A structure suitable for adaptive scanning of a phased array weather radar

Abstract

A structure suitable for adaptive scanning of phased array weather radar, a back antenna, a control module, a signal processing module and an analysis module are added in the radar, the back antenna generates a back beam independent of the main array, the control module sets the working parameters according to the back beam as the working mode of leading or lagging, the signal processing module calculates the reflectivity intensity and radial velocity from the data samples of the back beam, and the analysis module adjusts the detection parameters of the main beam according to the reflectivity intensity and radial velocity to realize adaptive scanning; when the back beam is used as a leading beam, the pulse width, pulse repetition time, FFT point number and receiving beam number of the main beam are determined by processing the echo of the back beam; when the back beam is used as a lagging beam, the limited resources of the radar scanning are concentrated in the area of interest by processing the echo of the back beam and selecting the data quality control mode.

Description

Technical Field

[0001] This invention belongs to the field of radar technology, specifically relating to an antenna structure modification technology. Background Technology

[0002] Phased array weather radars offer fast beam scanning time, flexible energy scheduling, and high monitoring and measurement efficiency. Acquiring detailed three-dimensional structures of severe weather events and their time-varying evolution, enabling the monitoring and early warning of severe weather, has become the mainstream direction for the development of next-generation weather radars.

[0003] The paper "Research on Scanning Methods of Phased-Array Weather Radar" introduces a scanning method for phased-array weather radar, while the patent "Airborne Two-Dimensional Active Phased-Array Weather Radar Beam Scanning and Processing Method" presents a beam scanning method for phased-array weather radar. Existing technologies show that both ground-based and airborne phased-array weather radars continue the scanning patterns of the new generation of weather radars. They continuously and indiscriminately scan a designated airspace, without predicting meteorological targets, and cannot adaptively change radar operating parameters. After scanning, the back-end processing software identifies meteorological target characteristics, making it difficult to leverage the advantages of phased-array weather radar.

[0004] Phased array weather radar employs Digital Beamforming (DBF) to achieve beam multiplexing (BMX). Radar beams possess significant beam pointing and dwell time flexibility. Beams defined using a single pulse repetition time (PRT) have dwell time determined by the product of the PRT (in Ts) and the number of samples (in M). A phased array weather radar's BMX contains multiple PRT beams, and the dwell time is the sum of the products of all M and Ts corresponding to each PRT. This beam dwell time flexibility refers to the radar's ability to dynamically and in real-time reposition the scanning beam's M and Ts. Phased array weather radar utilizes this capability to reduce beam dwell time in areas without targets of interest. The design of phased array weather radar's scanning modes should leverage this characteristic to achieve adaptive scanning, a feature not available in mechanically scanned radars. Summary of the Invention

[0005] Radar suffers from a Doppler dilemma: increasing the Doppler velocity measurement range reduces the unambiguous detection range, while increasing the unambiguous detection range reduces the Doppler velocity measurement range. To address this problem in existing technologies, this invention proposes a structure suitable for adaptive scanning in phased-array weather radar by adding a backbeam.

[0006] A back-facing antenna, control module, signal processing module, and analysis module are added to the radar. The back-facing antenna generates a back-facing beam independent of the main array. The control module sets the operating parameters based on the back-facing beam as the lead or hysteresis operating mode. The signal processing module calculates the reflectivity intensity and radial velocity from the data samples of the back-facing beam. The analysis module adjusts the detection parameters of the main beam based on the reflectivity intensity and radial velocity to achieve adaptive scanning.

[0007] When the backbeam is used as the leading beam, its echo is processed to determine the pulse width, pulse repetition time, FFT points, and number of receiving beams for the main beam. When the beam is used as the lagging beam, its echo is processed to select the data quality control method, thus concentrating the limited radar scanning resources on the region of interest.

[0008] This invention balances three performance metrics: data quality (variance of estimated values), spatial sampling (number and pointing of beam positions), and temporal resolution. By interleaving beams with different pointing angles and dwell times, it improves the beam flexibility of phased array weather radar. To achieve the above objectives, this invention employs the following technical solution.

[0009] The back-facing antenna includes a digital TR module and several slot waveguides. The spacing between the slot waveguides of the back-facing antenna is the same as that between the slot waveguides of the main antenna. It is mounted on the back of the array antenna frame and the angle of the covered airspace is adjustable. The digital TR module is used to transmit the back beam and receive the echo, and amplify, down-convert and digitize it. Each slot waveguide is driven by a transmit / receive channel of the digital TR module. The input and output ports of each channel are connected to the DBF element of the main antenna array. The back beam is generated by the DBF processing unit.

[0010] Furthermore, let θ be the beam pointing angle, E(sinθ) be the radiation pattern at angle θ, N be the number of slotted waveguides, w(n) be the weighting value of the nth slotted waveguide, and j be the imaginary part operation. Let θ0 = (N-1)∆θ / 2, and use the formula... and The two complex signals received by the DBF module are added together to form a back beam.

[0011] When the operating mode is lead-beam, the operating parameter is set to 1, and the back beam is used as the lead beam, scanning the target before the main beam. The dwell time is shorter than that of the main beam, providing monitoring information of the region of interest for the main beam scanning. When the operating mode is lag-beam, the operating parameter is set to 0, and the back beam is used as the lag beam, scanning the target after the main beam. The dwell time is longer than that of the main beam, providing redundant information for the main beam scanning.

[0012] Using monitoring information provided by the lead beam, the maximum distance of the storm is calculated. The beam position and dwell time of the main beam scan are adjusted to observe weather echoes, reducing PRT, increasing the number of samples, selecting clutter filters to reduce estimation variance, matching the maximum distance, maximizing the use of radar resources, improving the estimation efficiency of radial velocity and spectral width, and enhancing algorithm performance.

[0013] Furthermore, the hysteresis beam uses a large Nyquist velocity Doppler to scan the target, alleviating velocity ambiguity and obtaining the target's maximum velocity.

[0014] Furthermore, a pencil beam or shaped beam can be generated in any beam, and a single dwell time can be designed, or the back beam can be made to alternate between the leading beam and the hysteresis beam, and a variable dwell time can be designed.

[0015] Let the real and imaginary parts of the data sample from the backbeam be I and Q, respectively; R1 be the first-order correlation of the received signal from the backbeam; Tr be the time period of the transmitted pulse; Im be the imaginary part operation; Re be the real part operation; and λ be the wavelength. Using the formula Z = |I + jQ| 2 The reflectivity intensity Z is calculated using the formula V=λ*arctg{Im[R1] / Re[R1]} / 4πT r Calculate the radial velocity V.

[0016] This invention treats the backbeam as a leading beam, breaking through the core technology of phased array weather radar processing. It reduces the measurement variance of intensity, velocity, and dual polarization parameters, rationally designs the maximum detection range of the main beam, increases the pulse accumulation number, and improves the data processing quality for meteorological targets, enabling refined detection and processing of meteorological targets. Treating the backbeam as a lagging beam reduces velocity ambiguity, improves the quality of detection data, enhances the equipment's monitoring and early warning capabilities for small- and medium-scale hazardous weather, and improves the radar's detection effectiveness. Implementation

[0017] The technical solution of the present invention will be specifically described below with reference to detailed working parameter settings.

[0018] The operating parameters for the pre-guide and post-hysteresis scanning modes are preset in the radar control module, as shown in the table below.

[0019]

[0020] When in pre-scan mode, preset pre-scan working parameters are sent to the digital TR component, DBF unit, signal processing module, and data analysis module.

[0021] The antenna rotates once, transmitting a signal with its back to the target beam. Upon encountering a target, it returns and receives the echo signal. This echo signal is then processed by the digital TR module, DBF unit, signal processing module, and data analysis module to complete the surveillance scan and record the target's maximum distance. The radar control module adjusts the main beam's operating parameters to achieve refined observation.

[0022] When the back beam detects a target within a maximum range of 100km in the 70° to 120° range, the operating parameters of the main beam in the 70° to 120° range are adaptively adjusted, as shown in the table below.

[0023]

[0024] The PRF frequency was adjusted from 2400Hz to 1400Hz, the transmit pulse width was adjusted from 80µs to 120µs, the number of processing points was adjusted from 64 to 128, and the dwell time was adjusted from 26.7ms to 91ms. Other azimuth angles remained unchanged.

[0025] When in hysteresis scanning mode, the antenna rotates one revolution and transmits the hysteresis beam. The echo signal passes through the digital TR component, DBF unit, signal processing module and data analysis module to complete the large Nyquist velocity Doppler scan, record the target's maximum velocity, and correct the detection results of the main beam.

[0026] The backbench beam detected a target with a maximum speed of 28 m / s in the azimuth range of 20° to 80°, as shown in the table below.

[0027]

[0028] The processing algorithm for the main beam in the azimuth range of 20° to 80° was changed from single PRF to DPRF, achieving a maximum radial velocity processing of 38.4 m / s.

[0029] When the antenna rotates, the back beam alternately completes the pre-lead and hysteresis scans, and a different operating mode is used for each beam position.

[0030] The above are embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A structure suitable for adaptive scanning in phased array weather radar, characterized in that, include: A back-facing antenna, control module, signal processing module, and analysis module are added to the radar. The back-facing antenna generates a back beam independent of the main array. The control module sets operating parameters based on the back beam as a lead- or hysteresis operating mode. The signal processing module calculates reflectivity intensity and radial velocity from data samples of the back beam. The analysis module adjusts the detection parameters of the main beam based on reflectivity intensity and radial velocity to achieve adaptive scanning. The back-facing antenna includes a digital TR module and several slotted waveguides. The spacing between the slotted waveguides of the back-facing antenna is the same as the spacing between the slotted waveguides of the main antenna. It is mounted on the back of the array antenna frame, and the angle of the covered airspace is adjustable. The digital TR module is used to transmit the back beam and receive the echo, amplify, down-convert, and digitize it. Each slotted waveguide is composed of one of the digital TR modules. Each transmit / receive channel is driven, with its input and output ports connected to the DBF (Diverterless Array) element of the main antenna array. The DBF processing unit generates a backbeam. When the backbeam is used as a leading beam, its operating parameters are set to 1. The backbeam scans the target before the main beam, with a shorter dwell time than the main beam, providing monitoring information for the region of interest for the main beam scan. By processing its echo, the pulse width, pulse repetition time, FFT points, and number of received beams of the main beam are determined. When the backbeam is used as a lagging beam, its operating parameters are set to 0. The backbeam scans the target after the main beam, with a longer dwell time than the main beam, providing redundant information for the main beam scan. By processing its echo, the data quality control method is selected to concentrate the limited radar scanning resources on the region of interest.

2. The structure suitable for adaptive scanning of phased array weather radar according to claim 1, characterized in that, The DBF processing unit generates a backbench beam, including: Let θ be the beam pointing angle, E(sinθ) be the radiation pattern at angle θ, N be the number of slotted waveguides, w(n) be the weighting value of the nth slotted waveguide, j be the imaginary part operation, and let θ0 = (N-1). / 2, using the formula and The two complex signals received by the DBF module are added together to form a back beam.

3. The structure suitable for adaptive scanning of phased array weather radar according to claim 1, characterized in that, Also includes: Using monitoring information provided by the lead beam, the maximum distance of the storm is calculated. The beam position and dwell time of the main beam scan are adjusted to observe weather echoes, reducing PRT, increasing the number of samples, selecting clutter filters to reduce estimation variance, matching the maximum distance, maximizing the use of radar resources, improving the estimation efficiency of radial velocity and spectral width, and enhancing algorithm performance.

4. The structure suitable for adaptive scanning of phased array weather radar according to claim 1, characterized in that, The hysteresis beam scans the target using a large Nyquist velocity Doppler, generating a pencil beam or a shaped beam in any beam, designing a single dwell time, or having the back beam alternate between the leading beam and the hysteresis beam to design a variable dwell time, alleviating velocity ambiguity and obtaining the target's maximum velocity.

5. The structure suitable for adaptive scanning of phased array weather radar according to claim 1, characterized in that, The calculation of reflectivity intensity and radial velocity includes: assuming the real and imaginary parts of the data sample from the backbeam are I and Q respectively, j is the imaginary part operation, R1 is the first-order correlation of the backbeam received signal, and T... r It is the time period of the transmitted pulse, Im is the imaginary part operation, Re is the real part operation, and λ is the wavelength, which can be expressed by the formula Z=|I+jQ|. 2 The reflectivity intensity Z is calculated using the formula V=λ*arctg{Im[R1] / Re[R1]} / 4πT r Calculate the radial velocity V.

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