| US 7,456,782 B2 | ||
| Timing calibration for fast signal reacquisition in navigational receivers | ||
| Chi-Shin Wang, Half Moon Bay, Calif. (US); Lianxue Xiong, Shanghai (China); Zhike Jia, San Jose, Calif. (US); Lei Dong, Cupertino, Calif. (US); and Jingbin Liu, Shanghai (China) | ||
| Assigned to SiRF Technology, Inc., San Jose, Calif. (US) | ||
| Filed on Dec. 29, 2005, as Appl. No. 11/322,654. | ||
| Prior Publication US 2007/0152876 A1, Jul. 05, 2007 | ||
| Int. Cl. G01S 5/14 (2006.01) | ||
| U.S. Cl. 342—357.02 [342/357.12; 342/357.15] | 27 Claims |
| 1. A method for calibrating a local clock of a navigation receiver, wherein the local clock is based on an oscillator, comprising:
calculating a clock calibration value based on a computed oscillator count for a period during which the receiver is in a
sleep state or for a duration of signal blockage; and
calibrating the local clock using the clock calibration value during reacquisition of GPS signals when the receiver wakes
up from the sleep state or comes out of signal blockage;
wherein the clock calibration value is compensated for Doppler frequency changes during the period of the sleep state or the
duration of signal blockage.
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