最小方差无偏估计方法提高Gm-APD啁啾调制光子雷达的测距精度

Improving the range accuracy of Gm-APD photon counting chirped amplitude modulation ladar with minimum variance unbiased estimation method

啁啾调制光子雷达由于探测器Gm-APD的死时间限制了采样频率和调制带宽的提高,FFT进行信号处理时存在着固有的频域采样间隔,使得测距精度的提高受到很大限制。按照啁啾光子雷达接收机的信号处理过程对回波信号进行了推导,获得了系统回波中频信号的解析表达式,并采用最小方差无偏估计的方法对中频频谱进行处理,最后对该方法进行了仿真,并用仿真结果与质心估计中频后处理方法的仿真结果进行了比较。最大测距误差可由4.3 m降低到0.4 m,表明最小方差无偏估计的中频处理方法可以有效提高Gm-APD啁啾光子雷达的测距精度。

Due to the limitation of the increase of the sampling frequency and modulation bandwidth resulting from the dead time of the Gm-APD detector of photon counting chirped amplitude modulation ladar and the discrete FFT spectrum of the echo signal,the improvement of range accuracy is hard to achieve.The echo signal was deduced according to the signal processing.The expression of the IF signal was obtained,and the method was processed.Finally,the method was simulated and its result was compared with the simulation result of the center of gravity estimation method.The result that the maximum range error is reduced from 4.3 m to 0.4 m shows that the IF signal processing method of the minimum variance unbiased estimation improves the range accuracy of photon counting chirped amplitude modulation ladar with Gm-APD as the detector greatly.