FPGA Realization of Code Tacking Loop in PN Code Ranging

The design of code tracking loop is one of the key part of the PN code /carrier ranging system.The structure of code tracking loop is analyzed.The key parts of the code tracking loop,NCO and loop filter,are designed by look-up table and quadratic loop,their corresponding circuits are presented.The simulation and test results on FPGA show that real time and exact PN code tracking is realized,and PN code length is less than carrier period length.It has some reference value for the engineering practice of code tracking loop.