北斗二代接收机中的跟踪程序，模块有载波环（二阶FLL，三阶PLL），FLL辅助PLL,码环是用二阶DLL，再用载波环辅助码环-Compass II receiver tracking program, module carrier ring (second-order FLL, the third-order PLL), FLL auxiliary PLL, code ring is by Second DLL, then the carrier ring auxiliary code ring