Design of Digital Tracking and Communication Composite Receiver for Four Quadrant Detector

With the rapid development of micro-nano satellite technology, the light and compact design of laser communication receiving terminals has become the current development trend. Quadrant detector is a kind of photodetector of which photosensitive surface quadrant distribution. This characteristic makes quadrant detector not only detect signal of light, but also detect the position of spot. In this paper digital tracking and communication composite receiver for four-quadrant detector is designed. First, the quadrant detector converts the optical signal into an electrical signal. And then the pre-transimpedance amplifier circuit amplifies the signal and converts it into a voltage signal. Next, the A/D module photoelectric signals are converted into digital signals, and the FPGA based digital algorithms perform tracking and communication related signal processing. By theoretical analysis, when the bit error rate is 10(-6), the communication rate is 10Mbps and the signal to noise ratio is 90.09, the detection sensitivity is -45.06dbm. Also it is realized the position resolution of 6.29 mu m. Through the software implementation of tracking and communication function, the feasibility of the design is further verified, which lays the foundation for further development of the receiver.