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直接探测多普勒测风激光雷达系统大多采用基于Fabry-Perot(F-P)标准具的条纹技术和边缘技术测量多普勒频移。但激光器频率漂移会使得透过率曲线的估计出现一定误差,为了抑制其影响,提出了一种基于谱估计的F-P标准具透过率曲线参数估计方法。首先将标准具全量程扫描结果进行重构得到观测矩阵。之后使用MUSIC算法得到透过率曲线的伪谱。对伪谱进行谱峰搜索后,将得到的谱峰位置进行线性拟合得到自由谱间距。然后将上步的拟合结果代入透过率函数,利用非线性最小二乘法对其他参数进行估计。在仿真分析的基础上,采用真实测量数据进行了实验验证。结果表明所提出的方法在扫描步点间隔达到50、信噪比大于10 d B的情况下,估计差小于1%。该算法扫描时间短,估计误差小,具有实际应用价值。
Direct detection Doppler wind lidar systems mostly use the fringe technique based on the Fabry-Perot (F-P) etalon and the edge technique to measure the Doppler shift. However, the drift of laser frequency leads to some error in the estimation of transmittance curve. In order to restrain its influence, a parameter estimation method of transmittance curve based on spectral estimation is proposed. First, the standard full-scale scan results were reconstructed to obtain the observation matrix. The MUSIC algorithm is then used to derive the pseudospectral of the transmittance curve. After searching the spectrum of the pseudospectral, the obtained spectral peak positions are linearly fitted to obtain the free spectral distance. Then, the fitting result of the previous step is substituted into the transmittance function, and the other parameters are estimated by using the non-linear least square method. Based on the simulation analysis, the real measurement data is used to verify the experiment. The results show that the proposed method has an estimated difference of less than 1% when the scanning step interval reaches 50 and the signal-to-noise ratio is greater than 10 d B. The algorithm has short scan time and small estimation error, which has practical value.