Research on Code Synchronization Technology of Direct Sequence Spread Spectrum Underwater Acoustic Communication
In order to reduce the dependence of spread spectrum code synchronization technol-ogy on hardware and improve the performance of underwater acoustic communication ma-chine,this paper makes some improvements on the basis of traditional spread spectrum code synchronization technology.The synchronization of spread spectrum code includes two sta-ges:code acquisition and code tracking.In the code acquisition stage,the double zero filling method is used to expand the received signal and the local spread spectrum code sequence of the receiver to meet the requirements of radix-2 fast fourier transform operation;In the con-trol logic part,the reservoir sampling algorithm is used to determine the calculation order of carrier frequency offset within the range,without traversing the carrier frequency offset within the range in a fixed order,so as to reduce the amount of calculation.In the code tracking stage,this paper adopts the full-time lead-lag incoherent correlated synchronous tracking loop and the design of double Δ value delay phase-locked loop,which expands the tracking range and reduces the probability of losing lock.Finally,a direct sequence spread spectrum underwater acoustic communication system is realized based on DSP platform,which has passed the test of water tank experimental environment.
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维普
