A multi-stage joint array multi-beam reconnaissance false alarm suppression method

Abstract

The present invention discloses a multi-stage joint array multi-beam reconnaissance false alarm suppression method. First, when digital beamforming (DBF) is performed at the front end of an array, a Blackman-Harris window function weighting method is used to reduce the sidelobe level of a receiving antenna, thereby reducing false alarms caused by the sidelobes during multi-beam reconnaissance. When multiple array surfaces work together, a data fusion method is used to achieve joint suppression of the side beams of a single array surface, ultimately achieving full airspace coverage and low sidelobe performance, improving the anti-interference capability of the equipment, and suppressing false alarm signals in array multi-beam reconnaissance.

Description

Technical Field

[0001] The invention belongs to the technical field of digital phased array systems, and in particular relates to a multi-stage combined array multi-beam reconnaissance false alarm suppression method. Background Art

[0002] With the advancement of microwave, semiconductor, and other electronic technologies, component quality and process technology have significantly improved. Radar technology has also gradually evolved to phased array multi-beam arrays. These radar beams offer advantages such as rapid spatial scanning, spatially directional synthesis, a low probability of interception, and strong anti-interference capabilities. Multi-beam array radars possess strong detection and tracking capabilities. They can detect long-range multiple targets and stealth aircraft in all weather conditions and perform intelligent information collection. These multi-beam array radars are composed of multiple low-power T / R modules. This type of antenna provides the necessary flexibility, low radar cross-section, and wide bandwidth for combat platforms.

[0003] However, from the perspective of interference countermeasures, external noise or interference is often relatively complex, and interference patterns often feature both noise and false targets, significantly increasing the false alarm rate in multi-beam reconnaissance. Due to the complexity of the interference signal, interference often creates sidelobe clutter, causing signal multiplication, which severely impacts the performance of array multi-beam reconnaissance and poses a serious challenge to the operational performance of combat defense systems.

[0004] To suppress false alarms in multi-beam reconnaissance, radars typically add sidelobe suppression antennas. Taking advantage of the fact that the gain of the sidelobe suppression antenna is smaller than that of the main antenna, the amplitudes of the main and secondary antennas are ratioed, and thresholds are used to suppress false alarm signals from sidelobe reconnaissance. While much research has been conducted domestically on algorithms for sidelobe suppression in phased array radars, the technical application of false alarm suppression methods for phased array multi-beam reconnaissance is still immature. Summary of the Invention

[0005] The present invention proposes a multi-stage combined array multi-beam reconnaissance false alarm suppression method.

[0006] The technical solution to achieve the present invention is: a multi-stage joint array multi-beam reconnaissance false alarm suppression method, the specific steps are:

[0007] Step 1: Use the window function weighting method to perform digital beam synthesis on the antenna array to obtain a low sidelobe pattern;

[0008] Step 2: Calculate the amplitude and phase information of the signal based on the output vector of the beamforming to obtain the pulse description word of the signal;

[0009] Step 3: Fuse the PDWs received by multiple arrays to suppress the side beams of a single array and achieve ultimate false alarm suppression.

[0010] Preferably, the specific formula of digital beamforming is:

[0011]

[0012] The above formula is expressed as Y=AX, where X is the intermediate frequency quantized signal vector of each antenna after frequency conversion, A is the synthesis weight coefficient, and Y is the output vector of beam synthesis. m is an element in Y, a m,n is an element in A, x n is an element in X.

[0013] Preferably, the operation matrix of the digital beamforming is decomposed into several sub-matrices, and one FPGA completes the operation of one sub-matrix.

[0014] Preferably, the control and data transmission between each array are realized by a serial RapidIO link based on optical fiber, and the synchronization is achieved by the synchronization pulse of the data fusion unit. The array in each quadrant has a unified time base.

[0015] Preferably, a flag bit is given in the same signal pulse description word. When a signal is incident from the middle of adjacent arrays, one of the signal pulse description words is removed in the data fusion board before the signal pulse description words are fused.

[0016] Preferably, when the arrival time and frequency difference between two signal pulse description words is within a set threshold, the pulse description word with a smaller amplitude is removed.

[0017] Compared with the prior art, the present invention has the following significant advantages: when performing digital beamforming (DBF) at the front end of the array, the present invention reduces the sidelobe level of the receiving antenna through a Blackman-Harris window function weighting method, thereby reducing false alarms caused by sidelobes during multi-beam reconnaissance; when multiple arrays work together, the present invention completes the joint suppression of the side beams of a single array through a data fusion method, ultimately achieving full airspace coverage and low sidelobe performance, improving the anti-interference capability of the equipment, and suppressing false alarm signals in array multi-beam reconnaissance.

[0018] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The flowchart of a multi-stage joint array multi-beam reconnaissance false alarm suppression method.

[0020] Figure 2 This is a diagram of the implementation method of DBF weighted synthesis.

[0021] Figure 3 is the weighted low sidelobe pattern.

[0022] Figure 4This is a block diagram of the four-array fusion unit.

[0023] Figure 5 Schematic diagram of multi-array broadband receiving data fusion. DETAILED DESCRIPTION

[0024] like Figure 1 As shown, a multi-stage joint array multi-beam reconnaissance false alarm suppression method is shown. The method performs primary processing during digital beam synthesis to reduce false alarms caused by excessive side lobes; secondary processing is performed when multiple arrays work together to reduce reconnaissance false alarms caused by array edge beam measurement errors. The method is easy to implement in engineering. The specific steps are as follows:

[0025] Step 1: Use the window function weighting method to perform digital beamforming (DBF) on the antenna array to obtain a low sidelobe pattern.

[0026] In this embodiment, the Blackman-Harris window weighting method is used to reduce the sidelobe level of the pattern. The principle of DBF synthesis is shown in formula (1):

[0027]

[0028] The above formula can be expressed as Y=AX, where X is the intermediate frequency quantized signal vector of each antenna after frequency conversion, A is the synthesis weight coefficient, and Y is the output vector of beam synthesis. m is an element in Y, a m,n is an element in A, x n are the elements in X. In general, the row vectors of A are independent of each other, so A is a full-rank matrix and the computational complexity cannot be reduced by reducing its scale.

[0029] To solve the problem of excessively large data sizes, operations need to be distributed across multiple FPGAs. Therefore, the matrix A is decomposed into several MxN sub-matrices in the following form:

[0030]

[0031] The implementation method of weighted synthesis is as follows Figure 2 As shown, a typical Systolic architecture is used, trading time for spatial scalability. Each subarray is processed in a single FPGA. This processing method increases processing latency, with the delay between each module being approximately 1µs. However, it avoids the problem of data being concentrated in a single device, preventing transmission or processing.

[0032] The phased array receiving antenna with low sidelobe is realized by DBF weighting. The low sidelobe radiation pattern formed after weighting is as follows: Figure 3 shown.

[0033] Step 2: Calculate the amplitude and phase information of the signal based on the output vector of the beamformer to obtain the pulse descriptor word (PDW) of the signal.

[0034] Step 3: Fuse the PDWs received by multiple arrays to suppress the side beams of a single array and achieve ultimate false alarm suppression.

[0035] A phased array receiver typically covers a 90° angle of view per array, requiring four quadrants to work together to achieve full airspace coverage. Within a single array, horizontal sidelobes can be suppressed by leveraging the amplitudes of adjacent beams, thereby reducing false alarms. However, the extreme left and right beams in each quadrant require the coordinated suppression of adjacent side beams.

[0036] The block diagram of the four-array fusion unit is as follows: Figure 4 As shown, control and data transmission between the various arrays is achieved via fiber-based serial RapidIO links, with synchronization achieved via synchronization pulses from the data fusion unit. Each quadrant of the array has a unified time base, so signals received by arrays in adjacent quadrants can be identified as belonging to the same signal based on their arrival time and frequency.

[0037] A flag is assigned to the same signal PDW. When a signal is incident between adjacent arrays, both arrays receive the signal, generating two PDWs with similar parameters, such as azimuth, elevation, frequency, and pulse width. In this case, one of the PDWs must be removed during PDW fusion on the data fusion board. When the TOA and frequency differences between the two PDWs are similar, the PDW with the smaller amplitude is removed.

[0038] Assuming the four array planes are divided into planes A, B, C, and D, when the signal is incident on plane A, plane A generates a PDW_A. Simultaneously, a false PDW may be generated on planes B, C, and D, denoted as PDW_B, PDW_C, and PDW_D. These three false PDWs are close in frequency to PDW_A and smaller in amplitude. Therefore, PDW_B, PDW_C, and PDW_D must be removed to avoid false alarm signals from planes B, C, and D. A schematic diagram of multi-plane broadband reception data fusion is shown below. Figure 5 shown.

Claims

1. A multi-stage joint array multi-beam reconnaissance false alarm suppression method, characterized in that: The specific steps are: Step 1: Use the window function weighting method to perform digital beam synthesis on the antenna array to obtain a low sidelobe pattern; Step 2: Calculate the amplitude and phase information of the signal based on the output vector of the beamforming to obtain the pulse description word of the signal; Step 3: Fuse the PDWs received by multiple arrays to suppress the side beams of a single array and achieve ultimate false alarm suppression.

2. The multi-stage combined array multi-beam reconnaissance false alarm suppression method according to claim 1 is characterized in that: The specific formula for digital beamforming is: The above formula is expressed as Y=AX, where X is the intermediate frequency quantized signal vector of each antenna after frequency conversion, A is the synthesis weight coefficient, and Y is the output vector of beam synthesis. m is an element in Y, a m,n is an element in A, x n is an element in X.

3. The multi-stage combined array multi-beam reconnaissance false alarm suppression method according to claim 1 or 2, characterized in that: The digital beamforming operation matrix is decomposed into several sub-matrices, and one FPGA completes the operation of one sub-matrix.

4. The multi-stage combined array multi-beam reconnaissance false alarm suppression method according to claim 1, characterized in that: The control and data transmission between each array are realized by the fiber-optic serial RapidIO link, and the synchronization is achieved by the synchronization pulse of the data fusion unit. The array in each quadrant has a unified time base.

5. The multi-stage combined array multi-beam reconnaissance false alarm suppression method according to claim 1, characterized in that: A flag bit is given in the same signal pulse description word. When a signal is incident from the middle of adjacent arrays, one of the signal pulse description words is removed in the data fusion board before the signal pulse description word fusion is performed.

6. The multi-stage combined array multi-beam reconnaissance false alarm suppression method according to claim 5, characterized in that: When the arrival time and frequency difference between two signal pulse description words is within the set threshold, the pulse description word with smaller amplitude is removed.

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