Coherent wind lidar calibration system and method

Abstract

The invention discloses a coherent wind lidar calibration system and method. The calibration system comprises a setting module used for setting a wind speed and an atmosphere scene; the modulation control module is used for calculating a frequency shift control signal according to a set wind speed and converting a set atmosphere scene into an intensity control signal; the modulation amplification module is used for performing frequency modulation and amplitude modulation on seed laser input by the tested radar system under the driving of the driving module, and performing optical power amplification to obtain an analog echo signal; and the coupler is used for coupling the analog echo signal into the tested radar system so as to perform inversion according to the data of the analog echo signal, and comparing the inverted data with the data of the analog echo signal so as to complete calibration. According to the invention, main photoelectric parameters and indexes of the coherent wind lidar can be calibrated in a laboratory or on-site environment.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic instruments, and in particular to a coherent wind laser radar calibration system and method. Background Art

[0002] The atmosphere provides a very important guarantee for human survival and development. The movement of atmospheric wind speed is closely related to human life. Accurate observation of atmospheric wind speed is of great significance for detecting atmospheric pollution, military environmental forecasting, improving the safety of aviation and aerospace, improving the accuracy of long-term weather forecasts, and improving climate research models. The observation of regional wind speed can not only provide guarantees for the safe takeoff and landing of aircraft, but also provide reasonable aircraft takeoff and landing density services for airports. At the same time, the impact on high-tech warfare is becoming increasingly important. On the artillery battlefield, the wind speed of the artillery, shells and arrow launch positions has an important impact on the shooting accuracy. On aircraft carriers and other ships, the safe takeoff and landing of the fleet depends on the accurate measurement of the surrounding atmospheric wind speed. In terms of satellite and missile launches, real-time wind speed data is not only a prerequisite for safety assurance, but also a large range of wind speed data is an important factor in improving the success rate of launch and the hit rate of missiles. In terms of the utilization of wind energy resources, accurate wind speed measurement can also improve the efficiency of wind power generation. Therefore, the measurement of atmospheric wind speed has received more and more attention. Organizations such as the International Civil Aviation Organization, the World Meteorological Organization, and aerospace research institutes of various countries in the world are actively conducting research and development of wind speed detection systems.

[0003] As a newly developed active atmospheric remote sensing instrument in recent years, wind lidar has the advantages of small size, high wind speed measurement accuracy, high time and space resolution, etc. Wind lidar mainly uses the principle of Doppler frequency shift to measure atmospheric wind speed. According to the different detection principles, it can be divided into phase detection (also known as heterodyne detection) and incoherent detection (also known as direct detection).

[0004] Coherent detection measures the atmospheric wind speed by the phase (beat frequency) of the atmospheric echo signal of the emitted laser and the local oscillator laser. The measurement accuracy of the wind laser radar is a crucial indicator, which mainly includes the accuracy of the wind speed and the direction. Common coherent wind laser radars are composed of fiber optic optical paths. Due to the differences in the line width, pulse shape, energy and repetition frequency of the coherent wind laser radar, as well as the specific properties of the optical fiber device and the end face reflection, these factors may cause differences in the accuracy of the wind laser radar. In addition, the selection of balanced detectors and the signal processing differences of the subsequent electronic systems are also important reasons for the differences in the accuracy of coherent wind laser radars.

[0005] The calibration of wind-measuring lidar generally uses wind cups and anemometers to compare with the data in the meteorological wind tower. The calibration is usually carried out under field conditions, and the atmospheric wind speed in the field is uncontrollable, making it difficult to calibrate the wind speeds of different wind force levels within a certain period of time. The wind also occurs at different times, which will affect the calibration. At the same time, the radar working aerosol environments in different regions are different. The existing calibration methods are difficult to meet the requirements of calibrating the wind speed measurement results under different aerosol environments within a certain period of time at the same location, and are difficult to meet the needs of autonomous, regular, and on-site calibration.

[0006] Therefore, it is necessary to invent a coherent wind measurement lidar hardware calibration system to calibrate the main optoelectronic parameters and algorithms of the coherent wind measurement lidar under laboratory or field conditions. Summary of the invention

[0007] The main purpose of the present invention is to provide a coherent wind measurement laser radar calibration system and method which can calibrate the main optoelectronic parameters and algorithms of the coherent wind measurement laser radar under laboratory or field environmental conditions.

[0008] The technical solution adopted by the present invention is:

[0009] A coherent wind laser radar calibration system is provided, comprising a setting module, a modulation control module, a driving module, a modulation amplification module and a coupler, wherein:

[0010] Setting module, used to set wind speed and atmospheric scenes;

[0011] A modulation control module is connected to the input module and is used to calculate the Doppler frequency shift corresponding to different time points according to the set wind speed and convert it into a frequency shift control signal; the modulation control module is also used to convert the set atmospheric scene into an intensity control signal;

[0012] The modulation and amplification module is used to perform frequency modulation and amplitude modulation on the seed laser input by the radar system under test according to the frequency shift control signal and intensity control signal generated by the modulation control module under the drive of the driving module, and perform optical power amplification to obtain a simulated echo signal;

[0013] The coupler is used to couple the analog echo signal into the radar system under test, and generate a beat frequency signal with the seed laser of the radar system under test, so that the radar system under test obtains the data of the analog echo signal according to the beat frequency signal for inversion, and completes the calibration by comparing the inverted data with the data of the analog echo signal.

[0014] According to the above technical solution, the modulation and amplification module is time synchronized with the coherent wind measurement laser radar system under test, and the synchronization signal is provided by the coherent wind measurement laser radar system under test.

[0015] According to the above technical solution, the modulation and amplification module specifically matches the radar system under test with different repetition frequencies through the synchronization signal.

[0016] In accordance with the above technical solution, the coupler is also used to control the divergence angle of the simulated echo signal diverged through the flat top to be much larger than the receiving field of view angle of the laser radar to be tested.

[0017] According to the above technical solution, the modulation and amplification module performs intermediate frequency modulation on the seed laser, and the range is 80MHz-200MHz.

[0018] In accordance with the above technical solution, the setting module is specifically used to freely set the wind speed information and the atmospheric scene through user input, or to set them by selecting preset wind speeds and atmospheric scenes of different levels.

[0019] According to the above technical solution, the preset different levels of wind speed include squall frequency, strong wind frequency and gentle wind frequency.

[0020] Following the above technical solution, different preset atmospheric scenes include heavy pollution, moderate pollution and light pollution, and different atmospheric scenes correspond to different aerosol particles' absorption and scattering of light.

[0021] The present invention also provides a coherent wind laser radar calibration method, comprising the following steps:

[0022] Set wind speed and atmospheric scenes;

[0023] The Doppler frequency shift corresponding to different time points is calculated according to the set wind speed and converted into a frequency shift control signal; the set atmospheric scene is converted into an intensity control signal;

[0024] The seed laser input to the radar system under test is frequency modulated and amplitude modulated according to the frequency shift control signal and the intensity control signal, and the optical power is amplified to obtain a simulated echo signal;

[0025] The simulated echo signal is coupled into the radar system under test, and a beat frequency signal is generated with the seed laser of the radar system under test, so that the radar system under test obtains data of the simulated echo signal according to the beat frequency signal for inversion;

[0026] The inverted data is compared with the data of the simulated echo signal to complete the calibration.

[0027] According to the above technical solution, when frequency modulation and amplitude modulation are performed, the coherent wind measurement laser radar system under test provides a synchronization signal to achieve time synchronization.

[0028] The beneficial effects of the present invention are as follows: the system of the present invention can obtain frequency shift control signals corresponding to different time points according to the set wind speed, and obtain intensity control signals according to the set atmospheric scenes. According to these two control signals, the seed laser input to the radar system under test can be frequency modulated and amplitude modulated to obtain a simulated echo signal. The radar system under test performs inversion according to the data of the simulated echo signal, and then compares it with the data of the simulated echo signal. If it meets the preset conditions, it means that the radar system under test meets the calibration standard, otherwise it does not meet the calibration, thereby completing the calibration; in addition, the parameters of the radar system under test can be adjusted according to the comparison results to make it meet the calibration conditions. The present invention innovatively realizes the simulation of echo signals of various wind speeds and atmospheric scenes, thereby adapting to the calibration requirements of various different radar systems under test.

[0029] Furthermore, the modulation and amplification module is time synchronized with the coherent wind measurement lidar system under test, and the synchronization signal is provided by the coherent wind measurement lidar system under test, that is, the time when the radar emits a pulse light beam is consistent with the time of the synchronization signal. The light beam flight time can be calculated through time synchronization. The light beam flight time is the subtraction of the received echo time and the emitted pulse time. By accurately measuring the time interval of the light beam flight time and combining it with the propagation speed of the laser in the atmosphere, the distance between the atmospheric scene (corresponding to different target aerosols) and the coherent wind measurement lidar can be accurately calculated.

[0030] Furthermore, by utilizing the pulse synchronization signal of the coherent wind laser radar to be calibrated to synchronize the optical pulse, the laser radar systems with different repetition frequencies can be calibrated.

[0031] Furthermore, the optical signal after modulation and amplification of the present invention is flat-top divergent, and its divergence angle is much larger than the receiving field angle of the laser radar to be tested, so that its coupling efficiency is only related to the coupling distance, and is insensitive to the angle between the optical axes of the two.

[0032] Furthermore, the seed laser is modulated at an intermediate frequency to adapt to the coherent wind measurement lidar system with different intermediate frequencies.

[0033] Furthermore, due to the complexity of aerosol concentration, composition and distribution, the present invention freely sets wind speed information and atmospheric scenes through user input, or sets them by selecting preset wind speeds and atmospheric scenes of different levels, thereby being able to more conveniently simulate various levels of wind speeds and atmospheric scenes of different concentrations and distributions of aerosols.

[0034] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1A It is a schematic diagram of the structure of a coherent wind laser radar calibration system according to an embodiment of the present invention;

[0037] Figure 1B It is a structural schematic diagram of a coherent wind laser radar calibration system according to another embodiment of the present invention;

[0038] Figure 2 Schematic diagram of signal input of a coherent wind laser radar calibration system according to an embodiment of the present invention;

[0039] Figure 3 It is a schematic diagram of the working process of a coherent wind laser radar calibration system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] It should be noted that the illustrations provided in the embodiments of the present invention are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout type may also be more complicated.

[0042] In the present invention, it is also necessary to explain that, if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first" and "second" appear, they are only used for description and distinction purposes, and cannot be understood as indicating or implying relative importance.

[0043] Wind LiDAR is an important tool for detecting and measuring atmospheric wind speed, aerosol distribution and atmospheric dynamic changes. In practical applications, the echo intensity is affected by many factors, resulting in large changes, including the inverse square law of distance, exponential decay, uneven aerosol distribution, etc.

[0044] For a single laser pulse, at the transmitter emission wavelength λ (nm), the power P(λ,X) of the atmospheric backscattered echo signal received from a distance X (m) can be expressed as:

[0045]

[0046] Among them, T L is the total transmittance of the emitting system, E 0 (J) is the energy of a single laser pulse, c(ms -1 ) is the speed of light, A R (m 2 ) is the effective area of ​​the receiving telescope, β(λ,X)(m -1 sr -1 ) is the total backscattering coefficient, α(λ,X)(m -1 ) is the total extinction coefficient.

[0047] First, according to the lidar equation, the echo intensity is inversely proportional to the square of the target distance. The farther the distance, the weaker the echo intensity. Secondly, during laser propagation, the light intensity decays exponentially due to the absorption and scattering of gases and aerosol particles in the atmosphere. The distribution of aerosols is usually uneven, resulting in uneven scattering and absorption of lasers when propagating in the atmosphere, further affecting the intensity and stability of the echo signal. In addition, different types of aerosols and gases have different reflection and scattering characteristics for lasers, and these differences will affect the echo intensity.

[0048] The present invention aims to provide a coherent wind laser radar calibration system and method which are easy to operate and have high accuracy in simulating echo signals.

[0049] like Figure 1A As shown, the coherent wind laser radar calibration system of the embodiment of the present invention includes a setting module, a modulation control module, a driving module, a modulation amplification module and a coupler, wherein:

[0050] Setting module, used to set wind speed and atmospheric scenes;

[0051] A modulation control module is connected to the input module and is used to calculate the Doppler frequency shift corresponding to different time points according to the set wind speed and convert it into a frequency shift control signal; the modulation control module is also used to convert the set atmospheric scene into an intensity control signal;

[0052] The modulation and amplification module is used to perform frequency modulation and amplitude modulation on the seed laser input by the radar system under test according to the frequency shift control signal and intensity control signal generated by the modulation control module under the drive of the driving module, and to amplify the optical power to obtain a simulated echo signal; it can be seen that the amplitude modulation of the system is used to simulate the scattering and extinction of laser by atmospheric components (aerosols and molecules, etc.), and the frequency modulation is used to simulate the radial wind speed.

[0053] The coupler is used to couple the analog echo signal into the radar system under test, and generate a beat frequency signal with the seed laser of the radar system under test, so that the radar system under test obtains the data of the analog echo signal according to the beat frequency signal for inversion, and completes the calibration by comparing the inverted data with the data of the analog echo signal.

[0054] The system uses the seed light of the coherent wind laser radar to be calibrated for modulation, thereby ensuring that the beat frequency (same phase) can be performed, generating a beat frequency signal, and measuring through coherent light.

[0055] Specifically, in a preferred embodiment of the present invention, the modulation and amplification module is time-synchronized with the coherent wind laser radar system being measured, and the synchronization signal is provided by the coherent wind laser radar system being measured. That is, the time when the radar emits a pulse beam is consistent with the time of the synchronization signal. The beam flight time can be calculated through time synchronization. The beam flight time is the time interval of the received echo and the emission pulse time. By accurately measuring the time interval of the beam flight time and combining it with the propagation speed of the laser in the atmosphere, the distance between the atmospheric scene (corresponding to different target aerosols) and the coherent wind laser radar can be accurately calculated.

[0056] Furthermore, the modulation and amplification module specifically matches the radar systems under test with different repetition frequencies through synchronization signals. The laser radar systems with different repetition frequencies are calibrated by synchronizing the optical pulses with the pulse synchronization signal of the coherent wind laser radar to be calibrated.

[0057] Furthermore, the coupler is also used to control the divergence angle of the simulated echo signal through the flat-top divergence to be much larger than the receiving field angle of the laser radar to be tested. By setting the divergence angle of the flat-top divergence to be one order of magnitude larger than the receiving field angle of the laser radar to be tested, its coupling efficiency is only related to the coupling distance, and is insensitive to the angle between the optical axes of the two.

[0058] Furthermore, the modulation and amplification module performs intermediate frequency modulation on the seed laser, and the range is 80MHz-200MHz. The modulation and amplification module can perform frequency modulation of 80MHz-200MHz without amplitude attenuation on the light input by the seed laser (the laser of the radar system under test in the present invention) to adapt to the coherent wind laser radar system under test with different intermediate frequencies.

[0059] Furthermore, the setting module is specifically used to freely set wind speed information and atmospheric scenes through user input, or to set by selecting preset wind speeds and atmospheric scenes of different levels. The preset wind speeds of different levels include squall frequency, high wind frequency and gentle wind frequency. The preset different atmospheric scenes include heavy pollution, moderate pollution and light pollution, and different atmospheric scenes correspond to different aerosol particles' absorption and scattering of light. Figure 2 As shown, the specific frequencies of various wind speeds and aerosol scenarios under various pollution levels are given.

[0060] like Figure 1B , Figure 2 As shown, in another embodiment of the present invention, the coherent wind laser radar calibration system A1 includes a user interface input module A2, a drive module A3, a modulation control module A4, a modulation and amplification module A5, and a coupler A7. The user interface input module A2 is used to set wind speed information and aerosol background, and input wind speed. The user can freely set wind speed information in the user interface, and can also select the preset wind speed in the system for setting, such as wind speed of different wind force levels (such as Figure 2 The user can freely set the aerosol background in the user interface, and the system has a variety of preset aerosol backgrounds: heavy pollution, moderate pollution, and light pollution (such as Figure 2 The user interface input module can have multiple input forms, all of which are used to simulate and set different meteorological environmental conditions such as atmospheric wind speed and aerosol.

[0061] The driving module A3 of this embodiment is responsible for generating and providing the electrical drive and control signals required by the fiber laser amplifier and the acousto-optic modulator. At the same time, the frequency drift of this module is less than 10kHz, which can simulate a radial wind speed (wind velocity) of 0.01 meters per second; the switching speed of this driving module can reach tens of nanoseconds, which meets the requirement of 10m spatial resolution of the wind laser radar. Through the effective management of this driving module, the user can drive the acousto-optic modulator to perform frequency modulation or amplitude modulation or simultaneous time-frequency modulation, so as to coordinate and realize the coherent wind laser radar atmospheric echo signal that simulates the set scene wind speed. The driving module A3 may include a wind speed mapping module, a power supply to drive each device, and a circuit to control the seed laser, the modulation and amplification module, and the beam switch. The wind speed mapping module uses the set wind speed information (such as Figure 2 The corresponding Doppler frequency shift is calculated and converted into a frequency shifter control signal to drive the frequency shifter to perform accurate frequency shifting (as shown in the upper left). Figure 2 The aerosol background information is converted into the intensity control signal of the simulated echo signal, which is used to drive the amplitude modulation module to control the signal intensity of the simulated echo light signal (as shown in the lower left). Figure 2The amplified signal power can also be configured for the driver of the amplifier module.

[0062] The seed light A6 is output by the continuous wave narrow linewidth seed laser A9 of the coherent wind laser radar system A13 under test, and is divided into two parts, one part is connected to the balanced detector of the system under test, and the other part is connected to the calibration system for modulation. Coherent laser radar measures Doppler frequency shift through coherent detection, which means that by continuously scanning the interference fringes of two beams of light with strong coherence and small frequency difference, the changes in the light signal in the interference field are obtained and converted into electrical signals, that is, beat frequency + photoelectric conversion. One condition for the beat frequency is that the echo is in the same phase as the radar local oscillator light. Using the seed laser of the radar system under test can make the simulated echo modulated by the calibration system and the radar local oscillator light beat in the same phase.

[0063] The modulation and amplification module of this embodiment includes a modulation module and an amplification module, which are mainly responsible for modulating and amplifying the seed light in the wind measurement laser radar system being measured. In this process, the seed light is modulated accordingly according to the preset meteorological environmental conditions such as aerosol and wind speed to simulate the corresponding wind speed and aerosol environment. Among them, the modulation module can realize amplitude modulation with a high suppression ratio, so that it can quantitatively simulate the real coherent wind measurement laser radar echo signal, thereby meeting the quantitative calibration of the detection distance of the coherent wind measurement laser radar. At the same time, the signal is amplified by the amplification module to ensure that the intensity of the simulated laser radar echo signal meets the requirements of coupling into the coherent wind measurement laser radar system, thereby realizing the accurate calibration of parameters such as the detection distance and wind measurement accuracy of the coherent wind measurement laser radar.

[0064] The modulation module can also include a frequency modulation module and an amplitude modulation module. The frequency modulation module can perform frequency modulation of the light input by the seed laser at 80MHz-200MHz without amplitude attenuation to adapt to the coherent wind measurement laser radar system under test with different intermediate frequencies. The amplitude modulation module can simulate the atmospheric scene set by the user for amplitude modulation. The amplification module amplifies the modulated optical signal with configurable output power and then connects it to the coupler A7. The frequency modulation module A5 converts the digital control signal of the control module A4 into a corresponding electrical signal for frequency modulation. The amplitude modulation module converts the digital control signal of the driving module A3 into a corresponding electrical signal for amplitude modulation. In the modulation and amplification process, time synchronization with the coherent wind measurement laser radar system under test is required. The synchronization signal A12 is provided by the system under test and can match laser radar systems with different repetition rates such as 1kHz, 5kHz, 10kHz, 20kHz, and 30kHz. Time synchronization is mainly used to calculate the beam flight time. The time when the radar emits a pulse beam is consistent with the time of the synchronization signal. The beam flight time is the time when the echo is received and the time when the pulse is emitted. From this, the distance between the aerosol that generates the echo and the telescope can be calculated. The time of flight (TOF) of the lidar refers to the time interval after the laser emits a pulse laser, the pulse signal propagates to reach the target aerosol, and then the detector receives the aerosol echo signal. By accurately measuring this time interval and combining it with the propagation speed of the laser in the atmosphere, the distance between the target aerosol and the coherent wind lidar can be accurately calculated.

[0065] In practical applications, due to the complexity of aerosol concentration, composition and distribution, this lidar system is designed with an adjustable aerosol simulation module that can simulate various aerosol scenes with different concentrations and distributions. This module can generate aerosol echo signals of different distance gates by adjusting the laser reflection intensity and propagation characteristics.

[0066] The divergence angle of the coupling module A7 can be set to be much larger than the field of view angle of the coherent wind measurement laser radar system under test, which is easy to couple and can ensure that the coupled optical signal is quantitatively input into the system under test.

[0067] like Figure 3 As shown in the figure, the light output by the seed laser of the coherent wind laser radar system under test enters the frequency modulation module for frequency modulation, then enters the amplitude modulation module for amplitude modulation, and then enters the amplifier for controllable output power amplification, and finally couples the output through the coupler to enter the telescope of the system under test. The synchronization signal required for the process is given by the radar under test.

[0068] After the wind speed is set, the corresponding Doppler frequency shift is calculated by the following formula and the Doppler frequency shift amount is converted into frequency shift amount according to the intermediate frequency of the frequency shifter used.

[0069] fd =2V Los /

[0070] Among them, V Los is the radial wind speed of the radar telescope under test, f d is the calculated Doppler shift, and λ is the wavelength of light.

[0071] Using the calculated frequency shift amount ( Figure 2 Left data upload) controls the frequency modulation module to frequency modulate the light generated by the seed laser, and uses the echo signal intensity corresponding to the aerosol background ( Figure 2 The right data is uploaded) to control the amplitude modulation module for amplitude modulation. After the modulation is completed, the signal enters the amplifier for adjustable power amplification, and finally the coupler is used to couple the simulated echo light signal with the telescope of the laser radar under test and input it into the telescope A11 of the laser radar under test. By comparing the preset wind speed standard data with the wind speed data calculated by the laser radar under test, the accuracy of the wind speed measurement and wind speed inversion of the laser radar under test can be obtained.

[0072] Example: The intermediate frequency of the laser radar under test is 80MHz, the number of available points of the frequency shifter is 128, and the wind speed information is set ( Figure 2 -B1) is converted into the control signal of the frequency shifter ( Figure 2 -B3). Set the aerosol background ( Figure 2 -B2) is converted into the amplitude information of the analog echo signal, which is further converted into the control signal of the frequency shifter ( Figure 2 -B4). In order to achieve frequency modulation without amplitude attenuation during frequency modulation, a frequency shifter with an intermediate frequency of 200MHz and small amplitude attenuation is selected for modulation, and then a negative 120MHz frequency shift is performed to match the intermediate frequency of 80MHz of the system under test.

[0073] In actual use, it is only necessary to couple the coupler of the calibration system with the telescope of the system under test, connect the seed light generated by the laser of the system under test to the calibration system, and use the synchronization signal A12 generated by the system under test as the trigger A8 to input the calibration system. Figure 3The figure shows a coherent wind laser radar with a wavelength of 1550nm, a laser pulse repetition frequency of 10kHz, and a single pulse energy of 110uJ. During the test, the seed light of the radar under test is divided into two parts. One part is connected to the balanced detector A10 of the radar under test for frequency beat, and the other part is connected to the modulation and amplification module A5 of the calibration system for frequency and amplitude modulation. The modulation process is controlled by the driver module A3 according to the preset information. After modulation, the output power is adjusted for amplification. Finally, the coupler is connected to the telescope of the radar under test. The synchronization signal trigger required for the modulation process is given by the synchronization signal of the radar under test. The radar under test inverts the received signal, and the user can calibrate the radar under test by comparing the data inverted by the radar under test with the standard data given by the calibration system.

[0074] The present invention also provides a coherent wind laser radar calibration method, comprising the following steps:

[0075] S1. Set wind speed and atmospheric scene;

[0076] S2. Calculate the Doppler frequency shift corresponding to different time points according to the set wind speed and convert it into a frequency shift control signal; convert the set atmospheric scene into an intensity control signal;

[0077] S3, frequency modulating and amplitude modulating the seed laser input to the radar system under test according to the frequency shift control signal and the intensity control signal, and performing optical power amplification to obtain a simulated echo signal;

[0078] S4, coupling the simulated echo signal into the radar system under test, and generating a beat signal with the seed laser of the radar system under test, so that the radar system under test obtains data of the simulated echo signal according to the beat signal for inversion;

[0079] S5. Compare the inverted data with the data of the simulated echo signal to complete the calibration.

[0080] Furthermore, when frequency modulation and amplitude modulation are performed, a synchronization signal is provided by the coherent wind measurement lidar system being measured to achieve time synchronization.

[0081] The method is mainly based on the above-mentioned calibration system, and is used to calibrate the main optoelectronic parameters and indicators of the coherent wind measurement lidar to be tested under laboratory or field environmental conditions. Through the system and method embodiments of the present invention, indicators such as wind speed measurement accuracy and detection distance of the coherent wind measurement lidar to be tested can be quantitatively obtained.

[0082] The present application also provides a computer-readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., an SD or DX memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a disk, an optical disk, a server, an App application store, etc., on which a computer program is stored, and when the program is executed by a processor, a corresponding function is realized. When the computer-readable storage medium of this embodiment is executed by a processor, the coherent wind laser radar calibration method of the method embodiment is realized.

[0083] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0084] The order of execution of each step in the above embodiment does not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0085] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A coherent wind laser radar calibration system, characterized in that: It includes a setting module, a modulation control module, a driving module, a modulation amplification module and a coupler, wherein: Setting module, used to set wind speed and atmospheric scenes; A modulation control module is connected to the input module and is used to calculate the Doppler frequency shift corresponding to different time points according to the set wind speed and convert it into a frequency shift control signal; the modulation control module is also used to convert the set atmospheric scene into an intensity control signal; The modulation and amplification module is used to perform frequency modulation and amplitude modulation on the seed laser input by the radar system under test according to the frequency shift control signal and intensity control signal generated by the modulation control module under the drive of the driving module, and perform optical power amplification to obtain a simulated echo signal; The coupler is used to couple the analog echo signal into the radar system under test, and generate a beat frequency signal with the seed laser of the radar system under test, so that the radar system under test obtains the data of the analog echo signal according to the beat frequency signal for inversion, and completes the calibration by comparing the inverted data with the data of the analog echo signal.

2. The coherent wind laser radar calibration system according to claim 1, characterized in that: The modulation and amplification module is time synchronized with the coherent wind measurement laser radar system under test, and the synchronization signal is provided by the coherent wind measurement laser radar system under test.

3. The coherent wind laser radar calibration system according to claim 1, characterized in that: The modulation and amplification module specifically matches the radar system under test with different repetition frequencies through a synchronization signal.

4. The coherent wind laser radar calibration system according to claim 1, characterized in that: The coupler is also used to control the divergence angle of the simulated echo signal diverged through the flat top to be much larger than the receiving field of view angle of the laser radar to be tested.

5. The coherent wind laser radar calibration system according to claim 1, characterized in that: The modulation and amplification module performs intermediate frequency modulation on the seed laser, and the range is 80MHz-200MHz.

6. The coherent wind laser radar calibration system according to claim 1, characterized in that: The setting module is specifically used to freely set the wind speed information and the atmospheric scene through user input, or to set them by selecting preset wind speeds and atmospheric scenes of different levels.

7. The coherent wind laser radar calibration system according to claim 6, characterized in that: The preset different levels of wind speed include squall frequency, strong wind frequency and moderate wind frequency.

8. The coherent wind laser radar calibration system according to claim 6, characterized in that: The preset different atmospheric scenes include heavy pollution, moderate pollution and light pollution. Different atmospheric scenes correspond to different aerosol particles' absorption and scattering of light.

9. A coherent wind laser radar calibration method, characterized in that: The following steps are involved: Set wind speed and atmospheric scenes; The Doppler frequency shift corresponding to different time points is calculated according to the set wind speed and converted into a frequency shift control signal; the set atmospheric scene is converted into an intensity control signal; The seed laser input to the radar system under test is frequency modulated and amplitude modulated according to the frequency shift control signal and the intensity control signal, and the optical power is amplified to obtain a simulated echo signal; The simulated echo signal is coupled into the radar system under test, and a beat frequency signal is generated with the seed laser of the radar system under test, so that the radar system under test obtains data of the simulated echo signal according to the beat frequency signal for inversion; The inverted data is compared with the data of the simulated echo signal to complete the calibration.

10. The coherent wind laser radar calibration method according to claim 9, characterized in that: When frequency modulation and amplitude modulation are performed, the coherent wind measurement lidar system under test provides a synchronization signal to achieve time synchronization.

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