深空光通信中图像信标的捕获和跟踪

Acquisition and Tracking of Image Beacon for Deep Space Optical Communication

用激光进行深空探测科学数据回传,上行信标光衰减严重,不能提供足够高的跟踪速率,因此常采用自然天体图像作为信标。对该信标的捕获和跟踪是深空光通信链路成功建立和保持的关键。在航天器上存储一幅目标天体图像做参考,利用该图像和探测图像的相关性对该信标进行捕获,理论分析和仿真结果都表明,可以精确地确定光通信天线的初始对准方向,使跟瞄系统进入跟踪模式。基于离散傅里叶变换和极大似然方法对信标的平移进行计算,需要解一个非线性方程组,线性近似计算结果表明平移量总误差在0.5个像素以内,X方向的平移误差为3.3%,Y方向的平移误差为2.7%,可以满足深空通信的要求,因而是一种可行的方案。

With laser to return the scientific data of deep space exploration to earth, the up beacon cannot provide enough tracking rate for its serious optical attenuation, so the image of a natural object is usually used as the beacon. Successful acquisition and beacon tracking is the key of setting and keeping the deep space optical communication link. Storing an image in the aircraft as the reference, using the correlation of the reference image and the detected image to acquire the beacon, the theoretical analysis and computer simulation show that it can accurately confirm the initialized pointing direction of the optical antenna and make PAT subsystem enter the tracking model. Calculating the translation of beacon based on discrete Fourier transform （DFT） and maximum likelihood criterion, need solve two nonlinear equations, and the linearly approximated result shows that the total translation error is below 0.5 pixel, the translation error in X direction is 3.3 %, and the translation error in Y the direction is 2.7 %, can meet the need of deep space optical communication, so it is a feasible scheme.