Fpga-based High Dynamic Gps Digital If Despreading Technology Research

At present, satellite navigation industry represented by the global positioning system (GPS) has become one of the fastest developing information industries. GPS can provide precise position & velocity and time information all weather worldwide. It's widely used in traffic, navigation, vehicle location and so on.The topic is from the NCUT's key project that is three-in-one receiver with differential communication function.The topic will research dispreading the GPS digital IF signal. Despreading spectrum techniques is one of the key techniques of GPS receiver. It has significant influences on the GPS receiver's performances. This topic has contributed to the key project's development. This topic will research on the dispreading of GPS L1 signal. The dispreading has three states that is acquisition, tracking and synchronization. In order to fit high dynamic mode, the bandwith of acquisition is±10KHz and the precision of PN code is 1/16 code.This paper first introduce the fundamental principle of GPS, explaining the fundamental principle of spread spectrum technique. Then the paper will analysis the project's indicators. This topic choice modified serial search algorithm as the GPS signal acquisition algorithm and choice delay-lock loop for the PN code tracking and PLL+FLL for carrier tracking. There are AD & plural down-conversion & PN code generating & carrier NCO & code-NCO & correlator & Frame and bit synchronizer time base generation modules in FPGA by using Verilog Hardware Description Language.The GPS receiver could get a precise position in the environment of high dynamic generated by GPS simulator.It also have perfect performance on static positing. Use for reference the thinking of researching GPS receiver. It can contribute to the research of GNSS receiver.