Method and system for detecting atmospheric laser radar signal interference

Abstract

The application provides a method and system for detecting atmospheric laser radar signal interference, comprising: dividing atmospheric scattering signals into first and second atmospheric scattering signals; coupling the first atmospheric scattering signals into a first photoelectric detector to collect a first signal strength output by the first photoelectric detector; coupling the second atmospheric scattering signals into a second photoelectric detector to collect a second signal strength output by the second photoelectric detector; calculating signal strength ratios of the first and second signal strengths at each height position; judging whether the signal strength ratios at different height positions change; when the signal strength ratios at different height positions remain unchanged, it is considered that there is no interference in the atmospheric laser radar signal; and when the signal strength ratios at different height positions change, it is considered that there is interference in the atmospheric laser radar signal. The technical scheme of the application is used to solve the technical problem that atmospheric laser radar signal interference is difficult to identify in the prior art.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, and in particular to a method and system for detecting atmospheric lidar signal interference. Background Technology

[0002] Atmospheric lidar is a type of lidar that uses the scattering signal of laser light from the atmosphere to measure parameters such as atmospheric density, temperature, wind field, and composition. Types include Mie scattering lidar, Rayleigh scattering lidar, and resonant fluorescence scattering lidar, with detection ranges covering from near-ground to 100 km. Atmospheric lidar has important applications in weather forecasting, atmospheric science research, space physics research, environmental monitoring, space launch activities, and civil aviation flight environment.

[0003] Atmospheric scattering signals are relatively weak, and sensitive low-light detection devices are generally used for signal detection. However, these devices are susceptible to interference from the external environment, and the output atmospheric scattering signal may contain interference, affecting the accuracy of the detection results. To ensure the accuracy of atmospheric lidar measurements, it is necessary to detect and identify interference in the signal.

[0004] Current research and inventions on lidar anti-interference mainly focus on target detection lidar. These efforts aim to improve the anti-interference capability of lidar from aspects such as methods, devices, and information processing. The invention patent "Lidar and its Anti-interference Method" (application number 201910410468.0) proposes modulating the lidar's transmission time by injecting random time jitter into the time interval of the transmission time sequence. It improves the lidar's anti-interference capability based on the correlation between the lidar's transmission time and the expected echo reception. The invention patent "A Lidar Anti-interference Method and Device" (application number 202110126177.6) utilizes the determination of the laser transmission sequence interval to improve anti-interference capability. The invention patent "An Information Processing Method to Improve Lidar Anti-interference Capability" (application number 202111585275.2) performs anti-interference processing on the interfered laser samples to obtain a unique and correct pulse signal. This anti-interference processed laser sample signal serves as the gate clock signal for the radar echo signal, ensuring the correctness of the lidar's information processing.

[0005] However, these research and inventions on anti-interference for lidar are applicable to target detection lidar, where the target's scattered signal has a short duration, making it easy to improve anti-interference capabilities by matching the laser emission time with the target's scattered signal reception time. Atmospheric lidar, on the other hand, requires measuring the scattered signal over the laser's flight distance, where the signal duration is long, and interference signals can appear at any point within the detection altitude range, making signal interference detection quite challenging.

[0006] The main sources of interference with atmospheric lidar signals include electrical interference, optical interference, and detector anomalies, which manifest as signal enhancement in the atmospheric scattering signal profile. Stronger interference can be identified by changes in signal intensity; however, detecting weak interference is more difficult. Summary of the Invention

[0007] This invention provides a method and system for detecting interference in atmospheric lidar signals, which can solve the technical problem that atmospheric lidar signal interference is difficult to identify in the prior art.

[0008] According to one aspect of the present invention, a method for detecting interference in an atmospheric lidar signal is provided. The method includes: splitting atmospheric scattering signals received by the atmospheric lidar at different altitudes into a first atmospheric scattering signal and a second atmospheric scattering signal using a beam splitter, wherein the two beam splitters have different splitting ratios; coupling the first atmospheric scattering signal into a first photodetector and acquiring a first signal intensity output by the first photodetector; coupling the second atmospheric scattering signal into a second photodetector and acquiring a second signal intensity output by the second photodetector; calculating the signal intensity ratio of the first signal intensity and the second signal intensity at each altitude; determining whether the signal intensity ratio at different altitudes changes; if the signal intensity ratio remains constant, it is considered that there is no interference in the atmospheric lidar signal; if the signal intensity ratio changes, it is considered that there is interference in the atmospheric lidar signal.

[0009] Furthermore, the signal intensity of the first atmospheric scattering signal is S1 = S*p1, and the signal intensity of the second atmospheric scattering signal is S2 = S*p2, where S is the signal intensity of the atmospheric scattering signal received by the atmospheric lidar, S1 is the signal intensity of the first atmospheric scattering signal, S2 is the signal intensity of the second atmospheric scattering signal, p1 is the first beam splitting ratio of the beam splitter, and p2 is the second beam splitting ratio of the beam splitter.

[0010] Furthermore, when there is no interference in the atmospheric lidar signal, the first signal strength is N1 = S*p1*q1, and the second signal strength is N2 = S*p2*q2, where q1 is the signal conversion coefficient of the first photodetector, q2 is the signal conversion coefficient of the second photodetector, N1 is the first signal strength when there is no interference, and N2 is the second signal strength when there is no interference.

[0011] Furthermore, when there is no interference in the atmospheric lidar signal, the signal strength ratio R = N1 / N2 = (p1*q1) / (p2*q2) at different altitudes remains unchanged.

[0012] Furthermore, when interference exists in the atmospheric lidar signal, the first signal strength is N1' = S*p1*q1 + ΔN1', and the second signal strength is N2' = S*p2*q2 + ΔN2', where S is the signal strength of the atmospheric scattering signal received by the atmospheric lidar, p1 is the first splitting ratio of the beam splitter, p2 is the second splitting ratio of the beam splitter, q1 is the signal conversion coefficient of the first photodetector, q2 is the signal conversion coefficient of the second photodetector, N1' is the first signal strength when interference exists, ΔN1' is the first interference signal strength, N2' is the second signal strength when interference exists, and ΔN2' is the second interference signal strength.

[0013] Furthermore, when there is interference in the atmospheric lidar signal, the signal strength ratio R'=N1' / N2'=(S*p1*q1+ΔN1') / (S*p2*q2+ΔN2') at different altitudes changes.

[0014] According to another aspect of the present invention, a system for detecting atmospheric lidar signal interference is provided, which uses the method for detecting atmospheric lidar signal interference as described above to perform signal interference detection.

[0015] Furthermore, the system for detecting interference in atmospheric lidar signals includes a beam splitter, a first coupling mirror, a second coupling mirror, a first photodetector, a second photodetector, and an interference detection unit. The beam splitter is used to separate the atmospheric scattering signals received by the atmospheric lidar at different altitudes into a first atmospheric scattering signal and a second atmospheric scattering signal. The first coupling mirror is used to couple the first atmospheric scattering signal into the first photodetector, which is used to acquire the first signal strength output by the first photodetector. The second coupling mirror is used to couple the second atmospheric scattering signal into the second photodetector, which is used to acquire the second signal strength output by the second photodetector. The interference detection unit is used to detect whether interference exists in the atmospheric lidar signal based on the first and second signal strengths.

[0016] This invention provides a method for detecting interference in atmospheric lidar signals. The method uses a beam splitter to divide the received scattered signal into two parts, and two photodetectors to detect the signal intensity of each part. The ratio of the recorded signal intensities is calculated, and the signal interference is determined based on the change in the ratio. This method performs dual-channel measurement on the received light scattered signal and determines the location of the interference based on the change in the signal intensity ratio, thus obtaining the range of undisturbed signal altitudes. Therefore, compared with existing technologies, the method for detecting atmospheric lidar signal interference provided by this invention can effectively detect signal interference of varying degrees throughout the entire detection altitude range. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0018] Figure 1 A schematic diagram of a system for detecting atmospheric lidar signal interference according to a specific embodiment of the present invention is shown.

[0019] Figure 2 A schematic diagram of an atmospheric scattering signal provided according to a specific embodiment of the present invention is shown;

[0020] Figure 3 A schematic diagram of the ratio of two-channel atmospheric scattering signals provided according to a specific embodiment of the present invention is shown.

[0021] The above figures include the following reference numerals:

[0022] 10. Beam splitter; 20. First coupling mirror; 30. Second coupling mirror; 40. First photodetector; 50. Second photodetector. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0026] like Figures 1 to 3 As shown in the figure, a method for detecting interference in atmospheric lidar signals is provided according to a specific embodiment of the present invention. The method includes: dividing atmospheric scattering signals received by the atmospheric lidar at different altitudes into a first atmospheric scattering signal and a second atmospheric scattering signal using a beam splitter 10, wherein the two beam splitting ratios of the beam splitter 10 are different; coupling the first atmospheric scattering signal into a first photodetector 40 and collecting the first signal intensity output by the first photodetector 40; coupling the second atmospheric scattering signal into a second photodetector 50 and collecting the second signal intensity output by the second photodetector 50; calculating the signal intensity ratio of the first signal intensity and the second signal intensity at each altitude; determining whether the signal intensity ratio at different altitudes changes; if the signal intensity ratio remains unchanged, it is considered that there is no interference in the atmospheric lidar signal; if the signal intensity ratio changes, it is considered that there is interference in the atmospheric lidar signal.

[0027] This configuration provides a method for detecting interference in atmospheric lidar signals. The method uses a beam splitter to divide the received scattered signal into two parts, and two photodetectors detect the signal intensity of each part separately. The ratio of the recorded signal intensities is calculated, and the signal interference is determined based on the change in the ratio. By performing dual-channel measurements on the received light scattered signal and determining the location of signal interference based on changes in the signal intensity ratio, this method can determine the range of undisturbed signal altitudes. Therefore, compared with existing technologies, the method for detecting atmospheric lidar signal interference provided by this invention can effectively detect signal interference of varying degrees throughout the entire detection altitude range.

[0028] Specifically, such as Figure 3As shown, when interference occurs, the ratio of the first signal strength to the second signal strength changes, while within other height ranges where interference does not occur, the ratio remains constant. Therefore, the height range corresponding to the protrusion in the diagram indicates the location of the interference. Furthermore, the greater the interference, the more pronounced the protrusion. The degree of protrusion can be used to determine the magnitude of the interference.

[0029] Furthermore, in this invention, in order to detect interference with the atmospheric lidar signal, after the atmospheric lidar receives the atmospheric scattering signal S, it first uses a beam splitter to divide the received atmospheric scattering signal into a first atmospheric scattering signal S1 and a second atmospheric scattering signal S2. The signal strength of the first atmospheric scattering signal S1 is S1 = S * p1, and the signal strength of the second atmospheric scattering signal S2 is S2 = S * p2, where S is the signal strength of the atmospheric scattering signal received by the atmospheric lidar, S1 is the signal strength of the first atmospheric scattering signal, S2 is the signal strength of the second atmospheric scattering signal, p1 is the first beam splitting ratio of the beam splitter 10, and p2 is the second beam splitting ratio of the beam splitter 10.

[0030] After acquiring the first atmospheric scattering signal and the second atmospheric scattering signal, the first atmospheric scattering signal can be coupled into the first photodetector 40 to collect the first signal intensity output by the first photodetector 40.

[0031] Specifically, when there is no interference in the atmospheric lidar signal, the first signal strength is N1 = S*p1*q1, and the second signal strength is N2 = S*p2*q2, where q1 is the signal conversion coefficient of the first photodetector 40, q2 is the signal conversion coefficient of the second photodetector 50, N1 is the first signal strength when there is no interference, and N2 is the second signal strength when there is no interference. When there is no interference in the atmospheric lidar signal, the signal strength ratio R = N1 / N2 = (p1*q1) / (p2*q2) at different altitudes remains unchanged.

[0032] When interference exists in the atmospheric lidar signal, the first signal strength is N1' = S*p1*q1 + ΔN1', and the second signal strength is N2' = S*p2*q2 + ΔN2', where S is the signal strength of the atmospheric scattered signal received by the atmospheric lidar, p1 is the first splitting ratio of the beam splitter 10, p2 is the second splitting ratio of the beam splitter 10, q1 is the signal conversion coefficient of the first photodetector 40, q2 is the signal conversion coefficient of the second photodetector 50, N1' is the first signal strength when interference exists, ΔN1' is the first interference signal strength, N2' is the second signal strength when interference exists, and ΔN2' is the second interference signal strength. When interference exists in the atmospheric lidar signal, the signal strength ratio R' = N1' / N2' = (S*p1*q1 + ΔN1') / (S*p2*q2 + ΔN2') at different altitudes changes.

[0033] According to another aspect of the present invention, a system for detecting atmospheric lidar signal interference is provided, which uses the method for detecting atmospheric lidar signal interference as described above to perform signal interference detection.

[0034] This configuration provides a system for detecting interference in atmospheric lidar signals. The system uses a beam splitter to divide the received scattered signal into two parts, and two photodetectors detect the signal intensity of each part separately. The ratio of the recorded signal intensities is calculated, and the signal interference is determined based on changes in this ratio. This method, by performing dual-channel measurements on the received light scattered signal and determining the location of signal interference based on changes in the signal intensity ratio, can obtain the range of undisturbed signal altitudes. Therefore, compared with existing technologies, the atmospheric lidar signal interference detection system provided by this invention can effectively detect signal interference of varying degrees throughout the entire detection altitude range.

[0035] Furthermore, in this invention, to detect atmospheric lidar signal interference, the system for detecting atmospheric lidar signal interference can be configured to include a beam splitter 10, a first coupling mirror 20, a second coupling mirror 30, a first photodetector 40, a second photodetector 50, and an interference judgment unit. The beam splitter 10 is used to divide the atmospheric scattering signals received by the atmospheric lidar at different altitudes into a first atmospheric scattering signal and a second atmospheric scattering signal. The first coupling mirror 20 is used to couple the first atmospheric scattering signal into the first photodetector 40, which is used to collect the first signal strength output by the first photodetector 40. The second coupling mirror 30 is used to couple the second atmospheric scattering signal into the second photodetector 50, which is used to collect the second signal strength output by the second photodetector 50. The interference judgment unit is used to detect whether there is interference in the atmospheric lidar signal based on the first signal strength and the second signal strength.

[0036] To gain a further understanding of the present invention, the following description is provided in conjunction with... Figures 1 to 3 The method for detecting atmospheric lidar signal interference provided by the present invention will be described in detail.

[0037] like Figures 1 to 3 As shown in the figure, a method for detecting atmospheric lidar signal interference is provided according to a specific embodiment of the present invention, the method specifically including the following steps.

[0038] After the atmospheric lidar receives the atmospheric scattering signal S, it uses a beam splitter to divide the received atmospheric scattering signal into two parts, S1 and S2.

[0039] By selecting beam splitters with splitting ratios p1 and p2 respectively, the intensities of the two signal components are made as follows:

[0040] S1 = S·p1, S2 = S·p2

[0041] Since the Doppler has two channels, one passing through a frequency discriminator and the other not, the interference signals are all electrical interferences, and the interference characteristics are that the magnitude of the interference is the same. If the beam splitter ratios are different, a change in the ratio indicates interference, while no change indicates no interference; if the beam splitter ratios are the same, no interference can be observed. Therefore, in this invention, the beam splitter ratio p1 cannot be equal to p2.

[0042] The two scattered signals are coupled into two photodetectors via a first coupling lens and a second coupling lens, respectively, with the performance of the two photodetectors being as consistent as possible. In this invention, the performance of the photodetectors specifically includes quantum efficiency, for example, ensuring identical reflected light intensity given the same amount of light. Interference signals of the same type are consistent, and ensuring that the performance of the two photodetectors is as consistent as possible effectively eliminates variables caused by the detector model.

[0043] The signal strength values ​​of the two photodetectors acquired by the data acquisition unit are N1 = S*p1*q1 and N2 = S*p2*q2, where q1 is the signal conversion coefficient of the first photodetector 40 and q2 is the signal conversion coefficient of the second photodetector 50.

[0044] When there is no interference in the lidar signal, the ratio of the signal strength of the two parts is: R = N1 / N2 = (p1·q1) / (p2·q2), which is a constant value and does not change with altitude.

[0045] When there is interference in the lidar signal, the signal strength values ​​of the two parts are: N1'=S*p1*q1+ΔN1', N2'=S*p2*q2+ΔN2', where ΔN1' and ΔN2' are the interference strengths of the two parts of the signal.

[0046] When there is interference in the lidar signal, the ratio of the signal strength of the two parts is: R'=N1' / N2'=(S*p1*q1+ΔN1') / (S*p2*q2+ΔN2').

[0047] Interference was detected at an altitude where R' is not equal to R. In this embodiment, the atmospheric scattering signal is divided into two parts for signal strength measurement, and signal interference is identified by the change in the signal strength ratio.

[0048] In summary, this invention provides a method for detecting interference in atmospheric lidar signals. This method uses a beam splitter to divide the received scattered signal into two parts, employs two photodetectors to detect the signal intensity of each part, calculates the ratio of the recorded signal intensities, and identifies signal interference based on changes in the ratio. This method performs dual-channel measurements on the received light scattered signal and determines the location of signal interference based on changes in the signal intensity ratio, thus obtaining the range of undisturbed signal altitudes. Therefore, compared with existing technologies, the method for detecting atmospheric lidar signal interference provided by this invention can effectively detect signal interference of varying degrees throughout the entire detection altitude range.

[0049] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0050] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting interference in atmospheric lidar signals, characterized in that, The method for detecting interference with atmospheric lidar signals includes: The atmospheric scattering signals received by the atmospheric lidar at different altitudes are divided into a first atmospheric scattering signal and a second atmospheric scattering signal using a beam splitter (10). The two beam splitters (10) have different splitting ratios. The first atmospheric scattering signal is coupled into the first photodetector (40) to collect the first signal intensity output by the first photodetector (40); The second atmospheric scattering signal is coupled into the second photodetector (50), and the intensity of the second signal output by the second photodetector (50) is collected; Calculate the signal strength ratio of the first signal strength and the second signal strength at each height position; The system determines whether the signal strength ratio changes at different altitudes. If the signal strength ratio remains constant, the atmospheric lidar signal is considered to be free of interference; if the signal strength ratio changes, the atmospheric lidar signal is considered to be free of interference.

2. The method for detecting atmospheric lidar signal interference according to claim 1, characterized in that, The signal intensity of the first atmospheric scattering signal is S1 = S*p1, and the signal intensity of the second atmospheric scattering signal is S2 = S*p2, where S is the signal intensity of the atmospheric scattering signal received by the atmospheric lidar, S1 is the signal intensity of the first atmospheric scattering signal, S2 is the signal intensity of the second atmospheric scattering signal, p1 is the first beam splitting ratio of the beam splitter (10), and p2 is the second beam splitting ratio of the beam splitter (10).

3. The method for detecting atmospheric lidar signal interference according to claim 2, characterized in that, When there is no interference in the atmospheric lidar signal, the first signal strength is N1 = S * p1 * q1, and the second signal strength is N2 = S * p2 * q2, where q1 is the signal conversion coefficient of the first photodetector (40), q2 is the signal conversion coefficient of the second photodetector (50), N1 is the first signal strength when there is no interference, and N2 is the second signal strength when there is no interference.

4. The method for detecting atmospheric lidar signal interference according to claim 3, characterized in that, When there is no interference in the atmospheric lidar signal, the signal strength ratio R = N1 / N2 = (p1*q1) / (p2*q2) at different altitudes remains unchanged.

5. The method for detecting atmospheric lidar signal interference according to claim 2, characterized in that, When there is interference in the atmospheric lidar signal, the first signal strength is N1' = S*p1*q1 + ΔN1', and the second signal strength is N2' = S*p2*q2 + ΔN2', where S is the signal strength of the atmospheric scattering signal received by the atmospheric lidar, p1 is the first beam splitting ratio of the beam splitter (10), p2 is the second beam splitting ratio of the beam splitter (10), q1 is the signal conversion coefficient of the first photodetector (40), q2 is the signal conversion coefficient of the second photodetector (50), N1' is the first signal strength when there is interference, ΔN1' is the first interference signal strength, N2' is the second signal strength when there is interference, and ΔN2' is the second interference signal strength.

6. The method for detecting atmospheric lidar signal interference according to claim 5, characterized in that, When there is interference in the atmospheric lidar signal, the signal strength ratio R'=N1' / N2'=(S*p1*q1+ΔN1') / (S*p2*q2+ΔN2') at different altitudes changes.

7. A system for detecting interference with atmospheric lidar signals, characterized in that, The system for detecting atmospheric lidar signal interference uses the method for detecting atmospheric lidar signal interference as described in any one of claims 1 to 6 to perform signal interference detection.

8. The system for detecting atmospheric lidar signal interference according to claim 7, characterized in that, The system for detecting interference in atmospheric lidar signals includes a beam splitter (10), a first coupling mirror (20), a second coupling mirror (30), a first photodetector (40), a second photodetector (50), and an interference judgment unit. The beam splitter (10) is used to divide the atmospheric scattering signals received by the atmospheric lidar at different altitudes into a first atmospheric scattering signal and a second atmospheric scattering signal. The first coupling mirror (20) is used to couple the first atmospheric scattering signal into the first photodetector (40), which is used to collect the first signal intensity output by the first photodetector (40). The second coupling mirror (30) is used to couple the second atmospheric scattering signal into the second photodetector (50), which is used to collect the second signal intensity output by the second photodetector (50). The interference judgment unit is used to detect whether there is interference in the atmospheric lidar signal based on the first signal intensity and the second signal intensity.

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