四象限探测器在通信与跟踪复用模式下的性能研究

Performance Research on Four-Quadrant Detector in Communications and Tracking Compound Mode

针对星间链路中测距与通信统一系统的需求，提出了一种使用四象限探测器作为跟踪探测器，同时兼顾激光载波通信的方案，使光通信端机在单探测器条件下就能完成通信与跟踪的任务。在室内条件下建立了相应的通信与跟踪复用的测试实验，对四象限探测器在通信模式下的通信速率、极限灵敏度、探测器响应能力等探测性能进行测试。利用曼彻斯特编码特点，采用低通滤波电路对调制光信号进行处理，实现对信号光脱靶量的标定与提取。在光斑不能完全覆盖探测器所有象限时，对探测器输出的通信信号进行优化选取，提高信号信噪比。实验结果表明，采用光敏面直径1mm的PIN型InGaAs四象限探测器，在曼彻斯特编码条件下．通信速率可以达到10Mbps，探测极限灵敏度为-33dBm，误码率为10^-7初步确定了四象限探测器用于通信与跟踪复用模式的可行性，为未来星间激光测距光端机轻小型化奠定基础。

Aiming at the communications requirement of inter-satellite links laser ranging, a scheme of using fourquadrant detector as the communications detector and simultaneous tracking for the communications laser is proposed. The system can complete the communications and tracking missions in the condition of single detector. The corresponding communications and tracking compound mode experiment is established in laboratory and the detection performance which includes communications rate, limiting sensibility, photoresponse ability is tested. The calibration and extraction of communications laser miss distance is using low pass filter to deal with the modulate signal by the characters of Manchester code. When the laser spot could not cover all quadrants of the detector, the output communications signal is optimized and selected to improve the signal-to-noise ratio（SNR）. The experimental results show that by using the PIN type InGaAs four-quadrant detector which photosensitive surface diameter is lmm, the communication rate can achieve 10Mbps , the detection limiting sensitivity is -33 dBm and the SNR is 10^-7. Initially the feasibility of four-quadrant detector in communications and tracking compound mode is confirmed and will lay the foundations for satellite miniaturization in future.