| 20090002225 | Keeping Accurate Time For A Hybrid GPS Receiver And Mobile Phone When Powered Off - A hybrid navigation satellite receiver and mobile telephone uses only two crystal oscillators. One that operates a master clock around 27-MHz and that consumes milliwatts of power. The other oscillator consumes only microwatts of power and operates continuously on battery power at about 32-KHz. Only the second, low frequency oscillator is kept running during power “off”. On power “restart”, a real-time-clock counter is consulted to cause an estimate of the GPS system time to be regenerated and supplied to the GPS-DSP to quicken its initialization. The master clock is GPS-calibrated, and the accurate clock is used to drive NCO's for the mobile telephone part and host CPU. | 01-01-2009 |
