Environmental feedback-based signal detection circuit for ultrasonic anemograph

Abstract

The utility model belongs to the technical field of ultrasonic anemometers, particularly relates to a signal detection circuit based on environment feedback for an ultrasonic anemometer, and solves the technical problem that the conventional signal detection circuit cannot perform targeted compensation according to different degrees of attenuation generated by ultrasonic waves in air in different environments. Wherein the model of the program control logarithmic amplifier U1 is AD8310, a programmable resistor U2 used for adjusting slope change is additionally arranged between a pin 4 VOUT and a pin 6 BFIN of the program control logarithmic amplifier U1, and the MCU can change the resistance value of the programmable resistor U2 through I2C protocol communication; the programmable resistor U2 is used as a resistor with a changeable resistance value and is used for adjusting the gain of the amplification link; the signal detection circuit further comprises a temperature and humidity sensor U7 which is used for monitoring temperature and humidity changes in the environment in real time. According to the utility model, the ultrasonic attenuation degree difference caused by different environmental conditions is compensated, so that the wind speed measurement precision of the whole set of system under the time difference method is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of ultrasonic anemometers, in particular to a signal detection circuit based on environmental feedback and used for ultrasonic anemometers. Background Art

[0002] The signal detection circuit of the existing ultrasonic wind speed sensor generally has a processing flow of: after receiving the ultrasonic wave, the transducer converts it into an electrical signal, which is amplified by the transistor amplifier circuit, then passes through the narrowband filter circuit, and then undergoes amplification and envelope detection. Finally, the MCU detects the peak value through hardware or software methods, obtains the time difference and calculates the wind speed.

[0003] The attenuation of ultrasonic wave propagation speed in air is related to the ambient temperature and humidity. Once the gain of existing signal detection circuits is determined, it is difficult to change, making it impossible to compensate for the varying degrees of ultrasonic wave attenuation in air under different environments. The signal detection circuit described in this patent can modify the logarithmic amplification circuit based on actual environmental factors, thereby achieving targeted compensation for the attenuation of ultrasonic wave amplitude under different temperatures and humidity conditions. Utility Model Content

[0004] In order to overcome the technical defect that the existing signal detection circuit cannot perform targeted compensation according to the different degrees of attenuation of ultrasonic waves in the air under different environments, the utility model provides a signal detection circuit based on environmental feedback for an ultrasonic anemometer.

[0005] The utility model provides a signal detection circuit based on environmental feedback for an ultrasonic anemometer, comprising a transistor amplifier circuit for primary signal transmission, a second-order active negative feedback bandpass filter circuit, a programmable logarithmic amplifier, an envelope detection circuit and an MCU, characterized in that the model of the programmable logarithmic amplifier U1 is AD8310, a programmable resistor U2 for adjusting the slope change is added between the 4th pin VOUT and the 6th pin BFIN of the programmable logarithmic amplifier U1, the model of the programmable resistor U2 is MCP4017T-503E / LT, the 1st pin and the 2nd pin of the programmable resistor U2 are power supply interfaces and are connected to VDD and GND respectively; the programmable resistor U2 is a power supply interface, wherein ... Pins 3 and 4 of resistor U2 serve as communication pins connected to pins 31 and 32 of the MCU respectively. The MCU can change the resistance of the programmable resistor U2 through I2C protocol communication; pins 5 and 6 of the programmable resistor U2 are connected to pin 4 VOUT and pin 6 BFIN of the AD8310 chip respectively. The programmable resistor U2 is used as a resistor with changeable resistance value to adjust the gain of the amplification link; the signal detection circuit also includes a temperature and humidity sensor U7, which is connected to the MCU, and the model of the temperature and humidity sensor U7 is SHT30-DIS-B10KS; the temperature and humidity sensor U7 is used to monitor the temperature and humidity changes in the environment in real time.

[0006] This utility model focuses on compensating for differences in ultrasonic attenuation amplitude caused by varying ambient temperature and humidity. After receiving the signal from the transmitter, the ultrasonic transducer is amplified by a transistor amplifier circuit and then processed by a second-order active negative feedback bandpass filter circuit to remove invalid signals received by the system. After gain adjustment by a programmable logarithmic amplifier, envelope detection is performed. Finally, window detection is performed after A / D conversion by the STM32F407. The MCU measures time to calculate wind speed.

[0007] This utility model uses the AD8310 chip as the programmable logarithmic amplifier U1. The AD8310 is a multi-stage demodulating logarithmic amplifier whose output is a linear representation of the logarithmic value of the input signal. The slope represents the change in output voltage for every 1dB change in the input signal. Without adding additional resistors, the AD8310's slope is designed to be 24mV / dB.

[0008] In the AD8310 circuit, pin 4 (VOUT) is the demodulated and filtered RSSI (Received Signal Strength Indicator) output, while pin 6 (BFIN) is the output before the buffer amplifier, which provides an unbuffered, single-ended voltage that is proportional to the RSSI output but not amplified. The AD8310 circuit design allows for this by adding a resistor between these two pins. R slope To adjust the slope. When adding a resistor between pin 4 VOUT and pin 6 BFIN R slope When , this resistor forms a voltage divider with the internal circuit. The voltage divider changes the voltage output to the load, thereby changing the slope. R slope The value of can accurately control the change of slope.

[0009] In order to achieve software control, we use the programmable resistor U2 to act as a resistor R slope .

[0010] The programmable resistor U2 chip uses the MCP4017T-503E / LT. The MCP4017T-503E / LT is a 7-bit single I2C digital potentiometer with volatile memory. It contains a 7-bit register that provides 128 resistance value settings (from 0x00 to 0x7F), achieving high-precision resistance adjustment. The MCP4017T-503E / LT variable resistor has an adjustable range of 0-60 kΩ , the adjustment step is 393.7 Ω In actual use, the resistance value used is about 9.45 kΩ- 60 kΩ, the corresponding slope is about 28mV / dB to 1000mV / dB, but because too large a slope will reduce the dynamic range of the output signal, it is generally taken as 24mV / dB-150mV / dB.

[0011] This utility model also uses the SHT30-DIS-B10KS to measure temperature and humidity data, enabling real-time monitoring of ambient temperature and humidity changes and converting these changes into digital output signals with an accuracy of ±3%RH (relative humidity) and ±0.3°C, respectively. Communication with the MCU is via the I2C protocol. Decreases in temperature and humidity increase the attenuation of the received ultrasonic signal. Therefore, the resistance of programmable resistor U2 increases with increasing temperature or humidity, reducing the slope of the logarithmic amplifier to compensate for the amplitude attenuation. The propagation speed of ultrasonic waves in air is also affected by temperature and humidity. After acquiring the time difference, this solution combines real-time temperature and humidity data to compensate for the ultrasonic velocity before using it to calculate wind speed.

[0012] Compared with the prior art, the technical solution provided by the present invention has the following technical effects: the present invention uses environmental conditions as feedback factors to optimize the signal processing process by adjusting the hardware circuit, and provides a more accurate signal processing circuit for ultrasonic wind sensor signal processing. The present invention compensates for the differences in ultrasonic attenuation caused by different environments, thereby improving the accuracy of the entire system in measuring wind speed under the time difference method, and has better performance in environments with drastic changes in temperature and humidity, and is applicable to more diverse environments; the programmable resistor is connected to the MCU, realizing the use of intelligent control to change the key parameters of the signal processing circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention, and together with the description, serve to explain the principles of the present invention.

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 This is an overall system block diagram of a signal detection circuit based on environmental feedback for an ultrasonic anemometer according to an embodiment of the present invention;

[0016] Figure 2 This is an overall circuit schematic diagram of a signal detection circuit based on environmental feedback for an ultrasonic anemometer according to an embodiment of the present invention;

[0017] Figure 3 A circuit connection schematic diagram of a transistor amplifier circuit and a second-order active negative feedback bandpass filter circuit in a signal detection circuit based on environmental feedback for an ultrasonic anemometer according to an embodiment of the present invention;

[0018] Figure 4 A schematic diagram of the circuit connection between the programmable gain amplifier and the envelope detection circuit in a signal detection circuit based on environmental feedback for an ultrasonic anemometer according to an embodiment of the present invention;

[0019] Figure 5 This is a chip pin connection diagram of the control part MCU in a signal detection circuit based on environmental feedback for an ultrasonic anemometer described in an embodiment of the present invention;

[0020] Figure 6 This is a circuit schematic diagram of the control part MCU in a signal detection circuit based on environmental feedback for an ultrasonic anemometer according to an embodiment of the present invention;

[0021] Figure 7 The present invention is a circuit schematic diagram of a temperature and humidity sensor in a signal detection circuit based on environmental feedback for an ultrasonic anemometer according to an embodiment of the present invention.

[0022] In the figure: U1, programmable logarithmic amplifier; U2, programmable resistor; U7, temperature and humidity sensor. DETAILED DESCRIPTION

[0023] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0024] In this description, it should be noted that the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms based on specific circumstances.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0026] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] In one embodiment, Figure 1 As shown, a signal detection circuit based on environmental feedback for an ultrasonic anemometer includes a transistor amplifier circuit for primary signal transmission, a second-order active negative feedback bandpass filter circuit, a programmable logarithmic amplifier, an envelope detection circuit and an MCU, characterized in that the model of the programmable logarithmic amplifier U1 is AD8310, a programmable resistor U2 for adjusting the slope change is added between the 4th pin VOUT and the 6th pin BFIN of the programmable logarithmic amplifier U1, the model of the programmable resistor U2 is MCP4017T-503E / LT, the 1st pin and the 2nd pin of the programmable resistor U2 are power supply interfaces and are connected to VDD and GND respectively; the programmable resistor U Pins 3 and 4 of 2 serve as communication pins connected to pins 31 and 32 of the MCU respectively. The MCU can change the resistance value of the programmable resistor U2 through I2C protocol communication; pins 5 and 6 of the programmable resistor U2 are connected to pin 4 VOUT and pin 6 BFIN of the AD8310 chip respectively. The programmable resistor U2 is used as a resistor with changeable resistance value to adjust the gain of the amplification link; the signal detection circuit also includes a temperature and humidity sensor U7, which is connected to the MCU, and the model of the temperature and humidity sensor U7 is SHT30-DIS-B10KS; the temperature and humidity sensor U7 is used to monitor the temperature and humidity changes in the environment in real time.

[0028] This utility model focuses on compensating for differences in ultrasonic attenuation amplitude caused by varying ambient temperature and humidity. After receiving the signal from the transmitter, the ultrasonic transducer is amplified by a transistor amplifier circuit and then processed by a second-order active negative feedback bandpass filter circuit to remove invalid signals received by the system. After gain adjustment by a programmable logarithmic amplifier, envelope detection is performed. Finally, window detection is performed after A / D conversion by the STM32F407. The MCU measures time to calculate wind speed.

[0029] This utility model uses the AD8310 chip as the programmable logarithmic amplifier U1. The AD8310 is a multi-stage demodulating logarithmic amplifier whose output is a linear representation of the logarithmic value of the input signal. The slope represents the change in output voltage for every 1dB change in the input signal. Without adding additional resistors, the AD8310's slope is designed to be 24mV / dB.

[0030] In the AD8310 circuit, pin 4 (VOUT) is the demodulated and filtered RSSI (Received Signal Strength Indicator) output, while pin 6 (BFIN) is the output before the buffer amplifier, which provides an unbuffered, single-ended voltage that is proportional to the RSSI output but not amplified. The AD8310 circuit design allows for this by adding a resistor between these two pins. R slopeTo adjust the slope. When adding a resistor between pin 4 VOUT and pin 6 BFIN R slope When , this resistor forms a voltage divider with the internal circuit. The voltage divider changes the voltage output to the load, thereby changing the slope. R slope The value of can accurately control the change of slope.

[0031] In order to achieve software control, we use the programmable resistor U2 to act as a resistor R slope .

[0032] The programmable resistor U2 chip uses the MCP4017T-503E / LT. The MCP4017T-503E / LT is a 7-bit single I2C digital potentiometer with volatile memory. It contains a 7-bit register that provides 128 resistance value settings (from 0x00 to 0x7F), achieving high-precision resistance adjustment. The MCP4017T-503E / LT variable resistor has an adjustable range of 0-60 kΩ , the adjustment step is 393.7 Ω In actual use, the resistance value used is about 9.45 kΩ- 60 kΩ , the corresponding slope is about 28mV / dB to 1000mV / dB, but because too large a slope will reduce the dynamic range of the output signal, it is generally taken as 24mV / dB-150mV / dB.

[0033] This utility model also uses the SHT30-DIS-B10KS to measure temperature and humidity data, enabling real-time monitoring of temperature and humidity changes in the environment and converting these changes into digital output signals with an accuracy of ±3%RH (relative humidity) and ±0.3°C, respectively. Communication with the MCU is via the I2C protocol. Decreases in temperature and humidity increase the attenuation of the received ultrasonic signal, so the resistance of programmable resistor U2 increases with increasing temperature or humidity. The propagation speed of ultrasonic waves in air is also affected by temperature and humidity. This solution obtains the actual sound velocity after acquiring the time difference. This is then combined with real-time temperature and humidity data to compensate for the ultrasonic velocity before being used to calculate wind speed.

[0034] The above description is only a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions have been made with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments, and they should all be covered by the scope of protection of the claims.

Claims

1. A signal detection circuit based on environmental feedback for an ultrasonic anemometer, comprising a transistor amplifier circuit for primary signal transmission, a second-order active negative feedback bandpass filter circuit, a programmable logarithmic amplifier, an envelope detection circuit, and an MCU, characterized in that: The model of the programmable logarithmic amplifier U1 is AD8310. A programmable resistor U2 for adjusting the slope change is added between the 4th pin VOUT and the 6th pin BFIN of the programmable logarithmic amplifier U1. The model of the programmable resistor U2 is MCP4017T-503E / LT. Pins 1 and 2 of the programmable resistor U2 are power supply interfaces and are connected to VDD and GND respectively; pins 3 and 4 of the programmable resistor U2 serve as communication and are connected to pins 31 and 32 of the MCU respectively. The MCU can change the resistance value of the programmable resistor U2 through I2C protocol communication; pins 5 and 6 of the programmable resistor U2 are connected to the 4th pin VOUT and the 6th pin BFIN of the AD8310 chip respectively. The programmable resistor U2 is a resistor with changeable resistance value and is used to adjust the gain of the amplification link; the signal detection circuit also includes a temperature and humidity sensor U7, which is connected to the MCU, and the model of the temperature and humidity sensor U7 is SHT30-DIS-B10KS; the temperature and humidity sensor U7 is used to monitor the temperature and humidity changes in the environment in real time.

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