A methane monitoring and early warning circuit based on four-dimensional stochastic resonance

Abstract

The utility model provides a kind of methane monitoring early warning circuit based on four-dimensional random resonance, including the secondary processing of the noise reduction pretreatment, filter smooth of signal acquisition, signal display and early warning function, can monitor weak methane concentration signal in time to realize early warning under strong noise environment.The circuit includes four-dimensional random resonance circuit, second-order active low-pass filter circuit, adjustable DC power supply circuit and signal display and early warning circuit consisting of MCU minimum system module, signal conditioning and acquisition module, parameter setting and control interface module, LCD man-machine interactive display module, temperature control management drive module, UART communication module and sound-light alarm module.The device transmits weak signal collected by methane sensor to four-dimensional random resonance circuit for signal noise reduction and amplification processing;Then filter and smooth processing is carried out on signal using second-order active low-pass filter circuit;Finally, signal digitization, visualization, early warning judgment operation is realized in signal display and early warning circuit.

Description

Technical Field

[0001] This utility model belongs to the category of weak signal processing in electronic devices, and specifically relates to a methane concentration detection circuit based on random resonance. Background Technology

[0002] Methane (CH4), as a major greenhouse gas and flammable gas, requires precise concentration detection for environmental protection, industrial safety, and public health. In scenarios such as coal mining, natural gas transportation, and landfilling, methane leaks can trigger explosions. Once the volume fraction of methane gas in a confined environment reaches the critical threshold of 5%, an explosion is possible; in natural gas pipelines, the long-term accumulation of even small leaks poses a threat of major safety accidents. Although current methane detection technology is relatively mature, traditional detection techniques focus on noise suppression, employing a "lower noise, then amplify signal" approach. In contrast, stochastic resonance systems can convert noise signal energy into signal energy, simultaneously reducing noise and minimizing signal damage. Compared to traditional detection techniques, stochastic resonance systems offer a simpler signal processing method and are more sensitive to weak signals, making them particularly suitable for noisy environments.

[0003] To address the aforementioned issues, this invention constructs a methane monitoring and early warning circuit based on four-dimensional random resonance. This circuit acquires signals via a methane sensor. First, the acquired signals are preprocessed by a four-dimensional random resonance circuit, effectively enhancing the noise immunity of the signal transmission and making it suitable for noisy environments. Then, a second-order active low-pass filter circuit is used to filter out interference signals. Next, the signal is input to a signal conditioning and acquisition module (C2), where it is digitized and input into a minimum microcontroller system. The signal is then displayed on the signal conditioning and acquisition module and simultaneously displayed on an external display via a UART communication module. The data is compared with a preset threshold to determine whether to trigger the audible and visual alarm module and the temperature control management drive module. This circuit achieves the detection and early warning function of methane concentration under strong noise conditions, improving detection sensitivity and system stability. Summary of the Invention

[0004] Based on the aforementioned background technology, this utility model designs a methane monitoring and early warning circuit based on four-dimensional random resonance. This circuit acquires signals through a methane sensor, inputs the signals into a four-dimensional random resonance circuit for signal noise reduction and enhancement, further utilizes a second-order active low-pass filter circuit for filtering and smoothing, then converts the analog signal into a digital signal and transmits it to the MCU minimum system module. The value is then displayed on a screen and transmitted to an external display via serial communication to achieve real-time monitoring. Furthermore, threshold judgment is performed to execute corresponding operations based on different thresholds. In addition, the early warning threshold can be adjusted through a parameter setting and control interface module to adapt to different environments.

[0005] To achieve the above functions, the present invention provides the following technical solution: a methane monitoring and early warning circuit based on four-dimensional random resonance, characterized in that the circuit includes a four-dimensional random resonance circuit (a), a second-order active low-pass filter circuit (b), a signal display and early warning circuit (c), and an adjustable DC regulated power supply circuit (d).

[0006] The above-mentioned methane monitoring and early warning circuit based on four-dimensional random resonance is characterized in that: the four-dimensional random resonance circuit (a) includes a first-dimensional circuit (a1), a second-dimensional circuit (a2), a third-dimensional circuit (a3), and a fourth-dimensional circuit (a4).

[0007] In the first-dimensional circuit (a1), one end of resistors R1, R2, R3, R4, and R5 is connected to the inverting input of operational amplifier U1; the other end of resistor R1 is connected to the output of operational amplifier U3; the other end of resistor R2 is connected to the output of analog multiplier M1; one input of analog multiplier M1 is connected to the output of operational amplifier U6; the other input of analog multiplier M1 is connected to the output of operational amplifier U9; the other end of resistor R3 is connected to the output of analog multiplier M2; one input of analog multiplier M2 is connected to the output of operational amplifier U8; and analog multiplier M2... The other input terminal is connected to the output terminal of operational amplifier U12. The other end of resistor R4 is connected to the output terminal of operational amplifier U5. The other end of resistor R5 is connected to the output terminal of the methane sensor. Resistor R6 is connected between the input and output terminals of operational amplifier U1. One end of resistor R7 is connected to operational amplifier U1. The other end of resistor R7 is connected to the inverting input terminal of operational amplifier U2. Capacitor C1 is connected between the input and output terminals of operational amplifier U2. Operational amplifier U2 is connected to the inverting input terminal of operational amplifier U3 via resistor R8. Resistor R9 is connected between the non-inverting input and output terminals of operational amplifier U3.

[0008] In the second dimension circuit (a2) of the four-dimensional random resonance circuit (a), one end of resistors R10 and R11 is connected to the output terminal of operational amplifier U3, the other end of resistor R10 is connected to the output terminal of operational amplifier U3, the other end of resistor R11 is connected to the output terminal of operational amplifier U5, resistor R12 is connected between the input and output terminals of operational amplifier U4, the output terminal of operational amplifier U4 is connected to the left end of resistor R13, the right end of resistor R13 is connected to the inverting input terminal of operational amplifier U5, the non-inverting input terminal of operational amplifier U5 is grounded, capacitor C2 is connected between the non-inverting input terminal and the output terminal of operational amplifier U5, the output terminal of operational amplifier U5 is connected to the left end of resistor R14, the right end of resistor R14 is connected to the inverting input terminal of operational amplifier U3, the non-inverting input terminal of operational amplifier U3 is grounded, and resistor R15 is connected between the input and output terminals of operational amplifier U6.

[0009] In the third-dimensional circuit (a3) ​​of the four-dimensional random resonance circuit (a), one end of resistors R16, R17, and R18 is connected to the inverting input of operational amplifier U7, the other end of resistor R16 is connected to the output of analog multiplier M3, one input of analog multiplier M3 is connected to the output of operational amplifier U3, the other input of analog multiplier M3 is connected to the output of operational amplifier U6, the other end of resistor R17 is connected to the output of operational amplifier U8, the other end of resistor R18 is connected to the output of operational amplifier U7, one end of resistor R19 is connected to the output of operational amplifier U7, the other end of resistor R19 is connected to the inverting input of operational amplifier U8, capacitor C3 is connected between the inverting input and output of operational amplifier U8, operational amplifier U8 is connected to the inverting input of operational amplifier U9 via resistor R20, and resistor R21 is connected between the input and output of operational amplifier U9.

[0010] In the fourth dimension circuit (a4) of the four-dimensional random resonance circuit (a), one end of resistors R22 and R23 is connected to the inverting input terminal of operational amplifier U10, the other end of resistor R22 is connected to the output terminal of operational amplifier U3, the other end of resistor R23 is connected to the output terminal of operational amplifier U11, R24 is connected between the inverting input terminal and the output terminal of operational amplifier U10, the output terminal of operational amplifier U10 is connected to one end of resistor R25, the other end of resistor R25 is connected to the inverting input terminal of operational amplifier U11, capacitor C4 is connected between the inverting input terminal and the output terminal of operational amplifier U11, the output terminal of operational amplifier U11 is connected to one end of resistor R26, the other end of resistor R26 is connected to the inverting input terminal of operational amplifier U12, and resistor R27 is connected between the input terminal and the output terminal of operational amplifier U12.

[0011] The non-inverting input terminals of all the above operational amplifiers U1, U2, U3, U4, U5, U6, U7, U8, U9, U10, U11, and U12 are connected to the ground terminal (i.e., grounded).

[0012] The second-order active low-pass filter circuit (b) includes resistors R28, R29, R30, R31, R32, and R33, operational amplifiers U13 and U14, and capacitors C5 and C6. The circuit is divided into two stages: an active filter circuit and an amplifier circuit. The first-stage active filter circuit includes an RC low-pass filter network composed of resistors R28 and R30 and capacitors C5 and C6, and R29 can adjust the signal waveform. The second-stage amplifier circuit includes resistors R32 and R33 and operational amplifier U14.

[0013] In the second-order active low-pass filter circuit (b), one end of resistors R28, R29, and R30 is connected to one end of capacitor C5, and the other end of capacitor C5 is grounded. The other end of resistor R28 is connected to the output terminal of operational amplifier U3 in the four-dimensional random resonance circuit (a). The other end of resistor R29 is connected to one end of capacitor C6. The other end of resistor R30 is connected to the other end of capacitor C6 and connected to the inverting input terminal of operational amplifier U13. One end of resistor R31 is connected to the non-inverting input terminal of operational amplifier U13, and the other end is grounded. The output terminal of operational amplifier U13 is connected to one end of R32. The other end of R32 is connected to the inverting input terminal of operational amplifier U14. R33 is connected across the input and output terminals of operational amplifier U14. The non-inverting input terminals of operational amplifiers U13 and U14 are both connected to the ground terminal.

[0014] The above-mentioned methane concentration detection circuit based on random resonance is characterized in that: the signal display and early warning circuit (c) includes seven modules: MCU minimum system module (c1), signal conditioning and acquisition module (c2), parameter setting and control interface module (c3), LCD human-machine interaction display module (c4), temperature control management drive module (c5), UART communication module (c6), and sound and light alarm module (c7).

[0015] In the signal display and early warning circuit (c), capacitors C7 and C8, electrolytic capacitor C9, crystal oscillator X1, button K1, resistor R34, and AT89C52 microcontroller form the MCU minimum system module (c1); ADC0832 digital-to-analog converter chip forms the signal conditioning and acquisition module (c2); buttons k2, k3, and k4 form the parameter setting and control interface module (c3); adjustable resistor RV1, display screen LCD, and resistor array RP1 form the LCD human-machine interaction display module (c4); resistors R35, R36, R37, and R38, temperature sensor DS18B20, relay OP1, transistor Q1, diode D1, and fan F1 form the temperature management drive module (c5); serial port COMPINE, external display screen, and single-pole double-throw switch form the UART communication module (c6); LED1, LED2, resistors R39 and R40, PNP transistor, and buzzer group The system comprises an audible and visual alarm module (c7); a signal conditioning and acquisition module (c2) connected to pins P1.2, P1.3, and P1.6 of the MCU minimum system module (c1); a parameter setting and control interface module (c3) connected to pins P1.2, P1.7, and P3.2 of the MCU minimum system module (c1); an LCD human-machine interaction display module (c4) connected to pins P0.0, P0.1, P0.2, P0.3, P0.4, P0.5, P0.6, and P0.7 of the MCU minimum system module (c1); a temperature control management drive module (c5) connected to pins P1.1 and P3.7 of the MCU minimum system module (c1); a UART communication module (c6) connected to pins P3.0 and P3.1 of the MCU minimum system module (c1); and an audible and visual alarm module (c7) connected to pins P2.1, P2.4, and P2.5 of the MCU minimum system module (c1).

[0016] In the adjustable DC regulated power supply circuit (d), the output terminal of AC power supply V1 is connected to the primary winding of transformer T1, and the secondary winding of transformer T1 is connected to the AC input terminal of rectifier bridge D01; the positive terminal of the DC output terminal of rectifier bridge D01, the positive terminal of polarized capacitor C10, one end of capacitor C11, and the Vin terminal of voltage regulator LM317 are connected, the other end of capacitor C11 is grounded, and diode D2 is connected across the Vin and Vout terminals of voltage regulator LM317. 3. Connected between the Vout terminal and ADJ terminal of the voltage regulator LM317, the positive terminal of polarized capacitor C12 and the anode of diode D3 are connected to one end of sliding rheostat RV2, and the other end of sliding rheostat RV2 is connected to one end of R42; the negative terminal of polarized capacitor C12 and the other end of R42 are connected and grounded; resistor R41 is connected in parallel with diode D3; the positive terminal of polarized capacitor C13 is connected to the 5V port of the microcontroller, and the negative terminal is grounded; capacitor C14, load resistor R43 and polarized capacitor C13 are connected in parallel.

[0017] The beneficial effects of this utility model are as follows:

[0018] This invention uses a methane sensor to collect gas concentration signals and transmits them to a four-dimensional random resonance circuit for signal noise reduction and enhancement. The signal is then further filtered by a second-order active low-pass filter to remove interference. The processed signal is then transmitted to a signal conditioning and acquisition module for digital processing. The parameter setting and control interface module can autonomously adjust the warning threshold. The system features dual monitoring of methane concentration and temperature. The MCU minimum system module processes the data and compares it with the preset warning threshold. If the methane concentration exceeds the threshold, a red LED illuminates and a buzzer alarm is triggered; if it is below the threshold, no action is taken. If the temperature exceeds the warning threshold, a yellow LED illuminates, a buzzer alarm is triggered, and a relay is activated to make the fan run; if it is below the threshold, no action is taken. If both monitored values ​​exceed the warning threshold, both red and yellow LEDs illuminate simultaneously, a buzzer alarm is triggered, and the fan runs. An external display connected to an LCD screen and a serial communication port can display the monitoring values ​​in real time, enabling human-machine interaction.

[0019] Compared to traditional methane concentration detection methods, the methane monitoring and early warning circuit based on four-dimensional random resonance proposed in this invention has stronger adaptability to noisy environments and higher sensitivity to weak signals. This circuit not only reduces the intensity of noise but also enhances the intensity of useful signals. It effectively utilizes the noise reduction characteristics and high sensitivity to weak signals of the random resonance system to achieve preprocessing of the acquired signals. Combined with a minimum single-chip microcomputer system, it realizes analog-to-digital conversion, signal visualization, temperature monitoring, and methane concentration early warning functions. It can efficiently monitor minute changes in methane concentration in complex working environments and can be applied to various occasions. Furthermore, it integrates the autonomous response function of an intelligent temperature control drive circuit on the basis of system monitoring and early warning, further improving the system's intelligence and reducing human resource losses. Attached Figure Description

[0020] Figure 1 The present invention provides an overall block diagram of a methane monitoring and early warning circuit based on random resonance.

[0021] Figure 2 This is a flowchart illustrating the process of this utility model.

[0022] Figure 3 This is a circuit diagram of the four-dimensional random resonance circuit of this utility model.

[0023] Figure 4 This is a circuit diagram of the second-order active low-pass filter of this utility model.

[0024] Figure 5 This is the circuit diagram for the signal display and early warning of this utility model.

[0025] Figure 6 This is the circuit diagram of the adjustable DC regulated power supply of this utility model.

[0026] Figure 7 The present invention provides an overall circuit diagram of a methane monitoring and early warning circuit based on four-dimensional random resonance. Detailed Implementation

[0027] To clearly illustrate the design objectives, technical features, and innovative advantages of this utility model, the following description, in conjunction with the accompanying drawings and actual operation, further explains this utility model:

[0028] like Figure 1 As shown, a methane monitoring and early warning circuit based on four-dimensional random resonance can realize signal preprocessing, signal display and early warning functions. The overall circuit is divided into four parts: four-dimensional random resonance circuit (a), second-order active low-pass filter circuit (b); signal display and early warning circuit (c), which includes: MCU minimum system module (c1), signal conditioning and acquisition module (c2), parameter setting and control interface module (c3), LCD human-machine interaction display module (c4), temperature control management drive module (c5), UART communication module (c6), sound and light alarm module (c7), and adjustable DC regulated power supply circuit (d).

[0029] like Figure 2 As shown, the workflow of a methane concentration detection circuit based on stochastic resonance is as follows:

[0030] L1. The analog voltage signal acquired by the methane sensor is subjected to noise reduction and enhancement processing. First, the methane sensor acquires the signal, and then transmits it to the signal input port of the four-dimensional random resonance circuit (a). Then, the four-dimensional random resonance circuit (a) performs noise conversion to improve the signal strength and enhance the signal characteristics.

[0031] L2. The analog voltage signal processed by the four-dimensional random resonance circuit (a) is further smoothed; the signal processed by the circuit is input into the second-order active low-pass filter circuit (b) to perform filtering and smoothing operation on the signal and filter out noise.

[0032] L3. The signal processed by the second-order active low-pass filter circuit (b) is digitally processed, visualized, and used for early warning judgment. The signal processed by the second-order active low-pass filter circuit (b) is input into the signal conditioning and acquisition module (c2) to convert the analog signal into a digital signal, and then input into the MCU minimum system module (c1) for display, numerical judgment, and early warning processing. The system is equipped with dual early warning. If the methane concentration exceeds the early warning threshold, an audible and visual alarm is triggered. If the temperature exceeds the early warning threshold, an audible and visual alarm is triggered and the fan is started to perform cooling operation. At the same time, a parameter setting and control interface module (c4) is added to provide autonomous adjustment function.

[0033] like Figure 3 As shown: The four-dimensional random resonant circuit (a) includes a first-dimensional circuit (a1), a second-dimensional circuit (a2), a third-dimensional circuit (a3), and a fourth-dimensional circuit (a4); wherein the first-dimensional circuit (a1) includes resistors R1, R2, R3, R4, R5, R6, R7, R8, and R9, analog multipliers M1 and M2, capacitor C1, and operational amplifiers U1, U2, and U3; the second-dimensional circuit (a2) includes resistors R10, R11, and R12. R13, R14, R15, capacitor C2 and operational amplifiers U4, U5, U6; the third-dimensional circuit (a3) ​​includes resistors R16, R17, R18, R19, R20, R21, analog multiplier M3, capacitor C3 and operational amplifiers U7, U8, U9; the fourth-dimensional circuit (a4) includes resistors R22, R23, R24, R25, R26, R27, capacitor C4 and operational amplifiers U10, U11, U12;

[0034] In the four-dimensional random resonance circuit (a), the IN port of the methane sensor is used to acquire signals, the OUT port is used to output signal m(t), and the GND port is grounded; the OUT terminal of the methane sensor is connected to the signal input port of the four-dimensional random resonance circuit (a), the signal m(t) is processed by the random resonance system for noise reduction and enhancement, and the first dimension is used as the output dimension.

[0035] In the first dimension circuit (a1) of the four-dimensional random resonance circuit (a), one end of resistor R1 is connected to the output terminal of operational amplifier U3, one end of resistor R2 is connected to the output terminal of analog multiplier M1, one input terminal of analog multiplier M1 is connected to the output terminal of operational amplifier U3, and the other input terminal is connected to the output terminal of operational amplifier U8, one end of resistor R3 is connected to the output terminal of analog multiplier M2, one input terminal of analog multiplier M2 is connected to the output terminal of operational amplifier U8, and the other input terminal is connected to operational amplifier U12, one end of resistor R4 is connected to the output terminal of operational amplifier U5, resistor R5 is connected to the output terminal of methane sensor, and resistor R1... The other ends of resistors R2, R3, R4, and R5 are connected together and connected to the inverting input of operational amplifier U1. R6 is connected between the input and output of operational amplifier U1. One end of R7 is connected to the output of operational amplifier U2, and the other end of R7 is connected to the inverting input of operational amplifier U3. Capacitor C1 is connected between the inverting input and output of operational amplifier U2. One end of R8 is connected to the output of operational amplifier U3, and the other end of R8 is connected to the inverting input of operational amplifier U3. Resistor R9 is connected between the inverting input and output of operational amplifier U3. The non-inverting inputs of operational amplifiers U1, U2, and U3 are all grounded.

[0036] In the second dimension circuit (a2) of the four-dimensional random resonance circuit (a), one end of resistor R10 is connected to the output terminal of operational amplifier U3, resistor R11 is connected to the output terminal of operational amplifier U5, the other ends of resistors R10 and R11 are connected together and connected to the inverting input terminal of operational amplifier U4, and R12 is connected between the inverting input terminal and the output terminal of operational amplifier U4; one end of R13 is connected to the output terminal of operational amplifier U4, and the other end of R13 is connected to the inverting input terminal of operational amplifier U5, and capacitor C2 is connected between the inverting input terminal and the output terminal of operational amplifier U5; one end of R14 is connected to the output terminal of operational amplifier U5, and the other end of R14 is connected to the inverting input terminal of operational amplifier U6, and resistor R15 is connected between the inverting input terminal and the output terminal of operational amplifier U6, and the non-inverting input terminals of operational amplifiers U4, U5, and U6 are all grounded.

[0037] In the third-dimensional circuit (a3) ​​of the four-dimensional random resonance circuit (a), one end of resistor R16 is connected to the output of analog multiplier M3. One input of analog multiplier M3 is connected to the output of operational amplifier U3, and the other input is connected to the output of operational amplifier U6. One end of resistor R17 is connected to the output of operational amplifier U8. The other ends of resistors R16 and R17 are connected together and connected to the inverting input of operational amplifier U7. R18 is connected between the input and output of operational amplifier U7. One end of R19 is connected to the output of operational amplifier U7, and the other end of R19 is connected to the inverting input of operational amplifier U8. Capacitor C1 is connected between the inverting input and output of operational amplifier U8. One end of R20 is connected to the output of operational amplifier U9, and the other end of R20 is connected to the inverting input of operational amplifier U9. Resistor R21 is connected between the inverting input and output of operational amplifier U9. The non-inverting inputs of operational amplifiers U7, U8, and U9 are all grounded.

[0038] In the fourth dimension circuit (a4) of the four-dimensional random resonance circuit (a), one end of resistor R22 is connected to the output terminal of operational amplifier U3, resistor R23 is connected to the output terminal of operational amplifier U11, the other ends of resistors R22 and R23 are connected together and connected to the inverting input terminal of operational amplifier U10, and R24 is connected between the inverting input terminal and the output terminal of operational amplifier U10; one end of R25 is connected to the output terminal of operational amplifier U10, and the other end of R25 is connected to the inverting input terminal of operational amplifier U11, and capacitor C2 is connected between the inverting input terminal and the output terminal of operational amplifier U11; one end of R26 is connected to the output terminal of operational amplifier U11, and the other end of R26 is connected to the inverting input terminal of operational amplifier U12, and resistor R26 is connected between the inverting input terminal and the output terminal of operational amplifier U12, and the non-inverting input terminals of operational amplifiers U10, U11, and U12 are all grounded.

[0039] The mathematical model of the four-dimensional stochastic resonant circuit (a) described above is as follows:

[0040] In the formula, is the state variable, with dimension being the system output dimension, i.e., signal_1; is the external signal input of the system, i.e., the signal collected by the methane sensor; are the system parameters, with values ​​a=2, b=5, c=1, d=4, e=9, f=5, g=2, j=1, which are set according to the amplitude range of the analog voltage signal collected by the sensor.

[0041] To apply this to hardware circuits, the circuit state equations are rewritten as follows:

[0042] Combined formula and resistance R i= 10kΩ (i=1,3,4,5,6,7,8,9,12,13,14,15,16,18,19,20,21,25,26,27), R i= 5kΩ i =2,10,22), R 11 =2kΩ, R 17 =2.5kΩ, R 23 =9kΩ, R 24 =45kΩ, C i =100nF, ( i =1,2,3).

[0043] like Figure 4 As shown: The second-order active low-pass filter circuit (b) includes resistors R28, R29, R30, R31, R32, and R33, operational amplifiers U13 and U14, and capacitors C5 and C6. The first-dimensional signal output from the above four-dimensional random resonant circuit (a) is used as the input signal signal_1. The second-order active low-pass filter circuit (b) further filters out high-frequency noise or other interference signals that were not fully processed by the first-stage circuit, retaining only the useful signal frequency band. At this time, the output signal is signal_2. This second-order active filter circuit (b) includes two stages: an active filter circuit and an amplifier circuit.

[0044] The pre-stage active filter circuit includes an RC low-pass filter network composed of resistors R28 and R30 and capacitors C5 and C6, the values ​​of which determine the cutoff frequency.

[0045] The resistor R29 is inversely proportional to the quality factor Q (a physical quantity describing the ratio of energy storage to loss in a resonant system, defined as the ratio of resonant frequency to bandwidth): the larger the resistance, the weaker the feedback (the higher the Q value), and the more pronounced the "resonance peak" of the filter curve; the smaller the resistance, the stronger the feedback, and the "flattening" of the resonance peak. The numerical relationship is detailed in the following formula:

[0046] The subsequent amplifier circuit includes resistors R32 and R33 and operational amplifier U14, forming an inverting proportional amplifier. Its working principle is as follows: it allows signals below the cutoff frequency to pass through while suppressing signals in other frequency bands, especially high-frequency signals; the quality factor Q is controlled by adjusting the resistance value of R29, thereby affecting the smoothness of the output waveform; changing the values ​​of resistors R32 and R33 changes the signal gain, thereby achieving signal filtering and smoothing.

[0047] like Figure 5As shown: The signal display and early warning circuit (c) includes the minimum single-chip microcomputer system circuit AT89C52 (c1), signal conditioning and acquisition module (c2), parameter setting and control interface module (c3), sound and light alarm module (c4), and LCD human-machine interaction display module (c5).

[0048] The minimum microcontroller system circuit AT89C52 (c1) includes a crystal oscillator circuit and a reset circuit. The crystal oscillator circuit consists of crystal oscillator X1, capacitor C7, and capacitor C8. One end of capacitor C7 is connected to XTAL1 of the microcontroller AT89C52, and one end of capacitor C8 is connected to XTAL2 of the microcontroller AT89C52. The other ends of capacitors C7 and C8 are both grounded. Crystal oscillator X1 is connected between capacitors C7 and C8. The reset circuit consists of a power supply, button K1, capacitor C9, and resistor R34. Button K1 and capacitor C9 are connected in parallel, one end of which is connected to the power supply, and the other end is connected to one end of resistor R34 and then connected to RST of the microcontroller. The other end of R34 is grounded. Its function is to restore the registers and circuits of the microcontroller to their initial state by providing a specific level signal when the microcontroller system starts up or when it is malfunctioning, so as to ensure that the system can start up normally and run stably.

[0049] The signal conditioning and acquisition module (c2) includes a power supply and an ADC0832 analog-to-digital converter chip U4. The signal signal_2, after being processed by the second-order active low-pass filter circuit (b), is input to the CH0 terminal of the ADC0832 analog-to-digital converter chip. The analog voltage signal is converted into a digital signal that can be recognized by the microcontroller through analog-to-digital conversion.

[0050] The parameter setting and control interface module (c3) includes buttons K2, K3, and K4. Button K2 can switch system modes; the system has two modes: 0 and 1. 0—Normal monitoring mode: displays the threshold normally and makes early warning judgments; 1—Threshold adjustment mode: stops displaying the threshold and early warning operation, and enters the preset value adjustment mode. Button K3 can increase the early warning threshold, and button K4 can decrease the early warning threshold, both with 1 as the adjustment scale. Pressing the button can increase or decrease by 1; it enhances autonomy and allows manual adjustment of values.

[0051] The LCD human-machine interaction display module (c4) includes a power supply, an LCD1602 display screen, a sliding rheostat RV1, and a resistor array RP1. The VSS pin of the LCD1602 display screen is grounded. The RW pin is also grounded, meaning the LCD1602 display screen is only in write mode. The VDD pin is connected to the sliding rheostat RV1, with one end of RV1 connected to the power supply and the other end grounded. Adjusting the sliding rheostat controls the display screen's contrast; the smaller the resistance, the lower the voltage applied to the VEE pin, and the higher the display screen contrast. The higher the resistance, the higher the voltage on the VEE pin, and the lower the contrast. The RS pin of the LCD1602 display is connected to P2.7 of the microcontroller. The E pin of the LCD1602 display is connected to P2.6 of the microcontroller. The D0, D1, D2, D3, D4, D5, D6, and D7 pins of the LCD1602 display are connected to pins 1, 2, 3, 4, 5, 6, 7, 8, and 9 of the resistor array RP1, respectively, and are sequentially connected to the P0 port of the microcontroller. Their function is to display the numerical information after analog-to-digital conversion in real time.

[0052] The temperature control management drive module (c5) includes resistors R35 and R36, a temperature sensor DS18B20, a relay module consisting of resistors R37 and R38, diode D1, and NPN transistor Q1, and a fan module F1. The VCC terminal of the temperature sensor DS18B20 is connected to the power supply, the GND terminal is grounded, and the DQ terminal is connected to pin P1.1 of the microcontroller. Resistor R35 is connected across the VCC and DQ terminals of the temperature sensor DS18B20. One end of resistor R37 is connected to pin P3.7 of the microcontroller, and the other end is connected to the relay module. The output of transistor Q1 in the relay module is connected to one end of the fan. This circuit can activate the fan to achieve a cooling effect when the ambient temperature is too high, constructing an intelligent mechanism integrating monitoring, early warning, and response. Simultaneously, the fan module supports intelligent temperature control, adjusting its operating status based on real-time data to achieve a balance between energy saving and safety, thereby ensuring a more user-friendly, efficient, and practical system.

[0053] The UART communication module (c6) includes a single-pole double-throw switch SW1, a serial port COPIM, and an external display screen. The single-pole double-throw switch SW1 controls the signal transmission direction; here, it is configured to transmit data from the microcontroller to the display screen. The RXD pin of the serial port COPIM is connected to P3.0 of the microcontroller, and the TXD pin is connected to P3.1. This circuit can display and record multiple lines of data in real time, expanding information storage and processing capabilities and enabling human-computer interaction.

[0054] The audible and visual alarm module (c7) includes a power supply, a red LED LED1, a yellow LED LED2, resistors R39 and R40, a transistor Q1, and a buzzer. One end of the red LED LED1 is connected to the microcontroller P2.1, and the other end is connected to one end of resistor R35. One end of the yellow LED LED2 is connected to the microcontroller P2.4, and the other end is connected to one end of resistor R36. The other ends of resistors R35 and R36 are connected together and connected to the power supply. One end of resistor R37 is connected to the microcontroller P2.5, and the other end is connected to the base of transistor Q1. The collector of transistor Q1 is connected to the power supply, and the emitter of transistor Q1 is connected to one end of the buzzer. The other end of the buzzer is grounded. Its function is to light up the red LED and trigger the buzzer when the methane concentration exceeds the warning threshold, and to light up the yellow LED and trigger the buzzer when the temperature exceeds the warning threshold. If both are within the safe range, no action is taken.

[0055] In the adjustable DC regulated power supply circuit (d), the output terminal of AC power supply V1 is connected to the primary winding of transformer T1, and the secondary winding of transformer T1 is connected to the AC input terminal of rectifier bridge D01. The positive terminal of the DC output terminal of rectifier bridge D01, the positive terminal of polarized capacitor C10, one end of capacitor C11, and the Vin terminal of voltage regulator LM317 are connected. The other end of capacitor C11 is grounded. Diode D2 is connected between the Vin and Vout terminals of voltage regulator LM317, and diode D3 is connected between the Vout and ADJ terminals of voltage regulator LM317. The positive terminal of capacitor C12 and the anode of diode D3 are connected to one end of sliding rheostat RV2, and the other end of sliding rheostat RV2 is connected to one end of R42; the negative terminal of polarized capacitor C12 and the other end of R42 are connected and grounded; resistor R41 is connected in parallel with diode D3; the positive terminal of polarized capacitor C13 is connected to the 5V port of the microcontroller, and the negative terminal is grounded; capacitor C14, load resistor R43 and electrolytic capacitor C13 are connected in parallel. This circuit converts 220V AC power into DC power in the range of 3-13V by adjusting the resistance value of the sliding rheostat to provide power to the overall circuit.

[0056] like Figure 6 The diagram shows the overall circuit diagram of a methane detection circuit based on random resonance, which consists of a four-dimensional random resonance circuit (a), a second-order active low-pass filter circuit (b), a signal display and early warning module (c), an MCU minimum system module (c1), a signal conditioning and acquisition module (c2), a parameter setting and control interface module (c3), an LCD human-machine interaction display module (c4), a temperature control management drive module (c5), a UART communication module (c6), an audible and visual alarm module (c7), and an adjustable DC regulated power supply circuit (d).

Claims

1. A methane monitoring and early warning circuit based on four-dimensional random resonance, characterized in that: It includes a four-dimensional random resonance circuit (a), a second-order active low-pass filter circuit (b), a signal display and concentration warning circuit (c), and an adjustable DC regulated power supply circuit (d). The output of the four-dimensional random resonance circuit (a) is connected to the input of the second-order active low-pass filter circuit (b). The output of the second-order active low-pass filter circuit (b) is connected to the signal display and concentration warning circuit (c), and the input of the second-order active low-pass filter circuit (b) is connected to the output of the four-dimensional random resonance circuit (a). The input terminal of the signal display and concentration warning circuit (c) is connected to the output terminal of the second-order active low-pass filter circuit (b); The adjustable DC regulated power supply circuit (d) is connected in parallel with the four-dimensional random resonance circuit (a), the second-order active low-pass filter circuit (b), and the signal display and concentration warning circuit (c).

2. The methane monitoring and early warning circuit based on four-dimensional random resonance according to claim 1, characterized in that, The four-dimensional random resonance circuit (a) consists of a first-dimensional circuit (a1), a second-dimensional circuit (a2), a third-dimensional circuit (a3), and a fourth-dimensional circuit (a4). In the first-dimensional circuit (a1), one end of resistors R1, R2, R3, R4, R5, and R6 is connected to the inverting input of operational amplifier U1, the other end of resistor R1 is connected to the output of operational amplifier U3, the other end of resistor R2 is connected to the output of analog multiplier M1, and the two inputs of analog multiplier M1 are connected to the outputs of operational amplifiers U6 and U9, respectively. The other end of resistor R3 is connected to the output of analog multiplier M2, and the two inputs of analog multiplier M2 are connected to the outputs of operational amplifiers U8 and U12, respectively. The two circuits are connected as follows: the other end of resistor R4 is connected to the output of operational amplifier U5, the other end of resistor R5 is connected to the output of methane sensor, the other end of resistor R6 and one end of resistor R7 are connected to the output of operational amplifier U1, the other end of resistor R7 is connected to the inverting input of operational amplifier U2, capacitor C1 is connected between the inverting input and output of operational amplifier U2, operational amplifier U2 is connected to the inverting input of operational amplifier U3 via resistor R8, and resistor R9 is connected between the inverting input and output of operational amplifier U3. In the second-dimensional circuit (a2), one end of resistors R10, R11, and R12 is connected to the inverting input of operational amplifier U4, the other end of resistor R10 is connected to the output of operational amplifier U3, the other end of resistor R11 is connected to the output of operational amplifier U5, resistor R12 is connected between the input and output of operational amplifier U4, one end of resistor R13 is connected to the output of operational amplifier U4, the other end of resistor R13 is connected to the inverting input of operational amplifier U5, capacitor C2 is connected between the inverting input and output of operational amplifier U5, operational amplifier U5 is connected to the inverting input of operational amplifier U8 via resistor R14, and resistor R15 is connected between the input and output of operational amplifier U6. In the third-dimensional circuit (a3), one end of resistors R16, R17, and R18 is connected to the inverting input of operational amplifier U7, the other end of resistor R16 is connected to the output of analog multiplier M3, the two inputs of multiplier M3 are connected to the outputs of operational amplifiers U3 and U6 respectively, the other end of resistor R17 is connected to the output of operational amplifier U8, the other end of resistor R18 is connected to the output of operational amplifier U8, one end of resistor R19 is connected to the output of operational amplifier U8, the other end of resistor R19 is connected to the inverting input of operational amplifier U8, capacitor C3 is connected between the inverting input and output of operational amplifier U8, operational amplifier U8 is connected to the inverting input of operational amplifier U9 via resistor R20, and resistor R21 is connected between the inverting input and output of operational amplifier U9. In the fourth-dimensional circuit (a4), one end of resistors R22, R23, and R24 is connected to the inverting input terminal of operational amplifier U10, the other end of resistor R22 is connected to the output terminal of operational amplifier U3, one end of resistor R23 is connected to the output terminal of operational amplifier U11, one end of resistor R24 ​​is connected to the output terminal of operational amplifier U10, one end of resistor R25 is connected to the inverting input terminal of operational amplifier U11, capacitor C4 is connected between the inverting input terminal and the output terminal of operational amplifier U11, operational amplifier U11 is connected to the inverting input terminal of operational amplifier U12 via resistor R26, and resistor R27 is connected between the inverting input terminal and the output terminal of operational amplifier U12. The non-inverting input terminals of operational amplifiers U1, U2, U3, U4, U5, U6, U7, U8, U9, U10, U11, and U12 are connected to the ground terminal.

3. The methane monitoring and early warning circuit based on four-dimensional random resonance according to claim 1, characterized in that, The second-order active low-pass filter circuit (b) includes resistors R28, R29, R30, R31, R32, and R33, capacitors C5 and C6, and operational amplifiers U13 and U14. In the signal display and early warning circuit (c), capacitors C7 and C8, electrolytic capacitor C9, crystal oscillator X1, button K1, resistor R34, and AT89C52 microcontroller form the MCU minimum system module (c1); ADC0832 digital-to-analog converter chip forms the signal conditioning and acquisition module (c2); buttons k2, k3, and k4 form the parameter setting and control interface module (c3); adjustable resistor RV1, display screen LCD, and resistor array RP1 form the LCD human-machine interaction display module (c4); resistors R35, R36, R37, and R38, temperature sensor DS18B20, relay OP1, transistor Q1, diode D1, and fan F1 form the temperature management drive module (c5); serial port COMPINE, external display screen, and single-pole double-throw switch form the UART communication module (c6); and LED1, LED2, resistors R39 and R40, PNP transistor, and buzzer form the sound and light alarm module (c7). The adjustable DC regulated power supply circuit (d) includes: transformer T1, AC power supply V1, rectifier bridge D01, voltage regulator LM317, diodes D2 and D3, polarized capacitors C10, C12 and C13, capacitors C11 and C14, sliding rheostat RV2, and resistors R41, R42 and R43.

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