptive processing may be performed in the sub-array-pulse domain or the sub-array-Doppler domain.

[0033] A system for a non-stationary clutter suppression method for a space-based early warning radar, comprising an array element transmitting module, a frequency increment module, an analog-to-digital conversion module, a subarray synthesis module, a matched filter, a decoding module, and a space-time adaptive module;

[0034] The array element transmitting module is used to transmit array element transmitting signals in all directions through the antenna of the space-based early warning radar, and encode them in the transmitting signals of different pulses and directions;

[0035] The frequency increasing module is used to increase the frequency of the signal transmitted by the antenna at each elevation array element;

[0036] The analog-to-digital conversion module is used to receive the echo signal through the radar, perform down-conversion processing, perform analog-to-digital conversion, and store the digitized echo data;

[0037] The subarray synthesis module is used to perform pitch subarray synthesis on the data of the digitized echo signal into a single-channel receiving channel, and simultaneously perform subarray synthesis on the data of the echo signal receiving azimuth into a multi-channel receiving channel;

[0038] The matched filtering and decoding module is used to perform matched filtering on the receiving channel of each azimuth respectively and decode the transmission signal of each azimuth;

[0039] The space-time adaptive module is used to extract the corresponding elevation main lobe echo in each receiving channel through the elevation spatial domain filter according to the decoded transmission signal, and perform space-time adaptive processing on the extracted elevation main lobe echo to filter out clutter.

[0040] The beneficial effects of the present invention are as follows:

[0041] The present invention performs encoding in the transmission signals of different pulses and azimuths, increases the frequency of the signal transmitted by the antenna in each elevation array element, synthesizes it into a single elevation channel and multiple azimuth receiving channels through subarrays, performs matched filtering on the receiving channels of each azimuth, decodes the transmission signal of each azimuth, and realizes the analysis of non-stationary clutter in the case of range ambiguity; and filters the clutter through space-time adaptive processing. Therefore, the present invention solves the problem that the prior art cannot effectively suppress non-stationary clutter in the case of range ambiguity, and has the characteristics of accuracy and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The present invention is a flowchart of a method for suppressing non-stationary clutter in a space-based early warning radar. DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] like Figure 1 As shown, a method for suppressing non-stationary clutter of a space-based early warning radar comprises the following steps:

[0046] S1. Transmit signals through the transmitting elements of the antenna of the space-based early warning radar in all directions, and encode them in the transmitted signals of different pulses and directions;

[0047] S2. Incrementally increase the frequency of the signal transmitted by the antenna at each elevation element;

[0048] S3. The radar receives the echo signal, performs down-conversion processing, performs analog-to-digital conversion, and stores the digitized echo data;

[0049] S4. The digitized echo signal data is synthesized into a single-channel receiving channel by pitch sub-arrays, and the return signal receiving azimuth data is synthesized into a multi-channel receiving channel by sub-arrays;

[0050] S5. Perform matched filtering on the receiving channel of each azimuth respectively, and decode the transmission signal of each azimuth;

[0051] S6. Design an elevation spatial domain filter, extract the corresponding elevation main lobe echo in each receiving channel through the elevation spatial domain filter according to the decoded transmission signal, and perform space-time adaptive processing on the extracted elevation main lobe echo to filter out clutter.

[0052] Example 2

[0053] More specifically, in a specific embodiment, in step S1, the signals transmitted by the transmitting array elements in each direction of the antenna are mutually orthogonal signals.

[0054] In a specific embodiment, in the step S1, encoding is performed in the transmission signals of different pulses and orientations, specifically:

[0055]

[0056] Where n is the number of azimuths of the transmitting array element, k is the number of pulses, N is the maximum number of azimuths, K is the maximum number of pulses, and γ k is a parameter that varies with the pulse, C epc is the encoded transmission signal.

[0057] In this embodiment, N=64, M=12, and K=16.

[0058] In a specific embodiment, in step S2, the frequency of the signal transmitted by the antenna at each elevation element is increased incrementally, specifically:

[0059] f m =f 0 +(m-1)Δf,m=1,2,…,M

[0060] Where m is the number of pitch transmission array element signals, M is the maximum number of pitch transmission array element signals, and f 0 is the original reference frequency of the pitch transmitting array element signal, and Δf is the incremental frequency interval of the pitch transmitting array element signal.

[0061] In a specific embodiment, in step S5, matched filtering is performed on the receiving channel of each orientation respectively to decode the transmission signal of each orientation, specifically:

[0062]

[0063] Among them, g t =mod K (kp t ), p t is the range ring number corresponding to the elevation main lobe echo signal, C decode is the decoded transmission signal.

[0064] In a specific embodiment, after step S6, CFAR detection is further performed on the data after the space-time adaptive processing.

[0065] In a specific embodiment, in step S2, the frequency of the signal transmitted by the antenna at each elevation element is increased in a stepped frequency manner.

[0066] In a specific embodiment, in step S4, the subarray synthesis may be performed in three orders according to the type of radar:

[0067] The first sequence is a direct microwave-level synthetic cross-structure channel, which is suitable for traditional phased array radars;

[0068] The second sequence is to perform analog-to-digital conversion on the received data after microwave-level synthesis, and then perform digital-level synthesis of the cross-structure channel, which is suitable for sub-array-level digital radar;

[0069] The third sequence is to directly receive the data and then perform analog-to-digital conversion, and then perform digital-level synthesis of the cross-structure channel, which is suitable for all-digital array radars.

[0070] In a specific embodiment, in step S6, the space-time adaptive processing may be performed in the sub-array-pulse domain or the sub-array-Doppler domain.

[0071] The present invention performs encoding in the transmission signals of different pulses and azimuths, increases the frequency of the signal transmitted by the antenna in each elevation array element, synthesizes it into a single elevation channel and multiple azimuth receiving channels through subarrays, performs matched filtering on the receiving channels of each azimuth, decodes the transmission signal of each azimuth, and realizes the analysis of non-stationary clutter in the case of range ambiguity; and filters the clutter through space-time adaptive processing. Therefore, the present invention solves the problem that the prior art cannot effectively suppress non-stationary clutter in the case of range ambiguity, and has the characteristics of accuracy and stability.

[0072] Example 3

[0073] A system for a non-stationary clutter suppression method for a space-based early warning radar, comprising an array element transmitting module, a frequency increment module, an analog-to-digital conversion module, a subarray synthesis module, a matched filter, a decoding module, and a space-time adaptive module;

[0074] The array element transmitting module is used to transmit array element transmitting signals in all directions through the antenna of the space-based early warning radar, and encode them in the transmitting signals of different pulses and directions;

[0075] The frequency increasing module is used to increase the frequency of the signal transmitted by the antenna at each elevation array element;

[0076] The analog-to-digital conversion module is used to receive the echo signal through the radar, perform down-conversion processing, perform analog-to-digital conversion, and store the digitized echo data;

[0077] The subarray synthesis module is used to perform pitch subarray synthesis on the data of the digitized echo signal into a single-channel receiving channel, and simultaneously perform subarray synthesis on the data of the echo signal receiving azimuth into a multi-channel receiving channel;

[0078] The matched filtering and decoding module is used to perform matched filtering on the receiving channel of each azimuth respectively and decode the transmission signal of each azimuth;

[0079] The space-time adaptive module is used to extract the corresponding elevation main lobe echo in each receiving channel through the elevation spatial domain filter according to the decoded transmission signal, and perform space-time adaptive processing on the extracted elevation main lobe echo to filter out clutter.

[0080] In this embodiment, in the array element transmitting module, the transmitting signals of each array element are orthogonal to each other, the transmitting array element signals of each azimuth are encoded with pulses, and the transmitting signals of each elevation transmitting array element are frequency diverse; the transmitting signals of each array element of the planar array can be expressed as:

[0081]

[0082] in, T p is the signal pulse width; s nm () is the baseband envelope of the signal, satisfying (·)* represents the conjugate operation; f m =f 0 +(m-1)Δf, m=1, 2, ..., M is the carrier frequency of the transmitting array element at different elevations; It is an azimuth element-pulse coding format.

[0083] In this embodiment, in the sub-array synthesis module, the echo data is firstly synthesized by the pitch sub-array, and the pitch sub-array synthesis transformation matrix is It can be expressed as:

[0084]

[0085] Among them, s se,0 (m) is the pitch steering vector corresponding to the pitch main lobe The mth element in sub is the number of array elements in the elevation synthesis subarray. In this example, M sub =, so after the sub-array is synthesized, there is no more pitch freedom to participate in the subsequent adaptive processing.

[0086] In this embodiment, after the elevation sub-array is synthesized, the azimuth sub-array is synthesized, and the azimuth sub-array synthesis transformation matrix of the echo data is: It can be expressed as:

[0087]

[0088] Among them, s sa,0 (n) is the target direction guidance vector The nth element in θ 0 and are the target azimuth and elevation angle respectively; N sub is the number of array elements in the azimuth synthesis subarray. In this case, N sub Take 16.

[0089] In this embodiment, at this time, the entire spatial transformation matrix It can be expressed as

[0090]

[0091] in, is a space-time dimension reduction matrix, represents the unit diagonal matrix.

[0092] In this embodiment, in the matched filtering and decoding module, firstly, all orthogonal signals in the echo signals of each receiving channel need to be identified and extracted, and stored for subsequent signal processing. In this example, there are 16 receiving channels, and each receiving channel extracts M×N signals, and the final data size is 16×M×N.

[0093] Then, the signal of each channel is decoded by array element-pulse, and the decoding expression is as follows:

[0094]

[0095] where g t =mod K (kp t ), p t is the fuzzy range ring number corresponding to the elevation main lobe echo signal. After decoding, the azimuth spatial frequency can be expressed as:

[0096]

[0097] In the formula, g = mod K (kp), p is the fuzzy range ring number, θ is the azimuth angle, φ p is the pitch angle of the pth fuzzy distance, p t is the range ring number corresponding to the elevation main lobe echo signal, where γ g+1 g-γ gt+1 g tIt is the offset of the azimuth spatial frequency. After decoding, the azimuth spatial frequency of the elevation sidelobe clutter is inconsistently distributed between different pulses, so coherent accumulation cannot be performed, while the elevation mainlobe signal is not affected. When the number of coherent pulses is large enough, the energy will be greatly weakened. In addition, due to the offset of the azimuth spatial frequency of the elevation sidelobe clutter, the elevation sidelobe clutter originally located in the azimuth mainlobe is offset to the azimuth sidelobe, so that the energy is further weakened after beamforming, thereby completing the suppression. The above process is called the pre-whitening process of the elevation sidelobe clutter.

[0098] In this embodiment, the matched filtering and decoding module first performs secondary distance dependence compensation by using the echo frequency diversity characteristic to increase the spatial interval between the elevation main lobe echo and the elevation side lobe echo, and constructs the minimum variance distortion-free adaptive weight to extract the elevation main lobe echo and suppress the remaining elevation side lobe echo. The weight value can be expressed as

[0099]

[0100] in The constant coefficient representing the weight, R c is the covariance matrix of the remaining elevation sidelobe clutter. Since the elevation angle of the remaining elevation sidelobe clutter can be calculated, this matrix can be calculated in advance, s( pt ) represents the pitch steering vector of the pitch main lobe signal, which can also be obtained in advance.

[0101] In this embodiment, the space-time adaptive module performs STAP processing on the extracted elevation main lobe echo. The STAP adaptive weight can be expressed as:

[0102] w=μR z -1 s z (5)

[0103] in, The constant coefficient representing the weight, R z =T H RT represents the clutter covariance matrix after time domain transformation, E[·] means taking the expectation, T means the time domain dimension reduction matrix, s z =T H s represents the target vector after time domain transformation to the spatial domain.

[0104] In this embodiment, a constant false alarm detection processing unit is also included, which is used to perform constant false alarm processing on the data after adaptive processing to complete the detection and processing of moving targets of the space-based early warning radar.

[0105] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for suppressing non-stationary clutter of a space-based early warning radar, characterized in that: The following steps are involved: S1. Transmit signals through the transmitting elements of the antenna of the space-based early warning radar in all directions, and encode them in the transmitted signals of different pulses and directions; S2. Incrementally increase the frequency of the signal transmitted by the antenna at each elevation element; S3. receiving the echo signal through the radar, performing down-conversion processing, performing analog-to-digital conversion, and storing the digitized echo data; S4. The digitized echo signal data is synthesized into a single-channel receiving channel by pitch sub-arrays, and the echo signal receiving direction data is synthesized into a multi-channel receiving channel by sub-arrays; S5. Perform matched filtering on the receiving channel of each direction respectively, and decode the transmission signal of each direction; S6. Design an elevation spatial domain filter, extract the corresponding elevation main lobe echo in each receiving channel through the elevation spatial domain filter according to the decoded transmission signal, and perform space-time adaptive processing on the extracted elevation main lobe echo to filter out clutter.

2. The method for suppressing non-stationary clutter of a space-based early warning radar according to claim 1, characterized in that: In the step S1, the signals transmitted by the transmitting elements in each direction of the antenna are mutually orthogonal signals.

3. The method for suppressing non-stationary clutter of a space-based early warning radar according to claim 2, characterized in that: In the step S1, encoding is performed in the transmission signals of different pulses and orientations, specifically: Where n is the number of azimuths of the transmitting array element, k is the number of pulses, N is the maximum number of azimuths, and K is the maximum number of pulses. is a parameter that varies with the pulse. is the encoded transmission signal.

4. The method for suppressing non-stationary clutter of a space-based early warning radar according to claim 3, characterized in that: In the step S2, the frequency of the signal transmitted by the antenna at each elevation element is increased step by step, specifically: Where m is the number of pitch transmission array element signals, M is the maximum number of pitch transmission array element signals, is the original reference frequency of the pitch transmitting array element signal, is the incremental frequency spacing of the elevation transmitting array element signal.

5. The method for suppressing non-stationary clutter of a space-based early warning radar according to claim 4, characterized in that: In the step S5, matched filtering is performed on the receiving channel of each azimuth respectively to decode the transmission signal of each azimuth, specifically: in, , is the range ring number corresponding to the elevation main lobe echo signal, is the decoded transmission signal.

6. The method for suppressing non-stationary clutter of a space-based early warning radar according to claim 1, characterized in that: After step S6, CFAR detection is also performed on the data after the space-time adaptive processing.

7. The method for suppressing non-stationary clutter of a space-based early warning radar according to claim 1, characterized in that: In the step S2, the frequency of the signal transmitted by the antenna at each elevation element is increased in a stepped frequency manner.

8. The method for suppressing non-stationary clutter of a space-based early warning radar according to claim 1, characterized in that: In step S4, the subarray synthesis may be performed in any of three sequences depending on the type of radar: The first sequence is a direct microwave-level synthetic cross-structure channel, which is suitable for traditional phased array radars; The second order is to perform analog-to-digital conversion on the received data after microwave-level synthesis, and then perform digital-level synthesis of the cross-structure channel, which is suitable for sub-array-level digital radar; The third sequence is to directly receive the data and then perform analog-to-digital conversion, and then perform digital-level synthesis of the cross-structure channel, which is suitable for all-digital array radars.

9. The method for suppressing non-stationary clutter of a space-based early warning radar according to claim 1, characterized in that: In the step S6, the space-time adaptive processing may be performed in the sub-array-pulse domain or the sub-array-Doppler domain.

10. A system for a non-stationary clutter suppression method for a space-based early warning radar, characterized in that: It includes array element transmission module, frequency increment module, analog-to-digital conversion module, subarray synthesis module, matched filtering and decoding module, and space-time adaptation module; The array element transmitting module is used to transmit array element transmitting signals in all directions through the antenna of the space-based early warning radar, and encode them in the transmitting signals of different pulses and directions; The frequency increasing module is used to increase the frequency of the signal transmitted by the antenna at each elevation array element; The analog-to-digital conversion module is used to receive the echo signal through the radar, perform down-conversion processing, perform analog-to-digital conversion, and store the digitized echo data; The subarray synthesis module is used to perform pitch subarray synthesis on the data of the digitized echo signal into a single-channel receiving channel, and simultaneously perform subarray synthesis on the data of the echo signal receiving azimuth into a multi-channel receiving channel; The matched filtering and decoding module is used to perform matched filtering on the receiving channel of each azimuth respectively and decode the transmission signal of each azimuth; The space-time adaptive module is used to design an elevation spatial domain filter according to the decoded transmission signal, extract the corresponding elevation main lobe echo in each receiving channel through the elevation spatial domain filter, and perform space-time adaptive processing on the extracted elevation main lobe echo to filter out clutter.

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