Laser detection signal gain adaptive control method and system

Abstract

The invention relates to a laser detection signal gain adaptive control method and system, and the method comprises the steps: S1, setting the parameters of a laser, a digital potentiometer and a detector; s2, a laser emits laser to the gas chamber, a detector detects the laser passing through the gas chamber, and data signals are collected; s3, determining a waveform position based on the data signal, and calculating a waveform amplitude in a preset period; and S4, the gear of the digital potentiometer is adjusted according to the waveform amplitude so that the laser, the air chamber and the detector can achieve signal matching, the processor is connected with the digital potentiometer and the signal conditioning circuit, and the signal conditioning circuit is connected with the digital potentiometer so that the gear of the digital potentiometer can be controlled. The signal conditioning circuit based on the digital potentiometer dynamically adjusts the gear of the digital potentiometer, so that the laser, the gas chamber and the detector are in optimal signal matching, and the signal-to-noise ratio and the detection precision of laser gas detection are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to gas leakage concentration detection technology, in particular to a laser detection signal gain adaptive control method and system. BACKGROUND

[0002] The gas detector is a device for detecting gas leakage concentration. Common gas detection methods include electrochemical method, catalytic combustion method, solid electrolyte method, and infrared spectroscopic absorption method. Among them, the infrared spectroscopic absorption method uses the characteristic spectrum of specific gas molecules for detection, and has high resolution and good selectivity for different gas molecules.

[0003] However, in the existing laser hazardous gas detection system, the "laser output optical power-cavity light output rate-detector responsivity" is difficult to be in the best matching state. The gain resistor in the detector related circuit needs to be manually changed, resulting in low production efficiency, inconvenient debugging, complex circuit, high cost, etc. SUMMARY

[0004] The purpose of the present application is to provide a laser detection signal gain adaptive control method and system to solve the problem of poor matching of the "laser output optical power-cavity light output rate-detector responsivity" state in the existing laser hazardous gas detection system.

[0005] To solve the above problems, the present application adopts the following technical solutions:

[0006] The first aspect of the present application provides a laser detection signal gain adaptive control method, comprising the following steps:

[0007] S1, setting the parameters of the laser, digital potentiometer and detector;

[0008] S2, the laser emits laser to the gas chamber, and the detector detects the laser passing through the gas chamber and collects data signals;

[0009] S3, based on the data signal, determining the waveform position and calculating the waveform amplitude in the preset period;

[0010] S4, adjusting the gear of the digital potentiometer according to the waveform amplitude, so that the laser, the gas chamber and the detector achieve signal matching, wherein the processor is connected with the digital potentiometer and the signal conditioning circuit, and the signal conditioning circuit is connected with the digital potentiometer, so as to control the gear of the digital potentiometer.

[0011] By adjusting the gear of the digital potentiometer, the gain resistor in the digital potentiometer does not need to be manually changed, the gear of the digital potentiometer can be automatically adjusted, a simple and fast debugging process is realized, the production efficiency of the laser hazardous gas detection system is improved, and the resolution of the detection system is improved.

[0012] Further, based on the data signal, the waveform position is determined, and the waveform amplitude in the preset period is calculated, specifically including:

[0013] Based on the position of the highest point of the filtered waveform in the data signal, the amplitude of the preset period sinusoidal wave near the position is calculated by the FFT algorithm.

[0014] By using the FFT algorithm to calculate the amplitude of the sinusoidal wave in the preset period, the gas concentration change can be more accurately determined, and the gas leakage situation can be monitored in real time, thereby improving the accuracy of gas detection.

[0015] Further, the parameters of the laser, the digital potentiometer and the detector are set, specifically including:

[0016] According to the data manual of the laser and the absorption spectrum of the target gas, the scanning current and the working temperature of the laser are determined, and the digital potentiometer is set to the maximum gear.

[0017] According to the data manual of the laser and the absorption spectrum of the target gas, the scanning current and the working temperature are determined to ensure that the laser operates in the best working state, optimize the performance of the laser, thereby improving the working efficiency and providing high-quality detection signals.

[0018] Further, the gear of the digital potentiometer is adjusted to make the laser, the gas chamber and the detector reach signal matching, specifically including:

[0019] A preset amplitude range is provided.

[0020] The waveform amplitude in the preset period is compared with the amplitude range, and if the waveform amplitude in the preset period is less than the minimum value in the amplitude range, the digital potentiometer is downshifted.

[0021] By providing a preset amplitude range, the gear of the digital potentiometer can be more accurately adjusted to realize signal matching between the laser, the gas chamber and the detector, and the adaptive ability of the system is enhanced, so that the system can adapt to different working environments.

[0022] Further, after the step of comparing the waveform amplitude in the preset period with the amplitude range, it further includes:

[0023] If the waveform amplitude in the preset period is greater than the maximum value in the amplitude range after the digital potentiometer is downshifted, the digital potentiometer is upshifted.

[0024] By comparing the waveform amplitude in the preset period with the amplitude range and increasing the preset step position as necessary, the position of the digital potentiometer can be adjusted more accurately, the adaptability and flexibility of the system are enhanced, the detection process is optimized, and the stability and reliability of the system are improved.

[0025] Further, the digital potentiometer is downshifted and upshifted by bisection.

[0026] Downshifting and upshifting by bisection can quickly narrow the search range, reduce the number of adjustments, and improve the efficiency of adjusting the position of the digital potentiometer.

[0027] Further, the signal conditioning circuit includes a filter amplification circuit and a potentiometer control circuit, the filter amplification circuit is connected to the processor and the detector respectively, and the potentiometer control circuit is connected to the processor and the filter amplification circuit respectively.

[0028] The introduction of the filter amplification circuit can effectively remove noise and interference in the signal, improve the purity of the signal, and thus improve the accuracy and reliability of subsequent signal processing, and enhance the adaptability of the system.

[0029] The second aspect of the present application provides a control system for adaptive gain of laser detection signal, comprising:

[0030] The acquisition module is configured to acquire a data signal after the laser emits laser to the gas chamber and the detector detects the laser passing through the gas chamber.

[0031] The calculation module is configured to determine the waveform position based on the data signal and calculate the waveform amplitude in the preset period.

[0032] The adjustment module is configured to adjust the position of the digital potentiometer to achieve signal matching of the laser, the gas chamber and the detector.

[0033] By introducing the acquisition module, the calculation module and the adjustment module, the adaptive control of the laser detection signal gain is realized, the gain resistor in the detector related circuit does not need to be manually changed, the debugging process is simplified to achieve signal matching without manual intervention.

[0034] Further, the control system for adaptive gain of laser detection signal further comprises a filter amplification module, and the filter amplification module is configured to filter and amplify the acquired data signal.

[0035] The introduction of the filter amplification module can effectively remove noise and interference in the acquired data signal, improve the purity of the signal, and thus improve the accuracy and reliability of subsequent signal processing, and optimize signal transmission and processing.

[0036] Compared with the prior art, the application has the beneficial effects that: since the waveform amplitude is calculated according to the data signal, the gear of the digital potentiometer is adjusted, and the gain resistance of the digital potentiometer is changed, the debugging time is greatly reduced, and the debugging process is simplified. The adaptive control method can automatically adjust the gear of the digital potentiometer according to the actual detection signal, so that the signal matching between the laser, the gas chamber and the detector reaches the best state, thereby improving the stability of the detection system and the resolution of the detection system, and the selectivity for different gas molecules is better. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A flow chart of a laser detection signal gain adaptive control method provided by an embodiment of the application is shown in the figure.

[0038] Figure 2 A system diagram of a laser detection signal gain adaptive control method provided by an embodiment of the application is shown in the figure.

[0039] Figure 3 A schematic diagram of a data signal provided by an embodiment of the application is shown in the figure.

[0040] Figure 4 A circuit diagram of a signal conditioning circuit provided by an embodiment of the application is shown in the figure.

[0041] Figure 5 Another schematic diagram of a data signal provided by an embodiment of the application is shown in the figure.

[0042] Figure 6 Another circuit diagram of a signal conditioning circuit provided by an embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0043] The specific embodiments of the application will be described in detail below with reference to the accompanying drawings.

[0044] It should be noted that the embodiments and technical features in the embodiments can be combined with each other without conflict, and the detailed description in the specific embodiments should be understood as an explanation and description of the purpose of the application, and should not be regarded as an improper limitation on the application.

[0045] It should be understood that the orientation or positional relationship is based on the orientation or positional relationship shown in the drawings. These orientation terms are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0046] With the development of semiconductor laser technology, tunable diode laser absorption spectroscopy (TDLAS) has become an important development direction in the field of gas detection. Compared with other gas detection technologies, this technology has the advantages of strong anti-interference, fast response speed and high detection precision, and has been widely used in gas leakage, environmental monitoring, industrial process control and other fields.

[0047] TDLAS technology utilizes the characteristics of narrow linewidth and wavelength change with injected current of tunable semiconductor laser, so that the output wavelength of the laser sweeps the characteristic absorption spectrum of the target gas. The signal received by the photodetector is amplified and filtered, and then the gas concentration is inverted, so as to realize the detection of trace gas. In the laser gas detection system, due to the inconsistency of the output optical power of the same laser at different environmental temperatures, the output optical power of different lasers, and the light output rate of the multi-reflection cavity and the responsivity of the detector, the output electrical signal of the detector signal conditioning circuit under fixed gain exists problems such as matching, saturation or too small.

[0048] The laser hazardous gas remote acquisition system and acquisition method (CN112051220A) and the laser gas detection system with self-diagnosis function and the gas real-time calibration method (CN115128023B) design a multi-stage amplification and filtering detector signal conditioning circuit and a multi-channel different gain detector signal conditioning circuit based on ADG704 analog switch device, which solves the matching problem of "laser output optical power-cavity light output rate-detector responsivity" to a certain extent, but cannot guarantee that it is the best match. If it is in the best match, it still needs to manually change the gain resistor in the detector signal conditioning circuit, which has the problems of low production efficiency, inconvenient debugging, complex circuit, high cost and does not meet the development direction of small size and low cost of laser gas detection system. Therefore, the present application proposes a laser detection signal gain adaptive control method.

[0049] Figure 1 A flow chart of a laser detection signal gain adaptive control method provided for an embodiment of the present application, Figure 2 A system diagram of a laser detection signal gain adaptive control method provided for an embodiment of the present application, Figure 3 A schematic diagram of a data signal provided for an embodiment of the present application, Figure 4 A circuit diagram of a signal conditioning circuit provided for an embodiment of the present application, Figure 5 Another schematic diagram of a data signal provided for an embodiment of the present application, Figure 6 Another circuit diagram of a signal conditioning circuit provided for an embodiment of the present application.

[0050] AsFigures 1-6 As shown, the embodiment of the present application provides a control method for laser detection signal gain self-adaption, including the following steps:

[0051] S1, setting the parameters of the laser, the digital potentiometer and the detector;

[0052] S2, the laser emits laser to the gas chamber, and the detector detects the laser passing through the gas chamber to collect data signals;

[0053] S3, based on the data signals, determining the waveform position and calculating the waveform amplitude in the preset period;

[0054] S4, adjusting the gear of the digital potentiometer according to the waveform amplitude, so that the laser, the gas chamber and the detector reach signal matching, wherein the processor is connected with the digital potentiometer and the signal conditioning circuit respectively, the signal conditioning circuit is connected with the digital potentiometer, to control the gear of the digital potentiometer.

[0055] Specifically, the laser is used to emit a laser beam, the detector is used to receive the laser beam passing through the gas chamber and convert the optical signal into an electrical signal, the digital potentiometer adjusts the signal gain, the signal conditioning circuit conditions the electrical signal output by the detector, and the processor processes the signal and controls the gear of the digital potentiometer. Wherein, the signal conditioning circuit includes a filter amplification circuit and a digital potentiometer control circuit.

[0056] At system startup, set the emission power of the laser, the initial gain value of the digital potentiometer, and the sensitivity of the detector, and other parameters. The laser emits a laser beam, which passes through the gas chamber. After the detector detects the laser beam, it outputs an electrical signal that reflects the intensity of the laser. The signal conditioning circuit processes the electrical signal output by the detector to determine the starting point and end point of the signal waveform. Calculate the waveform amplitude in the preset period, which represents the intensity of the laser signal. For example, the preset period is the position of the highest point of the data signal after the direct current filtering. Expand to the nearby several periods centered on this position. According to the signal amplitude obtained by the processor analysis, judge whether it is necessary to adjust the gain of the digital potentiometer. The processor sends instructions to the signal conditioning circuit, and the signal conditioning circuit adjusts the gear of the digital potentiometer according to the instructions to change the gain value. After adjustment, the processor detects the signal output by the detector again, and repeats step S3 until the signal output by the detector reaches the predetermined threshold or stabilizes in a reasonable range. It should be noted that before the waveform at the highest point of the data signal is not saturated, the greater the resistance output by the digital potentiometer, the greater the sine wave amplitude calculated by the algorithm. After the waveform at the highest point of the data signal is not saturated, the greater the resistance output by the digital potentiometer, the smaller the sine wave amplitude calculated by the algorithm. The processor communicates with the digital potentiometer through the IIC interface, dynamically adjusts the gain resistance in the detector signal conditioning circuit according to the preset algorithm, adjusts the gear of the digital potentiometer, and realizes the best signal matching of "laser-cavity-detector".

[0057] In practical applications, when the system detects that the laser intensity in the gas chamber exceeds the predetermined range, the processor will automatically adjust the digital potentiometer to match the signals between the laser, the gas chamber and the detector. For example, if the laser intensity is too high, the processor will reduce the gain of the digital potentiometer, and vice versa. This adaptive control method improves the stability and reliability of the system, reduces the need for manual debugging, and optimizes production efficiency.

[0058] By adjusting the gear of the digital potentiometer, it is not necessary to manually change the gain resistance in the digital potentiometer. The gear of the digital potentiometer can be automatically adjusted, realizing a simple and fast debugging process, improving the production efficiency of the laser hazardous gas detection system, and improving the resolution of the detection system.

[0059] In order to better understand the laser detection signal gain adaptive control method of the embodiments of the present application, the following will be specifically described in combination with Figures 2-4 .

[0060] The laser detection signal gain adaptive control includes a semiconductor laser, a photodetector, a laser temperature control driving circuit, and a signal conditioning circuit (a detector signal conditioning circuit based on a digital potentiometer). The detector signal conditioning circuit based on the digital potentiometer, such as Figure 3As shown. The circuit is composed of digital potentiometer, operational amplifier I / V amplification filter circuit.

[0061] According to the preset detector signal threshold, the processor communicates with the digital potentiometer through the IIC interface, and dynamically adjusts the gain resistance in the detector signal conditioning circuit according to the preset algorithm, so as to realize the best signal matching of "laser-cavity-detector". The specific implementation process is as follows:

[0062] (1) According to the laser data manual and the absorption spectrum of the target gas, the scanning current and working temperature of the laser are determined, and the digital potentiometer is set to the maximum gear.

[0063] (2) The detector realizes photoelectric conversion on the received signal, and the single-chip microcomputer collects after amplification and filtering.

[0064] (3) Determine the position of the laser scanning signal highest point waveform after the direct current filtering, and calculate the amplitude of several cycles of sinusoidal wave near the position by using FFT.

[0065] (4) According to the "the greater the resistance output by the digital potentiometer before the waveform of the laser scanning signal highest point position is not saturated, the greater the amplitude of the sinusoidal wave calculated by the FFT; the greater the resistance output by the digital potentiometer after the waveform of the laser scanning signal highest point position is saturated, the smaller the amplitude of the sinusoidal wave calculated by the FFT" rule, the processor communicates with the digital potentiometer through the IIC interface, and dynamically adjusts the gain resistance in the detector signal conditioning circuit according to the preset algorithm, so as to realize the best signal matching of "laser-cavity-detector".

[0066] It should be understood that, as Figure 5 and Figure 6 shown, the detector signal conditioning circuit based on the digital potentiometer needs one-way ADC and one-way IIC, has the characteristics of small required processor hardware resources, simple circuit, low cost, etc., and is beneficial to the miniaturization and low-cost development of the laser gas detection system. The detector signal conditioning circuit based on the digital potentiometer makes the developed laser gas detection system have the advantages of high production efficiency, convenient debugging and maintenance, etc. The detector signal conditioning circuit based on the digital potentiometer, combined with the dynamic gain adjustment algorithm, realizes the best signal matching of "laser-cavity-detector", improves the signal-to-noise ratio of the laser gas detection system, and also improves the gas detection precision.

[0067] In some embodiments, as Figure 3 and Figure 5 shown, based on the data signal, the waveform position is determined, and the waveform amplitude in a preset period is calculated, specifically including:

[0068] Based on the position of the highest point in the filtered waveform, the amplitude of the preset periodic sinusoidal wave near the position is calculated by the FFT algorithm.

[0069] Specifically, first, the relevant data signals are collected by sensors or other data acquisition devices, and the obtained data signals are subjected to a direct current (DC) filtering process to remove DC components or other interference components in the signals, for example, using a DC circuit or software algorithm, such as a sliding average filter, a Kalman filter, etc.

[0070] The highest point of the filtered signal is found, for example, by finding the maximum value of the signal, and the data near the highest point is subjected to a fast Fourier transform (FFT) algorithm, wherein the FFT algorithm can convert a time-domain signal into a frequency-domain signal, thereby analyzing the frequency components of the signal.

[0071] The result obtained by the FFT algorithm can calculate the amplitude of the preset periodic sinusoidal wave, for example, by selecting the frequency component corresponding to the position near the highest point and calculating its amplitude value, which is the amplitude of the sinusoidal wave to be solved. The calculated amplitude value is outputted for subsequent analysis and processing.

[0072] Through the above embodiments, the waveform amplitude in the preset period can be calculated according to the waveform position of the data signal, thereby realizing detailed analysis of the signal.

[0073] By using the FFT algorithm to calculate the amplitude of the sinusoidal wave in the preset period, the gas concentration change can be more accurately determined, and the gas leakage situation can be monitored in real time, thereby improving the accuracy of gas detection.

[0074] In some embodiments, the parameters of the laser, digital potentiometer, and detector are set, specifically including:

[0075] The scanning current and operating temperature of the laser are determined according to the data manual of the laser and the absorption spectrum of the target gas, and the digital potentiometer is set to the maximum gear.

[0076] Specifically, the data manual of the laser provides performance parameters of the laser, including related data of the scanning current and operating temperature. The absorption spectrum of the target gas is analyzed, for example, the absorption spectrum of the target gas is analyzed, to determine the specific wavelength range that the laser needs to scan.

[0077] The scanning current and operating temperature of the laser are determined according to the parameters in the data manual of the laser and the absorption spectrum of the target gas. The selection of the scanning current will affect the output power and wavelength of the laser, and the selection of the operating temperature will affect the stability and life of the laser. According to the experimental requirements and the specifications of the detector, the parameters of the detector, such as sensitivity and range, are set.

[0078] The digital potentiometer is set to the maximum gear to adjust the output power of the laser. The digital potentiometer has different gears, and different gears correspond to different resistances. By changing the gear, different resistance values can be accessed.

[0079] By setting the parameters of the laser, digital potentiometer, and detector, accurate measurement of the absorption spectrum of the target gas can be achieved. The scanning current and operating temperature are determined according to the laser data manual and the absorption spectrum of the target gas, ensuring that the laser operates in the best state and optimizing its performance, thereby improving its efficiency and providing high-quality detection signals.

[0080] In some embodiments, the gear of the digital potentiometer is adjusted to match the signals between the laser, the gas cell, and the detector, specifically including:

[0081] A preset amplitude range is set.

[0082] The waveform amplitude in the preset period is compared with the amplitude range. If the waveform amplitude in the preset period is less than the minimum value in the amplitude range, the digital potentiometer is downshifted.

[0083] Specifically, according to the detection requirements and system characteristics, a suitable amplitude range is preset, which can include the expected signal amplitude between the laser, gas cell, and detector under normal working conditions. The signal waveform between the laser, gas cell, and detector is monitored in real time through the data acquisition system, and the waveform amplitude in each preset period is calculated. The obtained waveform amplitude is compared with the preset amplitude range. If the waveform amplitude is less than the minimum value in the amplitude range, it indicates that the signal strength is lower than expected, and the digital potentiometer needs to be adjusted. For example, if the waveform amplitude is less than the minimum value of the preset range, the downshift operation is performed. This represents a decrease in the gear of the digital potentiometer by one level to increase the output power of the laser or adjust other related parameters so that the signal can reach the preset range. After downshifting, the waveform amplitude is re-detected and compared continuously. If the amplitude is still lower than the minimum value of the preset range, the downshift operation is repeated until the amplitude falls within the preset range. When the waveform amplitude falls within the preset range, it is considered that the signal between the laser, gas cell, and detector has reached a matching state. At this time, the adjustment of the digital potentiometer is stopped, and the current gear setting is recorded. Through the above method, the gear of the digital potentiometer is adjusted to match the signal between the laser, gas cell, and detector, thereby ensuring the normal operation and accurate measurement of the system.

[0084] By presetting the amplitude range, the gear of the digital potentiometer can be adjusted more accurately to match the signal between the laser, gas cell, and detector, enhancing the adaptive ability of the system and enabling the system to adapt to different working environments.

[0085] In some embodiments, after the step of comparing the waveform amplitude in the preset period with the amplitude range, the method further comprises:

[0086] If the waveform amplitude in the preset period is greater than the maximum value in the amplitude range after the digital potentiometer is downshifted, the digital potentiometer is upshifted.

[0087] Specifically, in the data acquisition system, the signal waveform between the laser, the gas cell and the detector is monitored in real time, and the waveform amplitude in each preset period is calculated. The obtained waveform amplitude is compared with the preset amplitude range. If the waveform amplitude is greater than the maximum value in the amplitude range, it indicates that the signal strength is higher than expected, and the digital potentiometer needs to be adjusted. At this time, if the waveform amplitude is greater than the maximum value in the preset range, the operation of increasing the preset step position is performed. This means that the position of the digital potentiometer is increased by a preset step, so as to reduce the output power of the laser or adjust other related parameters, so that the signal can fall within the preset range.

[0088] After increasing the preset step position, the waveform amplitude is detected again, and the comparison is continued. If the amplitude is still greater than the maximum value in the preset range, the operation of increasing the preset step position is repeated until the amplitude falls within the preset range.

[0089] When the waveform amplitude falls within the preset range, it can be considered that the signal between the laser, the gas cell and the detector has reached a matching state. At this time, the adjustment of the digital potentiometer is stopped, and the current position setting is recorded, so as to adjust the position of the digital potentiometer to make the signal between the laser, the gas cell and the detector match, so as to ensure the normal operation and accurate measurement of the system. In particular, the downshift and upshift of the digital potentiometer are both implemented by the bisection method. For example, the increase or decrease of the preset step position is implemented by the bisection method, so that the downshift and upshift operations can quickly narrow the search range, reduce the number of adjustments, and improve the efficiency of adjusting the position of the digital potentiometer.

[0090] By comparing the waveform amplitude in the preset period with the amplitude range and increasing the preset step position when necessary, the position of the digital potentiometer can be adjusted more accurately, the adaptability and flexibility of the system are enhanced, the detection process is optimized, and the stability and reliability of the system are improved.

[0091] In some embodiments, the signal conditioning circuit comprises a filter amplification circuit and a potentiometer control circuit, the filter amplification circuit is connected to the processor and the detector respectively, and the potentiometer control circuit is connected to the processor and the filter amplification circuit respectively.

[0092] Specifically, the signal conditioning circuit includes a filter-amplifier circuit and a digital potentiometer control circuit. The filter-amplifier circuit is used to filter and amplify the signal to improve the signal-to-noise ratio and stability of the signal. The potentiometer control circuit is used to control the gear of the digital potentiometer to adjust the amplitude of the signal. One input terminal of the filter-amplifier circuit is connected to the output terminal of the processor, and the other output terminal is connected to the input terminal of the detector. One input terminal of the digital potentiometer control circuit is connected to the output terminal of the processor, and the other output terminal is connected to the input terminal of the filter-amplifier circuit. In this way, the signal output by the processor is controlled by the potentiometer control circuit and then input to the filter-amplifier circuit. The filter-amplifier circuit includes a filter and an amplifier. The filter is used to remove noise and interference in the signal and only keep useful signal components. The amplifier is used to amplify the signal to increase the amplitude of the signal.

[0093] The potentiometer control circuit includes a digital potentiometer. The potentiometer control circuit is used to control the gear of the potentiometer, for example, to adjust the gain resistance of the digital potentiometer to adjust its gear.

[0094] The introduction of the filter-amplifier circuit can effectively remove noise and interference in the signal, improve the purity of the signal, and thus improve the accuracy and reliability of subsequent signal processing, and enhance the adaptability of the system.

[0095] As Figures 3-6 shown below, the control process of the laser detection signal gain self-adaptation is described. Among them, Figure 4 is a schematic diagram of the signal conditioning circuit, in which the electrical signal waveform (data signal) of Main1 is shown in Figure 3 . The Main2 waveform is a set of horizontal sine waves after capacitive direct current isolation and amplification filtering to become Adc_M2 waveform.

[0096] The size range of A is set to min and max in advance, where A is the amplitude of the highest point in the data signal, or A is the average value of the partial waveform data of the top waveform (see Figure 3 and Figure 5 ). Assuming that the gear of the digital potentiometer is 128 gears, the larger the gear number, the smaller the gain (total resistance R / current gear); the new machine defaults to 128 gears.

[0097] The detector signal gain is adjusted adaptively for the gas chamber. The adjustment method adopts dichotomy. If the detector signal gain A is smaller than the minimum value min at this time, the detector signal gain is adjusted to 64. The detector signal gain A is calculated. If the detector signal gain A is still smaller than the minimum value min, the detector signal gain is adjusted to 32. The detector signal gain A is calculated. If the detector signal gain A is larger than the maximum value max, the detector signal gain is adjusted to 48. The detector signal gain A is calculated. If the detector signal gain A is still larger than the maximum value max, the detector signal gain is adjusted to 56. The detector signal gain A is calculated. If the detector signal gain A is smaller than or equal to the maximum value max and larger than or equal to the minimum value min, the adjustment is successful. Otherwise, the adjustment is continued.

[0098] It should be noted that if the signal conditioning circuit shown in Figure 4 is used, two ADCs are needed to achieve the signal conditioning circuit. One ADC is used to collect the Main1 waveform to adjust the detector signal gain, and the other ADC is used to collect the Adc_M2 to calculate the gas concentration. To overcome the shortcoming, the following optimization is performed. After the optimization, only one ADC is needed to collect the Adc_M2 waveform. On the one hand, the detector signal gain is adjusted. After the adjustment, the gas concentration is calculated. As shown in Figure 5 and Figure 6 , before the waveform at point A is not saturated, the larger the detector signal gain resistor is, the larger the value at point A is. Corresponding to the Adc_M2 waveform, the first harmonic amplitude F0 of the waveforms calculated by FFT is larger. However, after the waveform at point A starts to be saturated, the larger the detector signal gain resistor is, the smaller the value at point A is. Corresponding to the Adc_M2 waveform, the first harmonic amplitude F0 of the waveforms calculated by FFT is smaller. The size range of F0 is set in advance as min and max. It is assumed that the digital potentiometer has 128 gears. The larger the number of gears is, the smaller the gain is (total resistance R / current gear). The new machine is set to 128 gears by default. The detector signal gain is adjusted adaptively for the new machine. The adjustment method adopts dichotomy. If the detector signal gain is 128 at this time, F0 is smaller than the minimum value min, and F0 of 127 gears is larger than F0 of 128 gears. The detector signal gain is adjusted to 64. If F0 is still smaller than the minimum value min, and F0 of 63 gears is larger than F0 of 64 gears. If F0 is still smaller than the minimum value min, but F0 of 63 gears is smaller than F0 of 64 gears, the detector signal gain is adjusted to 96 for further judgment. The detector signal gain is adjusted to 32. F0 is larger than the maximum value max, and F0 of 31 gears is larger than F0 of 32 gears. The detector signal gain is adjusted to 48. F0 is smaller than the maximum value max and larger than the minimum value min, and F0 of 47 gears is larger than F0 of 48 gears. The adjustment is successful.

[0099] The second aspect of the present application provides a laser detection signal gain adaptive control system, comprising:

[0100] The acquisition module is configured to collect a data signal after the laser emits laser to the gas chamber and the detector detects the laser passing through the gas chamber.

[0101] a calculation module configured to determine a waveform position based on the data signal and calculate a waveform amplitude within a preset period;

[0102] an adjustment module configured to adjust a gear of a digital potentiometer so that the laser, the gas chamber and the detector reach signal matching.

[0103] In particular, the control system for adaptive control of laser detection signal gain corresponds to the control method described above. By introducing the acquisition module, the calculation module and the adjustment module, the adaptive control of the laser detection signal gain is realized, without the need to manually change the gain resistor in the detector-related circuit, simplifying the debugging process to achieve signal matching without human intervention. In particular, the control system for adaptive control of laser detection signal gain further comprises a filter amplification module, which is configured to filter and amplify the acquired data signal.

[0104] The introduction of the filter amplification module can effectively remove noise and interference in the acquired data signal, improve the purity of the signal, and thus improve the accuracy and reliability of subsequent signal processing, and optimize signal transmission and processing.

[0105] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some technical features thereof. Such modifications or replacements do not cause the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present application.

Claims

1. A laser detection signal gain adaptive control method, characterized in that, The adaptive control method for laser detection signal gain includes the following steps: S1. Set the parameters for the laser, digital potentiometer, and detector; S2. The laser emits laser light into the gas chamber, and the detector detects the laser light passing through the gas chamber and collects data signals. S3. Based on the data signal, determine the waveform position and calculate the waveform amplitude within a preset period; S4. Adjust the range of the digital potentiometer according to the waveform amplitude to achieve signal matching between the laser, the gas chamber, and the detector. The processor is connected to the digital potentiometer and the signal conditioning circuit, respectively. The signal conditioning circuit is connected to the digital potentiometer to control the range of the digital potentiometer.

2. The laser detection signal gain adaptive control method according to claim 1, characterized in that, Based on the data signal, the waveform position is determined, and the waveform amplitude within a preset period is calculated, specifically including: Based on the position of the waveform after DC blocking filtering of the highest point in the data signal, the amplitude of the sine wave with a preset period near that position is calculated by the FFT algorithm.

3. The laser detection signal gain adaptive control method according to claim 1, characterized in that, Setting parameters for the laser, digital potentiometer, and detector includes: The scanning current and operating temperature of the laser are determined according to the laser's datasheet and the absorption spectrum of the target gas, and the digital potentiometer is set to the maximum setting.

4. The laser detection signal gain adaptive control method according to claim 3, characterized in that, Adjusting the range of the digital potentiometer to achieve signal matching between the laser, the gas chamber, and the detector specifically includes: Preset amplitude range; Compare the waveform amplitude within the preset period with the amplitude range. If the waveform amplitude within the preset period is less than the minimum value in the amplitude range, then downgrade the digital potentiometer.

5. The laser detection signal gain adaptive control method according to claim 4, characterized in that, After the step of comparing the waveform amplitude within the preset period with the amplitude range, the method further includes: If, after downgrading the digital potentiometer, the waveform amplitude within the preset period is greater than the maximum value in the amplitude range, then the digital potentiometer is upgraded.

6. The laser detection signal gain adaptive control method according to claim 5, characterized in that, The digital potentiometer is used for both downsizing and upsizing using a binary search method.

7. The laser detection signal gain adaptive control method according to claim 1, characterized in that, The signal conditioning circuit is used to control the digital potentiometer settings, and specifically includes a filter amplification circuit and a potentiometer control circuit. The filter amplification circuit is connected to the processor and the detector, respectively, and the potentiometer control circuit is connected to the processor and the filter amplification circuit, respectively.

8. A control system for adaptive laser detection signal gain, characterized in that, The laser detection signal gain adaptive control system includes: The acquisition module is used to acquire data signals after the laser emits laser light into the gas chamber and the detector detects the laser light passing through the gas chamber. The calculation module is used to determine the waveform position and calculate the waveform amplitude within a preset period based on the data signal. An adjustment module is used to adjust the range of the digital potentiometer to achieve signal matching between the laser, the gas chamber, and the detector.

9. A laser detection signal gain adaptive control system according to claim 8, characterized in that, The laser detection signal gain adaptive control system also includes a filtering and amplification module, which is used to filter and amplify the acquired data signal.

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