| 摘要 |
PURPOSE:To eliminate a fact that position measurement cannot be executed in case when track data is updated, etc. by providing a period for measuring a pseudo distance of a satellite, and a period for demodulating track data of the satellite, in a period of one bit of the track data from the satellite. CONSTITUTION:Track information and pseudo distance information are supplied to a track data demodulating part 4 and a pseudo distance measuring part 5, respectively. Its track data and pseudo distance data are supplied to a position measurement operating part 7 and a position measuring calculation is executed. In a period of one bit of the track data, the position measuring calculation is executed by measuring a pseudo distance for the satellite, which is required for the position measuring calculation by synchronizing with said period, with regard to four satellites. Also, in the remaining period, the track data of the satellite required for collecting the track data is demodulated. In this way, the track data of all satellites being up in the sky are always demodulated successively, therefore, the position measurement impossible time in case when updating the track data, or in case when changing the combination of the satellites can be eliminated. |
