A method for detecting atmospheric particle scattering using a photoelectric scattering detection instrument

Abstract

The present application discloses an atmospheric particle scattering detection method for a photoelectric scattering detection instrument, relating to the field of atmospheric particle scattering detection. The method modulates a light source with a modulation frequency much greater than the wingbeat frequency of flying insects. The method then extracts the coefficient of variation from the acquired scattered light sampling sequence from a statistical perspective to detect whether there are foreign objects in the sampling space. Furthermore, the method combines peak extraction operations in both the frequency domain and the time domain to identify different types of foreign objects, including flying insects and precipitation particles. Subsequently, when there are foreign objects in the sampling space, the inversion results of the scattered light sampling sequence within the current detection cycle can be processed differently to obtain more accurate atmospheric particle scattering detection results. The method is implemented based on the original optical path of the photoelectric scattering detection instrument and is beneficial for improving the accuracy and reliability of atmospheric particle scattering detection.

Description

Technical Field

[0001] The present application relates to the field of atmospheric particle scattering detection, and in particular to an atmospheric particle scattering detection method for a photoelectric scattering detection instrument. Background Art

[0002] Photoelectric scattering detectors are a type of measuring device widely used in meteorological observation. They primarily consist of a light emitting unit, a light receiving unit, and a signal processing unit. The light emitting unit generates a modulated light beam, which overlaps with the light receiving unit's field of view, forming a sampling space. After the light beam is scattered by particles within the sampling space, a portion of it enters the light receiving unit, generating a received signal that is fed to the signal processing unit. The signal processing unit analyzes the received signal to invert the measurement result.

[0003] Photoelectric scattering detection instruments used for atmospheric and meteorological research are usually installed outdoors. Therefore, in addition to microscopic particles, foreign matter such as flying insects and precipitation particles are prone to appear in the sampling space of the photoelectric scattering detection instrument. These foreign matter will also scatter the transmitted light beam, and the intensity of the scattered light generated by these foreign matter can be several orders of magnitude higher than that of microscopic particles. Therefore, these foreign matter will affect the measurement results of the photoelectric scattering detection instrument and reduce the accuracy of the inversion results. Summary of the Invention

[0004] In response to the above-mentioned problems and technical requirements, this application proposes a method for detecting atmospheric particle scattering using a photoelectric scattering detection instrument. The technical solution of this application is as follows:

[0005] An atmospheric particle scattering method for a photoelectric scattering detection instrument, the atmospheric particle scattering detection method comprising:

[0006] A pulse signal is used to drive a light emitting unit in a photoelectric scattering detection instrument to generate pulsed light, and a light receiving unit in the photoelectric scattering detection instrument obtains a pulsed received signal, wherein the frequency of the driving pulse of the light emitting unit is much greater than the wingbeat frequency of the flying insect;

[0007] Discretely sampling the received signal and obtaining a scattered light sampling sequence within each detection cycle, where the scattered light sampling sequence includes scattered light signals received by the light receiving unit at different sampling moments;

[0008] Obtain scattered light sampling sequences of the current detection cycle and the most recent several detection cycles before it and splice them in time sequence to form a detection sequence;

[0009] When it is detected that the data stability of the detection sequence meets the data stability requirements, it is determined that there is no foreign matter in the sampling space of the photoelectric scattering detection instrument, and the inversion result of the scattered light sampling sequence in the current detection cycle is used as the atmospheric particle scattering detection result of the current detection cycle;

[0010] When it is detected that the data stability of the detection sequence does not meet the data stability requirements, it is determined that there is a foreign object in the sampling space of the photoelectric scattering detection instrument. The type of foreign object in the sampling space is determined according to the peak detection results of the detection sequence in the frequency domain and time domain. The inversion results of the scattered light sampling sequence in the current detection period are post-processed according to the post-processing strategy corresponding to the foreign object type to obtain the atmospheric particle scattering detection results of the current detection period. Different foreign object types correspond to different post-processing strategies.

[0011] A further technical solution is to determine the types of foreign matter contained in the sampling space based on the peak detection results of the detection sequence in the frequency domain and time domain, including:

[0012] Extracting the frequency domain features of the detection sequence and performing peak detection on the frequency domain features of the detection sequence;

[0013] When it is determined according to the peak detection result in the frequency domain that the frequency domain characteristics of the detection sequence contain a single peak, it is determined that the scattered light sampling sequence in the current detection cycle contains a flying insect wing flapping signal and the type of the foreign object in the sampling space is determined to be a flying insect foreign object;

[0014] When it is determined according to the peak detection result in the frequency domain that the frequency domain characteristics of the detection sequence do not contain a single peak, it is determined that the sampling space does not contain flying insect foreign matter and the type of foreign matter in the sampling space is determined according to the peak detection result in the time domain of the detection sequence.

[0015] A further technical solution is to determine the type of foreign matter in the sampling space based on the peak detection result of the detection sequence in the time domain, including:

[0016] Peak detection is performed on the time domain characteristics of the detection sequence. When it is determined based on the time domain peak detection result that the time domain characteristics of the detection sequence contain at least one peak, the type of foreign matter in the sampling space is determined to be precipitation particle foreign matter; otherwise, it is determined that the sampling space contains other types of foreign matter.

[0017] A further technical solution is to discretely sample the received signal and obtain a scattered light sampling sequence within each detection period, including:

[0018] discretely sampling the received signal to obtain a received signal sampling sequence, where the received signal sampling sequence includes the received signal obtained by the optical receiving unit at each sampling moment;

[0019] Data preprocessing is performed on the received signal sampling sequence to eliminate the ambient light signal in the received signal to obtain the scattered light sampling sequence in each detection cycle.

[0020] A further technical solution is that discrete sampling of the received signal includes:

[0021] According to 0.5T MOD The received signal is discretely sampled at a sampling interval of , and the phase of the discrete sampling is adjusted so that one discrete sampling operation occurs before the end of the positive pulse of the received signal, T MOD is the pulse period of the driving pulse.

[0022] A further technical solution is to perform data preprocessing on the received signal sampling sequence to remove the ambient light signal in the received signal, including:

[0023] The received signal at the 2i-th sampling moment in the received signal sampling sequence is subtracted from the received signal at the 2i-th sampling moment in the received signal sampling sequence to obtain the scattered light signal received by the light receiving unit at the 2i-1th sampling moment. The scattered light at the 2i-1th sampling moment arranged in time sequence within each detection cycle is extracted to obtain the scattered light sampling sequence within the current detection cycle.

[0024] Among them, the starting value of the integer parameter i is 1. For any value of i, the 2i-1th sampling moment and the 2i-th sampling moment correspond to two discrete samplings performed within the same pulse period of the driving pulse, and the 2i-1th sampling moment corresponds to the discrete sampling performed before the end of the positive pulse of the receiving signal of the light receiving unit.

[0025] A further technical solution is that the pulse period T of the driving pulse for driving the light emitting unit to emit pulse light is MOD =1 / f MOD , and the frequency of the driving pulse f MOD It should be at least K times the highest wingbeat frequency of the flying insect, and the parameter K should be ≥ 20.

[0026] A further technical solution is to use a pulse signal to drive a light emitting unit in a photoelectric scattering detection instrument to generate pulse light, including:

[0027] The pulse signal is used to control the controlled constant current source in the light emitting unit to drive the light emitting element connected to the controlled constant current source to emit pulse light, and the output current rise time and fall time of the controlled constant current source are both no more than 0.1t ON , where t ON is the positive pulse width of the driving pulse.

[0028] A further technical solution is that obtaining a pulsed received signal by a light receiving unit in a photoelectric scattering detection instrument includes:

[0029] The photodiode in the light receiving unit detects the pulse light and outputs an electrical signal to the signal conditioning circuit, which then outputs a pulsed receiving signal. The current rise time and current fall time of the receiving signal output by the signal conditioning circuit are both less than 0.2t. ON , where t ON is the positive pulse width of the driving pulse.

[0030] A further technical solution is to detect whether the data stability of the test sequence meets the data stability requirements, including:

[0031] The mean μ and standard deviation σ of the detection sequence are calculated. When the standard deviation σ exceeds the mean μ and reaches a predetermined threshold, it is determined that the data stability of the detection sequence does not meet the data stability requirement. Otherwise, it is determined that the data stability of the detection sequence meets the data stability requirement.

[0032] The beneficial technical effects of this application are:

[0033] The present application discloses a method for detecting atmospheric particle scattering for a photoelectric scattering detection instrument. The method is implemented based on the universal optical path structure of the photoelectric scattering detection instrument. The coefficient of variation of the scattered light sampling sequence is extracted from a statistical perspective to detect whether there are foreign objects in the sampling space. A higher light source modulation frequency and signal sampling rate are used, and peak extraction operations in both the frequency domain and the time domain are combined to identify different types of foreign objects, including flying insects and precipitation particles. Subsequently, the inversion results of the scattered light sampling sequence within the current detection cycle are processed differently to obtain more accurate atmospheric particle scattering detection results.

[0034] This method directly identifies flying insects by detecting their wingbeat signals. Compared to first identifying precipitation particles and then combining other criteria to determine whether they are flying insects, it has higher recognition accuracy and is more suitable for use as a basis for data quality control. Furthermore, the presence of wingbeat signals is independent of the insect's size, species, or trajectory. Increasing the light source modulation frequency to over 20 times the maximum wingbeat frequency of an insect facilitates the detection of peak details in the received signal, thus improving recognition accuracy. Furthermore, this method eliminates the need for a precise optical path, reducing debugging time and facilitating mass production applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a system framework diagram of a photoelectric scattering detection instrument according to an embodiment of the present application.

[0036] Figure 2 It is a flow chart of a method for detecting atmospheric particle scattering according to an embodiment of the present application.

[0037] Figure 3This is a schematic diagram of removing the ambient light signal from the received signal sampling sequence to obtain the scattered light sampling sequence in an example of the present application. DETAILED DESCRIPTION

[0038] The specific implementation of this application will be further described below with reference to the accompanying drawings.

[0039] The present application discloses an atmospheric particle scattering detection method for a photoelectric scattering detection instrument. The atmospheric particle scattering detection method is applied to a photoelectric scattering detection instrument. The schematic diagram of the structure of the photoelectric scattering detection instrument is shown in FIG. Figure 1 As shown, it also includes a light emitting unit, a light receiving unit and a signal processing unit, and the overlapping area of ​​the light emitting unit's illumination area and the light receiving unit's receiving field of view is a three-dimensional sampling space. However, this application has modified and optimized the atmospheric particle scattering detection method performed by the signal processing unit, including:

[0040] Step 1: Use a pulse signal to drive the light emitting unit in the photoelectric scattering detection instrument to generate pulse light, wherein the frequency of the driving pulse of the light emitting unit (ie, the light source modulation frequency) is much greater than the wing flapping frequency of the flying insect.

[0041] The signal processing unit generates a driving pulse, the pulse period of which is recorded as T MOD , the positive pulse width of the driving pulse is recorded as t ON Since the frequency of insect wing flapping is relatively high, and the present application will subsequently detect insect foreign matter by detecting the frequency of insect wing flapping, in order to facilitate subsequent frequency detection, the driving pulse must have a relatively high pulse frequency, at least ensuring that the pulse frequency is much greater than the frequency of insect wing flapping. In one embodiment, the pulse period T of the driving pulse is MOD =1 / f MOD , and the modulation frequency of the driving pulse f MOD At least K times the highest wingbeat frequency of the flying insect, parameter K≥20. Generally, the highest wingbeat frequency of the flying insect is 1kHz, then the pulse period T MOD ≤20μs. In order to reduce the average power consumption as much as possible under the premise of higher pulse frequency, the positive pulse width t ON Take as small as possible. In one embodiment, t ON ≤0.1T MOD .

[0042] The light emitting unit includes a controlled constant current source and a light emitting element connected thereto. The light emitting element can be a common LED or LD. The above-generated driving pulse is used to control the controlled constant current source, which can drive the light emitting element to emit pulsed light. In order to ensure effective driving, the output current rise time t of the controlled constant current source must be kept constant. TX_R ≤0.1t ON And the output current fall time t of the controlled constant current sourceTX_F ≤0.1t ON Among them, the output current rise time t TX_R It refers to the time required for the controlled constant current source to rise from 10% to 90% of the current stable value, and the output current fall time t TX_F It refers to the time required for the controlled constant current source to drop from 90% to 10% of the stable current value.

[0043] Step 2: Obtain a pulsed receiving signal through the light receiving unit in the photoelectric scattering detection instrument. The signal period of the receiving signal is the same as the pulse period T of the driving pulse. MOD consistent.

[0044] In one embodiment, the light receiving unit includes a photodiode and a signal conditioning circuit connected thereto. The photodiode detects pulsed light and outputs an electrical signal to the signal conditioning circuit, which then conditions the signal and outputs a pulsed reception signal. To ensure effective reception, the current rise time t of the reception signal output by the signal conditioning circuit is RX_R <0.2t ON , the current fall time t of the received signal RX_F <0.2t ON .

[0045] Step 3: Discretely sample the received signal and obtain a scattered light sampling sequence within each detection cycle. The scattered light sampling sequence includes the scattered light signals received by the light receiving unit at different sampling times. The detection frequency of the detection cycle can be customized and is generally set to multiple pulse periods.

[0046] In reality, the received signal from the optical receiving unit often contains not only the scattered light signal within the sampling space but also the ambient light signal. Therefore, this step actually first discretely samples the received signal to obtain a received signal sampling sequence. This received signal sampling sequence includes the received signal acquired by the optical receiving unit at each sampling moment. The received signal sampling sequence is then further preprocessed to remove the ambient light signal from the received signal, thereby obtaining the scattered light sampling sequence within each detection cycle.

[0047] The discrete sampling operation in this step can be implemented by using the analog-to-digital conversion function of the signal processing unit, or by a dedicated analog-to-digital conversion module, such as Figure 1Taking the latter case as an example, the light receiving unit is connected to the signal processing unit after passing through the analog-to-digital conversion module. The analog-to-digital conversion module discretely samples the received signal output by the light receiving unit to obtain a received signal sampling sequence and output it to the signal processing unit. In one embodiment, the analog-to-digital conversion module includes an analog-to-digital converter, a FIFO memory, and necessary peripheral circuits. The analog-to-digital converter temporarily stores the received signals obtained at each sampling moment in the FIFO memory, and reads out the N received signals obtained in each detection cycle at a time and transmits them to the signal processing unit, continuously outputting them, where N is an integer parameter.

[0048] Then the signal processing unit further preprocesses the received signal sampling sequence to obtain the scattered light sampling sequence. In order to conveniently remove the ambient light signal from the received signal sampling sequence, the discrete sampling is designed as follows: according to 0.5T MOD The received signal is discretely sampled at a sampling interval of 100 ms and the phase of the discrete sampling is adjusted so that one discrete sampling operation occurs before the end of the positive pulse of the received signal. The quantization accuracy of the general analog-to-digital converter is required to be no less than 14 bits.

[0049] Please refer to Figure 2 As shown in the flowchart, after the signal processing unit receives the received signal sampling sequence, it subtracts the received signal at the 2i-1th sampling moment in the received signal sampling sequence from the received signal at the 2i-1th sampling moment in the received signal sampling sequence to obtain the scattered light signal received by the light receiving unit at the 2i-1th sampling moment, wherein the starting value of the integer parameter i is 1. For any value of i, the 2i-1th sampling moment and the 2i-th sampling moment correspond to two discrete samplings performed within the same pulse cycle of the driving pulse, and the 2i-1th sampling moment corresponds to the discrete sampling performed before the end of the positive pulse of the received signal of the light receiving unit. Therefore, the received signal at the 2i-1th sampling moment includes the scattered light signal of the ambient light signal, while the received signal at the 2i-th sampling moment only contains the ambient light signal. Since the 2i-1th sampling moment and the 2i-th sampling moment are within the same pulse cycle, it can be considered that the ambient light signals of the two are consistent, and the scattered light signal at the 2i-1th sampling moment can be obtained by subtracting them. Please refer to Figure 3 The scattered light signals at the 1st to 6th sampling moments are shown as an example, and the scattered light signals at the 1st, 3rd and 5th sampling moments can be obtained by interleaving subtraction.

[0050] Then, the scattered light at the 2i-1th sampling moment in each detection cycle is extracted according to the time sequence to obtain a scattered light sampling sequence for the current detection cycle. If the first received signal in the received signal sampling sequence output by the analog-to-digital conversion module to the signal processing unit during each detection cycle is located before the end of the positive pulse, and N is an integer power of 2, the scattered light sampling sequence for the current detection cycle obtained through the above operation will include N / 2 discrete points of the scattered light signal.

[0051] Step 4: Obtain the scattered light sampling sequences of the current detection cycle and the most recent several detection cycles before it and splice them in time sequence to form a detection sequence. This is because the present application will subsequently perform peak detection on the sampling sequence, and a single randomly divided detection cycle may not necessarily contain a complete peak. Therefore, for the accuracy of subsequent peak detection, several detection cycles will be comprehensively considered here to ensure the integrity of the signal characteristics. Generally, the scattered light sampling sequences of the current detection cycle and the previous detection cycle are spliced ​​to form a detection sequence. The first detection cycle can be directly the current detection cycle.

[0052] Step 5: Check whether the data stability of the above detection sequence meets the data stability requirements. This includes: calculating the mean μ and standard deviation σ of the detection sequence. When the standard deviation σ exceeds the mean μ and reaches a predetermined threshold, it is determined that the data stability of the detection sequence does not meet the data stability requirements; otherwise, it is determined that the data stability of the detection sequence meets the data stability requirements. In one example, when σ>10μ, it indicates that the data stability does not meet the data stability requirements. Figure 2 The flowchart is taken as an example.

[0053] Step 6. When it is detected that the data stability of the detection sequence meets the data stability requirements, it is determined that there is no foreign matter in the sampling space of the photoelectric scattering detection instrument, and the inversion result of the scattered light sampling sequence in the current detection cycle is directly used as the atmospheric particle scattering detection result of the current detection cycle. The specific data inversion method adopts the existing inversion method, which is not elaborated in this application.

[0054] Step 7: When it is detected that the data stability of the detection sequence does not meet the data stability requirements, it is determined that there is a foreign object in the sampling space of the photoelectric scattering detection instrument, and then the type of foreign object in the sampling space is further determined based on the peak detection results of the detection sequence in the frequency domain and time domain.

[0055] Common foreign matter types within the sampling space can be divided into three main categories based on the degree of their impact on the atmospheric particle scattering inversion results: flying insects, precipitation particles, and other foreign matter types. Flying insects are not typical atmospheric particles. Therefore, when there are flying insects within the sampling space, the inversion results obtained from the scattered light sampling sequence within the current detection cycle will have significant deviations and cannot represent the actual atmospheric particle scattering situation, making the data unusable. Rain, snow, and other precipitation particles are common and representative atmospheric particles. When there are precipitation particles within the sampling space, the inversion results obtained within the current detection cycle are reasonable, and in specific applications, only data correction is required. Other foreign matter types have a lower probability of occurrence than flying insects and precipitation particles, but there is still a certain chance of their occurrence. Therefore, in order to ensure the integrity of the solution, other foreign matter types are also retained.

[0056] As can be seen above, the impact of flying insects on the atmospheric particle scattering detection process is actually much greater than that of precipitation particles and other types of foreign matter. Therefore, the recognition mechanism adopted in this application is to first distinguish flying insects from the other two types of foreign matter based on the flying insect wingbeat signals, including:

[0057] (1) First, extract the frequency domain features of the detection sequence and perform peak detection on the frequency domain features of the detection sequence. In one embodiment, extracting the frequency domain features of the detection sequence includes first performing windowing processing on the detection sequence and then performing a fast Fourier transform to extract the frequency domain features. The actual method for extracting the frequency domain features and the method for peak detection can adopt various existing methods, and this application does not limit this.

[0058] (2) When the frequency domain peak detection results determine that the detection sequence's frequency domain characteristics contain a single peak, the scattered light sampling sequence of the current detection cycle is determined to contain a flying insect wingbeat signal, and the foreign object type in the sampling space is determined to be a flying insect foreign object. As described above, since flying insect foreign objects have the greatest impact on atmospheric particle scattering detection, no further subsequent judgment is required upon determining that the sampling space contains a flying insect foreign object, and the subsequent step 8 can be directly executed.

[0059] (3) When it is determined based on the peak detection results in the frequency domain that the frequency domain characteristics of the detection sequence do not contain a single peak, it is determined that the sampling space does not contain flying insect foreign matter, and the type of foreign matter in the sampling space is determined based on the peak detection results in the time domain of the detection sequence. That is, peak detection is performed on the time domain characteristics of the detection sequence. When it is determined based on the peak detection results in the time domain that the time domain characteristics of the detection sequence contain at least one peak, the type of foreign matter in the sampling space is determined to be precipitation particle foreign matter. Otherwise, the type of foreign matter in the sampling space is determined to be other foreign matter types. Various existing peak detection methods can also be used in the same time domain scenario.

[0060] Step 8: Perform data post-processing on the inversion results of the scattered light sampling sequence in the current detection period according to the post-processing strategy corresponding to the foreign body type to obtain the atmospheric particle scattering detection results of the current detection period.

[0061] Different foreign object types correspond to different post-processing strategies, and each post-processing strategy can be pre-calibrated. For example, as mentioned above, flying insects significantly impact atmospheric particle scattering. Post-processing the inversion results according to the post-processing strategy for flying insects involves discarding the inversion results for the current detection cycle, while the atmospheric particle scattering results from the most recent detection cycle can be used as the atmospheric particle scattering results for the current detection cycle. On the other hand, atmospheric particle scattering under the influence of precipitation particles is correlated with the inversion results. Therefore, post-processing the inversion results according to the post-processing strategy for precipitation particles involves correcting the inversion results according to a predetermined data correction method, which can be determined in advance through fitting or experimental methods. Post-processing strategies for other foreign object types can also be customized. Since flying insects and precipitation particles are typically the primary foreign objects, a prompt message can be provided when other foreign object types are detected, prompting maintenance personnel to promptly investigate whether the sampling space is affected and requires manual intervention.

[0062] The above description is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and variations directly derived or imagined by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the scope of protection of the present application.

Claims

1. A method for detecting atmospheric particle scattering in a photoelectric scattering detection instrument, characterized in that: The atmospheric particle scattering detection method comprises: A pulse signal is used to drive a light emitting unit in a photoelectric scattering detection instrument to generate pulsed light, and a light receiving unit in the photoelectric scattering detection instrument obtains a pulsed received signal, wherein the frequency of the driving pulse of the light emitting unit is much greater than the wingbeat frequency of the flying insect; discretely sampling the received signal and obtaining a scattered light sampling sequence within each detection period, wherein the scattered light sampling sequence includes scattered light signals received by the light receiving unit at different sampling moments; Obtain scattered light sampling sequences of the current detection cycle and the most recent several detection cycles before it and splice them in time sequence to form a detection sequence; When it is detected that the data stability of the detection sequence meets the data stability requirement, it is determined that there is no foreign matter in the sampling space of the photoelectric scattering detection instrument, and the inversion result of the scattered light sampling sequence in the current detection cycle is used as the atmospheric particle scattering detection result of the current detection cycle; When it is detected that the data stability of the detection sequence does not meet the data stability requirements, it is determined that there is a foreign object in the sampling space of the photoelectric scattering detection instrument, and the type of the foreign object in the sampling space is determined based on the peak detection results of the detection sequence in the frequency domain and the time domain. The inversion results of the scattered light sampling sequence in the current detection period are post-processed according to the post-processing strategy corresponding to the foreign object type to obtain the atmospheric particle scattering detection results of the current detection period, and different foreign object types correspond to different post-processing strategies; Among them, determining the type of foreign matter contained in the sampling space according to the peak detection results of the detection sequence in the frequency domain and time domain includes: extracting the frequency domain characteristics of the detection sequence and performing peak detection on the frequency domain characteristics of the detection sequence; when it is determined according to the peak detection result of the frequency domain that the frequency domain characteristics of the detection sequence contain a single peak, determining that the scattered light sampling sequence of the current detection period contains a flying insect wing flapping signal and determining that the type of foreign matter in the sampling space is a flying insect foreign matter; when it is determined according to the peak detection result of the frequency domain that the frequency domain characteristics of the detection sequence do not contain a single peak, determining that the sampling space does not contain a flying insect foreign matter and determining the type of foreign matter in the sampling space according to the peak detection result of the frequency domain.

2. The atmospheric particle scattering detection method according to claim 1, characterized in that: Determining the type of foreign matter in the sampling space according to the peak detection result of the detection sequence in the time domain includes: Peak detection is performed on the time domain characteristics of the detection sequence. When it is determined based on the time domain peak detection result that the time domain characteristics of the detection sequence contain at least one peak, the type of foreign matter in the sampling space is determined to be precipitation particle foreign matter; otherwise, it is determined that the sampling space contains other types of foreign matter.

3. The atmospheric particle scattering detection method according to claim 1, characterized in that: Discretely sampling the received signal and obtaining a scattered light sampling sequence within each detection period includes: discretely sampling the received signal to obtain a received signal sampling sequence, wherein the received signal sampling sequence includes received signals acquired by the optical receiving unit at each sampling moment; Data preprocessing is performed on the received signal sampling sequence to remove the ambient light signal in the received signal to obtain the scattered light sampling sequence in each detection cycle.

4. The atmospheric particle scattering detection method according to claim 3, characterized in that: The discrete sampling of the received signal comprises: according to The received signal is discretely sampled at a sampling interval of , and the phase of the discrete sampling is adjusted so that one discrete sampling operation occurs before the end of the positive pulse of the received signal, is the pulse period of the driving pulse.

5. The atmospheric particle scattering detection method according to claim 4, characterized in that: Performing data preprocessing on the received signal sampling sequence to remove the ambient light signal in the received signal includes: subtracting the received signal at the 2i-th sampling moment in the received signal sampling sequence from the received signal at the 2i-th sampling moment in the received signal sampling sequence to obtain the scattered light signal received by the light receiving unit at the 2i-1th sampling moment, and extracting the scattered light at the 2i-1th sampling moment arranged in time sequence within each detection cycle to obtain the scattered light sampling sequence within the current detection cycle; Among them, the starting value of the integer parameter i is 1. For any value of i, the 2i-1th sampling moment and the 2i-th sampling moment correspond to two discrete samplings performed within the same pulse period of the driving pulse, and the 2i-1th sampling moment corresponds to the discrete sampling performed before the end of the positive pulse of the receiving signal of the light receiving unit.

6. The atmospheric particle scattering detection method according to claim 1, characterized in that: The period of the driving pulse for driving the light emitting unit to emit pulsed light , and the frequency of the driving pulse It should be at least K times the highest wingbeat frequency of the flying insect, and the parameter K should be ≥ 20.

7. The atmospheric particle scattering detection method according to claim 1, characterized in that: Using a pulse signal to drive the light emitting unit in the photoelectric scattering detection instrument to generate pulse light includes: The pulse signal is used to control the controlled constant current source in the light emitting unit to drive the light emitting element connected to the controlled constant current source to emit pulse light, and the output current rise time and fall time of the controlled constant current source are both less than ,in, is the positive pulse width of the driving pulse.

8. The atmospheric particle scattering detection method according to claim 1, characterized in that: The pulsed received signal obtained by the light receiving unit in the atmospheric particle scattering instrument includes: The photodiode in the light receiving unit detects the pulse light and outputs an electrical signal to the signal conditioning circuit, and the signal conditioning circuit outputs a pulsed receiving signal, and the current rise time and current fall time of the receiving signal output by the signal conditioning circuit are both less than ,in, is the positive pulse width of the driving pulse.

9. The atmospheric particle scattering detection method according to claim 1, characterized in that: Checking whether the data stability of the test sequence meets the data stability requirements includes: Calculate the mean of the detection sequence and standard deviation , when the standard deviation Above average When the predetermined threshold is reached, it is determined that the data stability of the detection sequence does not meet the data stability requirement; otherwise, it is determined that the data stability of the detection sequence meets the data stability requirement.

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