Research And Development Of Narrow-band And High-speed CPFSK Modulation-demodulation System Based On DSP+FPGA

As a kind of continuous phase modulated signal, CPFSK(Continuous Phase Frequency Shift Keying) signal contains several outstanding features such as constant enveloping and high spectrally efficiency.This paper tends to approach a narrow-band and high-speed CPFSK modulation-demodulation system based on the platform of DSP+FPGA. First of all, this paper introduces the basic facts, the history of CPFSK, and then the general situation of DSP and FPGA chip. The properties of CPFSK signal with different modulation parameters are simulated and analyzed; thus leading to the establishment of specific parameters of CPFSK signal. Moreover, this paper provides the design of CPFSK modulation-demodulation system, which includes modulation, synchronization and demodulation. In terms of synchronization, this paper proposes a new type called combined synchronization, with which the precision of the synchronization can be improved. Finally, the results of the modulation-demodulation transmission system will be unveiled by showing the realization of the interface between DSP and FPGA, the simulation of the modulation-demodulation process, and the data record and pictures in the testing process.