| QPSK modulation and demodulation has series of notable fuatures,forexample fast, strong anti-interference abilitys, modulation and demodulation in the field of modern communications, widely used in satellite and mobile communications. Powerful FPGA capabilities, with a short design cycle, high reliability, and work fast FPGA to implement the function of the modulation and demodulation circuit device will have a small size, speed, more flexibility and control than any other chip as well as future software updates more flexibility. Therefore, based on FPGA-QPSK IF digital demodulation of great significance.This paper briefly introduces the basic principles of the QPSK demodulator, combined with software simulation of the QPSK demodulator system, draw the block diagram of the demodulation system according to the actual demodulation asked to select the appropriate chip to draw a circuit diagram produced the increase in the hardware circuit on the basis of the QPSK demodulator circuit board hardware, and according to actual needs of two computer data transmission module:CY68013(USB micro-controller) modules and fiber optic module. In this paper, QPSK demodulator module and the data transfer module hardware circuit design schematics and PCB drawing. After the complete set of hardware circuit, drawing and production, commissioning in good working condition the extent of the transmission module and a combination of the VHDL program of the QPSK demodulator demodulation functions, and computer acquisition demodulation results. The results show debugging of the design of the original design performance index.This paper describes the role of the QPSK demodulator design process as well as various small modules to achieve the goal of combining theoretical knowledge and practical design. After the completion of this design, small size, high integration, easy software updates, and convenient connection with the computer, have some practical significance. |
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