相干测风激光雷达带通采样方法的仿真研究

Simulation Research on Coherent Wind Lidar Bandpass Sampling Method

根据相干测风雷达回波信号载频高、带宽窄的特点,尤其星载相干测风雷达回波信号数千兆赫兹,采用传统采样方式对采集卡的采样率要求很高.鉴于采集卡的采样率和分辨力互相制约,提出将带通采样引入到相干测风雷达系统.本文以1.5μm全光纤相干测风激光雷达的实测数据作为仿真输入,经Simulink滤波、带通采样,结果表明,在对探测距离影响不大的情况下,与低通采样方式相比径向风速反演结果最大相差0.5m/s;数据处理的时间复杂度降低,其下降值是带通采样频率与低通采样频率的比值;但信噪比会恶化,其下降值介于1~3dB.

A band-pass sampling method was introduced for the coherent wind radar system to solve the problems in the echo signal sampling,including the high carrier frequency,narrow bandwidth,especially several GHz echo signal of the spaceborne wind coherent radar,high sampling rate of acquisition card required with the traditional sampling method,the mutual constraints of sampling rate and resolution of acquisition card.In this paper,a simulation test was carried out,taking the acquisition data collected from 1.5μm all-fiber coherent Doppler lidar system as the input information to do Simulink filter and band-pass sampling.Results show that,compared with the low-pass sampling,the maximum difference of sight speed inversion is about0.5 m/s when the change of detection distance is not large;furthermore,the time complexity of data processing is decreased,and its value is the ratio of bandpass sampling frequency and low pass sampling frequency.However,the ratio of signal to noise deteriorates,the value of which is about 1~3 dB.