Radar rain gauge echo signal gain amplification circuit

Abstract

A radar rain gauge echo signal gain amplification circuit is provided with a microwave radar receiving and transmitting module JP1 used for outputting analog baseband echo signals modulated by a frequency mixing circuit, and a first power supply module used for being electrically connected with the microwave radar receiving and transmitting module JP1 and providing power for the microwave radar receiving and transmitting module JP1; the numerical control resistor IC3 is a double-channel numerical control resistor, the variable resistance value of the first channel is configured to be Radj1, and the variable resistance value of the second channel is configured to be Radj2; the three-stage reverse amplification circuit is used for amplifying an echo signal of the microwave radar transceiver module JP1; the analog-to-digital converter IC7 is used for receiving the signal subjected to three-stage amplification; and the MCU is electrically connected with the analog-to-digital converter IC7 and is used for receiving the signal converted by the analog-to-digital converter IC7. According to the technical scheme of the utility model, the PCB can still be ensured to have excellent amplification performance without using a complicated bipolar power supply amplifier, and the dripping speed of raindrops can be obtained by performing Doppler analysis on a measurement result by using the MCU, so that a solid foundation is provided for realizing accurate rain intensity measurement.

Description

Technical Field

[0001] The utility model relates to the technical field of rainfall measurement, in particular to a radar rain gauge echo signal gain amplifier circuit. Background Art

[0002] Rain gauges are used to measure rainfall. Commonly used ones are mechanical rain gauges and photoelectric rain gauges. Among the mechanical rain gauges, the tipping bucket rain gauge is the most widely used. It has a simple structure and high measurement accuracy. However, in the case of heavy rainfall, the tipping bucket rain gauge will leak rain, get stuck mechanically, etc., resulting in reduced accuracy. The photoelectric rain gauge can accurately measure rainfall, but has relatively high requirements for light. In a bright environment, it will affect the measurement accuracy.

[0003] Radar technology is currently very common in measurement applications. In recent years, meteorological measurement instrument companies at home and abroad have begun to try to use microwave radar to sense the current rainfall intensity and rainfall, thereby replacing the traditional tipping bucket rain gauge.

[0004] However, since the echo signal of raindrops to microwave radar is very weak, and the size and spatial distribution of raindrops are very diverse, the echo signal is seriously distorted. After amplifying the distorted signal, the measured data obtained is seriously inconsistent with the actual data. Therefore, how to achieve distortion-free amplification of the echo signal has become a major problem in this field. Utility Model Content

[0005] One purpose of the utility model is to provide a radar rain gauge echo signal gain amplifier circuit. In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0006] A radar rain gauge echo signal gain amplifier circuit has a microwave radar transceiver module JP1 for outputting an analog baseband echo signal modulated by a mixing circuit, and also includes:

[0007] A first power supply module, used to be electrically connected to the microwave radar transceiver module JP1 and provide power thereto, the first power supply module comprising a voltage regulator IC8, the output end of the voltage regulator IC8 is connected to two resistors R21 and R22 connected in parallel, and the ratio of the resistors R21 and R22 is adjusted to adjust the power supply voltage of the microwave radar transceiver module;

[0008] The digital controlled resistor IC3 is a dual-channel digital controlled resistor, and the variable resistance value of the first channel is configured as Radj1, and the variable resistance value of the second channel is configured as Radj2;

[0009] A first-stage amplification circuit is connected to the output pin of the microwave radar transceiver module, including a first dual-channel amplifier IC4, an RC high-pass filter, and an RC low-pass filter. The RC high-pass filter and the RC low-pass filter constitute a series circuit, one end of which is connected to the first output pin of the first dual-channel amplifier IC4, and the other end is connected to the output pin of the microwave radar transceiver module JP1. The amplified signal is set on the first output pin of the first dual-channel amplifier IC4; the RC high-pass filter includes a capacitor C19 and a resistor R19 connected in series, and the RC low-pass filter includes a capacitor C16 and a resistor R8 connected in parallel;

[0010] A secondary amplifier circuit, used for performing secondary amplification on the signal configured on the first output pin of the first dual-channel amplifier IC4, one end of which is connected to the first output pin of the first dual-channel amplifier IC4, and the other end is connected to the second output pin of the first dual-channel amplifier IC4, and includes a capacitor C17 and a resistor R7 connected in series with each other, and also includes a resistor R6 connected in series with the first channel of the digitally controlled resistor IC3, and the amplified signal is configured at the second output pin of the first dual-channel amplifier;

[0011] A three-stage reverse amplifier circuit is used to perform a third-stage amplification on the signal configured at the second channel output pin of the first dual-channel amplifier IC4, one end of which is connected to the second channel output pin of the first dual-channel amplifier IC4 and the other end is connected to the first channel output pin of the second dual-channel amplifier IC5 configured with two channels. The three-stage reverse amplifier circuit includes a capacitor C23 and a resistor R11 connected in series with each other, and also includes a resistor R10 connected in series with each other in the second channel of the digitally controlled resistor IC3. The amplified signal is configured on the first channel output pin of the second dual-channel amplifier IC5;

[0012] The analog-to-digital converter IC7 is connected to the first channel output pin of the second dual-channel amplifier IC5 to receive the signal after three-stage amplification;

[0013] The MCU is electrically connected to the analog-to-digital converter IC7 and is used to receive the signal converted by the analog-to-digital converter IC7.

[0014] Furthermore, a voltage follower module is configured on the second channel of the second dual-channel amplifier to perform voltage following on the signal after three-stage amplification, and a resistor R12 and a capacitor C24 are connected in parallel to the second channel output pin of the second dual-channel amplifier IC5 to perform filtering on the voltage following.

[0015] Furthermore, a second power supply module is configured to power the two dual-channel amplifiers and the digitally controlled resistor IC3. The second power supply module includes a voltage regulator IC10, and the output end of the voltage regulator IC10 is provided with resistors R23 and R24 connected in parallel with each other. The ratio of the resistors R23 and R24 is adjusted to adjust the power supply voltage of the two dual-channel amplifiers and the digitally controlled resistor IC3.

[0016] Furthermore, the second power supply module is also configured with a voltage divider circuit for dividing the voltage of the first dual-channel amplifier IC4 and the second dual-channel amplifier IC5, the voltage divider circuit includes a resistor R13 and a resistor R14 connected in series with each other, and the voltage divider circuit is also configured with a decoupling capacitor C25 and a decoupling capacitor C26, and the decoupling capacitor C25 and the decoupling capacitor C26 are respectively arranged close to the first dual-channel amplifier IC4 and the second dual-channel amplifier IC5.

[0017] Furthermore, a third power supply module is included for supplying power to the analog-to-digital converter IC7, which includes a voltage regulator IC9, and decoupling capacitors C48 and C49 respectively arranged at the input and output ends of the voltage regulator IC9.

[0018] Furthermore, decoupling capacitors C52 and C53 connected in parallel are also arranged on the pin of the microwave radar transceiver module JP1 to which the first power supply module is connected.

[0019] Furthermore, the digital end of the analog-to-digital converter IC7 is configured as a spi interface and corresponds to adC sdo, adCsClk, adC din, and adC Cnv respectively, for direct connection with the MCU.

[0020] Furthermore, the MCU is configured with a FIR filter for filtering the digital signal received from the analog-to-digital converter so as to increase the steepness of the digital signal.

[0021] The beneficial effects produced by the utility model are as follows:

[0022] The radar rain gauge echo signal gain amplifier circuit and gain amplification method provided in the embodiment can use a low-cost single-power supply operational amplifier to form a multi-stage amplifier circuit, realize the gain variable function through a digitally controlled resistor in the amplifier circuit, realize noise suppression by combining a conventional RC filter and a FIR digital filter, realize analog-to-digital conversion through a high-performance SAR ADC, and complete the echo energy analysis and automatic gain control functions by an MCU. A large number of carefully selected decoupling capacitors are used in the design, and the analog part and the digital part are well divided. There is no need to use a complex bipolar power supply amplifier device, and the PCB circuit board can still be ensured to have excellent amplification performance. The MCU is used to perform Doppler analysis on the measurement results to obtain the dripping speed of raindrops, thereby providing a solid foundation for realizing accurate rainfall intensity measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is an overall circuit diagram of the utility model.

[0024] Figure 2 This is a circuit diagram of the first power supply module in the present utility model.

[0025] Figure 3 This is a circuit diagram of the second power supply module in the present utility model.

[0026] Figure 4 This is a circuit diagram of the third power supply module in the present utility model.

[0027] Figure 5 It is a circuit diagram of the analog-to-digital converter in the utility model.

[0028] Figure 6 It is a circuit diagram of the MCU in the utility model. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the embodiments and drawings, and the contents mentioned in the implementation modes are not intended to limit the present invention. The present invention is described in detail below in conjunction with the drawings.

[0030] The utility model embodiment provides a radar rain gauge echo signal gain amplifier circuit, such as Figure 1-6 As shown, it has a microwave radar transceiver module JP1, which is used to output an analog baseband echo signal modulated by a mixing circuit, and also includes: a first power supply module, which is used to be electrically connected to the microwave radar transceiver module JP1 and provide power to it, and the first power supply module includes a voltage regulator IC8, and the output end of the voltage regulator IC8 is connected to two resistors R21 and R22 connected in parallel, and the ratio of the resistors R21 and R22 is adjusted to adjust the power supply voltage of the microwave radar transceiver module;

[0031] The digitally controlled resistor IC3 is a dual-channel digitally controlled resistor, and the variable resistance of the first channel is configured as Radj1, and the variable resistance of the second channel is configured as Radj2; the dual-channel digitally controlled resistor IC3 can form a 256-level variable resistor at both ends of A1 / W1, B1, and at both ends of A2 / W2, B2. For convenience in the future, the maximum resistance of Radj1 and Radj2 can reach 1M ohm. The specific resistance value is realized by dpot_cs, dpot_clk, dpot_u / d, and dpot_sel through digital control.

[0032] A first-stage amplification circuit is connected to the output pin of the microwave radar transceiver module, including a first dual-channel amplifier IC4, an RC high-pass filter, and an RC low-pass filter. The RC high-pass filter and the RC low-pass filter constitute a series circuit, one end of which is connected to the first output pin of the first dual-channel amplifier IC4, and the other end is connected to the output pin of the microwave radar transceiver module JP1. The amplified signal is set on the first output pin of the first dual-channel amplifier IC4;

[0033] The RC high-pass filter includes a capacitor C19 and a resistor R19 connected in series, and the RC low-pass filter includes a capacitor C16 and a resistor R8 connected in parallel;

[0034] C19, R19, C16, R8 and the first op amp of IC4 form the first stage fixed gain reverse amplifier circuit, and C19 and R19 form an RC high-pass filter, and C16 and R8 form an RC low-pass filter. By properly selecting the resistance and capacitance values, only the signal of interest can be sent to the next stage to reduce out-of-band noise interference. The amplified signal is located at pin 1 of IC4.

[0035] A secondary amplifier circuit, used for performing secondary amplification on the signal configured on the first output pin of the first dual-channel amplifier IC4, one end of which is connected to the first output pin of the first dual-channel amplifier IC4, and the other end is connected to the second output pin of the first dual-channel amplifier IC4, and includes a capacitor C17 and a resistor R7 connected in series with each other, and also includes a resistor R6 connected in series with the first channel of the digitally controlled resistor IC3, and the amplified signal is configured at the second output pin of the first dual-channel amplifier;

[0036] The signal at pin 1 of IC4 is then reversely amplified in the second stage, where C17 and R7 form an RC high-pass filter. However, unlike the first stage, the second stage reverse amplification uses a variable resistor composed of Radj1 and R6 in series together with C17 and R7 to complete the reverse amplification. The larger Radj1 is, the greater the amplification gain is. The amplified signal is located at pin 7 of IC4.

[0037] A three-stage reverse amplifier circuit is used to perform a third-stage amplification on the signal configured at the second channel output pin of the first dual-channel amplifier IC4, one end of which is connected to the second channel output pin of the first dual-channel amplifier IC4 and the other end is connected to the first channel output pin of the second dual-channel amplifier IC5 configured with two channels. The three-stage reverse amplifier circuit includes a capacitor C23 and a resistor R11 connected in series with each other, and also includes a resistor R10 connected in series with each other in the second channel of the digitally controlled resistor IC3. The amplified signal is configured on the first channel output pin of the second dual-channel amplifier IC5;

[0038] The signal at pin 7 of IC4 is then reversely amplified in the third stage, where C13 and R11 form an RC high-pass filter. The variable resistor formed by Radj2 and R10 in series is used together with C13 and R11 to complete the reverse amplification. The larger the Radj2, the greater the amplification gain. The amplified signal is located at pin 1 of IC5.

[0039] The analog-to-digital converter IC7 is connected to the first channel output pin of the second dual-channel amplifier IC5 to receive the signal after three-stage amplification; the MCU is electrically connected to the analog-to-digital converter IC7 to receive the signal converted by the analog-to-digital converter IC7.

[0040] The analog-to-digital converter IC7 is a 16-bit SAR ADC that performs analog-to-digital conversion on adc sig, which can achieve better sampling and quantization effects than the traditional sigma-delta ADC;

[0041] JP1 is a small microwave radar transceiver module. It only needs to be powered through pin 1 to output analog baseband echo signals through the internal mixing circuit. However, since the echo signal is very microwave, it must be amplified before use. In order to avoid the power ripple coupling to the echo signal, 100nF decoupling capacitors C52 and C53 are added to the power port of JP1. In actual PCB design, more appropriate capacitance values ​​can be selected according to the wiring conditions to further improve the decoupling effect.

[0042] In order to achieve a better amplification effect, JP1 power supply selects LDO chips with high PSRR, such as SGM2032, whose PSRR can reach 75dB and adopts SOT2-3 small package, which is very suitable for space-constrained applications. Figure 2 As shown, in the first power supply module, the voltage regulator IC8 is the SGM2032 chip, and supports fine-tuning the radar module power supply voltage by modifying the ratio of R21 and R22. The input and output of IC8 both have two sets of decoupling capacitors, with typical values ​​of 10uF and 0.1uF.

[0043] The second channel of the second dual-channel amplifier is equipped with a voltage follower module for voltage following the signal after three-stage amplification. The second channel output pin of the second dual-channel amplifier IC5 is connected to a resistor R12 and a capacitor C24 in parallel for filtering the voltage follower.

[0044] In this embodiment, the second operational amplifier of IC5 is used to perform a first-stage voltage following process on the third-stage reverse amplification, and R12 and C24 perform an RC low-pass filtering process on the voltage following output again to obtain an adc sig signal, which has a strong driving capability and effectively suppresses noise and out-of-band interference, and can be sent to the ADC.

[0045] A second power supply module is also configured to supply power to the two dual-channel amplifiers and the digital control resistor IC3. The second power supply module includes a voltage regulator IC10, and the output end of the voltage regulator IC10 is provided with resistors R23 and R24 connected in parallel. The ratio of the resistors R23 and R24 is adjusted to adjust the supply voltage of the two dual-channel amplifiers and the digital control resistor IC3. IC10 also generates 3.3V analog power for SGM2032, which is used to provide analog power supply for the subsequent amplifier circuit and ADC (analog-to-digital converter) chip. The input and output decoupling capacitors are designed the same as IC8.

[0046] In order to provide more balanced power supply to IC4 and IC5, the second power supply module is also provided with a voltage divider circuit for dividing the voltage of the first dual-channel amplifier IC4 and the second dual-channel amplifier IC5, the voltage divider circuit includes resistors R13 and R14 connected in series, and the voltage divider circuit is also provided with decoupling capacitors C25 and C26, the decoupling capacitors C25 and C26 are respectively arranged close to the first dual-channel amplifier IC4 and the second dual-channel amplifier IC5. The bias voltage of the two operational amplifiers IC4 and IC5 is obtained by dividing 3.3VA by 1:1 by R13 and R14, that is, the bias voltage is 1.65V.

[0047] In this embodiment, a third power supply module is provided for supplying power to the analog-to-digital converter IC7, which includes a voltage regulator IC9, and decoupling capacitors C48 and C49 respectively provided at the input and output ends of the voltage regulator IC9. IC9 is an HT7333 chip that generates 3.3V digital power, and 10uF decoupling capacitors are added to both the input and output, and the analog part and the digital part are effectively divided during PCB design to reduce the interference of digital signals on weak analog signals.

[0048] The MCU is configured with a FIR filter for filtering the digital signal received from the analog-to-digital converter so that the digital signal has a steeper characteristic.

[0049] After acquiring the ADC data and performing FIR filtering (finite-length unit impulse response filter, also known as non-recursive filter) on it, the MCU performs spectrum analysis on the sampled data through fast Fourier transform (FFT) and calculates the Doppler frequency of the echo signal. This frequency is formed due to the relative motion between the raindrops and the radar module. The falling speed of the raindrops can be inferred based on the Doppler frequency calculation formula. The falling speed of the raindrops is mainly affected by their diameter. Therefore, the Doppler frequency can be used to estimate the diameter of the raindrops, calculate and count the current rainfall intensity, and realize the precise radar rain gauge measurement function.

[0050] This technical solution can achieve a typical receiving dynamic range of about 170dB at a relatively low hardware cost, and does not require the use of negative voltage power supply. It can form an amplifier circuit with reliable performance and excellent stability using only ordinary operational amplifiers and digitally controlled resistors. Based on MCU and SAR ADC devices, it realizes automatic gain control and Doppler analysis in the digital domain, meeting the requirements for distortion-free sampling of raindrop echo signals from weak rainfall to extremely heavy rain, and is suitable for radar rain gauge products.

[0051] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention is disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technology of the present invention, which do not depart from the content of the technical solution of the present invention, are within the scope of the technical solution of the present invention.

Claims

1. A radar rain gauge echo signal gain amplifier circuit, having a microwave radar transceiver module JP1, for outputting an analog baseband echo signal modulated by a mixing circuit, characterized in that: Also included are: A first power supply module, used to be electrically connected to the microwave radar transceiver module JP1 and provide power thereto, the first power supply module comprising a voltage regulator IC8, the output end of the voltage regulator IC8 is connected to two resistors R21 and R22 connected in parallel, and the ratio of the resistors R21 and R22 is adjusted to adjust the power supply voltage of the microwave radar transceiver module; The digital controlled resistor IC3 is a dual-channel digital controlled resistor, and the variable resistance value of the first channel is configured as Radj1, and the variable resistance value of the second channel is configured as Radj2; A first-stage amplification circuit is connected to the output pin of the microwave radar transceiver module, including a first dual-channel amplifier IC4, an RC high-pass filter, and an RC low-pass filter. The RC high-pass filter and the RC low-pass filter constitute a series circuit, one end of which is connected to the first output pin of the first dual-channel amplifier IC4, and the other end is connected to the output pin of the microwave radar transceiver module JP1. The amplified signal is set on the first output pin of the first dual-channel amplifier IC4; the RC high-pass filter includes a capacitor C19 and a resistor R19 connected in series, and the RC low-pass filter includes a capacitor C16 and a resistor R8 connected in parallel; A secondary amplifier circuit, used for performing secondary amplification on the signal configured on the first output pin of the first dual-channel amplifier IC4, one end of which is connected to the first output pin of the first dual-channel amplifier IC4, and the other end is connected to the second output pin of the first dual-channel amplifier IC4, and includes a capacitor C17 and a resistor R7 connected in series with each other, and also includes a resistor R6 connected in series with the first channel of the digitally controlled resistor IC3, and the amplified signal is configured at the second output pin of the first dual-channel amplifier; A three-stage reverse amplifier circuit is used to perform a third-stage amplification on the signal configured at the second channel output pin of the first dual-channel amplifier IC4, one end of which is connected to the second channel output pin of the first dual-channel amplifier IC4 and the other end is connected to the first channel output pin of the second dual-channel amplifier IC5 configured with two channels. The three-stage reverse amplifier circuit includes a capacitor C23 and a resistor R11 connected in series with each other, and also includes a resistor R10 connected in series with each other in the second channel of the digitally controlled resistor IC3. The amplified signal is configured on the first channel output pin of the second dual-channel amplifier IC5; The analog-to-digital converter IC7 is connected to the first channel output pin of the second dual-channel amplifier IC5 to receive the signal after three-stage amplification; The MCU is electrically connected to the analog-to-digital converter IC7 and is used to receive the signal converted by the analog-to-digital converter IC7.

2. A radar rain gauge echo signal gain amplifier circuit according to claim 1, characterized in that: The second channel of the second dual-channel amplifier is equipped with a voltage follower module for voltage following the signal after three-stage amplification. The second channel output pin of the second dual-channel amplifier IC5 is connected to a resistor R12 and a capacitor C24 in parallel for filtering the voltage follower.

3. The radar rain gauge echo signal gain amplifier circuit according to claim 1, characterized in that: A second power supply module is also configured to power the two dual-channel amplifiers and the digitally controlled resistor IC3. The second power supply module includes a voltage regulator IC10, and the output end of the voltage regulator IC10 is provided with resistors R23 and R24 connected in parallel with each other. The ratio of the resistors R23 and R24 is adjusted to adjust the power supply voltage of the two dual-channel amplifiers and the digitally controlled resistor IC3.

4. A radar rain gauge echo signal gain amplifier circuit according to claim 3, characterized in that: The second power supply module is also configured with a voltage divider circuit for dividing the voltage of the first dual-channel amplifier IC4 and the second dual-channel amplifier IC5. The voltage divider circuit includes a resistor R13 and a resistor R14 connected in series. The voltage divider circuit is also configured with a decoupling capacitor C25 and a decoupling capacitor C26. The decoupling capacitor C25 and the decoupling capacitor C26 are respectively arranged close to the first dual-channel amplifier IC4 and the second dual-channel amplifier IC5.

5. The radar rain gauge echo signal gain amplifier circuit according to claim 1, characterized in that: A third power supply module is also included for supplying power to the analog-to-digital converter IC7, which includes a voltage regulator IC9, and decoupling capacitors C48 and C49 respectively arranged at the input and output ends of the voltage regulator IC9.

6. The radar rain gauge echo signal gain amplifier circuit according to claim 1, characterized in that: Decoupling capacitors C52 and C53 connected in parallel are also arranged on the pin of the microwave radar transceiver module JP1 to which the first power supply module is connected.

7. The radar rain gauge echo signal gain amplifier circuit according to claim 1, characterized in that: The digital end of the analog-to-digital converter IC7 is configured as an SPI interface and corresponds to ADC SDO, ADC SCLK, ADC DIN, and ADC CNV respectively, and is used to be directly connected to the MCU.

8. The radar rain gauge echo signal gain amplifier circuit according to claim 1, characterized in that: The MCU is configured with a FIR filter for filtering the digital signal received from the analog-to-digital converter so that the digital signal has a steeper characteristic.

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