Internal calibration system and method for pulse coherent Doppler laser wind radar

Abstract

The present invention relates to a pulse coherent Doppler laser wind radar internal calibration system and method, belonging to the field of radio, the system includes a hardware system, the hardware system includes a first optical splitter, an acousto-optic modulator, an amplifier, a circulator, a beam combiner, a balanced detector, an acquisition card and a display and control terminal, and also includes a software system, the hardware system also includes a calibration link; the software system switches the radar calibration state and the working state by controlling the calibration link switching of the hardware system, and performs radial velocity calibration and horizontal wind speed calibration on the radar when switching to the calibration link, and switches the radar state to the working state after the calibration is completed. The present invention reduces the calibration difficulty of the laser wind radar; reduces the calibration site complexity of the laser wind radar; eliminates the risk of human external influence; improves the completion of the laser wind radar link calibration; improves the reliability of the laser wind radar index; and improves the correctness of the laser wind radar index.

Description

Technical Field

[0001] The invention relates to the field of radio, and in particular to an internal calibration system and method for a pulse coherent Doppler laser wind measuring radar. Background Art

[0002] Laser wind radar is an active wind radar that uses the Doppler heterodyne method to measure parameters such as wind speed and direction based on the Doppler frequency shift of the laser backscatter echo of particulate matter in the air (dust, cloud droplets, salt crystals, pollution aerosols, biomass combustion aerosols, high-level cirrus clouds, etc.). Laser wind radar has the characteristics of small detection blind area, high accuracy, small size and light weight. It is mainly used in meteorological climate monitoring, weather detection, air pollution tracking, disaster warning, atmospheric research and wind energy utilization. Laser wind radar can only directly obtain the relative movement speed and direction between the radar and the target, that is, "radial wind", through the frequency difference between the light backscattered by the irradiated target and the emitted light. However, the user is mainly concerned about the real moving speed and direction of the wind, that is, "horizontal wind". However, laser wind radar cannot directly detect and obtain "horizontal wind" and needs to use radial wind inversion to obtain it. However, the accuracy of the inverted "horizontal wind" is not only affected by the correctness of the inversion algorithm, but also directly affected by the "radial wind" data.

[0003] At present, there are two main calibration methods for the "radial wind" of the laser wind radar: one is the turntable method, in which the laser wind radar measures the linear velocity of the edge of the turntable to simulate the radial wind speed detection range of the laser wind radar. The laser wind radar and the turntable are located in the same horizontal plane, and the distance between them is greater than the radar detection blind area. The laser is emitted in the horizontal direction, and the up-conversion plate is used to find the light spot and act on the tangential edge of the turntable. The turntable speed and direction are adjusted to simulate the radial wind speed. When the direction of the laser emission is consistent with the direction of the linear velocity of the turntable edge, the measured radial velocity is positive, otherwise it is negative. Adjust the clockwise and counterclockwise rotation speeds of the turntable respectively, and check the corresponding relationship between the display of the laser wind radar and the radial velocity shown on the control terminal; the second is the Doppler frequency shift method, which uses the RF signal generator to generate the corresponding speed sine wave signal and input it into the laser wind radar acquisition card for data acquisition and processing, and check the corresponding relationship between the display of the laser wind radar and the radial velocity shown on the control terminal.

[0004] The two calibration methods mentioned above have their own advantages and disadvantages. Method 1 can calibrate the entire radar link, but due to the influence of radar form, blind area distance, turntable accuracy, etc., it will cause problems such as difficulty in operation and large footprint; although method 2 is simple to operate and highly accurate, it can only calibrate the radar link after photoelectric conversion, and cannot calibrate the optical path part, so the calibration is insufficient. In addition, the above two calibration methods cannot achieve the calibration of horizontal wind speed. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a pulse coherent Doppler laser wind radar internal calibration system and method to solve the deficiencies of the prior art.

[0006] The object of the present invention is achieved by the following technical solutions: a pulse coherent Doppler laser wind radar internal calibration system, the system includes a hardware system, the hardware system includes a first optical splitter, an acousto-optic modulator, an amplifier, a circulator, a beam combiner, a balanced detector, an acquisition card and a display and control terminal, and also includes a software system, the hardware system also includes a calibration link;

[0007] The software system switches the calibration link of the hardware system to realize the switching between the calibration state and the working state of the radar. When switching to the calibration link, the radar is calibrated for radial velocity and horizontal wind speed. After the calibration is completed, the radar state is switched to the working state.

[0008] The calibration link includes switch 1, switch 2, an acousto-optic frequency shifter, an electrically adjustable attenuator, a second optical splitter and a temperature control unit;

[0009] The reference light source outputs an optical signal to the first optical splitter, one output of the first optical splitter is sequentially connected to the acousto-optic modulator, the amplifier, the second optical splitter and the circulator, and the other output is sequentially connected to the switch 1, the beam combiner, the balanced detector, the acquisition card and the display and control terminal;

[0010] The switch 1 is also connected to the acousto-optic frequency shifter, the output end of the acousto-optic frequency shifter is connected to the electrically adjustable attenuator, the output end of the electrically adjustable attenuator is connected to the switch 1, and the temperature control unit is used to control the temperature of the acousto-optic frequency shifter and the electrically adjustable attenuator;

[0011] The second optical splitter and the circulator are connected to the switch 2, and the switch 2 is connected to the beam combiner.

[0012] In the working state, one output of the first optical splitter is connected to the beam combiner through switch 1, and the reference light directly enters the beam combiner through switch 1; the circulator is connected to the beam combiner through switch 2, and the return light signal received by the laser wind measurement radar directly enters the beam combiner through switch 2.

[0013] The calibration state includes calibration state 1 and calibration state 2. In calibration state 1, one output of the first optical splitter is connected to the beam combiner through switch 1, and the reference light directly enters the beam combiner through switch 1; one output of the second optical splitter is connected to the beam combiner through switch 2, and the modulated light of the laser wind measurement radar's own link passes through the second optical splitter and then enters the beam combiner through switch 2. At this time, the reference light of the laser wind measurement radar and the modulated light of its own link directly enter the beam combiner for beat frequency acquisition In this state , To fix a known frequency shift, is the actual frequency shift value of the laser wind radar link;

[0014] In calibration state 2, one output of the first optical splitter is connected to the acousto-optic frequency shifter, the electrically adjustable attenuator and the beam combiner in sequence through switch 1, and the reference light passes through the acousto-optic frequency shifter and the electrically adjustable attenuator and then enters the beam combiner through switch 1. One output of the second optical splitter is connected to the beam combiner through switch 2, and the modulated light of the laser wind measurement radar's own link passes through the second optical splitter and then enters the beam combiner through switch 2. At this time, the reference light of the laser wind measurement radar link passes through the acousto-optic frequency shifter and the electrically adjustable attenuator and then enters the beam combiner with the modulated light generated by the laser wind measurement radar's own link to obtain In this state , is the frequency shift value of the acousto-optic frequency shifter.

[0015] A pulse coherent Doppler laser wind measuring radar internal calibration method, the calibration method is implemented based on a pulse coherent Doppler laser wind measuring radar internal calibration system, the calibration method comprises:

[0016] When the radar link is switched to the calibration link and is in the calibration state, radial velocity calibration is performed through software parameter self-calibration or hardware parameter self-calibration;

[0017] The horizontal wind speed is calibrated based on the calibrated radial speed and the calibration result is judged. If the calibration result meets the requirements, the calibration is completed when the radar link is switched to the working state. If the calibration result does not meet the requirements, the horizontal wind speed calibration is performed again.

[0018] The method for self-calibration of software parameters includes:

[0019] The control hardware system is in calibration state 1, and determines whether the read radial speed is 0. When the speed is 0, , calibration is completed, no need to calibrate software parameters, is the reference frequency shift value, is the actual frequency shift value of the laser wind radar link;

[0020] When the speed is not 0, according to the formula Conclusion and Relative difference, Correction is made, and the correction value is , is the corrected reference frequency shift value, is the radial velocity, λ is the laser wavelength, For is the speed corresponding frequency obtained under the reference conditions;

[0021] Read the current speed value for verification. When the read speed is 0, the calibration is completed.

[0022] The method for self-calibration of hardware parameters includes:

[0023] The hardware system is controlled to be in calibration state 1, and the radial velocity read is judged to be 0. When the velocity is 0, the fixed frequency shift generated by the laser wind radar link is consistent with the theoretical value of the software parameter, and the calibration is completed without the need for hardware parameter correction.

[0024] When the speed is not 0, according to the formula Conclusion and Relative difference, actual frequency shift value of laser wind radar link Correction is made, and the correction value is , is the reference frequency shift value, is the actual frequency shift value of the laser wind radar link, is the radial velocity, λ is the laser wavelength, For is the speed corresponding frequency obtained under the reference conditions;

[0025] Control the hardware system to be in calibration state 2, control the acousto-optic frequency shifter to shift the frequency so that its frequency shift value , this frequency shift value enters the fixed frequency shift generated by the beam combiner and the acousto-optic modulator The hardware frequency shift value correction of the laser wind radar link is completed by superposition. The correction result is , is the frequency shift value of the acousto-optic frequency shifter;

[0026] Read the current speed value for verification. When the read speed is 0, the calibration is completed.

[0027] In the method for self-calibration of software parameters, the software parameters change synchronously with the hardware parameters of the laser wind measuring radar. When the hardware parameters of the laser wind measuring radar are abnormal, the software parameters are synchronously abnormal. At this time, the method for self-calibration of hardware parameters is adopted.

[0028] The method for calibrating the horizontal wind speed comprises:

[0029] The software system controls the acousto-optic frequency shifter Step forward, Corresponding frequency Set to the maximum value, Corresponding frequency Set to the minimum value, and perform sinusoidal frequency shift according to a sinusoidal cycle time t, It is the interval time of sinusoidal frequency sweep in the circle scanning cycle;

[0030] The radial velocity corresponding to each frequency shift is read and recorded by the software system. After completing a sinusoidal frequency shift, the VAD inversion method is used to invert the horizontal wind speed and horizontal wind direction. The conclusion obtained by the inversion is compared with the preset value to check its error.

[0031] If the error meets the error range, the calibration is completed. If not, the horizontal wind speed calibration is performed again.

[0032] The present invention has the following advantages: a pulse coherent Doppler laser wind measuring radar internal calibration system and method, which reduces the calibration difficulty of the laser wind measuring radar; reduces the complexity of the calibration site of the laser wind measuring radar; eliminates the risk of external human influence; improves the completion of the laser wind measuring radar link calibration; improves the reliability of the laser wind measuring radar indicators; and improves the correctness of the laser wind measuring radar indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the system of the present invention;

[0034] Figure 2 This is a schematic diagram of the switching principle of the calibration link;

[0035] Figure 3 It is a flowchart of the software parameter self-calibration method;

[0036] Figure 4 It is a flowchart of the hardware parameter self-calibration method;

[0037] Figure 5 Schematic diagram of the VAD wind field inversion sinusoidal curve. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application provided below in conjunction with the drawings is not intended to limit the scope of protection of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. The present invention is further described below in conjunction with the drawings.

[0039] One embodiment of the present invention relates to an internal calibration system of a pulse coherent Doppler laser wind measurement radar, which is composed of a hardware system and a software system. The software system is used to control the switching of the calibration link hardware system to achieve the switching of the calibration link hardware system state, radar calibration and working state switching. When switching to the calibration link, the radar system is calibrated, and after the calibration is completed, the radar state is switched to the working state.

[0040] like Figure 1 As shown, the hardware system includes a first optical splitter, an acousto-optic modulator, an amplifier, a circulator, a beam combiner, a balanced detector, an acquisition card and a display and control terminal.

[0041] The reference light source outputs the reference light signal of the radar system, which is divided into two light sources by the first beam splitter. One light source enters the acousto-optic modulator to be modulated into a pulse light signal with a specific repetition rate, pulse width, and frequency shift, and is output to the amplifier to be amplified to a specific power and then transmitted to the detection target through the optical lens. One light source enters the beam combiner to beat the return light signal received by the optical lens, obtains the offset generated by the output light signal, and outputs it to the balanced detector for photoelectric conversion. After the photoelectric conversion, the corresponding RF signal is analyzed by the acquisition card to output the digital signal. The software system identifies the digital signal with frequency shift information and calculates the radial velocity value.

[0042] Since the reference light source outputs an optical signal frequency The terahertz frequency cannot be recognized by the subsequent circuit, so a fixed known frequency shift is superimposed on the reference optical signal through an acousto-optic modulator. , the frequency of the radar laser emitted after the post-amplification is When the laser is reflected by the detection object and received by the radar, the frequency shift occurs due to the Doppler effect. , the frequency of the returned light received at this time is The actual frequency shift value of the laser wind radar link can be obtained by beating the return light with the reference light signal in the beam combiner. ,set up As the reference frequency, the Doppler frequency shift formula can be used to obtain The corresponding velocity (radial velocity).

[0043] From the above, we can see that the accuracy of laser wind radar speed measurement is mainly affected by Frequency stability, that is, whether the reference frequency is accurate or not, directly affects the final detected Doppler frequency shift value calculation result. To address this issue, a calibration link is added to the hardware system. To ensure that the newly added components do not affect the original radar link, the newly added calibration link units on the radar main link are all passive units. At the same time, to ensure the convenient application of the calibration link hardware system, the calibration link hardware system is designed independently. The calibration link consists of an electrically adjustable high-precision acousto-optic frequency shifter (AOFS), an electrically adjustable attenuator (VOA), a double-pole double-throw switch (switch 1), a single-pole double-throw switch (switch 2), a second optical splitter, and a temperature control unit.

[0044] Among them, the electrically adjustable high-precision acousto-optic frequency shifter is mainly used to realize the dynamic frequency shifting function of the reference optical signal, the electrically adjustable attenuator is mainly used to control the attenuation of the optical signal output by the acousto-optic frequency shifter to achieve the subsequent link protection function, the double-pole double-throw switch is mainly used to realize the switching between the radar calibration state and the working state, the single-pole double-throw switch is mainly used to realize the protection of the subsequent radar link devices, the second splitter is mainly used for the final output light sampling of the laser wind measurement radar, and the temperature control unit is mainly used to ensure the performance stability of the high-precision acousto-optic frequency shifter and the electrically adjustable attenuator in high and low temperature environments.

[0045] Furthermore, the acousto-optic frequency shifter and the electrically adjustable attenuator need to be temperature-controlled during design. The temperature control is implemented by the temperature control unit. The temperature control unit mainly monitors the ambient temperature of the area to increase or decrease the temperature, so that the temperature of the area is always constant in a certain temperature range. The temperature control unit is basically composed of an ambient temperature monitoring unit and a temperature adjustment unit. The implementation forms of these two units include but are not limited to air conditioners, semiconductor devices, fans, sensors, etc.

[0046] like Figure 2 As shown, switch 1 (double-pole double-throw switch) and switch 2 (single-pole double-throw switch) realize the switching between radar calibration state and working state, including the following contents:

[0047] Working status: The working status means that the laser wind radar is in normal operation.

[0048] In this state, the state of switch 1 is: the A end is closed to the internal contact 1, and the B end is closed to the internal contact 3. At this time, A-1-3-B is turned on. In this state, the reference light directly enters the combiner through switch 1.

[0049] In this state, the state of switch 2 is: the C end and the internal contact 1 are closed, and A-1-C is turned on. In this state, the return signal received by the laser wind measurement radar directly enters the combiner through switch 2.

[0050] Calibration state 1: The reference light of the laser wind radar and the modulated light of its own link directly enter the beam combiner for beat frequency In this state .

[0051] In this state, the state of switch 1 is: the A end is closed to the internal contact 1, and the B end is closed to the internal contact 3. At this time, A-1-3-B is turned on. In this state, the reference light directly enters the combiner through switch 1.

[0052] In this state, the state of switch 2 is: the C end and the internal contact 2 are closed, and B-2-C is turned on. In this state, the modulated light of the laser wind measurement radar's own link is split by the second splitter and then enters the combiner through switch 2.

[0053] Calibration state 2: The reference light of the laser wind radar link is obtained by beating the modulated light generated by the laser wind radar link itself through the acousto-optic frequency shifter and the electrically adjustable attenuator. In this mode , is the frequency shift value of the acousto-optic frequency shifter.

[0054] In this state, the state of switch 1 is: the A end and the internal contact 2 are closed, and the B end and the internal contact 4 are closed. At this time, A-2-4-B is turned on. In this state, the reference light is frequency-shifted by AOFS and attenuated by VOA, then enters the combiner through switch 1.

[0055] In this state, the state of switch 2 is: the C end and the internal contact 2 are closed, and B-2-C is turned on. In this state, the modulated light of the laser wind measurement radar's own link is split by the second splitter and then enters the combiner through switch 2.

[0056] Another embodiment of the present invention relates to an internal calibration method of a pulse coherent Doppler laser wind radar, which comprises:

[0057] When the radar link is switched to the calibration link and is in the calibration state, radial velocity calibration is performed through software parameter self-calibration or hardware parameter self-calibration;

[0058] The horizontal wind speed is calibrated based on the calibrated radial speed and the calibration result is judged. If the calibration result meets the requirements, the calibration is completed when the radar link is switched to the working state. If the calibration result does not meet the requirements, the horizontal wind speed calibration is performed again.

[0059] Furthermore, if Figure 3 As shown in the figure, the principle of the software parameter self-calibration method (method 1) is to correct the theoretical value of the software parameter to the actual value on the laser wind radar hardware link for calibration, which includes:

[0060] The control hardware system is in calibration state 1, and determines whether the read radial speed is 0. When the speed is 0, , calibration is completed, no need to calibrate software parameters, is the reference frequency shift value, is the actual frequency shift value of the laser wind radar link;

[0061] When the speed is not 0, according to the formula Conclusion and Relative difference, software calculates theoretical parameters Correction is required, and the correction value is , is the corrected reference frequency shift value, is the radial velocity, λ is the laser wavelength, For is the speed corresponding frequency obtained under the reference conditions;

[0062] After the software calculates and corrects the theoretical parameters, the current speed value is read through the software system for verification. When the speed read by the software system is 0, the calibration is completed.

[0063] Furthermore, if Figure 4 As shown in the figure, the principle of the hardware parameter self-calibration method (method 2) is to calibrate the frequency shift value of the modulated light of the laser wind radar hardware link to be consistent with the software configuration parameters through the frequency compensation of the calibration link, which includes:

[0064] The hardware system is controlled to be in calibration state 1, and the radial velocity read is judged to be 0. When the velocity is 0, the fixed frequency shift generated by the laser wind radar link is consistent with the theoretical value of the software parameter, and the calibration is completed without the need for hardware parameter correction.

[0065] When the speed is not 0, according to the formula Conclusion and Relative difference, actual frequency shift value of laser wind radar link Correction is made, and the correction value is , is the reference frequency shift value, is the actual frequency shift value of the laser wind radar link, is the radial velocity, λ is the laser wavelength, For is the speed corresponding frequency obtained under the reference conditions;

[0066] Control the hardware system to be in calibration state 2, control the acousto-optic frequency shifter to shift the frequency so that its frequency shift value , this frequency shift value enters the fixed frequency shift generated by the beam combiner and the acousto-optic modulator The hardware frequency shift value correction of the laser wind radar link is completed by superposition. The correction result is , is the frequency shift value of the acousto-optic frequency shifter;

[0067] After the hardware frequency shift value of the laser wind radar link is corrected, the current speed value is read through the software system for verification. When the speed read by the software system is 0, the calibration is completed.

[0068] The above two radial reference velocity calibration methods are essentially to calibrate the matching relationship between the frequency shift value generated by the hardware link of the laser wind radar and the software configuration parameters. Method 1 is to calibrate the software parameters with the hardware parameters, and method 2 is to calibrate the hardware parameters with the software parameters. There is no difference in the calibration results of the two methods.

[0069] However, since the software parameters in method 1 change synchronously with the hardware parameters of the laser wind radar, when the hardware parameters are abnormal, the software parameters are also abnormal synchronously. Therefore, this method is not suitable for calibration when the hardware parameters have the above abnormal conditions.

[0070] In method 2, the software parameters are fixed and unchanged. When the hardware parameters of the laser wind radar occur in the above situation, the frequency compensation is performed by calibrating the frequency shifter of the hardware system to align the frequency shift and always maintain , that is, method 2 is feasible under the current state.

[0071] Furthermore, the method of horizontal wind speed calibration includes:

[0072] The horizontal wind speed calibration theory is based on the VAD (Velocity Azimuth Display) wind field inversion principle and the assumption that the horizontal wind field is uniform or linear. This method analyzes the data in the laser radar scanning measurement mode and uses the velocity azimuth display to invert the horizontal wind field information, that is, , the frequency is calibrated with the horizontal wind speed and wind direction. is the radial wind speed, V is the horizontal wind speed, is the azimuth and φ is the wind direction.

[0073] The VAD inversion method selects radial wind speed circle (360°) data at the same height during calculation. These data are a series of points with sinusoidal trend, and then according to the formula Sine fitting is performed on these points to obtain a sinusoidal curve. Figure 5 After fitting the curve, read the maximum value That is, the radial component of the horizontal wind speed, divided by the cosine of the elevation angle, gives the wind speed at the height of the radial distance, and the minimum radial wind speed on the curve is The corresponding horizontal coordinate value is the wind direction.

[0074] According to the formula and get .

[0075] It can be seen from the VAD inversion method that the VAD inversion method needs to select the circular (2π) radial velocity data during calculation. These data change in a sinusoidal trend within the circular scanning period (t), which can invert the theoretical horizontal wind speed detected by the laser wind radar. With wind direction , combined with Figure 5 The VAD wind field inversion sinusoidal curve shown in the figure presets the circle scanning time t and the number of circle data n as known constant values, and the sinusoidal frequency sweep interval time within the circle scanning period can be obtained. .

[0076] By formula and , by substituting the preset values ​​of φ, V, t, and n, the radial data frequency shift corresponding to each azimuth angle within the sinusoidal scanning cycle can be obtained. Sine frequency sweep interval time within the circle scanning cycle .

[0077] During calibration, the software system controls the acousto-optic frequency shifter to Step forward, Corresponding frequency Set to the maximum value, Corresponding frequency Set it to the minimum value, and perform sinusoidal frequency shift according to a sinusoidal cycle time t. The radial velocity corresponding to each frequency shift is read and recorded by the software system. After completing a sinusoidal frequency shift, the VAD inversion method is used to invert the horizontal wind speed and horizontal wind direction. The conclusion obtained by the inversion is compared with the preset value to check its error (the error value is inversely proportional to the number of scanning azimuths n). If the error range is met, the calibration is completed. If not, the calibration verification is performed again.

[0078] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used for various other combinations, modifications and improvements, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A pulse coherent Doppler laser wind radar internal calibration system, the system comprising a hardware system, the hardware system comprising a first optical splitter, an acousto-optic modulator, an amplifier, a circulator, a beam combiner, a balanced detector, an acquisition card and a display and control terminal, characterized in that: It also includes a software system, and the hardware system also includes a calibration link; The software system switches the calibration link of the hardware system to realize the switching between the calibration state and the working state of the radar. When switching to the calibration link, the radar is calibrated for radial velocity and horizontal wind speed. After the calibration is completed, the radar state is switched to the working state. The calibration link includes switch 1, switch 2, an acousto-optic frequency shifter, an electrically adjustable attenuator, a second optical splitter and a temperature control unit; The reference light source outputs an optical signal to the first optical splitter, one output of the first optical splitter is sequentially connected to the acousto-optic modulator, the amplifier, the second optical splitter and the circulator, and the other output is sequentially connected to the switch 1, the beam combiner, the balanced detector, the acquisition card and the display and control terminal; The switch 1 is also connected to the acousto-optic frequency shifter, the output end of the acousto-optic frequency shifter is connected to the electrically adjustable attenuator, the output end of the electrically adjustable attenuator is connected to the switch 1, and the temperature control unit is used to control the temperature of the acousto-optic frequency shifter and the electrically adjustable attenuator; The second optical splitter and the circulator are connected to the switch 2, and the switch 2 is connected to the beam combiner.

2. The pulse coherent Doppler laser wind radar internal calibration system according to claim 1, characterized in that: In the working state, one output of the first optical splitter is connected to the beam combiner through switch 1, and the reference light directly enters the beam combiner through switch 1; the circulator is connected to the beam combiner through switch 2, and the return light signal received by the laser wind measurement radar directly enters the beam combiner through switch 2.

3. The pulse coherent Doppler laser wind radar internal calibration system according to claim 1, characterized in that: The calibration state includes calibration state 1 and calibration state 2. In calibration state 1, one output of the first optical splitter is connected to the beam combiner through switch 1, and the reference light directly enters the beam combiner through switch 1; One output of the second optical splitter is connected to the beam combiner through switch 2. The modulated light of the laser wind radar's own link passes through the second optical splitter and then enters the beam combiner through switch 2. At this time, the reference light of the laser wind radar and the modulated light of its own link directly enter the beam combiner for beat frequency. In this state , To fix a known frequency shift, is the actual frequency shift value of the laser wind radar link; In calibration state 2, one output of the first optical splitter is connected to the acousto-optic frequency shifter, the electrically adjustable attenuator and the beam combiner in sequence through switch 1, and the reference light passes through the acousto-optic frequency shifter and the electrically adjustable attenuator and then enters the beam combiner through switch 1. One output of the second optical splitter is connected to the beam combiner through switch 2, and the modulated light of the laser wind measurement radar's own link passes through the second optical splitter and then enters the beam combiner through switch 2. At this time, the reference light of the laser wind measurement radar link passes through the acousto-optic frequency shifter and the electrically adjustable attenuator and then enters the beam combiner with the modulated light generated by the laser wind measurement radar's own link to obtain In this state , is the frequency shift value of the acousto-optic frequency shifter.

4. A pulse coherent Doppler laser wind radar internal calibration method, characterized in that: The calibration method is implemented based on an internal calibration system of a pulse coherent Doppler laser wind radar according to any one of claims 1 to 3, and the calibration method comprises: When the radar link is switched to the calibration link and is in the calibration state, radial velocity calibration is performed through software parameter self-calibration or hardware parameter self-calibration; The horizontal wind speed is calibrated based on the calibrated radial speed and the calibration result is judged. If the calibration result meets the requirements, the calibration is completed when the radar link is switched to the working state. If the calibration result does not meet the requirements, the horizontal wind speed calibration is performed again.

5. The internal calibration method of a pulse coherent Doppler laser wind radar according to claim 4, characterized in that: The method for self-calibration of software parameters includes: The control hardware system is in calibration state 1, and determines whether the read radial speed is 0. When the speed is 0, , calibration is completed, no software parameter correction is required, is the reference frequency shift value, is the actual frequency shift value of the laser wind radar link; When the speed is not 0, according to the formula Conclusion and Relative difference, Correction is made, and the correction value is , is the corrected reference frequency shift value, is the radial velocity, is the laser wavelength, For is the speed corresponding frequency obtained under the reference conditions; Read the current speed value for verification. When the speed read is 0, the calibration is completed.

6. The internal calibration method of a pulse coherent Doppler laser wind radar according to claim 4, characterized in that: The method for self-calibration of hardware parameters includes: The hardware system is controlled to be in calibration state 1, and the radial velocity read is judged to be 0. When the velocity is 0, the fixed frequency shift generated by the laser wind radar link is consistent with the theoretical value of the software parameter, and the calibration is completed without the need for hardware parameter correction. When the speed is not 0, according to the formula Conclusion and Relative difference, actual frequency shift value of laser wind radar link Correction is made, and the correction value is , is the reference frequency shift value, is the actual frequency shift value of the laser wind radar link, is the radial velocity, is the laser wavelength, For is the speed corresponding frequency obtained under the reference conditions; Control the hardware system to be in calibration state 2, control the acousto-optic frequency shifter to shift the frequency so that its frequency shift value , this frequency shift value enters the fixed frequency shift generated by the beam combiner and the acousto-optic modulator The hardware frequency shift value correction of the laser wind radar link is completed by superposition. The correction result is , is the frequency shift value of the acousto-optic frequency shifter; Read the current speed value for verification. When the speed read is 0, the calibration is completed.

7. The internal calibration method of a pulse coherent Doppler laser wind radar according to claim 4, characterized in that: In the method for self-calibration of software parameters, the software parameters change synchronously with the hardware parameters of the laser wind measuring radar. When the hardware parameters of the laser wind measuring radar are abnormal, the software parameters are synchronously abnormal. At this time, the method for self-calibration of hardware parameters is adopted.

8. The internal calibration method of a pulse coherent Doppler laser wind radar according to claim 4, characterized in that: The method for calibrating the horizontal wind speed comprises: The software system controls the acousto-optic frequency shifter Step forward, Corresponding frequency Set to the maximum value, Corresponding frequency Set to the minimum value, and perform sinusoidal frequency shift according to a sinusoidal cycle time t, It is the interval time of sinusoidal frequency sweep in the circle scanning cycle; The radial velocity corresponding to each frequency shift is read and recorded by the software system. After completing a sinusoidal frequency shift, the VAD inversion method is used to invert the horizontal wind speed and horizontal wind direction. The conclusion obtained by the inversion is compared with the preset value to check its error. If the error meets the error range, the calibration is completed. If not, the horizontal wind speed calibration is performed again.

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