Design Of Direct Sequence Spread Spectrum Receiver Based On FPGA

With the rapid development of modern communication technology,the demand for reliability and bandwidth of communication system is increasing.The spread spectrum communication technology can improve the reliability of the system and expand the bandwidth of the system,so it is important for the research of the spread spectrum receiver.This paper mainly studies the design of direct sequence spread spectrum receiver based on FPGA,this paper introduces the basic theory of spread spectrum communication system,and discusses the various parts of the principle of spread spectrum communication systems,including the source principle,forming principle,principle of PN code acquisition and tracking principle of spread spectrum code tracking and carrier principle.The spread spectrum signal produced by the source is to provide the source for the receiver to realize the acquisition of the spread spectrum code,the tracking of the spread spectrum code and the carrier tracking.The overall design of the system includes hardware design and software design.The hardware design of the system is based on the software radio architecture,which is implemented by FPGA and AD9361.The system hardware focuses on the circuit design of FPGA and AD9361 and the design of the system hardware PCB.The system software design mainly includes the source module,the capture module,the pseudo code tracking module and the carrier tracking module.The modulation method of source data is phase shift keying BPSK.The acquisition algorithm of acquisition module is parallel FFT.The tracking loop of PN code tracking module is incoherent delay locked loop,and the tracking loop of carrier tracking module is improved in phase orthogonal loop.Finally,the whole system is tested by function.The Chipscope tool is used to complete the test.The test contents include the BPSK modulation signal test of the source part,and the function verification of spread spectrum code acquisition,spread spectrum code tracking and carrier tracking.Through the above test,it is proved that the system can work well.