Complete polarization continuous wave rain detection radar system and method

Abstract

The invention belongs to the technical field of radars, and relates to a complete polarization continuous wave rain detection radar system and method, and the system is fixedly installed on the ground and comprises a two-dimensional servo turntable, a transmitting and receiving antenna and a processing case. The transmitting antenna and the receiving antenna are respectively arranged on two sides of the two-dimensional servo turntable and carry out azimuth rotation and pitch angle adjustment along with the two-dimensional servo turntable. The transmitting antenna simultaneously transmits horizontal / vertical polarization signals, and the receiving antenna simultaneously receives dual-polarization echo signals. In the processing case, a transmitting assembly is connected with a transmitting antenna, and the excitation signal is radiated through the transmitting antenna after being amplified; the receiving component is connected with a receiving antenna and is used for performing low-noise amplification, down-conversion and the like on the echo signal; the frequency synthesizer board card generates a linear frequency modulation continuous wave excitation signal; the acquisition processing board card carries out AD sampling, pulse compression, clutter suppression, echo parameter estimation and other processing on the echo signal so as to realize raindrop characteristic analysis.

Description

Technical Field

[0001] This invention belongs to the field of radar technology and relates to a fully polarized continuous wave rain measurement radar system and method. Background Technology

[0002] In the field of meteorological monitoring, rain-measuring radar is the core equipment for obtaining precipitation information, and its technological development is crucial for meteorological early warning, flash flood prevention, and other work.

[0003] Rainfall radar is typically installed on mountaintops or in small to medium-sized river basins where access is difficult. Mechanical and phased array rainfall radar technologies are constantly innovating. However, most current mainstream mechanical and phased array rainfall radars use pulse systems, which have revealed limitations in practical applications. These radars are often deployed on mountaintops or in small to medium-sized river basins where access is difficult. Pulse-based radars have a transmission power exceeding 100 watts and a duty cycle of approximately 20%, resulting in excessively high radiated power, threatening the surrounding environment and human health; the blind zone is too large, making it difficult to capture close-range meteorological information, affecting the integrity of monitoring; the system power consumption is high, and solar power alone cannot meet the requirements, necessitating additional cabling, leading to high long-term operating costs; the equipment components are bulky, with low modularity and lightweighting, making transportation and installation difficult; the high transmission power also reduces the reliability of the transmission module and increases maintenance difficulty. These problems restrict the further development and widespread application of rainfall radar technology, urgently requiring researchers to overcome technical bottlenecks, upgrade rainfall radar performance, and meet the growing demands for precision and efficiency in the meteorological monitoring field. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a fully polarized continuous wave rain measurement radar system and method to address the shortcomings of the prior art, thereby solving the technical problems of large blind zone, high radiated power, high power consumption and low resolution of the pulse system rain measurement radar with integrated transmit and receive antennas in the prior art.

[0005] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a fully polarized continuous wave rain measurement radar system, which is installed on a ground-based fixed basis and includes a two-dimensional servo turntable, a transmitting antenna, a receiving antenna, and a processing chassis. The transmitting antenna and the receiving antenna are respectively arranged on both sides of the two-dimensional servo turntable; the transmitting antenna and the receiving antenna rotate in azimuth and adjust in pitch angle with the two-dimensional servo turntable; The transmitting antenna is used to simultaneously transmit horizontally polarized signals and vertically polarized signals; the receiving antenna is used to simultaneously receive horizontally polarized echo signals and vertically polarized echo signals. The processing chassis includes a transmitting component, a receiving component, a frequency synthesizer board, and a data acquisition and processing board. The transmitting component is connected to a transmitting antenna and is used to amplify the excitation signal and drive the transmitting antenna to radiate horizontally polarized and vertically polarized signals. The receiving component is connected to a receiving antenna and is used to perform low-noise amplification, down-conversion, and analog deskewing processing on the horizontally polarized and vertically polarized echo signals. The frequency synthesizer board is used to generate an excitation signal, which is a linear frequency modulated continuous wave signal. The data acquisition and processing board is used to perform AD sampling, pulse compression, and clutter suppression processing on the echo signal received by the receiving component to obtain raindrop characteristic analysis results.

[0006] As a further improvement of the present invention, the transmitting component and the receiving component adopt an X-band radio frequency circuit, the X-band radio frequency circuit adopts a single down-conversion, and the local oscillator signal required for the down-conversion is provided by the frequency synthesizer board.

[0007] As a further improvement of the present invention, the linear frequency modulated continuous wave signal is:

[0008] in, For carrier frequency, For signal duration, For frequency modulation slope, , For signal bandwidth, It is a cosine function. Pi is the mathematical constant of a circle.

[0009] As a further improvement of the present invention, the linear frequency modulated continuous wave signal adopts a sawtooth wave modulated signal; The signal frequency of the sawtooth wave modulated signal starts from the initial frequency. f 0 linearly increases to f 0+B; The starting frequency is:

[0010] In the formula, The starting frequency; B is the carrier frequency; B is the signal bandwidth.

[0011] As a further improvement of the present invention, the transmitting antenna and the receiving antenna are disposed inside a truncated spherical radome. The radome is formed by splicing together regular pentagonal and non-uniform pentagonal radome plates. The radome plate material is fiberglass, and the radome plates are connected by screws with a specified strength medium.

[0012] As a further improvement of the present invention The acquisition and processing board includes an AD chip, an FPGA chip, and an interface chip. The operations performed by the acquisition and processing board are as follows: The system receives horizontally polarized echo signals and vertically polarized echo signals output from the receiving component. It then performs AD sampling on the horizontally polarized echo signals and vertically polarized echo signals using an AD chip to obtain digital echo signals. Finally, it performs FFT processing on the digital echo signals using an FPGA chip to obtain distance dimension information of the digital echo signals for several cycles. Coherent accumulation and spectral analysis are performed on digital echo signals of several cycles according to distance units to obtain echo analysis data, which is then uploaded through an interface chip.

[0013] As a further improvement of the present invention, the acquisition and processing board is also connected to an industrial control computer. The industrial control computer is used to receive the echo analysis data transmitted by the acquisition and processing board, calculate the intensity, velocity, velocity spectrum width and dual polarization parameters of the rainfall echo based on the echo analysis data, and generate corresponding meteorological products.

[0014] As a further improvement of the present invention, the industrial control computer performs clutter suppression on the echo analysis data using the GMAP algorithm, and performs noise power estimation, clutter boundary detection and Gaussian fitting signal recovery processing on the digital echo signal.

[0015] Secondly, the present invention provides a fully polarized continuous wave rainfall measurement method, applied to the aforementioned fully polarized continuous wave rainfall measurement radar system, comprising: Simultaneously transmit horizontally polarized signals and vertically polarized signals, and simultaneously receive dual-polarized echoes; The received dual-polarized echo is de-slanted to obtain a de-slanted signal; the de-slanted signal includes a horizontal polarization de-slanted signal and a vertical polarization de-slanted signal. The echo distance is obtained by performing FFT processing on the deskewing signal; The deskewing signal after FFT processing is subjected to distance correction, and the corrected signal is subjected to clutter suppression and signal recovery. The recovered signal is analyzed to generate rainfall echo parameters; the rainfall echo parameters include at least echo intensity, velocity, velocity spectral width, differential reflectivity factor, differential propagation phase shift, differential propagation phase shift rate, and correlation coefficient.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The fully polarized continuous wave rain measurement radar system provided by the present invention can acquire the complete scattering characteristics of raindrops in the horizontal / vertical dual polarization channel by simultaneously transmitting horizontal and vertical polarization signals and synchronously receiving the echo signals of the two polarizations. Compared with traditional single-polarization or dual-polarization radar (which can only acquire some polarization parameters), the fully polarized information can more accurately invert key parameters such as raindrop spectrum distribution, precipitation rate, and liquid water content, especially significantly enhancing the identification ability of complex precipitation (such as mixed phase precipitation and large droplet precipitation).

[0017] This invention employs a continuous wave system with separate transmit and receive antennas, resulting in a significantly smaller radar blind zone compared to pulse-based radars. This leads to a smaller radar range blind zone, lower transmit power, and higher reliability, greatly reducing long-term radar operating costs. The transmitting and receiving antennas are positioned on the left and right sides of the turntable, respectively. The transmitting antenna can simultaneously / time-divisionally transmit horizontally / vertically polarized signals, while the receiving antenna can simultaneously / time-divisionally receive horizontally / vertically polarized signals, achieving full polarization detection of raindrops. The received horizontal and vertical echo signals undergo simulated deskewing processing. The large-bandwidth signal is transformed into a narrow-band signal for sampling after simulated deskewing, reducing system complexity and significantly improving the resolution of rain-measuring radar compared to the several MHz signal bandwidth of existing rain-measuring radars. This system features low radiation, a small blind zone, low power consumption, high resolution, and high integration. Compared to traditional rain-measuring radars, it has stronger site adaptability and higher performance, making it more conducive to improving the monitoring, forecasting, and early warning capabilities for floods and flash floods in small and medium-sized river basins in my country. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the external structure of a fully polarized continuous wave rain measurement radar system provided in an embodiment of the present invention; Figure 2 A block diagram of a fully polarized continuous wave rain measurement radar system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the receiver deslant processing of a fully polarized continuous wave rain measurement radar system provided in an embodiment of the present invention; Figure 4 A flowchart of a signal processing algorithm for a fully polarized continuous wave rain measurement radar system provided in an embodiment of the present invention; The components include: 1. Antenna radome; 2. Two-dimensional servo turntable; 3. Transmitting antenna; 4. Receiving antenna; 5. Processing chassis; 6. Industrial control computer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and marked in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] Example 1 The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1-2 This invention provides a fully polarized continuous wave rain measurement radar system. The system is installed on a ground-based fixed installation (e.g., a mountaintop platform or a watershed monitoring base station foundation). The system consists of a two-dimensional servo turntable 2, a transmitting antenna 3, a receiving antenna 4, a processing chassis 5, a truncated spherical radome 1, and an industrial control computer 6. Specifically, the two-dimensional servo turntable 2, transmitting antenna 3, receiving antenna 4, and processing chassis 5 are integrated within the truncated spherical radome 1. The radome 1 is fixed to the installation platform by a steel structure support, and its bottom is connected to the equipment room (where the industrial control computer 6 is placed) via a cable well. The transmitting antenna 3 and receiving antenna 4 are symmetrically arranged on the left and right sides of the two-dimensional servo turntable 2. The processing chassis 5 is placed on top of the two-dimensional servo turntable 2 and fixed with screws. All components are connected via waveguides, RF cables, and data lines, forming a complete signal transmission, reception, and processing link. Furthermore, the transmitting antenna 3 and receiving antenna 4 can be electrically adjusted synchronously with the two-dimensional servo turntable 2, rotating from 0° to 360° in azimuth and from -5° to 90° in elevation.

[0024] The transmitting antenna 3 is used to simultaneously transmit horizontally polarized and vertically polarized signals, while the receiving antenna 4 is used to simultaneously receive horizontally polarized and vertically polarized echo signals. To protect the antennas from external environmental influences, the transmitting antenna 3 and the receiving antenna 4 are housed within a truncated spherical radome 1. This radome 1 is formed by splicing regular pentagonal and asymmetrical pentagonal panels, and the panels are made of fiberglass, which has good weather resistance and mechanical properties. The panels are connected by screws with a specified strength medium to ensure the structural stability of the radome 1. In this embodiment, both the transmitting antenna 3 and the receiving antenna 4 are parabolic antennas.

[0025] In this embodiment, the processing chassis 5 serves as the core processing unit of the system, and integrates a transmitting component, a receiving component, a frequency synthesizer board, and a data acquisition and processing board.

[0026] In this embodiment, the transmitting component is connected to the transmitting antenna 3. Its main function is to amplify the excitation signal and drive the transmitting antenna 3 to radiate horizontally polarized and vertically polarized signals. The transmitting component uses an X-band radio frequency circuit, which employs a single down-conversion method. The local oscillator signal required for down-conversion is provided by the frequency synthesizer board. The X-band is suitable for rain measurement scenarios, and the single down-conversion design enables effective reception and deskewing of the echo signal. Specifically, the transmitting component has two channels. The transmitting component is connected to the horizontally polarized transmitting antenna 3 and the vertically polarized transmitting antenna 3 respectively through waveguides. The radio frequency signal amplified by the transmitting component is radiated out through the horizontally polarized transmitting antenna 3 and the vertically polarized transmitting antenna 3.

[0027] The receiving component is connected to the receiving antenna 4 and is responsible for low-noise amplification, down-conversion, and analog de-skewing processing of the horizontally polarized and vertically polarized echo signals. Like the transmitting component, the receiving component also uses X-band RF circuitry, and the local oscillator signal required for down-conversion is also provided by the frequency synthesizer board. Specifically, the horizontally polarized receiving antenna 4 and the vertically polarized receiving antenna 4 simultaneously receive the horizontally polarized and vertically polarized echoes of raindrops. The horizontally polarized and vertically polarized echoes are input to the two-channel receiving component via waveguides. The receiving component amplifies and de-skews the horizontally polarized and vertically polarized echoes. After de-skewing, the echo signal is converted from a linear frequency modulated signal to a point frequency signal. In this embodiment, the sampling clock and local oscillator signal of the radar system are provided by the frequency synthesizer board.

[0028] The frequency synthesizer board is used to generate the excitation signal, which is a linear frequency modulated (LFM) continuous wave signal. The expression for the LFM continuous wave signal is:

[0029] in, For carrier frequency, For signal duration, For frequency modulation slope, , For signal bandwidth, It is a cosine function. Pi is the mathematical constant of a circle.

[0030] This linear frequency modulated continuous wave signal uses a sawtooth wave modulation signal, and the signal frequency of the sawtooth wave modulation signal starts from the initial frequency. f 0 linearly increases to f 0+B; The starting frequency is:

[0031] In the formula, The starting frequency; B is the carrier frequency; B is the signal bandwidth.

[0032] The acquisition and processing board includes an AD chip, an FPGA chip, and an interface chip. Its main operations are as follows: It receives horizontally polarized and vertically polarized echo signals from the receiving components. The AD chip performs AD sampling on these two types of echo signals to obtain digital echo signals. Subsequently, the FPGA chip performs FFT processing on the digital echo signals to obtain the range dimension information of several cycles of digital echo signals. Finally, it performs coherent accumulation and spectrum analysis on the several cycles of digital echo signals according to the range units to obtain echo analysis data, which is then uploaded to the industrial control computer via the interface chip. Specifically, the acquisition and processing board receives horizontally polarized and vertically polarized raindrop echo signals from two receiving components. Each received signal is converted into a digital signal through AD sampling. FFT processing is performed on the digital signals, followed by coherent accumulation and spectrum analysis on all range units of the multiple cycles of raindrop echoes. The data processed by the acquisition and processing board is sent via network to the industrial control computer 6 in the computer room for calculation of parameters such as the intensity, velocity, spectral width, and dual polarization parameters of the rain echo, and is displayed in real time on the interface of the industrial control computer 6. The acquisition and processing board is also responsible for the generation of timing signals for the entire machine, as well as the reception of radar commands and radar operating parameters.

[0033] Furthermore, the radome 1 is formed by splicing together regular pentagonal and non-uniform pentagonal radomes. The radome material is fiberglass, and the radomes are connected by screws with a set strength medium.

[0034] The system also includes an industrial computer 6, which is connected to the data acquisition and processing board and is used to receive echo analysis data transmitted from the board. The industrial computer 6 calculates the intensity, velocity, velocity spectrum width, and dual polarization parameters of the rainfall echoes based on the echo analysis data, and generates corresponding meteorological products.

[0035] During data processing, the industrial control computer 6 uses the GMAP algorithm to suppress clutter in the echo analysis data. Specifically, this includes noise power estimation, clutter boundary detection, and Gaussian fitting signal recovery processing of the digital echo signal to improve the accuracy and reliability of the data and provide a high-quality data source for meteorological analysis.

[0036] Example 2 See Figure 3 and Figure 4 One embodiment of the present invention provides a fully polarized continuous wave rainfall measurement method, which is based on the above-mentioned fully polarized continuous wave rainfall measurement radar system and includes the following steps: Step S1: Use the monitor 6 in the computer room to set the radar's operating frequency. Time bandwidth Parameters such as turntable speed and pitch scanning range.

[0037] Step S2: Based on the parameter settings and timing relationships in Step S1, the frequency synthesizer board generates an RF excitation signal. The excitation signal (i.e., the transmit signal) is a linear frequency modulated continuous wave signal, specifically represented as follows:

[0038] in, The carrier frequency of the transmitted signal. For signal duration, For frequency modulation slope, , This refers to the signal bandwidth.

[0039] Step S201: Modulate the continuous wave signal using sawtooth wave modulation, with the signal frequency starting from... It started to increase, and after a period of time Increase to Then, from Continue adding more, and repeat in this cycle to obtain a sawtooth wave modulated signal.

[0040] Step S202: The sawtooth wave modulated signal is output to two identical transmitting components. The transmitting components transmit two signals, which are connected to a horizontally polarized transmitting antenna and a vertically polarized transmitting antenna, respectively, via waveguide antennas. Horizontal and vertical polarized signals can be transmitted simultaneously or in a time-division manner through the horizontally and vertically polarized transmitting antennas.

[0041] Step S3: The horizontally polarized and vertically polarized receiving antennas can simultaneously receive rain echo signals with different polarizations. Therefore, during horizontally polarized transmission, both horizontally transmitted and horizontally received (HH) and horizontally transmitted and vertically received (HV) echo signals can be obtained simultaneously; during vertically polarized transmission, both vertically transmitted and horizontally received (VH) and vertically transmitted and vertically received (VV) echo signals can be obtained simultaneously. By alternately transmitting horizontally polarized and vertically polarized signals, fully polarized rain echo signals of HH, HV, VH, and VV can be obtained.

[0042] Based on the transmitted linear frequency modulated continuous wave signal, the echo signal received by the radar is:

[0043] in, For signal delay, , Echo distance (i.e., the straight-line distance between the radar system in this embodiment and the target being detected (such as rain particles, cloud clusters, etc.)). At the speed of light, The time delay corresponding to the farthest target is generally Much larger , .

[0044] Step S301: After receiving the echo signal, the receiving antenna 4 performs deskewing on the echo; first, the transmitted signal is used as the local oscillator signal and the echo signal are mixed.

[0045]

[0046] This represents the local oscillator signal.

[0047] The mixer output is then:

[0048] Then, after the high-frequency components are filtered out by a low-pass filter, the de-scrambled echo signal is obtained, which is represented as:

[0049] in The output after mixing is a beat signal. .

[0050] Using the above method, the echoes received by the horizontally polarized antenna and the vertically polarized antenna after deskewing are respectively expressed as: , .

[0051] The echo distance can be obtained by performing FFT processing on the de-skewing echo signal. The value of .

[0052] Step S4: After deskewing, the horizontal / vertical echo signals are converted from analog to digital signals through two-channel AD sampling. The sampled horizontal / vertical digital echo signals are then subjected to pulse compression processing, as detailed below:

[0053]

[0054] Therefore, the extracted signal frequency is:

[0055] Therefore, the echo distance can be obtained as:

[0056] Step S5: Send the echo analysis data (horizontal / vertical digital echo signals processed by the acquisition and processing board) to the industrial control computer in the computer room.

[0057] Step S501: The industrial control computer first performs range correction on the echo analysis data. Rain echoes of the same intensity will have different signal strengths received by the radar due to different operating distances. To reflect the true intensity of rain echoes at different distances, range correction is needed. The range correction method is to multiply the square of the echo distance by the echo intensity, as follows:

[0058]

[0059] Step S502: The GMAP algorithm is used to suppress clutter and recover the signal from the range-corrected echo analysis data. The processing flow is as follows: Step 1: Windowing and FFT processing of the distance-corrected echo analysis data.

[0060] First, the input echo data (i.e., the horizontal / vertical digital echo signal after distance correction) is windowed using a Hamming window, and then DFT processing is performed to obtain the Doppler power spectrum.

[0061] Step 2: Calculate the noise power.

[0062] First, the Doppler power spectrum intensity is sorted in ascending order.

[0063] Secondly, the total power from 5% to 40% of the power spectrum intensity is calculated, and this is used to fit the theoretical curve of the noise spectrum. Specifically: for M samples, the interval points from 5% to 40% are selected for... express:

[0064] in The parameters are determined by the quantiles corresponding to the sample points. The exponential distribution parameters can be estimated using the above formula. And calculate the theoretical curve.

[0065] Next, the points where the actual power intensity is greater than 40% of the theoretical curve are compared. If the difference between the actual power and the theoretical curve power is greater than 2dB, then the actual power at that point is determined as the boundary between the noise region and the signal / clutter region. The area below this boundary is the noise region, and the area above it is the signal or clutter region.

[0066] Finally, the noise power below the boundary line is averaged to obtain the noise power value.

[0067] Step 3: Filter out clutter.

[0068] The filter searches outward from zero speed. Within the maximum searchable range, the boundary of the clutter is determined by the first point of power increase outside the clutter region. Points within the clutter boundary are replaced with noise power values.

[0069] Step 4: Signal recovery.

[0070] Because some raindrop echoes have low velocities, some spectral components of the raindrop echoes are filtered out in the third step. Gaussian curve fitting is then used to fit the spectral components filtered out in the third step. This process is iterated until the calculated power change is less than 0.2 dB, at which point the iterated points replace the noise power values. This completes the recovery of the weather signal using Gaussian fitting.

[0071] The incremental equation for Gaussian fitting using the Gauss-Newton method is:

[0072] in, , For Jacobian matrices, The objective function is... This represents the parameter increment in the k-th iteration.

[0073] Step S6: Analyze the recovered signal to generate rainfall echo parameters; rainfall echo parameters include, but are not limited to, dual polarization parameters such as echo intensity, velocity, spectral width, differential reflectivity factor, differential propagation phase shift, differential propagation phase shift rate, and correlation coefficient, and their estimation methods are as follows: 1) Echo intensity: Echo intensity is the reflectivity factor This represents the sum of the sixth power of the diameters of all cloud and precipitation particles per unit volume. (Unit: ...) In practical applications, decibels are commonly used to express this value. Acquired from the horizontal channel Starting from the signal, after noise suppression, ground clutter filtering, and parameter correction, the reflectivity factor can be directly obtained, and its expression is:

[0074] In the formula, Signal-to-noise ratio; The radial distance of the target from the radar, in units ; This is the atmospheric attenuation coefficient, which is related to the radar frequency. This is a correction factor related to radar system parameters. This is the clutter correction factor, which is related to the power of the echo signal before and after filtering.

[0075] 2) Velocity and velocity spectral width: Assuming echoes for the same range cell The power spectrum is:

[0076] Average frequency:

[0077] Spectrum width The square of is:

[0078] velocity spectrum :

[0079] speed Assuming the Doppler cell where the target is located is Then its corresponding Doppler frequency shift for:

[0080]

[0081] , The pulse repetition frequency, This represents the number of pulses.

[0082]

[0083] in, λ is the wavelength.

[0084] 3) Differential reflectivity factor: Differential reflectivity factor The reflectivity factor of the horizontal channel Reflectivity factor of vertical channel The ratio, The calculation is as follows:

[0085] 4) Formulas for differential propagation phase shift and differential propagation phase shift rate: For the same precipitation area, the phase changes caused by horizontally polarized waves and vertically polarized waves during propagation are different, and the difference between them is related to the shape and concentration of particles in the precipitation area. (Differential propagation phase shift) Calculate as follows:

[0086] Differential propagation phase shift rate , defined as the change in phase shift per unit distance during differential propagation, is calculated as follows:

[0087] , These represent the distances from the radar to two measurement points within the precipitation area.

[0088] 5) Correlation coefficient For dual-polarization radars that transmit and receive simultaneously, the correlation coefficient... The calculation is as follows:

[0089] in: , In the formula, , Indicates the first A horizontally and vertically polarized echo pulse This represents the number of pulses.

[0090] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 fully polarized continuous wave rain measurement radar system, characterized by ground-based fixed installation, wherein... Includes a two-dimensional servo turntable, transmitting antenna, receiving antenna, and processing chassis; The transmitting antenna and the receiving antenna are respectively arranged on both sides of the two-dimensional servo turntable; the transmitting antenna and the receiving antenna rotate in azimuth and adjust in pitch angle with the two-dimensional servo turntable; The transmitting antenna is used to simultaneously transmit horizontally polarized signals and vertically polarized signals; the receiving antenna is used to simultaneously receive horizontally polarized echo signals and vertically polarized echo signals. The processing chassis includes a transmitting component, a receiving component, a frequency synthesizer board, and a data acquisition and processing board. The transmitting component is connected to a transmitting antenna and is used to amplify the excitation signal and drive the transmitting antenna to radiate horizontally polarized and vertically polarized signals. The receiving component is connected to a receiving antenna and is used to perform low-noise amplification, down-conversion, and analog deskewing processing on the horizontally polarized and vertically polarized echo signals. The frequency synthesizer board is used to generate an excitation signal, which is a linear frequency modulated continuous wave signal. The data acquisition and processing board is used to perform AD sampling, pulse compression, and clutter suppression processing on the echo signal received by the receiving component to obtain raindrop characteristic analysis results.

2. The fully polarized continuous wave rain measurement radar system according to claim 1, characterized in that, The transmitting and receiving components employ X-band radio frequency circuitry, which uses a single down-conversion. The local oscillator signal required for the down-conversion is provided by the frequency synthesizer board.

3. The fully polarized continuous wave rain measurement radar system according to claim 1, characterized in that, The linear frequency modulated continuous wave signal is: in, For carrier frequency, For signal duration, For frequency modulation slope, , For signal bandwidth, It is a cosine function. Pi is the mathematical constant of a circle.

4. The fully polarized continuous wave rain measurement radar system according to claim 3, characterized in that, The linear frequency modulated continuous wave signal is a sawtooth wave modulated signal. The signal frequency of the sawtooth wave modulated signal starts from the initial frequency. f 0 linearly increases to f 0+B; The starting frequency is: In the formula, The starting frequency; B is the carrier frequency; B is the signal bandwidth.

5. The fully polarized continuous wave rain measurement radar system according to claim 1, characterized in that, The transmitting and receiving antennas are housed within a truncated spherical radome. The radome is formed by splicing together regular pentagonal and non-uniform pentagonal radome plates. The radome plates are made of fiberglass and are connected to each other by screws with a specified strength.

6. The fully polarized continuous wave rain measurement radar system according to claim 1, characterized in that, The acquisition and processing board includes an AD chip, an FPGA chip, and an interface chip. The operations performed by the acquisition and processing board are as follows: The system receives horizontally polarized echo signals and vertically polarized echo signals output from the receiving component. It then performs AD sampling on the horizontally polarized echo signals and vertically polarized echo signals using an AD chip to obtain digital echo signals. Finally, it performs FFT processing on the digital echo signals using an FPGA chip to obtain distance dimension information of the digital echo signals for several cycles. The echo signals of several cycles are coherently accumulated and spectrally analyzed according to distance units to obtain echo analysis data, which is then uploaded through an interface chip.

7. The fully polarized continuous wave rain measurement radar system according to claim 6, characterized in that, The data acquisition and processing board is also connected to an industrial control computer, which is used to receive echo analysis data transmitted by the data acquisition and processing board, calculate the intensity, velocity, velocity spectrum width and dual polarization parameters of the rainfall echo based on the echo analysis data, and generate corresponding meteorological products.

8. The fully polarized continuous wave rain measurement radar system according to claim 7, characterized in that, The industrial control computer uses the GMAP algorithm to suppress clutter in the echo analysis data and performs noise power estimation, clutter boundary detection, and Gaussian fitting signal recovery processing on the digital echo signal.

9. A fully polarized continuous wave rainfall measurement method, applied to the fully polarized continuous wave rainfall measurement radar system according to any one of claims 1 to 8, characterized in that, include: Simultaneously transmit horizontally polarized signals and vertically polarized signals, and simultaneously receive dual-polarized echoes; The received dual-polarized echo is de-slanted to obtain a de-slanted signal; the de-slanted signal includes a horizontal polarization de-slanted signal and a vertical polarization de-slanted signal. The echo distance is obtained by performing FFT processing on the deskewing signal; The deskewing signal after FFT processing is subjected to distance correction, and the corrected signal is subjected to clutter suppression and signal recovery. The recovered signal is analyzed to generate rainfall echo parameters; the rainfall echo parameters include at least echo intensity, velocity, velocity spectral width, differential reflectivity factor, differential propagation phase shift, differential propagation phase shift rate, and correlation coefficient.

10. The fully polarized continuous wave rainfall measurement method according to claim 9, characterized in that, The echo distance is: in, For signal frequency, For signal duration, At the speed of light, This refers to the signal bandwidth.

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