Based On Sopc Spread Spectrum Receiver And Design,

The spread spectrum (SS) communication system has stronger ability ofresisting jamming, narrow band, and multipath interference than that of theconservation communication systems. And it also has the characteristics of lowprobability of intercept and multiple access secure communication. Nowadays,the SS technology has expanded from the military field to the commercial field.This dissertation discusses the de-spreading and demodulation of the digital Direct Sequence (DS) BPSK receiver,which will be used in aircraft telemeter,with focus on the techniques of digital down-convert(DDC),fast acquisition and tracking of pseudo noise (PN) sequence,carrier synchronization and data demodulation etc.This dissertation designs a scheme of de-spread and demodulation about DS-BPSK signal,analyzes its feasibility through simulation,and finally implements it on FPGA.Combining orthogonal DDC with the spectrum shifting by undersapling. Considering acquisition time and complexity of hardware,phase searching simultaneously in muti-channel,is used in PN acquisition. Then non-coherent delay lock loop aided with carrier tracking,which has good performance of high dynamic range,is chosen to realize the PN tracking. use FLL to track the residual frequency bias. In this process, Frequency Implementation method is improved. The whole scheme is implemented on FPGA concretely and skillfully.And the practical knowledge about the design and development of FPGA are also introduced.