A method, system, and medium for digital beamforming and amplitude / phase calibration of weather radar.

Abstract

This invention discloses a method, system, and medium for digital beamforming and amplitude / phase calibration of a weather radar. The method includes: simultaneously injecting a generated linear frequency modulated (LFM) calibration signal into 32 receiving channels via a power divider network; synchronously acquiring the LFM calibration signal through the 32 receiving channels to obtain 32 digital intermediate frequency (IF) signals; performing digital down-conversion processing on each of the 32 IF signals to obtain 32 zero-IF I / Q quadrature digital signals; using one of the 32 channels as a reference channel, extracting the amplitude and phase differences of the remaining 31 channels relative to the reference channel and using these as amplitude / phase calibration coefficients for each channel, and storing them in a calibration parameter memory; and, in normal operating mode, reading the amplitude / phase calibration coefficients of each channel, performing amplitude / phase calibration on the received weather echo signal, and then performing digital beamforming. This invention improves the accuracy of digital beamforming and weather detection performance while reducing the complexity and cost of the calibration system.

Description

Technical Field

[0001] This invention relates to the field of meteorological radar signal processing technology, specifically to a method, system, and medium for digital beamforming and amplitude-phase calibration of meteorological radar. Background Technology

[0002] Phased array weather radar employs a distributed transceiver system, with its radar array composed of numerous identical radiating elements, each independently controlled in phase and amplitude. Digital beamforming (DBF) is one of the key technologies of phased array weather radar, digitally compensating for time and phase differences between signals from different receiving channels to ensure in-phase superposition of signals from all channels, maximizing received energy in a specific direction. However, the following problems exist in practical systems:

[0003] First, due to factors such as mutual coupling between antenna elements, array element position errors, different signal transmission channel lengths, and asynchronous clock signals, there are time and phase differences between different receiving channels, resulting in antenna pattern distortion.

[0004] Second, multi-channel receivers suffer from significant parameter mismatch issues due to component differences, making it difficult to maintain consistent amplitude and phase characteristics across channels. Ideally, the multiple receiving channels of a multi-channel array radar system should have consistent amplitude and phase characteristics, meaning that the amplitude and phase relationship between the output signals of each channel remains unchanged as the signal passes through the array channels.

[0005] Third, linear frequency modulated (LFM) signals have advantages such as large bandwidth, concentrated energy, and pulse compression, and are widely used in weather radar. However, for broadband LFM signals, the amplitude-phase inconsistency between channels has a significant impact on adaptive beamforming performance. Multi-channel amplitude-phase correction in broadband digital beamforming systems requires channel amplitude-phase correction before digital beamforming.

[0006] Fourth, existing calibration methods often employ high-value instruments to form the calibration system, resulting in complex operation and high costs. For phased array weather radar systems with 32 or more channels, there is an urgent need for an efficient and low-cost amplitude and phase calibration method.

[0007] In view of the above, this application is hereby submitted. Summary of the Invention

[0008] The technical problem this invention aims to solve is that existing calibration methods often employ high-value instruments to form the calibration system, resulting in complex operation, high cost, and low calibration accuracy. This invention provides a method, system, and medium for digital beamforming and amplitude / phase calibration of weather radar. It effectively corrects amplitude / phase inconsistencies among 32 receiving channels, improves the accuracy of digital beamforming and meteorological detection performance, while reducing the complexity and cost of the calibration system. This invention is applicable to multi-channel receiving systems of phased array weather radars.

[0009] This invention is achieved through the following technical solution:

[0010] In a first aspect, the present invention provides a method for digital beamforming and amplitude-phase calibration of a weather radar, the method comprising:

[0011] S1 generates a linear frequency modulation calibration signal from an LFM signal source, and injects the linear frequency modulation calibration signal into the input terminals of 32 receiving channels simultaneously through a power divider network;

[0012] S2, 32 receiving channels synchronously acquire linear frequency modulation calibration signals to obtain 32 digital intermediate frequency signals;

[0013] S3 performs digital down-conversion processing on 32 channels of digital intermediate frequency signals to obtain 32 channels of zero intermediate frequency I / Q quadrature digital signals;

[0014] S4, using one of the 32 channels as a reference channel, extract the amplitude difference and phase difference of the remaining 31 channels relative to the reference channel;

[0015] S5, use the amplitude difference and phase difference as amplitude and phase calibration coefficients for each channel, and store the amplitude and phase calibration coefficients in the calibration parameter memory;

[0016] S6, in normal operating mode, reads the amplitude and phase calibration coefficients of each channel from the calibration parameter memory, performs amplitude and phase calibration on the received meteorological echo signal, and then performs digital beamforming.

[0017] Furthermore, the method also includes:

[0018] During radar operation, steps S1 to S5 are executed periodically to achieve dynamic updates of the amplitude and phase calibration coefficients.

[0019] Furthermore, in step S2, the sampling clocks for the 32 receiving channels are provided by the same clock source.

[0020] Furthermore, step S4 specifically includes:

[0021] After performing matched filtering on the I / Q quadrature digital signals of each channel, the amplitude and phase values ​​of each channel signal are obtained by utilizing the pulse compression characteristics of the linear frequency modulation calibration signal.

[0022] Set one of the 32 channels as the reference channel. Using the amplitude value of the reference channel as a benchmark, iterate through the remaining 31 channels to calculate the amplitude difference and phase difference of the 31 channels relative to the reference channel.

[0023] The amplitude difference is obtained by subtracting the amplitude value of each channel from the average amplitude value of the reference channel; the phase difference is obtained by subtracting the phase value of each channel from the average phase value of the reference channel.

[0024] Furthermore, in step S4, for the broadband LFM signal, multiple frequency points are selected within the bandwidth of the LFM signal, and the amplitude response and phase response of each channel at different frequency points are measured respectively. The amplitude-phase difference distribution and phase difference distribution within the full bandwidth are obtained by interpolation or fitting methods. Based on the amplitude-phase difference distribution and phase difference distribution, the mean amplitude and mean phase of the reference channel are obtained.

[0025] Furthermore, the amplitude and phase calibration coefficients include amplitude calibration coefficients and phase calibration coefficients, where the amplitude calibration coefficient is the amplitude difference and the phase calibration coefficient is the phase difference.

[0026] Furthermore, step S6 specifically includes:

[0027] In normal operating mode, 32 receiving channels receive meteorological echo signals, and the meteorological echo signals are digitally down-converted to obtain 32 I / Q quadrature digital signals.

[0028] The amplitude and phase calibration coefficients of each channel are read from the calibration parameter memory, and the amplitude and phase corrections of the I / Q quadrature digital signals of each channel are performed.

[0029] After amplitude and phase calibration, the 32 signals are digitally beamformed according to the preset beam direction to form a meteorological detection beam in the required direction; the digital beamformation includes time delay compensation and weighted summation.

[0030] Secondly, the present invention provides a weather radar digital beamforming and amplitude-phase calibration system, the system comprising:

[0031] The LFM signal source is used to generate a linear frequency modulation calibration signal, the bandwidth of which covers the operating frequency band of the weather radar.

[0032] A power divider network is used to distribute the linear frequency modulation calibration signal equally to 32 receiving channels;

[0033] The 32-channel receiver front end, including a low-noise amplifier, a downconverter, and a filter, is used to receive and process linear frequency modulation calibration signals and meteorological echo signals.

[0034] The multi-channel synchronous sampling module includes a 32-channel analog-to-digital converter, driven by the same clock source, to achieve synchronous acquisition of 32 channels of signals;

[0035] The digital signal processing module is used to perform digital downconversion, amplitude-phase difference extraction, amplitude-phase calibration coefficient calculation, and digital beamforming; the amplitude-phase difference includes amplitude difference and phase difference, and the amplitude-phase calibration coefficient includes amplitude calibration coefficient and phase calibration coefficient.

[0036] The calibration parameter memory is used to store the amplitude and phase calibration coefficients of each channel;

[0037] The beam control unit is used to generate beamforming weighting coefficients for each channel according to the preset beam direction.

[0038] Furthermore, the digital signal processing module is implemented using an FPGA.

[0039] Thirdly, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for digital beamforming and amplitude-phase calibration of a weather radar.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] This invention discloses a method, system, and medium for digital beamforming and amplitude / phase calibration of a weather radar. It effectively corrects amplitude / phase inconsistencies among 32 receiving channels, improving the accuracy of digital beamforming and weather detection performance, while reducing the complexity and cost of the calibration system. This invention can be widely applied to multi-channel systems such as phased array weather radar and digital array weather radar. The method and system architecture of this invention are rationally designed, simple to implement, low in cost, and highly accurate, possessing good industrial practical value and promising prospects for widespread application.

[0042] 1. High calibration accuracy: Utilizing the pulse compression and broadband characteristics of the linear frequency modulation calibration signal (i.e., LFM signal), the amplitude and phase response of each channel can be accurately measured across the entire operating bandwidth, resulting in high amplitude and phase calibration accuracy. After calibration, the amplitude and phase consistency between channels is significantly improved.

[0043] 2. Low implementation cost: No expensive instruments such as spectrum analyzers and high-speed oscilloscopes are required. Calibration can be completed with only an LFM signal source and a power divider network, which greatly reduces the system cost and complexity.

[0044] 3. Strong dynamic calibration capability: It supports the periodic execution of calibration procedures during radar operation intervals, realizing dynamic updates of amplitude and phase calibration coefficients, and effectively compensating for channel drift caused by environmental changes and device aging.

[0045] 4. High beamforming quality: Through precise amplitude and phase calibration, the influence of inter-channel amplitude and phase inconsistency on digital beamforming is eliminated, improving beam pointing accuracy and sidelobe suppression performance.

[0046] 5. Good scalability: The method and system architecture of this invention are not only applicable to 32 channels, but can also be easily extended to phased array weather radar systems with more channels. Attached Figure Description

[0047] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0048] Figure 1 This is a block diagram of the overall structure of a weather radar digital beamforming and amplitude-phase calibration system according to the present invention.

[0049] Figure 2 This is a flowchart of a method for digital beamforming and amplitude-phase calibration of a weather radar according to the present invention;

[0050] Figure 3 This is a schematic diagram of the structure of the 32-channel digital beamforming module of the present invention;

[0051] Figure 4 This is a schematic diagram of the amplitude-phase difference extraction process of the present invention;

[0052] Figure 5 This is a comparison chart of the amplitude consistency of the 32 channels before and after calibration in this invention;

[0053] Figure 6 This is a comparison diagram of the phase consistency of the 32 channels before and after calibration in this invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0055] Example 1

[0056] like Figure 1 As shown in the figure, this embodiment provides a specific implementation method for digital beamforming and amplitude-phase calibration of a weather radar.

[0057] like Figure 1 As shown, a weather radar digital beamforming and amplitude-phase calibration system includes: an LFM signal source 101, a power divider network 102, a 32-channel receiving front-end 103 (channel 1 to channel 32), a multi-channel synchronous sampling module 104, a digital signal processing module 105, a calibration parameter memory 106, and a beam control unit 107.

[0058] The linear frequency modulation calibration signal generated by the LFM signal source 101 is simultaneously input to the input terminals of each channel of the 32-channel receiving front-end 103 after being equally distributed by the power divider network 102. Each channel receiving front-end performs low-noise amplification, down-conversion, and filtering on the signal before sending it to the multi-channel synchronous sampling module 104 for analog-to-digital conversion. The digital signal processing module 105 performs digital down-conversion, amplitude-phase difference extraction, amplitude-phase calibration coefficient calculation, and digital beamforming on the sampled digital signal. It also stores the amplitude-phase calibration coefficients of each channel in the calibration parameter memory 106 and generates beamforming weighting coefficients for each channel according to the preset beam direction through the beam control unit.

[0059] like Figure 2 As shown, this invention provides a method for digital beamforming and amplitude / phase calibration of a weather radar. This method is implemented based on the above system and includes:

[0060] S0, System power-on initialization, loading historical calibration parameters;

[0061] S1, an LFM signal source generates a linear frequency modulation calibration signal (LFM signal) as a calibration reference source. The bandwidth of the LFM calibration signal covers the operating frequency band of the weather radar. The LFM calibration signal is simultaneously injected into the input of 32 receiving channels through a power divider network to ensure that each channel receives the same calibration signal.

[0062] S2, 32 receiving channels synchronously acquire and process linear frequency modulation calibration signals, including low-noise amplification, down-conversion, filtering and analog-to-digital conversion, to obtain 32 digital intermediate frequency signals; specifically, the sampling clocks of the 32 receiving channels are provided by the same clock source to ensure that the sampling start time of each channel is synchronized.

[0063] S3 performs digital down-conversion (DDC) processing on the 32 channels of digital intermediate frequency signals, including generating quadrature local oscillator signals by a numerically controlled oscillator (NCO), mixing, low-pass filtering, and decimation filtering, to obtain 32 channels of zero-IF I / Q quadrature digital signals;

[0064] S4, using the first channel out of 32 channels as the reference channel, extract the amplitude difference and phase difference of the remaining 31 channels (channels 2 to 32) relative to the reference channel;

[0065] Specifically, step S4 includes:

[0066] After performing matched filtering on the I / Q quadrature digital signals of each channel, the amplitude and phase values ​​of each channel signal are obtained by utilizing the pulse compression characteristics of the linear frequency modulation calibration signal.

[0067] The first channel out of 32 channels is set as the reference channel. Based on the amplitude value of the reference channel, the remaining 31 channels are iterated and the amplitude difference and phase difference of the 31 channels relative to the reference channel are calculated.

[0068] The amplitude difference is obtained by subtracting the amplitude value of each channel from the average amplitude value of the reference channel; the phase difference is obtained by subtracting the phase value of each channel from the average phase value of the reference channel.

[0069] Furthermore, in step S4, for a broadband LFM signal, N frequency points are selected within the bandwidth of the LFM signal. The amplitude and phase responses of each channel at different frequency points are measured respectively, and the amplitude and phase difference distributions over the entire bandwidth are obtained by interpolation or fitting methods. Based on the amplitude and phase difference distributions, the mean amplitude and mean phase of the reference channel are obtained.

[0070] S5, use the amplitude difference and phase difference as amplitude and phase calibration coefficients for each channel. The amplitude and phase calibration coefficients include amplitude calibration coefficients and phase calibration coefficients; that is, use the amplitude difference as the amplitude calibration coefficient and the phase difference as the phase calibration coefficient; and store the amplitude and phase calibration coefficients in the calibration parameter memory of the radar system.

[0071] Specifically, the formula for calculating the amplitude calibration coefficient is as follows:

[0072]

[0073] in, Let be the amplitude calibration coefficient for the i-th channel. The amplitude value of the reference channel. Let be the amplitude value of the i-th channel.

[0074] The formula for calculating the phase calibration coefficient is:

[0075]

[0076] in, Let i be the phase calibration coefficient for the i-th channel. The phase value of the reference channel. Let be the phase value of the i-th channel.

[0077] S6, in normal operating mode, reads the amplitude and phase calibration coefficients of each channel from the calibration parameter memory, performs amplitude and phase calibration on the received meteorological echo signal, and then performs digital beamforming.

[0078] In this embodiment, step S6 specifically includes:

[0079] In normal operating mode, 32 receiving channels receive meteorological echo signals, and the meteorological echo signals are digitally down-converted to obtain 32 I / Q quadrature digital signals.

[0080] The amplitude and phase calibration coefficients of each channel are read from the calibration parameter memory, and the amplitude and phase corrections of the I / Q quadrature digital signals of each channel are performed.

[0081] After amplitude and phase calibration, the 32 signals are digitally beamformed according to the preset beam direction to form a meteorological detection beam in the required direction; the digital beamformation includes time delay compensation and weighted summation.

[0082] Example 2

[0083] The difference between this embodiment and Embodiment 1 is that the method further includes:

[0084] S7. During radar operation, steps S1 to S5 are executed periodically to dynamically update the amplitude and phase calibration coefficients in order to compensate for channel amplitude and phase drift caused by factors such as temperature changes and device aging.

[0085] Specifically, during normal operation of the radar, a dynamic calibration process is triggered at regular intervals (such as every hour) or when the ambient temperature changes beyond a set threshold.

[0086] When the dynamic calibration process is executed, the radar pauses its meteorological detection mission (or utilizes the detection gap), the LFM signal source generates a calibration signal and injects it into the receiving channel, and the calibration process from step S1 to step S5 is executed to update the calibration coefficients in the calibration parameter memory.

[0087] After dynamic calibration is completed, the radar resumes its meteorological detection mission and uses the updated amplitude and phase calibration coefficients for digital beamforming.

[0088] The above dynamic calibration mechanism effectively compensates for channel amplitude and phase drift caused by factors such as temperature changes and device aging, ensuring the stability and reliability of the radar system during long-term operation.

[0089] Example 3

[0090] like Figure 1 As shown, this embodiment also provides a weather radar digital beamforming and amplitude-phase calibration system, which corresponds one-to-one with the weather radar digital beamforming and amplitude-phase calibration method in Embodiment 1; the system includes:

[0091] The LFM signal source is used to generate a linear frequency modulation calibration signal, the bandwidth of which covers the operating frequency band of the weather radar.

[0092] A power divider network is used to distribute the linear frequency modulation calibration signal equally to 32 receiving channels;

[0093] The 32-channel receiver front end, including a low-noise amplifier, a downconverter, and a filter, is used to receive and process linear frequency modulation calibration signals and meteorological echo signals.

[0094] The multi-channel synchronous sampling module includes a 32-channel analog-to-digital converter (ADC) driven by the same clock source to achieve synchronous acquisition of 32 channels of signals;

[0095] The digital signal processing module, including an FPGA or DSP chip, is used to perform digital downconversion, amplitude-phase difference extraction, amplitude-phase calibration coefficient calculation, and digital beamforming; the amplitude-phase difference includes amplitude difference and phase difference, and the amplitude-phase calibration coefficient includes amplitude calibration coefficient and phase calibration coefficient;

[0096] The calibration parameter memory is used to store the amplitude and phase calibration coefficients of each channel;

[0097] The beam control unit is used to generate beamforming weighting coefficients for each channel according to the preset beam direction.

[0098] The digital signal processing module of this invention is implemented using an FPGA to fully utilize its parallel processing capabilities and meet the requirements of 32-channel real-time signal processing.

[0099] In practice, a Xilinx Zynq UltraScale+ series FPGA was selected as the core of the digital signal processing, and the digital signal processing module was implemented using the FPGA. This FPGA has ample DSP and logic resources, enabling it to process 32 channels of real-time signals simultaneously.

[0100] The analog-to-digital converter (ADC) uses the AD9653, with a sampling rate of 100 MSPS and a resolution of 16 bits. Each ADC chip supports 4 channels of synchronous sampling, requiring a total of 8 AD9653 chips to achieve 32 channels of synchronous sampling. The sampling clock for all ADC chips is provided by the same low-phase-noise clock generator to ensure sampling synchronization.

[0101] Inside the FPGA, the digital signal processing link for each channel includes: a digital downconversion module (including NCO, mixer, CIC filter, and FIR filter), a matched filter module, an amplitude and phase error extraction module, and a beamforming module.

[0102] The digital downconversion module downconverts the digital intermediate frequency signal to zero intermediate frequency, outputting both I and Q signals. The matched filtering module performs matched filtering on the I and Q signals, utilizing the pulse compression characteristics of the LFM signal to obtain the amplitude and phase information of each channel.

[0103] The amplitude and phase error extraction module uses the first channel as a reference to calculate the amplitude difference and phase difference of each channel, and updates the amplitude and phase calibration coefficients accordingly.

[0104] After obtaining the amplitude and phase calibration coefficients, the beamforming module performs amplitude and phase calibration on the real-time echo signals of each channel, and then completes digital beamforming according to the beam control command.

[0105] like Figure 3 As shown, Figure 3 This is a schematic diagram of the beamforming structure of the digital beamforming module. It includes 32-channel amplitude and phase calibration units 301-1 to 301-32, time delay compensation units 302-1 to 302-32, weighting units 303-1 to 303-32, and summing unit 304.

[0106] The I / Q quadrature digital signals of each channel are first corrected for amplitude and phase by the amplitude and phase calibration unit, then the time delay compensation unit performs time delay compensation according to the beam direction, then the weighting unit applies amplitude weighting, and finally the summing unit accumulates to form the output beam.

[0107] Meanwhile, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-mentioned method for digital beamforming and amplitude-phase calibration of a weather radar.

[0108] Example 4

[0109] This embodiment also provides a method for verifying the amplitude and phase calibration effect.

[0110] In a microwave anechoic chamber environment, the antenna array of the 32-channel receiver front-end is positioned directly opposite a standard gain horn antenna. The LFM signal source transmits a linear frequency modulation calibration signal (i.e., an LFM calibration signal) through the standard gain horn antenna, and the 32 channels simultaneously receive this signal.

[0111] Amplitude and phase calibration was performed according to the method of this invention, and the amplitude and phase values ​​of each channel before and after calibration were recorded. For example... Figure 5 and Figure 6 As shown, the amplitude difference between the 32 channels before calibration can reach [amount missing]. Phase difference can reach The amplitude difference after calibration is controlled within Within, the phase difference is controlled within Within.

[0112] After calibration, digital beamforming tests were performed. The actual beam patterns formed were measured along multiple preset beam directions. The results show that the calibrated beam pointing accuracy is better than... The sidelobe level is better than The result is a significant improvement compared to before calibration.

[0113] In meteorological observation applications, a 32-channel digital beamforming system with amplitude and phase calibration can effectively suppress sidelobe interference such as ground clutter, and improve the detection accuracy and reliability of meteorological echoes.

[0114] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0115] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0116] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0117] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0118] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for digital beamforming and amplitude / phase calibration of a weather radar, characterized in that, The method includes: S1, A linear frequency modulation calibration signal is generated by an LFM signal source, and the linear frequency modulation calibration signal is simultaneously injected into the input terminals of 32 receiving channels through a power divider network; S2, 32 receiving channels synchronously acquire the linear frequency modulation calibration signal to obtain 32 digital intermediate frequency signals; S3, perform digital down-conversion processing on the 32 digital intermediate frequency signals respectively to obtain 32 zero intermediate frequency I / Q quadrature digital signals; S4, using one of the 32 channels as a reference channel, extract the amplitude difference and phase difference of the remaining 31 channels relative to the reference channel; S5, use the amplitude difference and phase difference as amplitude and phase calibration coefficients for each channel, and store the amplitude and phase calibration coefficients in the calibration parameter memory; S6. In normal operating mode, read the amplitude and phase calibration coefficients of each channel from the calibration parameter memory, perform amplitude and phase calibration on the received meteorological echo signal, and then perform digital beamforming.

2. The method for digital beamforming and amplitude / phase calibration of a weather radar according to claim 1, characterized in that, The method also includes: During radar operation, steps S1 to S5 are executed periodically to achieve dynamic updates of the amplitude and phase calibration coefficients.

3. The method for digital beamforming and amplitude / phase calibration of a weather radar according to claim 1, characterized in that, In step S2, the sampling clocks for the 32 receiving channels are provided by the same clock source.

4. The method for digital beamforming and amplitude / phase calibration of a weather radar according to claim 1, characterized in that, Step S4 specifically includes: After performing matched filtering on the I / Q quadrature digital signals of each channel, the amplitude and phase values ​​of each channel signal are obtained by utilizing the pulse compression characteristics of the linear frequency modulation calibration signal. One of the 32 channels is set as a reference channel. Based on the amplitude value of the reference channel, the remaining 31 channels are iterated and the amplitude difference and phase difference of the 31 channels relative to the reference channel are calculated. Wherein, the amplitude difference is obtained by subtracting the amplitude value of each channel from the average amplitude value of the reference channel; the phase difference is obtained by subtracting the phase value of each channel from the average phase value of the reference channel.

5. The method for digital beamforming and amplitude / phase calibration of a weather radar according to claim 4, characterized in that, In step S4, for a broadband LFM signal, multiple frequency points are selected within the bandwidth of the LFM signal, and the amplitude response and phase response of each channel at different frequency points are measured respectively. The amplitude-phase difference distribution and phase difference distribution over the entire bandwidth are obtained by interpolation or fitting methods. Based on the amplitude-phase difference distribution and phase difference distribution, the mean amplitude and mean phase of the reference channel are obtained.

6. The method for digital beamforming and amplitude / phase calibration of a weather radar according to claim 1, characterized in that, The amplitude and phase calibration coefficients include amplitude calibration coefficients and phase calibration coefficients, wherein the amplitude calibration coefficient is the amplitude difference and the phase calibration coefficient is the phase difference.

7. The method for digital beamforming and amplitude / phase calibration of a weather radar according to claim 1, characterized in that, Step S6 specifically includes: In normal operating mode, 32 receiving channels receive meteorological echo signals, which are then digitally down-converted to obtain 32 I / Q quadrature digital signals. The amplitude and phase calibration coefficients of each channel are read from the calibration parameter memory, and the amplitude and phase of the I / Q quadrature digital signals of each channel are corrected. After amplitude and phase calibration, the 32 signals are digitally beamformed according to the preset beam direction to form a meteorological detection beam in the required direction; wherein, the digital beamformation includes time delay compensation and weighted summation.

8. A digital beamforming and amplitude / phase calibration system for weather radar, characterized in that, The system includes: An LFM signal source is used to generate a linear frequency modulation calibration signal, the bandwidth of which covers the operating frequency band of the weather radar. A power divider network is used to distribute the linear frequency modulation calibration signal equally to 32 receiving channels; The 32-channel receiving front end includes a low-noise amplifier, a downconverter, and a filter for receiving and processing the linear frequency modulation calibration signal and the meteorological echo signal. The multi-channel synchronous sampling module includes a 32-channel analog-to-digital converter, driven by the same clock source, to achieve synchronous acquisition of 32 channels of signals; The digital signal processing module is used to perform digital down-conversion, amplitude-phase difference extraction, amplitude-phase calibration coefficient calculation, and digital beamforming; the amplitude-phase difference includes amplitude difference and phase difference, and the amplitude-phase calibration coefficient includes amplitude calibration coefficient and phase calibration coefficient. The calibration parameter memory is used to store the amplitude and phase calibration coefficients of each channel; The beam control unit is used to generate beamforming weighting coefficients for each channel according to the preset beam direction.

9. A weather radar digital beamforming and amplitude / phase calibration system according to claim 8, characterized in that, The digital signal processing module is implemented using an FPGA.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements a method for digital beamforming and amplitude-phase calibration of a weather radar as described in any one of claims 1 to 7.

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