A wind speed measurement system and method based on a homologous isomorphic light wave wind radar

Abstract

The present application relates to a kind of wind speed measurement system and method based on homologous isomorphism light wave wind radar, wherein system includes light millimeter wave signal source module, in the module, first laser and second laser are used to generate light millimeter wave by beat frequency, based on light millimeter wave, local signal is obtained, based on second laser, local light is obtained;Millimeter wave radar wind measurement transceiver module, for radiating light millimeter wave to target space, receive echo signal and mix with local signal, output intermediate frequency signal;Laser radar wind measurement transceiver module, for emitting second laser to target space, receive echo light and with the local light of second laser, coherent beam combination output electric signal;Signal processing module, receive intermediate frequency signal and electric signal, based on intermediate frequency signal and electric signal, calculate comprehensive wind speed.Compared with prior art, the present application provides a kind of simplified and more flexible generation method of homologous laser-millimeter wave signal, can realize more accurate and reliable wind measurement.

Description

Technical Field

[0001] This invention relates to wind field detection and radar fusion technology, and in particular to a wind speed measurement system and method based on homogeneous optical wave wind radar. Background Technology

[0002] Wind speed and direction information play a crucial role in wind farm power prediction, aviation safety, meteorological monitoring, shipping scheduling, and military defense. With the rapid development of large-scale wind farms and the increasing demand for refined weather forecasts, wind measurement technology not only requires long-range, all-weather, and high-precision performance but also adaptability to complex weather conditions. Lidar uses Doppler coherent detection, with echoes primarily formed by aerosol particle scattering. It boasts high spatial resolution and high ranging accuracy due to its short wavelength; however, it is sensitive to aerosol content, and echo energy significantly attenuates in rain, fog, dust, and low-visibility environments, reducing wind measurement reliability. Millimeter-wave radar retrieves wind fields through Doppler analysis of echoes scattered by media such as water droplets and cloud particles. Benefiting from its longer wavelength and stronger scattering response to precipitation and fog droplets, it maintains good detection stability even in adverse weather conditions such as rain, fog, and snow. However, its spatial resolution and velocity measurement accuracy are generally lower than lidar. However, millimeter-wave radar has lower spatial resolution and velocity measurement accuracy than lidar; at the same time, traditional millimeter-wave signal sources, based on electronic oscillators and frequency doubling chains, suffer from high phase noise and poor frequency stability, which affect velocity measurement accuracy.

[0003] To improve the adaptability of wind measurement systems under complex weather conditions and achieve all-weather operation, combining lidar and millimeter-wave radar offers significant advantages. Lidar is suitable for clear environments and can achieve high-precision detection; millimeter-wave radar performs stably in low-visibility or rainy conditions. Current multi-band fusion wind measurement schemes generally use independent lidar and millimeter-wave radar to perform wind measurements separately, then fuse the wind speed data during signal processing. Taking Chinese patent application CN116520312A as an example, it simultaneously collects radial wind speed data from both types of radar and performs flag position determination, selecting either lidar or millimeter-wave radar as the dominant system, and then uses a weighted method to fuse the results. While this improves upon the shortcomings of a single system under different weather conditions to some extent, it is essentially still a heterogeneous combination of two independent radar systems: lidar dominates under clear conditions, and millimeter-wave radar dominates under rainy and foggy conditions. The fusion is based solely on weighted selection at the result layer, relying on external state judgments and fixed weighting rules, making it a typical example of... Loose coupling of heterogeneous independent systems fails to achieve unification at the signal link level, resulting in limited robustness and dynamic adaptability. Furthermore, Chinese patent application CN116859384A includes independent millimeter-wave radar and lidar modules in its proposed device. After each module performs wind measurement, Kalman filtering is used in the fusion module to achieve wind speed fusion. Although adaptive weighting improves adaptability under different weather conditions, this method still relies on two separate radar systems, significantly increasing system complexity and hardware costs. Simultaneously, its fusion remains at the result layer (data backend), representing a retrospective heterogeneous redundancy fusion that lacks utilization of the commonality and real-time consistency of the signal link, resulting in insufficient dynamic performance and overall integration.

[0004] The aforementioned methods not only require two independent signal sources, leading to complex system structure, hardware redundancy, large size, and high cost, but also increase the difficulty of calibration and synchronization. Furthermore, traditional millimeter-wave signal sources, based on electronic oscillators or frequency multiplier chains, suffer from high phase noise and poor frequency stability at high frequencies, severely limiting speed measurement accuracy and system coherence performance. To address these technical problems, Chinese patent application CN111693988A provides a laser-millimeter-wave integrated ranging and speed measurement radar method. This method modulates the optical signal and filters it to generate broadband linear frequency modulated (LFM) laser and millimeter-wave signals in two channels, respectively. These LFM laser and millimeter-wave signals are then used for ranging and speed measurement, achieving integrated generation of laser and millimeter-wave signals and avoiding the problems associated with independent signal sources. However, it still suffers from the following issues:

[0005] 1) Complex structure and process: This method requires complex optical structures such as a phase modulator, a frequency modulation signal generator, and a fundamental frequency signal generator to generate a fundamental frequency signal from a single laser. The fundamental frequency signal needs to be mixed, filtered, and amplified to obtain a mixed signal. The mixed signal needs to be phase modulated to separate the laser signal and the millimeter wave signal from the same source. The process is cumbersome and has high hardware requirements. In addition, losses and errors are easily introduced in the above process, which affects the reliability of the measurement results.

[0006] 2) Inflexible frequency control: The frequency adjustment of this method depends on the bandwidth and modulation parameters of the optical filter. If the operating frequency band needs to be changed, the filter must be replaced or the modulator must be reconfigured, making it difficult to achieve fast frequency switching and limiting the adaptability of the method in changing environments.

[0007] Therefore, providing a simplified and more flexible method for generating homogeneous laser-millimeter wave signals to enable more accurate and reliable wind measurement is a technical problem that needs to be solved. Summary of the Invention

[0008] The purpose of this invention is to overcome the defects of the prior art and provide a wind speed measurement system and method based on homogeneous optical wave wind radar. By using two narrow-linewidth lasers to achieve photoelectric beat frequency in the same optical link, a millimeter-wave signal is directly derived, which serves as the unified source of radio frequency and local oscillator of the millimeter-wave radar. At the same time, it is used in conjunction with homogeneous lasers to achieve laser Doppler wind measurement.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] According to a first aspect of the present invention, a wind speed measurement system based on a homogeneous optical wave wind-measuring radar is provided, the system comprising:

[0011] The optically generated millimeter-wave signal source module includes two lasers, a polarization control unit, an optical fiber coupler, and a photodetector. The two lasers generate a first laser with an adjustable frequency and a second laser with a fixed frequency. After the polarization state is adjusted by the polarization control unit, they are coherently combined in the optical fiber coupler. The photodetector uses the beat frequency of the coherently combined laser to generate an optically generated millimeter-wave. The local oscillator signal is obtained based on the optically generated millimeter-wave, and the local oscillator light is obtained based on the second laser.

[0012] The millimeter-wave radar wind measurement transceiver module is used to radiate the aforementioned optically generated millimeter waves to the target space, receive the echo signal and mix it with the local oscillator signal to output an intermediate frequency signal.

[0013] The lidar wind measurement transceiver module is used to transmit the second laser to the target space, receive the echo light, and coherently combine it with the local oscillator light of the second laser to output an electrical signal.

[0014] The signal processing module receives the intermediate frequency signal and the electrical signal, calculates the photogenerated millimeter wave wind speed and the laser wind speed based on the intermediate frequency signal and the electrical signal respectively, and calculates the comprehensive wind speed based on the photogenerated millimeter wave wind speed and the laser wind speed.

[0015] As a preferred technical solution, the optically generated millimeter-wave signal source module further includes a phase-locked loop (PLL), in which the optically generated millimeter-wave and a reference signal are compared to generate a deviation signal, and the deviation signal is fed back to the laser to guide the frequency adjustment of the first laser; the reference signal is an ideal millimeter-wave signal.

[0016] As a preferred technical solution, the frequency of the photogenerated millimeter wave is the difference between the frequencies of the first laser and the second laser.

[0017] As a preferred technical solution, the millimeter-wave radar wind measurement transceiver module includes a transmitting unit, a receiving unit, and a mixing unit;

[0018] The transmitting unit includes a millimeter-wave transmitting cascade subunit and a transmitting antenna; the millimeter-wave transmitting cascade subunit receives the optically generated millimeter waves, filters and amplifies the signals, and inputs them to the transmitting antenna; the transmitting antenna receives the output of the millimeter-wave transmitting cascade subunit and radiates it into the target space;

[0019] The receiving unit includes a receiving antenna and a millimeter-wave receiving cascaded subunit; the receiving antenna receives the echo signal, and the millimeter-wave receiving cascaded subunit amplifies and adjusts the gain of the echo signal.

[0020] The mixing unit receives the echo signal processed by the millimeter-wave receiver cascade subunit and mixes it with the local oscillator signal to output an intermediate frequency signal.

[0021] As a preferred technical solution, the lidar wind measurement transceiver module includes a transmitting and receiving unit and an electrical signal processing unit;

[0022] The transmitting and receiving unit includes a laser transmitting cascade subunit, a telescope, and a circulator; the laser transmitting cascade subunit adjusts the frequency and amplifies the power of the second laser; the telescope is used to transmit the second laser and receive the echo light; and the circulator is used to guide the second laser processed by the laser transmitting cascade subunit to the telescope for transmission and to guide the echo light to the receiving path.

[0023] The electrical signal processing unit is used to achieve coherent mixing of the echo light and the local oscillator light, and to convert the optical signal into an electrical signal.

[0024] As a preferred technical solution, the signal processing module includes a data receiving unit, a spectrum analysis unit, a wind speed calculation unit, and a wind speed fusion unit;

[0025] The data receiving unit receives the intermediate frequency signal and electrical signal and performs digital-to-analog conversion to obtain millimeter-wave signal and laser signal, which are then input to the spectrum analysis unit.

[0026] The spectrum analysis unit receives the millimeter-wave signal and the laser signal, performs spectrum analysis, extracts the millimeter-wave Doppler frequency shift and the laser Doppler frequency shift, and inputs them to the wind speed calculation unit;

[0027] The wind speed calculation unit calculates the optically generated millimeter-wave wind speed and the laser wind speed based on the millimeter-wave Doppler frequency shift and the laser Doppler frequency shift, respectively, and inputs them into the wind speed fusion unit;

[0028] The wind speed fusion unit calculates the joint reliability of the optically generated millimeter wave and the second laser based on the signal-to-noise ratio of the optically generated millimeter wave and the second laser, the wind speed of the optically generated millimeter wave, and the wind speed of the laser, respectively. Based on the joint reliability, it calculates the fusion weight, and based on the fusion weight, it fuses the millimeter wave wind speed and the laser wind speed to output the comprehensive wind speed.

[0029] As a preferred technical solution, the wind speed fusion unit performs the following steps to calculate the fusion weight:

[0030] Obtain the signal-to-noise ratio of the optically generated millimeter wave and the second laser, and calculate the quality reliability of the millimeter wave and the laser, respectively.

[0031] ,

[0032] ,

[0033] in, Indicates the reliability of laser quality; Indicates the second laser signal-to-noise ratio; Indicates the signal-to-noise ratio of optically generated millimeter waves; Indicates the reliability of millimeter-wave quality;

[0034] Based on the aforementioned millimeter-wave wind speed and laser wind speed, the variances of the millimeter-wave wind speed and laser wind speed are calculated respectively, and the reliability of the millimeter-wave stability and the reliability of the laser stability are also calculated.

[0035] ,

[0036] ,

[0037] in, Indicates the reliability of laser stability; Indicates the reliability of millimeter-wave stability; To prevent zero parameters; Indicates the variance of laser wind speed; Indicates the variance of millimeter-wave wind speed;

[0038] The joint credibility is calculated using the following expression: , , Indicates the credibility of laser joint testing. Indicates the joint credibility of millimeter waves, Indicates the adjustable trade-off coefficient;

[0039] The joint confidence scores are normalized to obtain the laser fusion weight and the millimeter-wave fusion weight.

[0040] According to a second aspect of the present invention, a wind speed measurement method based on a homogeneous optical wave wind-measuring radar, implemented based on the above-described system, includes:

[0041] A first laser with a controllable frequency and a second laser with a fixed frequency are generated respectively, and the first laser and the second laser are beat at the same frequency to generate an optical millimeter wave.

[0042] Wind speed is measured using the aforementioned photogenerated millimeter wave, and echo signals are collected. The echo signals are then mixed with the local oscillator signal of the photogenerated millimeter wave to obtain an intermediate frequency signal.

[0043] The second laser is used to measure wind speed, and the echo light is collected. The echo light and the local oscillator light of the second laser are coherently combined to obtain an optical signal, which is then converted into an electrical signal.

[0044] Spectral analysis is performed on the intermediate frequency signal and electrical signal respectively to extract the corresponding Doppler frequency shift, and the optically generated millimeter wave wind speed and laser wind speed are calculated based on the Doppler frequency shift.

[0045] Obtain the signal-to-noise ratio of the optically generated millimeter wave and the second laser, as well as the variance of the wind speed of the optically generated millimeter wave and the wind speed of the laser. Calculate the fusion weight based on the signal-to-noise ratio and variance, and calculate the comprehensive wind speed based on the fusion weight.

[0046] As a preferred technical solution, the frequency of the photogenerated millimeter wave is the difference between the frequencies of the first laser and the second laser.

[0047] As a preferred technical solution, the method for calculating the fusion weight is as follows:

[0048] Obtain the signal-to-noise ratio of the optically generated millimeter wave and the second laser, and calculate the quality reliability of the millimeter wave and the laser, respectively.

[0049] ,

[0050] ,

[0051] in, Indicates the reliability of laser quality; Indicates the second laser signal-to-noise ratio; Indicates the signal-to-noise ratio of optically generated millimeter waves; Indicates the reliability of millimeter-wave quality;

[0052] Based on the aforementioned millimeter-wave wind speed and laser wind speed, the variances of the millimeter-wave wind speed and laser wind speed are calculated respectively, and the reliability of the millimeter-wave stability and the reliability of the laser stability are also calculated.

[0053] ,

[0054] ,

[0055] in, Indicates the reliability of laser stability; Indicates the reliability of millimeter-wave stability; To prevent zero parameters; Indicates the variance of laser wind speed; Indicates the variance of millimeter-wave wind speed;

[0056] The joint credibility is calculated using the following expression: , , Indicates the credibility of laser joint testing. Indicates the joint credibility of millimeter waves, Indicates the adjustable trade-off coefficient;

[0057] The joint confidence scores are normalized to obtain the laser fusion weight and the millimeter-wave fusion weight.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] 1) This invention provides a simple optical millimeter wave generation module that eliminates the need for laser channel splicing through phase modulation and narrowband optical filtering. Instead, it directly obtains the electrical domain difference frequency by frequency beat in a high-speed photodetector, followed by stabilization via a phase-locked loop, ensuring the generation of optical millimeter waves with stable frequency differences. This not only eliminates systematic errors such as frequency drift, phase jitter, and time offset caused by independent local oscillators and clocks in traditional heterogeneous systems, significantly reducing the complexity of cross-channel alignment and calibration, but also simplifies the complex physical structure and usage of existing homogeneous devices. Furthermore, compared to electronic oscillators or frequency doubling chain schemes, the optical millimeter waves generated by this invention have lower phase noise and higher frequency stability, with smaller short-term jitter and long-term drift, resulting in more accurate Doppler frequency shift extraction and higher coherent integral gain. Ultimately, this improves the velocity measurement accuracy, data consistency, and robustness under complex weather conditions for both millimeter wave and laser channels.

[0060] 2) In this invention, a numerically controlled synthesizer, i.e. a phase-locked loop, is used to set and lock the frequency difference between the first laser and the second laser. Based on the frequency difference feedback control, the frequency-adjustable first laser is rapidly switched between frequency points to maintain the stability of the optically generated millimeter-wave signal source. There is no need to change the optical filter and modulation parameters, making the process simpler.

[0061] 3) This invention uses homogeneous laser and photogenerated millimeter wave radar for wind measurement. The wind speeds measured by the two channels are weighted and fused to obtain a comprehensive wind speed. During the fusion process, the signal-to-noise ratio of the signal itself and the stability of the wind speed measured by the two channels are considered to calculate the fusion weight. This ensures that the all-weather adaptability and strong penetration capability of millimeter wave radar and the high resolution and high precision inversion characteristics of lidar can be utilized to the greatest extent. This achieves high stability in complex meteorological environments such as rain, fog, and dust, and maintains accurate inversion capability under clear sky conditions, thereby improving the accuracy of wind speed measurement. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the overall structure of the system of the present invention;

[0063] Figure 2 This is a schematic diagram of the wind measurement system of the present invention;

[0064] Figure 3 This is a flowchart of the method of the present invention. Detailed Implementation

[0065] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0066] Example 1

[0067] To address the problems existing in the prior art, this invention provides a wind speed measurement system based on a homogeneous optical wave wind-measuring radar. It utilizes two narrow-linewidth laser beams with controllable frequency difference to generate millimeter-wave signals, simultaneously driving both the lidar and millimeter-wave radar wind-measuring modules. This achieves a system architecture of dual-radar collaboration and shared signal source. Compared to traditional multi-source heterogeneous solutions, this significantly reduces system hardware redundancy, improves coherence and synchronization accuracy, and enhances the system's robustness and wind measurement accuracy under adverse weather conditions. It provides an innovative path for building a highly integrated, low-noise, all-weather wind speed sensing platform. The detailed system structure is as follows: Figure 1 As shown, and in accordance with Figure 2 The framework shown operates in the following manner: a photoelectric millimeter-wave signal source module, a millimeter-wave radar wind measurement transceiver module, a lidar wind measurement transceiver module, and a signal processing module.

[0068] a) Photogenerated millimeter-wave signal source module.

[0069] The module includes two narrow linewidth lasers (DFB, 1550nm band, linewidth <10kHz), a polarization control unit (in this embodiment, the polarization control unit is a fiber optic polarization controller with a polarization extinction ratio >20dB), a fiber optic coupler, a phase-locked loop (in this embodiment, the loop bandwidth is set to 100kHz, and the phase noise is ≤-92dBc / Hz), a beam splitter, a power divider, and a photodetector (in this embodiment, a high-speed UTC-PD is used, with a 3dB bandwidth ≥100GHz and a responsivity ≥0.4A / W).

[0070] In detail, two lasers generate a first laser f1 with an adjustable frequency and a second laser f2 with a fixed frequency. f2 serves as the reference light source for the lidar system, and its local oscillator light is output via a beam splitter. After the first and second lasers are input to a polarization control unit for polarization state adjustment, they are coherently combined in an optical fiber coupler. The photodetector uses the beat frequency of the coherently combined lasers to generate an optically generated millimeter wave. The frequency of this optically generated millimeter wave is the difference between the frequencies of the first and second lasers. ,in, Indicates the frequency of the first laser. This indicates the frequency of the second laser.

[0071] The generated millimeter wave and the reference signal are compared in the phase-locked loop to generate a deviation signal. The deviation signal is fed back to the laser to guide the frequency adjustment of the first laser. The aforementioned reference signal is an ideal millimeter wave signal. Specifically, the drive current or cavity length of the laser that generates the first laser is controlled in a closed loop based on the deviation signal in the phase-locked loop to stabilize the frequency difference between the two laser beams at the target value, while suppressing phase noise and slow drift. The phase-locked loop status signals, such as locked, unlocked, loop bandwidth, residual, etc., are sent out for monitoring.

[0072] In addition, this module simultaneously allocates a unified reference clock and sampling trigger to the millimeter wave and laser channels to achieve time-frequency consistency across the entire link. The locked millimeter wave beat frequency signal is split into two paths by a power divider: one path serves as the RF input of the millimeter wave radar transmission link, and the other path serves as the local oscillator signal of the millimeter wave receiving link. The second laser is processed by a beam splitter and split into two paths: one path serves as the laser input of the lidar transmission link, and the other path serves as the local oscillator light of the laser receiving link. A monitoring port is reserved for the optically generated millimeter wave for online power and frequency verification.

[0073] b) Millimeter-wave radar wind measurement transceiver module.

[0074] This module is used to radiate millimeter-wave radiation to the target space, receive the echo signal, and mix it with the local oscillator signal to output an intermediate frequency signal. It includes a transmitting unit, a receiving unit, and a mixing unit, wherein:

[0075] b1) The transmitting unit includes a millimeter-wave transmitting cascade subunit and a transmitting antenna. The millimeter-wave transmitting cascade subunit includes a two-stage bandpass filter and a three-stage power amplifier structure for receiving optically generated millimeter waves, filtering and amplifying the signals, and inputting them to the transmitting antenna.

[0076] Specifically, the first-stage bandpass filter is located at the output of the power divider. It is used to suppress residual low-frequency components and spurious signals in the beat frequency signal and input the processed signal to the driver amplifier. The driver amplifier provides initial gain to ensure that the signal can effectively drive subsequent stages and is input to the next stage amplifier. The intermediate power amplifier further increases the signal amplitude and maintains linearity and is input to the final stage amplifier. The final stage power amplifier boosts the signal power to the level that meets the antenna radiation requirements and is input to the second-stage bandpass filter. The second-stage bandpass filter suppresses harmonics and nonlinear spurious signals generated during the amplification process, ensuring a clean output spectrum. Finally, the transmitting antenna radiates the millimeter-wave signal to the atmospheric target area.

[0077] b2) The receiving unit includes a receiving antenna and a millimeter-wave receiving cascade subunit. The receiving antenna receives the echo signal, and the millimeter-wave receiving cascade subunit amplifies and adjusts the gain of the echo signal.

[0078] Specifically, the millimeter-wave receiver cascade subunit includes a low-noise amplifier and a digitally controlled attenuator. The low-noise amplifier amplifies the weak echo received by the receiving antenna to improve the signal-to-noise ratio and inputs it to the digitally controlled attenuator. The digitally controlled attenuator programmably adjusts the signal amplitude to avoid strong echoes causing system saturation and to ensure dynamic range, and inputs it to the mixer unit.

[0079] b3) The mixing unit receives the echo signal processed by the millimeter-wave receiving cascaded sub-unit and mixes it with the local oscillator signal to output the intermediate frequency signal.

[0080] This unit mixes the amplified and gain-controlled echo signal with the local oscillator signal from the same source to generate an intermediate frequency (IF) signal containing Doppler frequency shift information. The IF amplifier linearly amplifies the output IF signal and outputs it to the subsequent signal processing module. Since the local oscillator signal and sampling trigger are both provided by the optically generated millimeter-wave signal source module, the time-frequency consistency of the transmission, reception and data acquisition links can be ensured.

[0081] c) LiDAR wind measurement transceiver module.

[0082] This module is used to emit a second laser beam into the target space, receive the echo light, and coherently combine it with the local oscillator beam of the second laser to output an electrical signal. It includes a transmitting / receiving unit and an electrical signal processing unit, specifically:

[0083] c1) The transmitting and receiving unit includes a laser transmitting cascade subunit, a telescope, and a circulator.

[0084] The laser emission cascade subunit performs frequency adjustment and power amplification on the second laser, including an acousto-optic frequency shifter and an optical fiber amplifier. The acousto-optic frequency shifter is used to shift or modulate the frequency of the second laser to achieve the local oscillator differential required for Doppler detection. The optical fiber amplifier amplifies the power of the laser signal processed by the frequency shifter to enhance the echo detection capability, so as to ensure that the laser signal can be radiated to the target area by the telescope.

[0085] The telescope is used to transmit the second laser beam and receive the echo light.

[0086] The circulator is used to isolate the transmitting and receiving optical paths, guides the second laser, which has been processed by the laser transmitting cascade subunit, to the telescope for transmission, and guides the echo light to the receiving path.

[0087] c2) The electrical signal processing unit includes an optical fiber coupler and a photodetector, which are used to achieve coherent mixing of the echo light and the local oscillator light and convert the optical signal into an electrical signal.

[0088] The fiber optic coupler is used to coherently combine the echo light and the local oscillator light. The photodetector converts the coherent optical signal into an electrical signal, which is then amplified and output to the subsequent processing unit. The weak current output by the photodetector is converted and amplified into a voltage signal by the transimpedance amplifier. If necessary, the amplitude is further increased by the low-noise amplifier to ensure that the signal processing module can extract the Doppler frequency shift of the atmospheric scattered echo.

[0089] Both the millimeter-wave radar wind measurement transceiver module and the millimeter-wave radar wind measurement transceiver module share a unified light source and reference clock to ensure the consistency of the two types of detection links in terms of frequency and time references.

[0090] d) Signal processing module.

[0091] This module is used to receive intermediate frequency signals and electrical signals, calculate the photogenerated millimeter wave wind speed and laser wind speed based on the intermediate frequency signals and electrical signals respectively, and calculate the comprehensive wind speed based on the photogenerated millimeter wave wind speed and laser wind speed.

[0092] In detail, it includes a data receiving unit, a spectrum analysis unit, a wind speed calculation unit, and a wind speed fusion unit. It can synchronously acquire the intermediate frequency signal and electrical signal from the dual radar feedback based on a reference clock, extract the Doppler frequency shift through spectrum analysis to calculate the radial wind speed, combine the radial wind speed data from multiple directions to calculate the horizontal and vertical wind speeds, and finally output the comprehensive wind speed by weighted fusion of the wind speed data from the lidar and millimeter-wave radar.

[0093] d1) Data receiving unit, used to receive intermediate frequency signals and electrical signals and perform digital-to-analog conversion to obtain millimeter wave signals and laser signals, and input them to the spectrum analysis unit.

[0094] Under the unified reference clock and trigger provided by the photogenerated millimeter-wave signal source module, the intermediate frequency signal formed by the millimeter-wave radar echo and the electrical signal formed by the lidar are synchronously acquired. During the sampling process, a timestamp is added to each frame of data to achieve accurate time alignment of cross-channel samples. A synchronous monitoring mechanism is built into the acquisition stage to detect clock deviation and trigger loss in real time, and output alarm flags when abnormalities occur to ensure the time and frequency consistency of subsequent processing.

[0095] d2) Spectrum analysis unit, used to receive millimeter wave signals and laser signals, perform spectrum analysis, extract millimeter wave Doppler frequency shift and laser Doppler frequency shift, and input them to wind speed calculation unit.

[0096] The original intermediate frequency signal or electrical signal is de-DC biased and weighted using a Hanning window to suppress sidelobe leakage. Then, a fast Fourier transform (FFT) is performed to obtain the power spectrum distribution.

[0097] In the power spectrum, the Doppler frequency shift of the target signal is extracted using peak search and fitting methods, and the peak signal-to-noise ratio (SNR) and full width at half maximum (FWHM) of the original photogenerated millimeter wave or the second laser are calculated simultaneously to reflect the signal effectiveness and atmospheric turbulence characteristics.

[0098] d3) Wind speed calculation unit, which calculates the photogenerated millimeter-wave wind speed and laser wind speed based on millimeter-wave Doppler frequency shift and laser Doppler frequency shift respectively, and inputs them to the wind speed fusion unit.

[0099] In detail, the radial wind speed is calculated based on the Doppler frequency shift in this unit. The horizontal and vertical wind speeds are then calculated by combining radial wind speed data from multiple directions. The radial wind speed is calculated based on the Doppler relationship.

[0100] ,

[0101] in, The Doppler frequency shift of radial wind speed, λ is the wavelength of the laser.

[0102] Based on this, the wind speed inversion stage begins. Since a single beam can only provide the projected velocity of the wind in that direction, to obtain complete wind field information, it is necessary to combine multi-beam observation results. Within the same detection time window, the wind speed calculation unit can calculate the radial wind speed from different directions based on the Doppler frequency shift of optically generated millimeter waves or lasers in different directions, denoted as:

[0103] ,

[0104] in, Indicates the first Radial wind speed of beam-generated millimeter waves or laser beams; These are the wind speed components in the east-west, north-south, and vertical directions, respectively. The first The elevation and azimuth angles of a beam-generated millimeter wave or laser beam.

[0105] When the radial wind speeds in three or more different directions are obtained, a system of equations can be established:

[0106] ,

[0107] Record ,in Let A be the radial wind speed observation vector, and let A be the direction cosine matrix. Let be the three-dimensional wind speed vector to be determined.

[0108] when When the beams are not coplanar, the solution can be obtained using the least squares method:

[0109]

[0110] This allows us to obtain the horizontal wind speed measured by photogenerated millimeter waves or lasers. ,wind direction With vertical wind speed .

[0111] d4) The wind speed fusion unit calculates the joint credibility of the optically generated millimeter wave and the second laser based on the signal-to-noise ratio of the optically generated millimeter wave and the second laser, the wind speed of the optically generated millimeter wave and the wind speed of the laser, respectively. Based on the joint credibility, the fusion weight is calculated. Based on the fusion weight, the millimeter wave wind speed and the laser wind speed are fused, and the comprehensive wind speed is output.

[0112] In this unit, firstly, quality weights are constructed based on the peak signal-to-noise ratio (SNR), with channels having higher SNRs receiving greater weights. Secondly, stability weights are constructed based on the inverse of the wind speed variance within a short time window to highlight channels with stable results. The final fusion weight is a normalized combination of the two types of weights. After the wind speeds along the two paths are weighted and superimposed, the fused wind speed and reliability index are output. The detailed steps for this unit are as follows:

[0113] d4-1. Obtain the signal-to-noise ratio of the optically generated millimeter wave and the second laser, and calculate the quality reliability of the millimeter wave and the laser, respectively.

[0114] ,

[0115] ,

[0116] in, Indicates the reliability of laser quality; Indicates the second laser signal-to-noise ratio; Indicates the signal-to-noise ratio of optically generated millimeter waves; This indicates the reliability of millimeter-wave quality.

[0117] d4-2. Calculate the variance of millimeter-wave wind speed and the variance of laser wind speed based on millimeter-wave wind speed and laser wind speed respectively, and calculate the reliability of millimeter-wave stability and the reliability of laser stability.

[0118] ,

[0119] ,

[0120] in, Indicates the reliability of laser stability; Indicates the reliability of millimeter-wave stability; To prevent zero parameters; Indicates the variance of laser wind speed; This represents the variance of millimeter-wave wind speed.

[0121] d4-3. Calculate the joint credibility, the expression of which is: , , Indicates the credibility of laser joint testing. Indicates the joint credibility of millimeter waves, This represents the adjustable tradeoff coefficient.

[0122] d4-4. Normalize the joint confidence level to obtain the laser fusion weight and the millimeter-wave fusion weight, the expressions of which are:

[0123] ,

[0124] ,

[0125] in, Indicates the laser fusion weights; This represents the millimeter-wave fusion weights.

[0126] d4-5. Calculate the overall wind speed as follows: , , The wind speeds are measured by lidar and millimeter-wave radar, respectively, and are calculated based on horizontal wind speed, wind direction, and vertical wind speed.

[0127] Through the processing of the signal processing unit, the optically generated millimeter wave and lidar signals are deeply fused from the same source, combining the all-weather adaptability and strong penetration capability of millimeter wave radar with the high resolution and high-precision inversion characteristics of lidar.

[0128] That is, the system provided by the present invention relies on a low phase noise optically generated millimeter wave signal source and combines an adaptive dual-weight fusion algorithm to achieve high stability under complex meteorological environments (rain, fog, dust, etc.) and accurate inversion under clear sky conditions.

[0129] Example 2

[0130] Furthermore, this invention also provides a wind measurement method, which utilizes the system provided in Embodiment 1 to measure wind, and the process is as follows: Figure 3 As shown, it includes the following steps:

[0131] S1. Two laser sources in the above system generate a first laser with a controllable frequency and a second laser with a fixed frequency, respectively. The first laser and the second laser are beat to generate a photogenerated millimeter wave. In this embodiment, the frequency of the photogenerated millimeter wave is the difference between the frequencies of the first laser and the second laser.

[0132] S2. Wind speed is measured using photogenerated millimeter waves. Echo signals are collected, and the echo signals are mixed with the local oscillator signal of the photogenerated millimeter waves to obtain an intermediate frequency signal.

[0133] S3. Use the second laser to measure wind speed, collect the echo light, coherently combine the echo light with the local oscillator light of the second laser to obtain an optical signal, and convert the optical signal into an electrical signal.

[0134] S4. Perform spectrum analysis based on intermediate frequency signal and electrical signal respectively, extract the corresponding Doppler frequency shift, and calculate the photogenerated millimeter wave wind speed and laser wind speed based on the Doppler frequency shift.

[0135] S41. Radial wind speed is calculated based on Doppler frequency shift. Horizontal and vertical wind speeds are obtained by combining multi-directional radial wind speed data. The radial wind speed is calculated based on the Doppler relationship.

[0136] ,

[0137] in, The Doppler frequency shift of radial wind speed, λ is the wavelength of the laser.

[0138] S42. Building upon S41, the wind speed inversion stage begins. Since a single beam can only provide the projected velocity of the wind in that direction, to obtain complete wind field information, it is necessary to combine multi-beam observation results. Within the same detection time window, the wind speed calculation unit can calculate the radial wind speeds from different directions based on the Doppler frequency shift of optically generated millimeter waves or lasers in different directions, denoted as:

[0139] ,

[0140] in, Indicates the first Radial wind speed of beam-generated millimeter waves or laser beams; These are the wind speed components in the east-west, north-south, and vertical directions, respectively. The first The elevation and azimuth angles of a beam-generated millimeter wave or laser beam.

[0141] S43. When obtaining radial wind speeds in three or more different directions, a system of equations can be established:

[0142] ,

[0143] Record ,in Let A be the radial wind speed observation vector, and let A be the direction cosine matrix. Let be the three-dimensional wind speed vector to be determined.

[0144] when When the beams are not coplanar, the solution can be obtained using the least squares method:

[0145]

[0146] This allows us to obtain the horizontal wind speed measured by photogenerated millimeter waves or lasers. ,wind direction With vertical wind speed .

[0147] S5. Obtain the signal-to-noise ratio of the photogenerated millimeter wave and the second laser, as well as the variance of the wind speed of the photogenerated millimeter wave and the wind speed of the laser. Calculate the fusion weight based on the signal-to-noise ratio and the variance, and calculate the comprehensive wind speed based on the fusion weight.

[0148] S51. Obtain the signal-to-noise ratio of the optically generated millimeter wave and the second laser, and calculate the quality reliability of the millimeter wave and the laser, respectively.

[0149] ,

[0150] ,

[0151] in, Indicates the reliability of laser quality; Indicates the second laser signal-to-noise ratio; Indicates the signal-to-noise ratio of optically generated millimeter waves; This indicates the reliability of millimeter-wave quality.

[0152] S52. Calculate the variance of millimeter-wave wind speed and the variance of laser wind speed based on millimeter-wave wind speed and laser wind speed respectively, and calculate the reliability of millimeter-wave stability and the reliability of laser stability. The expressions are as follows:

[0153] ,

[0154] ,

[0155] in, Indicates the reliability of laser stability; Indicates the reliability of millimeter-wave stability; To prevent zero parameters; Indicates the variance of laser wind speed; This represents the variance of millimeter-wave wind speed.

[0156] S53. Calculate the joint credibility, the expression of which is: , , Indicates the credibility of laser joint testing. Indicates the joint credibility of millimeter waves, This represents the adjustable tradeoff coefficient.

[0157] S54. Normalize the joint confidence level to obtain the laser fusion weight and millimeter-wave fusion weight, the expressions of which are:

[0158] ,

[0159] ,

[0160] in, Indicates the laser fusion weights; This represents the millimeter-wave fusion weights.

[0161] S55. Calculate the overall wind speed as follows: , , The wind speeds are measured by lidar and millimeter-wave radar, respectively, and are calculated based on horizontal wind speed, wind direction, and vertical wind speed.

[0162] Furthermore, this embodiment also provides an electronic device including a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (ROM) or loaded from a storage unit into random access memory (RAM). The RAM can also store various programs and data required for device operation. The CPU, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0163] Multiple components in the device are connected to the I / O interface, including: input units such as keyboards and mice; output units such as various types of displays and speakers; storage units such as disks and optical discs; and communication units such as network interface cards (NICs), modems, and wireless transceivers. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0164] The processing unit executes the various methods and processes described above, such as methods S1 to S5. For example, in some embodiments, methods S1 to S5 may be implemented as computer software programs tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via ROM and / or a communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of methods S1 to S5 described above may be performed. Alternatively, in other embodiments, the CPU may be configured to execute methods S1 to S5 by any other suitable means (e.g., by means of firmware).

[0165] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application Standard Products (ASSPs), System-on-Chip (SoCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0166] The program code used to implement the methods of the present invention can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0167] In the context of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0168] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A wind speed measurement system based on homogeneous optical wave wind-measuring radar, characterized in that, The system includes: The optically generated millimeter-wave signal source module includes two lasers, a polarization control unit, an optical fiber coupler, and a photodetector. The two lasers generate a first laser with an adjustable frequency and a second laser with a fixed frequency. After the polarization state is adjusted by the polarization control unit, they are coherently combined in the optical fiber coupler. The photodetector uses the beat frequency of the coherently combined laser to generate an optically generated millimeter-wave. The local oscillator signal is obtained based on the optically generated millimeter-wave, and the local oscillator light is obtained based on the second laser. The millimeter-wave radar wind measurement transceiver module is used to radiate the aforementioned optically generated millimeter waves to the target space, receive the echo signal and mix it with the local oscillator signal to output an intermediate frequency signal. The lidar wind measurement transceiver module is used to transmit the second laser to the target space, receive the echo light, and coherently combine it with the local oscillator light of the second laser to output an electrical signal. The signal processing module receives the intermediate frequency signal and the electrical signal, calculates the optically generated millimeter-wave wind speed and the laser wind speed based on the intermediate frequency signal and the electrical signal respectively, and calculates the comprehensive wind speed based on the optically generated millimeter-wave wind speed and the laser wind speed; the signal processing module includes a wind speed fusion unit, which calculates the joint reliability of the optically generated millimeter-wave and the second laser based on the signal-to-noise ratio of the optically generated millimeter-wave and the second laser, the optically generated millimeter-wave wind speed and the laser wind speed respectively, calculates the fusion weight based on the joint reliability, fuses the millimeter-wave wind speed and the laser wind speed based on the fusion weight, and outputs the comprehensive wind speed; the wind speed fusion unit performs the following steps to calculate the fusion weight: Obtain the signal-to-noise ratio of the optically generated millimeter wave and the second laser, and calculate the quality reliability of the millimeter wave and the laser, respectively. ， ， in, Indicates the reliability of laser quality; Indicates the second laser signal-to-noise ratio; Indicates the signal-to-noise ratio of optically generated millimeter waves; Indicates the reliability of millimeter-wave quality; Based on the aforementioned millimeter-wave wind speed and laser wind speed, the variances of the millimeter-wave wind speed and laser wind speed are calculated respectively, and the reliability of the millimeter-wave stability and the reliability of the laser stability are also calculated. ， ， in, Indicates the reliability of laser stability; Indicates the reliability of millimeter-wave stability; To prevent zero parameters; Indicates the variance of laser wind speed; Indicates the variance of millimeter-wave wind speed; The joint credibility is calculated using the following expression: , , Indicates the credibility of laser joint testing. Indicates the joint credibility of millimeter waves, Indicates the adjustable trade-off coefficient; The joint confidence scores are normalized to obtain the laser fusion weight and the millimeter-wave fusion weight.

2. The wind speed measurement system based on homogeneous optical wave wind radar according to claim 1, characterized in that, The optically generated millimeter-wave signal source module further includes a phase-locked loop (PLL). The optically generated millimeter-wave and a reference signal are compared in the PLL to generate a deviation signal. The deviation signal is fed back to the laser to guide the frequency adjustment of the first laser. The reference signal is an ideal millimeter-wave signal.

3. The wind speed measurement system based on homogeneous optical wave wind radar according to claim 1, characterized in that, The frequency of the optically generated millimeter wave is the difference between the frequencies of the first laser and the second laser.

4. The wind speed measurement system based on homogeneous optical wave wind radar according to claim 1, characterized in that, The millimeter-wave radar wind measurement transceiver module includes a transmitting unit, a receiving unit, and a mixing unit; The transmitting unit includes a millimeter-wave transmitting cascade subunit and a transmitting antenna; the millimeter-wave transmitting cascade subunit receives the optically generated millimeter waves, filters and amplifies the signals, and inputs them to the transmitting antenna; The transmitting antenna receives the output of the millimeter-wave transmitting cascade subunit and radiates it into the target space; The receiving unit includes a receiving antenna and a millimeter-wave receiving cascaded subunit; the receiving antenna receives the echo signal, and the millimeter-wave receiving cascaded subunit amplifies and adjusts the gain of the echo signal. The mixing unit receives the echo signal processed by the millimeter-wave receiver cascade subunit and mixes it with the local oscillator signal to output an intermediate frequency signal.

5. A wind speed measurement system based on a homogeneous optical wave wind-measuring radar according to claim 1, characterized in that, The aforementioned lidar wind measurement transceiver module includes a transmitting and receiving unit and an electrical signal processing unit; The transmitting and receiving unit includes a laser transmitting cascade subunit, a telescope, and a circulator; the laser transmitting cascade subunit adjusts the frequency and amplifies the power of the second laser; the telescope is used to transmit the second laser and receive the echo light; and the circulator is used to guide the second laser processed by the laser transmitting cascade subunit to the telescope for transmission and to guide the echo light to the receiving path. The electrical signal processing unit is used to achieve coherent mixing of the echo light and the local oscillator light, and to convert the optical signal into an electrical signal.

6. A wind speed measurement system based on a homogeneous optical wave wind-measuring radar according to claim 1, characterized in that, The signal processing module also includes a data receiving unit, a spectrum analysis unit, and a wind speed calculation unit; The data receiving unit receives the intermediate frequency signal and electrical signal and performs digital-to-analog conversion to obtain millimeter-wave signal and laser signal, which are then input to the spectrum analysis unit. The spectrum analysis unit receives the millimeter-wave signal and the laser signal, performs spectrum analysis, extracts the millimeter-wave Doppler frequency shift and the laser Doppler frequency shift, and inputs them to the wind speed calculation unit; The wind speed calculation unit calculates the optically generated millimeter-wave wind speed and the laser wind speed based on the millimeter-wave Doppler frequency shift and the laser Doppler frequency shift, respectively, and inputs them into the wind speed fusion unit.

7. A wind speed measurement method based on homogeneous optical wave wind-measuring radar, characterized in that, The method is implemented based on any one of the systems described in claims 1 to 6, and includes: A first laser with a controllable frequency and a second laser with a fixed frequency are generated respectively, and the first laser and the second laser are beat at the same frequency to generate an optical millimeter wave. Wind speed is measured using the aforementioned photogenerated millimeter wave, and echo signals are collected. The echo signals are then mixed with the local oscillator signal of the photogenerated millimeter wave to obtain an intermediate frequency signal. The second laser is used to measure wind speed, and the echo light is collected. The echo light and the local oscillator light of the second laser are coherently combined to obtain an optical signal, which is then converted into an electrical signal. Spectral analysis is performed on the intermediate frequency signal and electrical signal respectively to extract the corresponding Doppler frequency shift, and the optically generated millimeter wave wind speed and laser wind speed are calculated based on the Doppler frequency shift. Obtain the signal-to-noise ratio of the optically generated millimeter wave and the second laser, as well as the variance of the wind speed of the optically generated millimeter wave and the wind speed of the laser. Calculate the fusion weight based on the signal-to-noise ratio and variance, and calculate the comprehensive wind speed based on the fusion weight.

8. A wind speed measurement method based on a homogeneous optical wave wind-measuring radar according to claim 7, characterized in that, The frequency of the photogenerated millimeter wave is the difference between the frequencies of the first laser and the second laser.

9. A wind speed measurement method based on a homogeneous optical wave wind-measuring radar according to claim 7, characterized in that, The method for calculating the fusion weights is as follows: Obtain the signal-to-noise ratio of the optically generated millimeter wave and the second laser, and calculate the quality reliability of the millimeter wave and the laser, respectively. ， ， in, Indicates the reliability of laser quality; Indicates the second laser signal-to-noise ratio; Indicates the signal-to-noise ratio of optically generated millimeter waves; Indicates the reliability of millimeter-wave quality; Based on the aforementioned millimeter-wave wind speed and laser wind speed, the variances of the millimeter-wave wind speed and laser wind speed are calculated respectively, and the reliability of the millimeter-wave stability and the reliability of the laser stability are also calculated. ， ， in, Indicates the reliability of laser stability; Indicates the reliability of millimeter-wave stability; To prevent zero parameters; Indicates the variance of laser wind speed; Indicates the variance of millimeter-wave wind speed; The joint credibility is calculated using the following expression: , , Indicates the credibility of laser joint testing. Indicates the joint credibility of millimeter waves, Indicates the adjustable trade-off coefficient; The joint confidence scores are normalized to obtain the laser fusion weight and the millimeter-wave fusion weight.

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