Application Of DSP In Full Digital BPSK Demodulator

A full- digital demodulation technique is introduced in this paper, Which can make it easy and quick to design and achieve Binary Phase Shift Keying (BPSK) demodulator, and also can reduce the requirement of the oscillator frequency precision and the degree of stability of the receiver. At present, the way of BPSK demodulation is widely used in digital satellite communicating system, mobile satellite communicating system, telemetry system and telecontrol system. This is because this modulation system has a suitable spectrum availability and a low biterror rate for a given signal-to-noise ratio, which make it more and more important in telemetry system and telecontrol system.The movement of the satellites causes doppler frequency to drift, the receiver usually tracks the signal frequency the receiver through phase locked loop, in order to can demodulate the signal. But in fact, not all the demodulator can easily be designed and achieved, especially when the data transporting speed is quite low.There are many ways of modulating signal about BPSK such as Castas loop, square loop, etc. usually the carrier wave is put forward firstly, then the purified carrier wave is used to demodulate the output data( All these things are usually completed in the same loop). These methods have their strong points but at same times, it is difficult to design and achieve these ways. For example, when the speed of transporting is very low, it is very difficult to track the receiver signal frequency through the common phase locked loop. In this paper, we are going to use high speed digital signal processor ,track the carrier wave through the digital phase locked loop, and so to demodulate the modulating signal. It can overcome the difficult problems of the other ways.The system design of the digital signal processor (DSP) and the development of DSP are briefly introduced in this paper. And designed of the hard ware and soft ware of full digital BPSK demodulator through DSP and FPGA.