A system and method for fully automatic precipitation measurement using microwave radar

Abstract

The present invention provides a fully automatic precipitation measurement system using microwave radar, comprising a microwave radar transceiver module for real-time monitoring of precipitation echo signals; an echo high-gain amplification module that amplifies the precipitation echo signals, performs analog-to-digital conversion, and transmits the signals to a precipitation analysis and statistics module; an automatic gain control module connected to the precipitation analysis and statistics module and the echo high-gain amplification module; a temperature and humidity monitoring module for monitoring ambient temperature and humidity and the real-time temperature of a circuit board and transmitting the results to a precipitation subsystem and module; and a precipitation analysis and statistics module that sends real-time energy monitoring values ​​to the automatic gain control module and performs energy detection and Doppler analysis on the amplified echo signals after automatic gain control. The former is used to calibrate precipitation intensity, and the latter is used to detect precipitation type. The present invention is no longer affected by vertical wind speed interference, eliminates the measurement instability of conventional Doppler precipitation radars, and improves measurement accuracy.

Description

Technical Field

[0001] The present invention is mainly used in various automatic weather stations, and mainly involves radar signal processing, digital and analog high-speed circuits, programmable logic devices and microprocessor software development technologies, and specifically relates to a system and method for fully automatic precipitation measurement using microwave radar. Background Art

[0002] Precipitation is one of the most important measurement functions of a weather station. Traditional precipitation measurement is mainly based on various measuring instruments. For example, the most popular rain gauge currently uses various tipping bucket automatic measurement technologies. Although it does not require manual operation, its inherent mechanical structure defects limit its sensitivity and accuracy to a certain extent, and it is difficult to directly support the measurement of precipitation in the form of snowfall, hail, etc.

[0003] In addition to mechanical rain gauges, with the rapid development of electronic technology, researchers are also seeking to directly utilize the characteristics of certain electronic components to measure rainfall. Currently, two promising electronic rain measurement technologies are piezoelectric sensing and Doppler high-frequency radar. The former uses the energy generated by raindrops striking piezoelectric materials to directly sense rainfall intensity. While its algorithm is simple, it is limited by current material properties and has difficulty sensing weaker precipitation, or even if it can be sensed, the error is excessively large. It is also unsuitable for measuring precipitation forms such as snow and hail. Doppler high-frequency radar uses a transceiver antenna to radiate high-frequency electromagnetic waves into the sky. When precipitation occurs, these electromagnetic waves (hereinafter referred to as echo signals) are reflected back to the antenna and detected by subsequent circuitry. Different rainfall intensities correspond to different falling speeds, which directly affects the Doppler frequency of the echo signal. Therefore, by establishing a correct correlation between the echo Doppler frequency and precipitation amount and type, real-time precipitation measurement can be achieved.

[0004] Generally speaking, due to the limitations of their working principles, the sensitivity and measurement accuracy of mechanical and piezoelectric sensor rain gauges are unlikely to be significantly improved in the short term. While the sensitivity of Doppler high-frequency radar measurement is relatively high, it actually measures the composite velocity of raindrops and vertical wind speed. The measurement results are easily affected by wind speed interference, and usually require an auxiliary wind speed and direction measurement device to correct them, which also affects the popularity of this solution to a certain extent. Summary of the Invention

[0005] To avoid the above problems, a system and method for fully automatic precipitation measurement using microwave radar are provided.

[0006] The object of the present invention is achieved in the following manner:

[0007] A fully automatic precipitation measurement system using microwave radar includes a microwave radar transceiver module, which is connected to an echo high-gain amplifier module and is used to monitor precipitation echo signals in real time and transmit them to the echo high-gain amplifier module; the echo high-gain amplifier module is connected to a precipitation analysis and statistics module and is used to amplify the precipitation echo signals and then perform analog-to-digital conversion to transmit them to the precipitation analysis and statistics module; an automatic gain control module is respectively connected to the precipitation analysis and statistics module and the echo high-gain amplifier module and is used to automatically control the echo high-gain amplifier module according to the current precipitation intensity in the precipitation analysis and statistics module; a temperature and humidity monitoring module is used to monitor the precipitation echo signals in real time and transmit them to ... The module is connected to the precipitation analysis and statistics module and is used to monitor the ambient temperature and humidity and the real-time temperature of the circuit board and transmit them to the precipitation subsystem and module. The precipitation analysis and statistics module is used to receive the digital value of the amplified echo signal sent by the echo high-gain amplification module and the real-time on-board temperature value sent by the temperature and humidity monitoring module, and send the real-time energy monitoring value to the automatic gain control module. The module also performs energy detection and Doppler analysis on the amplified echo signal after automatic gain control, calibrates the precipitation intensity through the former, and detects the precipitation type through the latter. The energy statistics results are also corrected using the measurement values ​​of the temperature and humidity monitoring module.

[0008] The system also includes a secondary power supply module, which inputs a 12V power supply and outputs high-power direct current for the heating module, analog power for analog circuits, and digital power for digital circuits.

[0009] The system also includes a log recording and communication module, which is connected to the precipitation analysis and statistics module. The log recording and communication module includes an RTC real-time clock and a TF card reader, which records the precipitation analysis and statistics results and measurement results such as temperature and humidity sensor data in real time in a large-capacity TF card. At the same time, the measurement results are directly connected to the computer through an interface or wireless network and received and analyzed by dedicated host computer software.

[0010] The system also includes a heating module connected to the temperature and humidity monitoring module.

[0011] The microwave radar transceiver module includes an integrated transceiver antenna, a high-frequency voltage-controlled oscillator and a mixer. The high-frequency voltage-controlled oscillator radiates high-frequency electromagnetic waves through the integrated transceiver antenna. The mixer couples a small portion of the energy transmitted by the high-frequency voltage-controlled oscillator to the mixer for mixing with the echo signal, and outputs the echo baseband signal to the outside.

[0012] The echo high-gain amplification module includes a first-stage amplifier, a second-stage amplifier, and an analog-to-digital conversion chip connected in sequence; the adjustment of the amplification gain of the first-stage amplifier and the second-stage amplifier is controlled by the stepping gear of the digitally controlled resistor. The echo energy output by the two-stage amplifier is appropriately amplified, which is converted into a digital quantity by the analog-to-digital conversion chip and provided to the automatic gain control module and the precipitation analysis and statistics module.

[0013] The automatic gain control module selects a suitable amplification factor by controlling the echo high-gain amplification module through digitally controlled resistor stepping according to the current echo energy intensity.

[0014] A method for fully automatic precipitation measurement using microwave radar comprises the following steps:

[0015] S1: The microwave radar transceiver module receives the precipitation echo signal and outputs the echo baseband signal;

[0016] S2: The echo baseband signal is amplified by the echo high-gain amplifier module and converted into digital signal data and sent to the precipitation analysis and statistics module;

[0017] S3: The precipitation analysis and statistics module combines the real-time temperature value of the temperature sensor on the circuit board and corrects the actual amplification factor through the automatic gain control module to obtain the original echo energy value. The precipitation analysis and statistics module then performs energy detection and analysis to determine whether a precipitation event has occurred.

[0018] S3: The precipitation analysis and statistical results together with the corresponding RTC real-time clock information form a complete precipitation statistical information frame, and are sent to the log recording and external communication module to be saved in the TF card or transmitted to an external host computer.

[0019] The method further includes performing threshold judgment based on the Doppler frequency corresponding to the same energy detection to achieve differentiation of different precipitation types.

[0020] The working process of the precipitation analysis and statistics module is as follows: S1: determine whether a 1s interrupt is received. If so, perform bandpass filtering on multiple sets of baseband data received in the past 1s to filter out-of-band noise;

[0021] S2: Perform 2:1 data extraction on the multiple groups of baseband data filtered in S1 as sampling data;

[0022] S3: Using the current temperature on the circuit board to correct the amplification gain coefficient, the sampled data is normalized with the coefficient to obtain the true echo signal;

[0023] S4: Perform a fast Fourier transform on the normalized time domain sampling data and calculate the echo energy accumulation value E1 within the specified frequency range F1-F2. Does E1 exceed the set threshold 1? If not, no precipitation event has occurred, and the precipitation statistics information is sent to the log recording and external communication module; if so, find the corresponding maximum frequency component of the echo intensity after the fast Fourier transform and the energy value E2 of the adjacent component;

[0024] S5: Perform median filtering of a specified window size on E2 to obtain E3. Check whether E3 exceeds the set threshold 2 for more than 10 times in a row. If not, the reliable threshold condition is not met and it is considered abnormal interference and does not constitute a precipitation event. If so, a rainfall event occurs and E3 begins to be accumulated, which is recorded as ACC.

[0025] S6: Convert ACC into corresponding precipitation amount; obtain real-time clock information on the circuit board, and combine it with precipitation intensity data to form precipitation statistics information, and send the precipitation statistics information to the log recording and external communication module.

[0026] Beneficial Effects of the Present Invention: Unlike existing radar rain gauges that utilize the Doppler effect to measure velocity, the present invention primarily relies on precise analysis of echo intensity to achieve real-time precipitation statistics. This eliminates the interference of vertical wind speed, eliminates the measurement instability of conventional Doppler rain gauges, and improves measurement accuracy. To adapt to varying precipitation intensities, an automatic gain control module controls the amplification factor of the radar echo circuit in real time, consistently generating an amplified echo signal with sufficient energy and no distortion. Thanks to its superior analog circuit design, the maximum amplification factor can reach 4000x, enabling accurate sensing and measurement of even very weak precipitation events. Another advantage of the present invention is that it supports a variety of precipitation types, including rain, snow, and hail, all with high measurement accuracy. Measurement results can be stored locally or transmitted to a remote computer via wired or wireless means. The entire device is compact and operates on a single power supply, making it widely applicable in automatic weather stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the overall structural diagram of the present invention.

[0028] Figure 2 It is a diagram of the internal structure of the secondary power supply of the present invention.

[0029] Figure 3 It is a diagram of the internal structure of the microwave radar transceiver module of the present invention.

[0030] Figure 4 It is a diagram of the internal structure of the echo high-gain amplification module of the present invention.

[0031] Figure 5It is a schematic diagram of the statistical threshold of the automatic gain control module of the present invention.

[0032] Figure 6 It is a workflow diagram of the precipitation analysis and statistics module of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same technical meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. It should also be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] In the present invention, terms such as "fixed connection," "connected," and "connection" should be interpreted broadly to mean a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediary. Relevant researchers or technicians in this field may determine the specific meanings of these terms in the present invention based on specific circumstances, and they should not be construed as limitations of the present invention.

[0037] like Figure 1As shown, a system for fully automatic precipitation measurement using microwave radar includes a microwave radar transceiver module, which is connected to an echo high-gain amplification module and is used to monitor the precipitation echo signal in real time and transmit it to the echo high-gain amplification module; the echo high-gain amplification module is connected to a precipitation analysis and statistics module and is used to amplify the precipitation echo signal and then perform analog-to-digital conversion to transmit it to the precipitation analysis and statistics module; an automatic gain control module is respectively connected to the precipitation analysis and statistics module and the echo high-gain amplification module and is used to automatically control the echo high-gain amplification module according to the current precipitation intensity in the precipitation analysis and statistics module; a temperature and humidity monitoring module is used to monitor the precipitation echo signal in real time and transmit it to ... The control module is connected to the precipitation analysis and statistics module, and is used to monitor the ambient temperature and humidity and the real-time temperature of the circuit board and transmit them to the precipitation subsystem and module; the precipitation analysis and statistics module is used to receive the digital value of the amplified echo signal sent by the echo high-gain amplification module and the real-time on-board temperature value sent by the temperature and humidity monitoring module, and send the real-time energy monitoring value to the automatic gain control module, and perform energy detection and Doppler analysis on the amplified echo signal after automatic gain control. The former is used to calibrate the precipitation intensity, and the latter is used to detect the precipitation type. The energy statistical results are also corrected using the measurement values ​​of the temperature and humidity monitoring module.

[0038] The system also includes a secondary power supply module, which generates high-precision power required by various internal electronic components from the input 12V DC power supply. The module is mainly composed of two power supply chips: a switching power supply and a linear regulator. The former is used to generate intermediate power, heating power and power supply for commonly used digital chips, and the latter is used to generate low-ripple, high-quality analog power for various analog components. To achieve better results, the digital ground and analog ground are strictly separated, and a single-point grounding method is used on the circuit board to connect all ground wires to the common ground wire.

[0039] like Figure 2As shown, with the advancement of semiconductor technology, the number of electronic devices has reached tens of millions. Each device has different supply voltages, operating currents, and anti-interference capabilities. The present invention also requires the simultaneous use of multiple components and integrated circuits, including analog circuit chips, digital circuit chips, and mixed-signal circuit chips. The quality of the power supply system directly affects the normal operation of the circuits. To this end, the power consumption of the entire system is first divided into three categories: high-power DC power for the heating module, analog power for the analog circuit portion, and digital power for the digital circuit portion. The main characteristics of high-power DC power supply are high current but low ripple sensitivity, so it can be directly implemented using high-current switching power supply chips. Analog power is mainly used for radar modules, operational amplifiers, analog-to-digital conversion chips, etc. Radar echo signals are very weak. Excessive power supply ripple can directly obscure the useful signal in the output noise. Therefore, the present invention uses low-ripple linear power supplies for the analog power supply. However, due to the low efficiency of linear power supplies, another switching power supply is used to step down the 12V voltage to generate an intermediate power supply. Two linear power supplies are then used to output low-ripple analog power supplies 1 and 2. The four power outputs of the secondary power supply all have independent power return lines (i.e. ground lines). Different ground lines are connected through inductance to achieve the final common ground, while ensuring good isolation between them.

[0040] The system also includes a logging and communication module connected to the precipitation analysis and statistics module. This module, which includes an RTC (Real-Time Clock) and a TF card reader, records precipitation analysis and statistics, along with temperature and humidity sensor data, in real time onto a high-capacity TF card. Furthermore, the measurement results can be directly connected to a computer via the device's microUSB / RS485 interface and received and analyzed using dedicated host software. For applications where wired transmission is unsuitable, an IoT communication module can be added to the device to upload precipitation statistics directly via wireless or mobile communication technologies.

[0041] This module's functions are primarily implemented through the combined programming of MCU and FPGA hardware and software. The hardware runs on a Zynq processor. After obtaining precipitation statistics, frames are first recorded to an onboard TF card. To facilitate information exchange, the logging and external communication module utilizes the open-source FAT file management system, the FATFS library. This library directly recognizes FAT32-formatted TF cards and records detailed precipitation events as text files. The TF card can be read and written directly on any computer or mobile phone, and logs can be viewed. Dedicated host software can also be used to automatically analyze precipitation events.

[0042] In addition to storing precipitation information through a TF card, the module also provides a variety of external communication interfaces, including USB and RS485 wired transmission interfaces. The former is suitable for short-distance transmission and can be connected to an external computer via an ordinary microUSB data cable and use dedicated host software to view / record precipitation information in real time. RS485 is a differential half-duplex transmission bus commonly used in industry. It has strong anti-interference ability and a longer transmission distance, making it suitable for long-distance networking transmission.

[0043] For remote areas where wired transmission is unsuitable, data can be uploaded via mainstream wireless communication technologies. The choice of wireless communication technologies is very flexible, including LoRa, Zigbee, LTE, and GPRS. This implementation case uses an IoT communication module that supports GPRS communication, directly transmitting data to a designated server via a mobile communication company's base station. This server can be used to view precipitation statistics from a host computer or mobile phone.

[0044] The system also includes a heating module, connected to the temperature and humidity monitoring module. In winter, when temperatures drop below zero, the internal heating module automatically activates to heat the radar radome to melt ice and snow, thereby ensuring measurement accuracy. The infrared heating wires are selectively turned on and off based on the current ambient temperature and humidity data. Within the 12V power supply current, high-power heating wires are used to enhance the heating effect. Heating stops when the radome temperature rises above approximately 5°C.

[0045] The temperature and humidity monitoring module senses the ambient temperature and humidity of the instrument and the temperature of the circuit board through a temperature and humidity sensor and an onboard temperature sensor. The former is used to monitor the ambient temperature and humidity, and the latter is used to monitor the real-time temperature of the circuit board. Affected by the heat generated by electronic components, the temperature of the latter is usually higher than the former.

[0046] The microwave radar transceiver module includes an integrated transceiver antenna, a high-frequency voltage-controlled oscillator, and a mixer. The high-frequency voltage-controlled oscillator radiates high-frequency electromagnetic waves through the integrated transceiver antenna. The mixer couples a small portion of the energy emitted by the high-frequency voltage-controlled oscillator to the mixer for mixing with the echo signal, and outputs the echo baseband signal. Figure 3As shown, the module contains a high-frequency voltage-controlled oscillator (VCO) that radiates high-frequency electromagnetic waves through a specially designed patch antenna array. The radiation frequency can reach tens of GHz. In this case, the radiation frequency is 24 GHz, which has good directivity. To reduce costs, the module directly uses a transceiver antenna. The internal self-mixing structure directly couples a small portion of the original transmitted energy to the mixer for mixing with the echo signal, thereby directly outputting a zero-IF baseband signal. Its structural block diagram is shown. This module is an analog device, powered by a low-ripple analog power supply 1. The output is a weak radar echo signal. The echo strength ranges from tens of uV to several millivolts, depending on the precipitation intensity.

[0047] The echo high-gain amplification module includes a first-stage amplifier, a second-stage amplifier, and an analog-to-digital conversion chip connected in sequence. The amplification gain of the first-stage amplifier and the second-stage amplifier is adjusted through the step-by-step control of the digitally controlled resistor. The output of the two-stage amplifier is the appropriately amplified echo energy, which is converted into a digital value by the analog-to-digital conversion chip and provided to the automatic gain control module and the precipitation analysis and statistics module. Figure 4 As shown in the figure, the main function of this module is to realize the amplification and analog-to-digital conversion of weak echo signals. To ensure sufficient measurement sensitivity, the designed amplification factor is 10~4000 times, which is specifically implemented by a two-stage proportional operational amplifier + analog filter. The gain adjustment of the entire amplifier module is achieved through the step-by-step control of the digitally controlled resistor. The output of the two-stage amplifier is the echo energy after appropriate amplification, which is then converted to the digital domain by the analog-to-digital conversion chip and can be used by the subsequent automatic gain control and precipitation analysis and statistics modules.

[0048] The automatic gain control module selects the appropriate amplification factor based on the current echo energy intensity using a digitally controlled resistor stepper to control the echo high-gain amplifier module. To ensure that the amplified echo signal waveform is not distorted and has sufficient energy across all rainfall intensities, the current echo energy intensity must be dynamically and rapidly monitored to select the appropriate amplification factor. This module is primarily programmed with embedded software and operates on a Zynq processor. Its main principle is to regularly calculate the echo amplitude distribution within the previous cycle. By setting multiple thresholds and counting the number of sampling points exceeding these thresholds, the module adds the current amplification level to the corresponding true echo intensity, which is then used to determine the amplification level for the next cycle. The simulation curve shown in Figure 5 illustrates the module's operating principle. As shown in Figure 5, two typical amplified echo signal sampling curves are plotted with * and x symbols, respectively, while two threshold curves are plotted with left and right triangles. The thresholds are selected based on approximately half of the amplifier's maximum distortion peak-to-peak value. It can be seen that echo signals with different amplitudes correspond to different numbers of sampling points exceeding the given thresholds 1 and 2. The larger the amplitude, the more sampling points exceed the thresholds per unit cycle. These two statistical quantities are referred to as overflow number 1 and overflow number 2. The magnitude of overflow number 1 and overflow number 2 can be used to indirectly determine the energy intensity. When the value is too small, the amplification level needs to be increased. When the value is too large, the amplification level needs to be reduced. Within a certain range, the amplification level is maintained unchanged. To facilitate engineering implementation, this implementation divides the amplification level into eight levels, corresponding to different digitally controlled resistor step control gears. Automatic gain control is implemented based on overflow number 1 and overflow number 2, with a processing cycle of one second.

[0049] A method for fully automatic precipitation measurement using microwave radar, comprising the following steps:

[0050] S1: The microwave radar transceiver module receives the precipitation echo signal and outputs the echo baseband signal;

[0051] S2: The echo baseband signal is amplified by the echo high-gain amplifier module and converted into digital signal data and sent to the precipitation analysis and statistics module;

[0052] S3: The precipitation analysis and statistics module combines the real-time temperature value of the temperature sensor on the circuit board and corrects the actual amplification factor through the automatic gain control module to obtain the original echo energy value. The precipitation analysis and statistics module then performs energy detection and analysis to determine whether a precipitation event has occurred.

[0053] S3: The precipitation analysis and statistical results together with the corresponding RTC real-time clock information form a complete precipitation statistical information frame, and send it to the log Jiluo Road and external communication module to save it to the TF card or transmit it to an external host computer.

[0054] The method further includes performing threshold judgment based on the Doppler frequency corresponding to the same energy detection to achieve differentiation of different precipitation types.

[0055] The precipitation analysis and statistics module is primarily implemented through the combined programming of an MCU and FPGA hardware. The hardware runs on a Zynq processor, and its data comes from 20,000 sets of baseband data output by an analog-to-digital conversion chip (hereinafter referred to as ADC_DAT). Energy detection and analysis is initiated every 1 second. The processing flow for different precipitation types, such as rain, snow, and hail, is essentially the same, differing only in the corresponding frequency analysis ranges.

[0056] Taking rainfall statistics as an example, the typical raindrop velocity is 1 to 10 m / s. The microwave radar frequency is 24 GHz. Based on the Doppler effect calculation formula, the corresponding Doppler frequency is approximately 166 to 1666 Hz. In practice, a margin can be left, with a starting frequency F1 of 150 Hz and a cutoff frequency of 1800 Hz. Only echo energy within this frequency range is considered valid energy. The complete workflow of this module is shown in Figure 6. The operation of this module mainly depends on the 1S timing interrupt. After the interrupt is received, bandpass filtering is performed to filter out-of-band noise, and then data extraction is performed under the premise of complying with the sampling theorem, which can effectively reduce the subsequent data processing pressure. Finally, the time domain sampling data of each processing cycle is 10,000 points. Note that the sampling data has been amplified by the amplifier, so it needs to be normalized according to the current amplification level. In actual work, the gain of the amplifier circuit is mainly affected by the digital control resistor step, but it will also drift slightly with changes in operating temperature. The drift curve is relatively fixed, so it can be obtained in advance through temperature cycling environment tests, and then the actual amplification factor can be further corrected according to the on-board temperature sensor to obtain an accurate original echo energy value.

[0057] After obtaining the raw echo energy value, a fast Fourier transform is performed on it. To improve computational efficiency, a transform length of 16384 is selected. The cumulative echo energy value, E1, within the specified frequency range F1-F2 is then calculated. This cumulative value is very small when there is no precipitation. However, as precipitation intensity increases, E1 gradually increases. After exceeding the threshold, precipitation is preliminarily determined to be possible. The corresponding maximum echo intensity frequency component and its adjacent component energy values ​​are then identified and re-judged. In this second judgment, the precipitation analysis and statistics module introduces a nonlinear median filter, which has stronger resistance to outlier interference than traditional linear low-pass filtering, albeit with a slightly higher computational load. However, the Zynq on-chip ARM microprocessor used in this case has a main frequency exceeding 600 MHz, which is sufficient to perform this median filter.

[0058] After obtaining E3 through median filtering, to further improve anti-interference performance, it is necessary to calculate it to be greater than the set threshold of 2 for 10 consecutive times before it is considered a true precipitation process. Otherwise, it is considered abnormal interference, such as falling foreign objects or flying insects. During the precipitation event, E3 is accumulated to obtain ACC. ACC and actual precipitation have a clear statistical correspondence curve, so the current precipitation information RAINFALL can be obtained from ACC. This information, together with the corresponding RTC real-time clock information, constitutes a complete precipitation statistics information frame, which is sent to the logging and external communication module for storage on a TF card or transmission to an external host computer.

[0059] Different precipitation types can be distinguished based on the correspondence between energy value and the strongest frequency component. Under the same detection energy value, the falling speed of snowfall (typical value is 1~2m / s) is much smaller than that of rainfall, and the corresponding Doppler frequency is also significantly smaller than the Doppler frequency during rainfall. The falling speed of hail can exceed 15m / s. Under the same detection energy value, the corresponding Doppler frequency is significantly higher than that of rainfall. Therefore, the three precipitation types can be effectively distinguished by threshold judgment based on the corresponding Doppler frequency under the same energy detection value.

[0060] The working process is as follows: S1: Determine whether a 1s interrupt is received. If so, perform bandpass filtering on multiple sets of baseband data received in the past 1s to filter out-of-band noise;

[0061] S2: Perform 2:1 data extraction on the multiple groups of baseband data filtered in S1 as sampling data;

[0062] S3: Using the current temperature on the circuit board to correct the amplification gain coefficient, the sampled data is normalized with the coefficient to obtain the true echo signal;

[0063] S4: Perform a fast Fourier transform on the normalized time domain sampling data, calculate the echo energy accumulation value E1 within the specified frequency range F1-F2, and determine whether E1 exceeds the set threshold 1. If not, no precipitation event has occurred, and the precipitation statistics information is sent to the log recording and external communication module; if so, find the maximum frequency component of the echo intensity and the energy value E2 of the adjacent component after the fast Fourier transform;

[0064] S5: Perform median filtering of a specified window size on E2 to obtain E3. Check whether E3 exceeds the set threshold 2 for more than 10 times in a row. If not, the reliable threshold condition is not met and it is considered abnormal interference and does not constitute a precipitation event. If so, a rainfall event occurs and E3 begins to be accumulated, which is recorded as ACC.

[0065] S6: Convert ACC into corresponding precipitation amount; obtain real-time clock information on the circuit board, and combine it with precipitation intensity data to form precipitation statistics information, and send the precipitation statistics information to the log recording and external communication module.

[0066] The present invention's solution is compact and requires no specific installation location requirements. It can effectively measure extreme weather conditions such as rain, snow, and even hail. Requiring only a standard 12V DC power supply, it operates 24 / 7. Detailed measurement results are stored on the device's internal high-capacity memory card and can be transmitted in real time to an external computer via a USB cable or IoT data card. In winter, when temperatures drop below zero, an internal heating module automatically activates to heat the radar antenna cover to melt attached ice and snow, ensuring measurement accuracy.

[0067] The overall performance is superior to that of electronic rain gauges based on piezoelectric sensors. Through algorithmic innovation, it eliminates the problems of unstable measurement and susceptibility to wind direction interference of the original Doppler rain radar. Coupled with its complete log recording and external communication performance, it can be widely used in various automatic weather stations.

[0068] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

[0069] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A fully automatic precipitation measurement system using microwave radar, characterized by: It includes a microwave radar transceiver module, which is connected to the echo high-gain amplifier module and is used to monitor the precipitation echo signal in real time and transmit it to the echo high-gain amplifier module; the echo high-gain amplifier module is connected to the precipitation analysis and statistics module and is used to amplify the precipitation echo signal and then perform analog-to-digital conversion to transmit it to the precipitation analysis and statistics module; An automatic gain control module is connected to the precipitation analysis and statistics module and the echo high-gain amplification module, respectively, and is used to automatically control the echo high-gain amplification module according to the current precipitation intensity in the precipitation analysis and statistics module; a temperature and humidity monitoring module is connected to the precipitation analysis and statistics module, and is used to monitor the ambient temperature and humidity and the real-time temperature of the circuit board and transmit them to the precipitation analysis and statistics module; the precipitation analysis and statistics module is used to receive the digital value of the amplified echo signal sent by the echo high-gain amplification module and the real-time on-board temperature value sent by the temperature and humidity monitoring module, and transmit the real-time energy monitoring value to the automatic gain control module, and perform energy detection and Doppler analysis on the amplified echo signal after automatic gain control, calibrating the precipitation intensity through the former and detecting the precipitation type through the latter, and also correcting the energy statistics result using the measurement value of the temperature and humidity monitoring module; The main principle of the automatic gain control module is to regularly count the echo amplitude distribution in the previous cycle, set multiple thresholds and count the number of sampling points exceeding the threshold, and add the current amplification level to obtain the corresponding true echo strength, and use this to determine the amplification level of the next cycle; The microwave radar transceiver module includes an integrated transceiver antenna, a high-frequency voltage-controlled oscillator and a mixer. The high-frequency voltage-controlled oscillator radiates high-frequency electromagnetic waves through the integrated transceiver antenna. The mixer couples a small portion of the energy transmitted by the high-frequency voltage-controlled oscillator to the mixer for mixing with the echo signal, and outputs the echo baseband signal to the outside.

2. The system for fully automatic precipitation measurement using microwave radar according to claim 1, characterized in that: The system also includes a secondary power supply module, which inputs a 12V power supply and outputs high-power direct current for the heating module, analog power for analog circuits, and digital power for digital circuits.

3. The system for fully automatic precipitation measurement using microwave radar according to claim 1, characterized in that: The system also includes a log recording and communication module, which is connected to the precipitation analysis and statistics module. The log recording and communication module includes an RTC real-time clock and a TF card reader, which records the precipitation analysis and statistics results and the temperature and humidity sensor data measurement results in real time in a large-capacity TF card. At the same time, the measurement results are directly connected to the computer through an interface or wireless network and received and analyzed by dedicated host computer software.

4. The system for fully automatic precipitation measurement using microwave radar according to claim 1, wherein: The system also includes a heating module connected to the temperature and humidity monitoring module.

5. The system for fully automatic precipitation measurement using microwave radar according to claim 1, characterized in that: The echo high-gain amplification module includes a first-stage amplifier, a second-stage amplifier, and an analog-to-digital conversion chip connected in sequence; the adjustment of the amplification gain of the first-stage amplifier and the second-stage amplifier is controlled by the stepping gear of the digitally controlled resistor. The echo energy output by the two-stage amplifier is appropriately amplified, which is converted into a digital quantity by the analog-to-digital conversion chip and provided to the automatic gain control module and the precipitation analysis and statistics module.

6. The system for fully automatic precipitation measurement using microwave radar according to claim 1, characterized in that: The automatic gain control module selects a suitable amplification factor by controlling the echo high-gain amplification module through digitally controlled resistor stepping according to the current echo energy intensity.

7. A measurement method using the system according to claim 1, characterized in that: The following steps are involved: S1: The microwave radar transceiver module receives the precipitation echo signal and outputs the echo baseband signal; S2: The echo baseband signal is amplified by the echo high-gain amplifier module and converted into digital signal data and sent to the precipitation analysis and statistics module; S3: The precipitation analysis and statistics module combines the real-time temperature value of the temperature sensor on the circuit board with the automatic gain control module to correct the actual amplification factor. After obtaining the original echo energy value, the precipitation analysis and statistics module performs energy detection and analysis to determine whether a precipitation event has occurred. S4: The precipitation analysis and statistical results together with the corresponding RTC real-time clock information form a complete precipitation statistical information frame, and are sent to the log recording and external communication module to be saved in the TF card or transmitted to an external host computer.

8. The measuring method according to claim 7, wherein: The method further includes performing threshold judgment based on the Doppler frequency corresponding to the same energy detection to achieve differentiation of different precipitation types.

9. The measuring method according to claim 7, wherein: The working process of the precipitation analysis and statistics module is as follows: A1: Determine whether a 1s interrupt is received. If so, perform bandpass filtering on multiple sets of baseband data received in the past 1s to filter out-of-band noise; A2: Perform 2:1 data extraction on the multiple groups of baseband data filtered in A1 as sampling data; A3: Use the current temperature on the circuit board to correct the amplification gain coefficient and normalize the sampled data with this coefficient to obtain the true echo signal; A4: Perform a fast Fourier transform (FFT) on the normalized time-domain sampling data and calculate the cumulative echo energy value E1 within the specified frequency range F1-F2. Check whether E1 exceeds the set threshold 1. If not, no precipitation event has occurred. The precipitation statistics are sent to the logging and external communication module. If so, the corresponding frequency component with the maximum echo intensity and the energy value of the adjacent component E2 are found after the FFT. A5: Perform a median filter on E2 with a specified window size to obtain E3. Check whether E3 exceeds the set threshold 2 for more than 10 consecutive times. If not, the reliable threshold condition is not met and it is considered abnormal interference, not a precipitation event. If so, a rainfall event occurs and E3 begins to be accumulated, recorded as ACC. A6: Convert ACC to the corresponding precipitation amount; obtain the real-time clock information on the circuit board, and combine it with the precipitation intensity data to form precipitation statistics information, and send the precipitation statistics information to the logging and external communication module.

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