COMBINATION OF HYBRID NAVIGATION SATELLITE RECEIVER AND MOBILE TELEPHONE, UNIFIED SATELLITE NAVIGATION RECEIVER AND COMMUNICATIONS EQUIPMENT COMBINATION SYSTEM PROVIDED WITH SINGLE PORTABLE DEVICE INCLUDING GPS RECEIVER AND COMMUNICATION TRANSMISSION AND RECEPTION PART, AND METHOD FOR LIMITING THE NUMBER OF CRYSTALS NEEDED FOR REFERENCE OSCILLATOR WHEN INTEGRALLY COMBINING NAVIGATION RECEIVER AND MOBILE TELEPHONE

摘要

PPROBLEM TO BE SOLVED: To provide a method for keeping accurate time for a hybrid GPS receiver and mobile telephone, when power is shutdown. PSOLUTION: The hybrid navigation satellite receiver and mobile telephone uses only two crystal oscillators. One operates a master clock around 27 MHz and 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 an accurate clock is used to drive NCOs for the mobile telephone part and host CPU. PCOPYRIGHT: (C)2007,JPO&INPIT