The code pursuit section which pursues the code with

摘要

PPROBLEM TO BE SOLVED: To provide an apparatus for demodulating a signal for positioning with a simple construction capable of restraining an effect on the results of tracking a code by C/No and a carrier frequency and of tracking a code and a carrier frequency with high accuracy. PSOLUTION: When a search of a signal for positioning succeeds, a demodulating part 13 firstly operates only a code tracking part 33 to perform only the code tracking part to perform fitting of the code. A C/No measuring part 36 sequentially measures C/No of a reverse diffusion signal after a correlation processing to provide a tracking process controlling part 37 with it. The tracking process controlling part 37 determines a switching timing when a status for performing only a code tracking is switched to a status of performing a code tracking and a carrier tracking in parallel based on C/No input sequentially. When reaching a switching timing, the code tracking part 33 and a carrier tracking part 34 are connected to perform simultaneous tracking of a code and a carrier. An initial value of a carrier frequency of the carrier tracking part 34 is provided as an integrated value of a code doppler integrated by the code tracking part 33. PCOPYRIGHT: (C)2010,JPO&INPIT