A method and system for a sparse modulation wind measurement radar

Abstract

The present invention provides a method and system for a sparse modulation wind measurement radar. After a laser modulates an excellent signal, it emits a light beam. The light beam passes through a beam splitter, which divides the light beam into two light beams, one being the detection light beam and the other being the eigen light beam. The detection light beam is first modulated by an acousto-optic modulator to modulate an excellent signal. The power amplifier amplifies the light intensity and transmits it to the telescope through a circulator. The telescope emits the detection light beam. After the detection light beam is scattered by aerosols in the air, the signal light beam is returned. The signal light beam is received by the telescope and then transmitted to the coupler through the circulator. The eigen light beam is attenuated in light intensity by an attenuator and coupled with the signal light beam. The coupled light beam is sent to a balanced detector for adjustment and then processed by a data processor. By performing internal and external modulation on the light source, the wind speed and direction are obtained. This application can eliminate the influence of system echo interference and effectively reduce or eliminate the near-range blind area; reduce the detection bandwidth and improve the signal-to-noise ratio.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind measurement radar, and particularly relates to a method and system for a sparse modulation wind measurement radar. Background Art

[0002] The lidar emits a high-purity spectral beam into the detection airspace. The radar system receives the backscattering from aerosol particles. Since the aerosol has a very low backscattering coefficient, generally one-stage or multi-stage optical amplifiers are used to obtain a high transmission power; to identify the wind direction, generally a frequency shifter needs to be set; the coherent mixed optical signal becomes an alternating current signal through balanced detection, and then after analog-to-digital conversion, the processing unit identifies the generated Doppler frequency to obtain the wind field information.

[0003] Wind measurement radars generally have pulse systems and continuous systems, and the types of radar signal transmission and reception can be further divided into co-located transmission and reception and separated transmission and reception; there is interference in the co-located transmission and reception system itself; for example, the echo from the lens and the fiber end face will form a fixed interference frequency in the intermediate frequency spectrum after intrinsic mixing (the influence of the interference frequency is mainly reflected in two aspects: (1) affecting the lower limit of the measured wind speed; (2) reducing the signal-to-noise ratio of the effective signal; therefore, pulse system radars generally filter out this interference through range gates, and thus a measurement range blind area is generated, while continuous system radars use phase-locked loop circuits, etc. to suppress the interference but will affect the lower limit of wind speed measurement. Therefore, there is an urgent need to provide a sparse modulation wind measurement radar.

[0004] The indicators of frequency modulation continuous wave lidar are mainly limited by the performance parameters of the light source: the coherent detection methods at the receiving end are relatively mature; due to the rapid development of technologies such as high-speed analog-to-digital converters and digital signal processing, the acquisition and processing of backend data are not the bottleneck of the overall indicators at present; so how to generate an optical frequency modulation signal with excellent performance has become the focus of attention of FMCW lidar researchers. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a method and system for a sparse modulation wind measurement radar, which can improve the stability and reliability of detection.

[0006] The present invention is realized through the following technical solutions:

[0007] A method for a sparse modulation wind measurement radar, characterized by comprising the following steps:

[0008] S1: After a linearly varying signal is modulated by a laser and a light beam is emitted, the light beam passes through a beam splitter, and the beam splitter divides one beam of light into two beams of light, one beam is the detection light, and the other beam is the local light;

[0009] S2: The probe light first passes through an acousto-optic modulator for modulation to produce a linearly varying signal, and then passes through a power amplifier to amplify the light intensity and is transmitted to a telescope via a circulator. The telescope emits the probe light. After the probe light is scattered by the aerosol in the air, the signal light returns, which is received by the telescope and then transmitted to a coupler via the circulator;

[0010] S3: The intrinsic light passes through an attenuator to weaken the light intensity, is transmitted to the coupler through an optical path and is coupled with the returned signal light;

[0011] S4: The coupled light beam is sent to a balanced detector for adjustment and then processed by a data processor to obtain the wind speed and direction.

[0012] Furthermore, the modulation of the excellent signal in step S2 includes sparse internal modulation and sparse external modulation;

[0013] The sparse internal modulation is to modulate the laser signal at the laser source;

[0014] The sparse external modulation is to modulate the laser emitted by the laser with a frequency shifter.

[0015] Furthermore, the sparse internal modulation coarsely adjusts the cavity length negative feedback of the external cavity semiconductor laser through piezoelectric ceramic drive, and at the same time injects current into the external cavity semiconductor laser to change the refractive index of the gain medium in the cavity for fine adjustment of the optical length in the cavity.

[0016] Furthermore, the calculation process of the wind speed for the sparse internal modulation and the sparse external modulation is as follows:

[0017] The frequency of the transmitted signal linearly varies up and down periodically with time, the rise time is the same as the fall time, the average frequency is fc, the transmission delay from the circulator to the measured target and then scattered back to the receiving end is τ, and the change range of the signal frequency is the bandwidth B;

[0018] The frequency difference generated between the frequency of the received echo signal and the local oscillator signal is df;

[0019] The frequency difference is composed of the frequency change amount f R introduced by the distance delay τ and the Doppler frequency shift f d . The frequency difference Δf1 generated at the rising edge of the frequency and the frequency difference Δf2 generated at the falling edge of the frequency each differ from f R by f d ;

[0020] The differential frequency amount f R introduced by the distance and the Doppler frequency shift f d fd can be calculated from Δf1 and Δf2 by coherent demodulation:

[0021] R = 2CT * fd / (4B);

[0022] v = fd * c / (2fc cosθ);

[0023] Where: γ represents the frequency change rate of the transmitted signal, R represents the distance between the lidar and the target to be measured, c represents the speed of light, v represents the projection of the target speed on the line connecting the lidar and the target to be measured, fc represents the center frequency of the optical carrier of the transmitted signal, and θ is the angle between the transmitted laser and the moving direction of the particle to be measured.

[0024] Furthermore, the calculation process of the wind direction of the sparse internal modulation is as follows:

[0025] Perform linear frequency modulation at time t1 and no frequency modulation at time t2; then at time t1, the intermediate frequency f IF = f L + f d , where B is the modulation bandwidth, R is the detection distance, T fm is the time of linear frequency modulation, and c represents the speed of light;

[0026] Adopt a focusing lens, and the detection distance is the distance between the lens focusing position and the radar. Therefore, f L is a known quantity. If f IF > f L , it is the positive wind direction, otherwise it is the negative wind direction, and the judgment of the sparse internal modulation wind direction is completed.

[0027] Furthermore, the calculation process of the wind direction of the sparse external modulation is as follows:

[0028] When it is at time t2, the intermediate frequency spectrum will have the interference frequency generated by the frequency shifter and the wind speed signal. Only judge the magnitude of the wind signal frequency and the interference frequency to obtain the wind direction. The frequency shifter is f N , judge the magnitude of the wind signal frequency and f N . If it is greater than f N , the radial wind is positive, otherwise it is negative.

[0029] Furthermore, the sparse external modulation adopts a tuning method based on an electro-optic modulator, including the following steps:

[0030] Transmit the laser emitted by the laser to the electro-optic modulator, apply a voltage to the electro-optic crystal, the refractive index of the electro-optic crystal will change, and through the change of the laser characteristics of the crystal, modulate the phase, amplitude, intensity, and polarization state of the optical signal; output a linear optical frequency signal.

[0031] Furthermore, the sparse external modulation adopts a tuning method based on a cyclic frequency shift structure, including the following steps:

[0032] The light source is modulated by combining a cyclic frequency shift loop and a frequency sweep tuning light source. The laser beam emitted by the laser is transmitted to the cyclic frequency shift loop and the frequency sweep tuning device. The received laser beam is modulated by the cyclic frequency shift loop and the scanning tuning device to obtain a linear optical frequency signal.

[0033] A sparse modulation wind measurement radar system includes a seed source, a beam splitter, and an attenuator that are respectively connected to the seed source.

[0034] The output end of the beam splitter is sequentially connected to an AOM, an EDFA, and a circulator. The circulator is also connected to a telescope. The output ends of the attenuator and the circulator are respectively connected to a coupler. The output end of the coupler is sequentially connected to a balanced detector and an oscilloscope.

[0035] Compared with the prior art, the present invention has the following beneficial technical effects:

[0036] The present invention provides a method and system for a sparse modulation wind measurement radar. After a linearly varying signal is modulated by a laser, a light beam is emitted. The light beam passes through a beam splitter, which divides the light beam into two beams: one is the detection light beam and the other is the eigen light beam. The detection light beam is first modulated by an acousto-optic modulator to modulate a linearly varying signal, and then the optical intensity is amplified by a power amplifier and transmitted to a telescope through a circulator. The detection light beam is emitted by the telescope. After the detection light beam is scattered by aerosols in the air, a signal light beam is returned. The signal light beam is received by the telescope and then transmitted to a coupler through the circulator. The eigen light beam is attenuated in optical intensity by an attenuator and transmitted to the coupler through an optical path to be coupled with the signal light beam. The coupled light beam is sent to a balanced detector for adjustment and then processed by a data processor to obtain the wind speed and direction. This application can eliminate the influence of system echo interference, effectively reduce or eliminate the near-range blind area, reduce the detection bandwidth, and improve the signal-to-noise ratio. The internal frequency modulation mode under continuous wave modulation in this application can achieve wind direction discrimination without using a frequency shifter, which can reduce the system cost. Description of the Drawings

[0037] Figure 1 It is a flowchart of a method for a sparse modulation wind measurement radar according to the present invention;

[0038] Figure 2 It is a schematic diagram of a system for a sparse modulation wind measurement radar according to the present invention;

[0039] Figure 3 It is a schematic diagram of the time-frequency domain relationship between the transmitted signal and the received echo signal under triangular wave form frequency modulation according to the present invention;

[0040] Figure 4 It is a time-frequency relationship diagram of the beat signal obtained by coherent detection according to the present invention;

[0041] Figure 5The structure of the sparse internal modulation system of the present invention;

[0042] Figure 6 The controller of the present invention gives a modulation signal to the light source;

[0043] Figure 7 The structure of the sparse external modulation system of the present invention;

[0044] Figure 8 The flowchart of the wind signal frequency and frequency shifter judgment of the present invention. Detailed implementation manners

[0045] The following further describes the present invention in detail with specific embodiments, which are explanations rather than limitations of the present invention.

[0046] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0048] The present invention provides a method for a sparse modulation wind measurement radar, as Figure 1 shown, including the following steps:

[0049] S1: After modulating a linearly varying signal by a laser and emitting a light beam, the light beam passes through a beam splitter, and the beam splitter divides one beam of light into two beams of light, one beam is the detection light, and one beam is the eigen light;

[0050] S2: The detection light first passes through an acousto-optic modulator for modulation to produce a linearly varying signal, then passes through a power amplifier to amplify the light intensity and is transmitted to a telescope via a circulator. The telescope emits the detection light. After the detection light is scattered by the aerosol in the air, the signal light returns. The signal light is received by the telescope and then transmitted to a coupler via the circulator;

[0051] S3: The intrinsic light passes through an attenuator to weaken the light intensity, is transmitted through an optical path to the coupler and is coupled with the returned signal light;

[0052] S4: The coupled light beam is sent to a balanced detector for adjustment and then processed by a data processor to obtain the wind speed and direction.

[0053] Preferably, the modulation of the excellent signal in step S2 includes sparse internal modulation and sparse external modulation;

[0054] The sparse internal modulation is to modulate the laser signal at the laser source;

[0055] The sparse external modulation is to modulate the laser emitted by the laser with a frequency shifter.

[0056] Further, the sparse internal modulation coarsely adjusts the cavity length negative feedback of the external cavity semiconductor laser through piezoelectric ceramic drive, and at the same time injects current into the external cavity semiconductor laser to change the refractive index of the gain medium in the cavity for fine adjustment of the optical length in the cavity.

[0057] Preferably, the wind speed calculation processes of the sparse internal modulation and the sparse external modulation are as follows: As Figure 3 shown, the frequency of the transmitted signal linearly varies up and down periodically with time, the rise time is the same as the fall time, the average frequency is fc, the transmission delay from the circulator to irradiate the measured target and then scatter back to the receiving end is denoted as τ, and the change range of the signal frequency is denoted as the bandwidth B; Due to the Doppler effect caused by the linear change of the signal frequency with time and the relative displacement of the measured target, a frequency difference df is generated between the frequency of the received echo signal and the local oscillator signal. As Figure 4 shown, the frequency difference is composed of the frequency change amount f R introduced by the distance delay τ and the Doppler frequency shift f d . The frequency differences Δf1 generated at the frequency rising edge and Δf2 generated at the frequency falling edge each differ from f R by f d . Then, the difference frequency quantity f R introduced by the distance and the Doppler frequency shift f d can be calculated from Δf1 and Δf2 by coherent demodulation:

[0058] R = 2CT * f d / (4B);

[0059] v = f d *c / (2λcosθ);

[0060] Where: λ represents the wavelength of the transmitted signal, R represents the distance between the lidar and the target to be measured, c represents the speed of light, v represents the projection of the target speed on the line connecting the lidar and the target to be measured, and θ is the angle between the transmitted laser and the moving direction of the particle to be measured; thus, the distance R and relative speed v of the target to be measured can be demodulated.

[0061] Install the sparse modulation device at the seed source, emit continuous laser by the seed source, and finally select the most suitable modulation laser device according to the measurement effect.

[0062] Preferably, for a continuous-wave wind measurement radar, a sparse frequency modulation mode is adopted, and the system structure is as Figure 5 shown. The frequency-modulated light emitted by the laser is split into two paths by a beam splitter. One path serves as the eigenlight E L , and the other path serves as the probe light E S After passing through the amplifier and transmitting to the circulator, and passing through the lens to output and detect aerosol particles. The backscattering of the particles passes through the lens and is received after passing through the circulator, and is mixed with the eigenlight at the coupler; the mixed optical signal passes through the balanced detector to transmit its AC component to the signal processing unit, thereby obtaining the detection of the wind signal; the echo at the end face of the circulator or the lens will also be coherent with the eigenlight.

[0063] The controller gives the light source a modulation signal, as Figure 6 shown, that is, linearly frequency-modulates at time t1 and does not frequency-modulate at time t2; then at time t1, the intermediate frequency f IF = f L + f d , where B is the modulation bandwidth, R is the detection distance, T fm is the time of linear frequency modulation, c represents the speed of light, and fL represents the frequency of the local oscillator light; a focusing lens is used, and the detection distance is the distance between the lens focusing position and the radar. Therefore, f L is a known quantity, and thus the wind speed can be obtained. However, the wind speed result will be coupled with the distance, affecting the wind measurement accuracy. Therefore, only the wind direction is considered during the linear frequency modulation stage, that is, f IF > f L is the positive wind direction, and vice versa is the negative wind direction, realizing the judgment of the wind direction; the wind signal frequency is detected during the non-frequency modulation time period to obtain the wind speed, thereby realizing the measurement of the wind speed and wind direction.

[0064] In the frequency modulation system, since the distance of the system echo is much smaller than the detection distance, the system echo interference is all at low frequencies, and a high-pass filter can effectively eliminate its influence.

[0065] Preferably, as Figure 7As shown, the single-mode laser emitted by the laser is split into two paths by a beam splitter. One path serves as the intrinsic light E L , and the other path serves as the detection light E S . The detection light passes through an optical switch controlled by a controller. The optical switch is periodically modulated, that is, within time t1, the light diameter passes through the beam combiner, and within time t2, the light first passes through a frequency shifter and then through the beam combiner; then it is transmitted through an amplifier to a circulator and output to detect aerosol particles through a lens. The backscattering of the particles passes through the lens and is received after passing through the circulator, and is mixed with the local light in a coupler; the mixed optical signal passes through a balanced detector to transmit its AC component to a processing unit, thereby obtaining the detection of the wind signal; of course, the echo from the end face of the circulator or the lens will also be coherent with the intrinsic light. The controller outputs a synchronization signal to control the optical switch. When in time t2, the intermediate frequency spectrum will show the interference frequency generated by the frequency shifter and the wind speed signal; when in time t1, since E S and E L are zero beat frequencies, the intermediate frequency spectrum only has the wind signal; therefore, in time t2, only the magnitude of the wind signal frequency and the interference frequency are judged to obtain the wind direction. For example, if the frequency shifter is f N , judge the magnitude of the wind signal frequency and f N . If it is greater than f N , the radial wind is positive, otherwise it is negative; further, in time t1, the frequency value of the wind signal is obtained, and according to the relationship the radial wind speed is obtained, where f d represents the Doppler frequency and λ represents the emission light wavelength.

[0066] To judge the magnitude relationship between the wind signal frequency and f N , a processing unit is used as shown in Figure 8 . The filtering range is set to B < f N . If the frequency is less than f N , there is a wind signal in the intermediate frequency spectrum, otherwise there is no signal in the spectrum. Therefore, in time t2, only whether there is a signal within the bandwidth needs to be detected. If there is a signal, the wind direction is negative, and if there is no signal, the wind direction is positive; further, in time t1, the wind factor is detected, thereby realizing the measurement of wind speed and wind direction, suppressing the influence of the interference frequency, reducing the bandwidth under the same index, obtaining a high signal-to-noise ratio, and effectively reducing or eliminating the near-distance blind area.

[0067] Preferably, the sparse external modulation adopts a tuning method based on an electro-optic modulator, including the following steps:

[0068] Transmit the laser emitted by the laser into the electro-optic modulator, apply a voltage to the electro-optic crystal, the refractive index of the electro-optic crystal will change, and through the change of the laser characteristics of the crystal, the phase, amplitude, intensity, and polarization state of the optical signal are modulated to obtain a linear optical frequency signal.

[0069] Preferably, the sparse external modulation adopts a tuning method based on a cyclic frequency shift structure, including the following steps:

[0070] Modulate the light source by combining a cyclic frequency shift loop with a frequency-swept tuned light source, transmit the laser emitted by the laser to the cyclic frequency shift loop and the frequency-swept tuning device, and modulate the received laser by the cyclic frequency shift loop and the scanning tuning device to obtain a linear optical frequency signal.

[0071] The present invention provides a system for a sparse modulation wind measurement radar, as Figure 2 shown, including a seed source, a beam splitter, and an attenuator respectively connected to the seed source;

[0072] The output end of the beam splitter is sequentially connected with an AOM, an EDFA, and a circulator, and the circulator is also connected with a telescope; the output ends of the attenuator and the circulator are respectively connected to a coupler, and the output end of the coupler is sequentially connected with a balanced detector and an oscilloscope.

[0073] The AOM is an acousto-optic modulator, and the EDFA is a power amplifier;

[0074] Furthermore, the continuous coherent radar system is composed of a laser emission module and a signal reception module. The laser emission module includes a laser, a beam splitter, an acousto-optic modulator (AOM), a power amplifier (EDFA), a circulator, and a telescope; the signal reception module includes a coupler, a balanced detector, an acquisition card, and a data processor.

[0075] When the continuous coherent Doppler lidar for wind measurement works, a continuous laser with a central frequency of f0 is generated by the seed source. After being split into two parts of light by the beam splitter, one part is used as the local oscillator light and input into the coupler through the attenuator for beat frequency; the other part first passes through the AOM to frequency modulate the continuous light to generate a modulation frequency of fm. Then, the frequency-shifted light is power-amplified after passing through the EDFA, and then passes through the circulator and is expanded and diverged into the atmosphere through the telescope. The emitted laser generates backscattering with aerosol particles in the atmosphere and is received by the same telescope. The scattered echo signal is frequency-shifted by the optical Doppler effect, with a frequency shift amount of fd. Finally, it coherently beats with the local oscillator light at the coupler, is converted into an electrical signal by the balanced detector, is converted into a digital signal by analog-to-digital acquisition, and the Doppler frequency shift is calculated by the signal processing unit. According to the flight time of the laser pulse, the wind speed at different range resolution cells can be calculated.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for a sparse modulation wind measurement radar, characterized in that, The following steps are involved: S1: The laser modulates a linearly changing signal and then emits a light beam, which passes through a beam splitter. The beam splitter splits the light into two beams, one for the detection light and the other for the intrinsic light. S2: The detection light is first modulated by an acousto-optic modulator to produce a linearly changing signal, and then the light intensity is amplified by a power amplifier and transmitted to the telescope through a circulator. The telescope emits the detection light, which is then transmitted back to the signal light after being emitted by the aerosol in the air. The signal light is received by the telescope and then transmitted to the coupler through the circulator. The modulation of good signals includes sparse internal modulation and sparse external modulation; The sparse internal modulation is to modulate the laser signal at the laser source; The sparse internal modulation is used to roughly adjust the cavity length of the external cavity semiconductor laser through negative feedback by driving the piezoelectric ceramic, and at the same time, current is injected into the external cavity semiconductor laser to change the refractive index of the gain medium in the wall, which is used for feedback fine adjustment of the optical length in the cavity; The sparse external modulation is to modulate the laser emitted by the laser using a frequency shifter; S3: The intrinsic light is weakened by the attenuator, and then transmitted to the coupler through the optical path and coupled with the return signal light; S4: The coupled light beam is sent to a balance detector for adjustment and then processed by a data processor to obtain the wind speed and direction.

2. The method of a sparse modulation wind measurement radar according to claim 1, wherein The wind speed calculation process of the sparse internal modulation and sparse external modulation is: The frequency of the transmitted signal changes linearly with time, the rise time is the same as the fall time, the average frequency is fc, the transmission delay from the circulator to the target and then scattered back to the receiving end is τ, and the range of signal frequency change is bandwidth B; The frequency difference between the received echo signal and the frequency of the local oscillator signal is df; The frequency difference consists of the frequency change amount f introduced by the distance delay τ R and the Doppler frequency shift f d The frequency difference Δf1 generated at the rising edge of the frequency and the frequency difference Δf2 generated at the falling edge of the frequency each differ from f by f R ; d ; The difference frequency quantity f introduced by the distance R and the Doppler frequency shift f d fd can be calculated from Δf1 and Δf2 by means of coherent demodulation: R = 2CT*fd / (4B); v = fd * c / (2fc ); Where: γ represents the frequency change rate of the transmitted signal, R represents the distance between the laser radar and the target, c represents the speed of light, v represents the projection of the target speed on the line connecting the laser radar and the target, fc represents the center frequency of the transmitted signal optical carrier, and θ is the angle between the transmitted laser and the moving direction of the particle to be measured.

3. The method of a sparse modulation wind measurement radar according to claim 1, characterized in that The wind direction calculation process of the sparse internal modulation is: At time linear frequency modulation, at no frequency modulation; then at time, the intermediate frequency , where , is the modulation bandwidth, is the detection distance, is the time of linear frequency modulation, represents the speed of light; Using a focusing lens, the detection distance is the distance between the lens focusing position and the radar, so is a known quantity. If , it is the positive wind direction, otherwise it is the negative wind direction, completing the determination of the sparse internal modulation wind direction.

4. The method of a sparse modulation wind measurement radar according to claim 1, characterized in that, The sparse external modulation wind direction meter process is: When in time, the intermediate frequency spectrum will have interference frequencies generated by the frequency shifter and wind speed signals. Only by judging the magnitude of the wind signal frequency and the interference frequency can the wind direction be obtained. The frequency shifter is , judge the magnitude of the wind signal frequency and . If it is greater than , the radial wind is positive, otherwise it is negative.

5. The method of a sparse modulation wind measurement radar according to claim 1, characterized in that The sparse external modulation adopts a tuning method based on an electro-optical modulator, including the following steps: The laser emitted by the laser is transmitted to the electro-optic modulator, and the voltage is applied to the electro-optic crystal. The refractive index of the electro-optic crystal will change. Through the change of the laser characteristics of the crystal, the phase, amplitude, intensity and polarization state of the optical signal are modulated; a linear optical frequency signal is output.

6. The method of a sparse modulation wind measurement radar according to claim 1, wherein The sparse external modulation adopts a tuning method based on a cyclic frequency shift structure, including the following steps: The light source is modulated by combining a cyclic frequency shift loop with a swept frequency tuned light source. The laser emitted by the laser is transmitted to the cyclic frequency shift loop and the swept frequency tuned device. The cyclic frequency shift loop and the swept frequency tuned device modulate the received laser to obtain a linear optical frequency signal.

7. A system of a sparse modulation wind measurement radar, characterized in that, A method for sparse modulation wind measurement radar based on any one of claims 1 to 6, comprising a seed source and a beam splitter and an attenuator respectively connected to the seed source; The output end of the beam splitter is successively connected with an AOM, an EDFA, and a circulator, and the circulator is further connected with a telescope; the output ends of the attenuator and the circulator are respectively connected to a coupler, and the output end of the coupler is successively connected with a balanced detector and an oscilloscope.

Images