| 摘要 |
PROBLEM TO BE SOLVED: To shorten TTFT (time to first fix) at hot start time. SOLUTION: A time in a prescribed range from the time of RTC (real-time clock) is used as a candidate time, and a satellite position at the candidate time is calculated, based on ephemeris data, and a distance between the last located position and the satellite is calculated based on the calculated satellite position. Successively, a transmission time from the satellite relative to the candidate time is calculated based on the calculated distance; the satellite position at the transmission time is calculated; and a distance to a satellite receiver is calculated, based on the calculated satellite position and the last positioning position. Then, the difference between a part corresponding to the figure of 1 millimeter-second or less of the distance to the satellite receiver and a part of 1 millimeter-second or less of a pseudo-distance, actually received from the satellite is used as a pseudo-distance residue, and the pseudo-distance residue of each satellite is calculated for positioning; and the pseudo-distance residue at the positioning position is determined, and a candidate time having a small standard deviation is deduced. COPYRIGHT: (C)2011,JPO&INPIT |
