Abstract: An improved extended ephemeris navigation receiver includes a fully autonomous satellite navigation receiver for receiving microwave transmissions from orbiting navigation system satellites, and able to demodulate navigation messages that include the ephemerides for those navigation system satellites. The improvements include a force model of the accelerations acting on a particular satellite vehicle, and are exclusive to the receiver. A single observation of the ephemeris for each SV is input and propagated days into the future by integrating each SV's orbital position with its corresponding force model. The fully autonomous satellite navigation receiver thereafter has available to it extended ephemeris predictions that can be used as substitutes when said navigation messages from the respective SV cannot otherwise be immediately obtained and demodulated.

Abstract: 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.

Abstract: 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.

Abstract: A roving extended range high sensitivity satellite positioning system receiver provides position fixes in adverse signal conditions as low as minus 150 dbm and with as few as three satellites by measuring the bit phase of the navData message and the codephase, and finding a simultaneous solution. Previous position fixes that were obtained in the vicinity by earlier rovers are deposited in an indexed database for consultation. A cellular phone system can be used to simply communicate the current identity codes and their database entries.

Abstract: 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.

Abstract: A navigation satellite receiver accepts satellite-position table messages comprising truncated GPS ephemeris parameters. In particular, at least one of the two harmonic corrections to inclination angle, Cic and Cis, are not communicated and not used in the solution of navigation receiver position. In a first method embodiment of the present invention, both the two harmonic corrections to inclination angle, Cic and Cis, are omitted from the computation. In a second method embodiment of the present invention, only one of the two harmonic corrections to inclination angle, Cic and Cis, are omitted from the computation, depending on Min(Cis sin(2?k), Cis cos(2?k)).

Abstract: 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.

Abstract: A combination mobile phone and navigation satellite receiver comprises a circuit for correcting GPS receiver reference frequency drift by using VCO burst information periodically received by a PDC handset. A corrected GPS receiver reference frequency drift then enables faster initialization and stable operation of the position solutions made available to users. A GPS numeric controlled oscillator (NCO) receives a PDC handset VCO sample.

Abstract: A cellphone system comprises a GPS reference station located with a telephone cell site. Such GPS reference station tracks the GPS satellites visible to its local area and estimates the Doppler for each such GPS satellite. The system also includes mobile GPS receivers and cellphones that move around and through the operational area of the cell site. It is assumed that the satellite Dopplers seen by the GPS reference station will have insubstantial differences with the true Dopplers observed by other GPS receivers operating within the cell site's service area. The Doppler estimates are thus routinely communicated over a wireless telephone channel to the mobile GPS receivers and cellphones that register locally. Such mobile GPS receivers then can confidently adopt the surrogate Doppler estimates as a center starting point for their initialization frequency searches. The time required for such mobile GPS receivers and cellphones to initialize and provide a first fix is thereby substantially reduced.

Abstract: A navigation-satellite receiver comprises high-sensitivity radio frequency front-end and navigation processor associated with a client CPU. The client CPU runs an operating system that serially communicates with the navigation processor. The client CPU is also able to obtain navigation data system transmissions from a network server and provides such when the direct satellite signals in the high-sensitivity environment are too weak to be demodulated directly. A low power, low frequency oscillator with a watch-type crystal and counter are used as a real time clock to keep time uncertainty under fifty milliseconds when the receiver is hibernating. If the time uncertainty and position uncertainty are below certain maximums when the receiver is re-awakened, then a minimum number of satellites will be needed and making a preliminary z-count to each can be avoided.

Abstract: A navigation-satellite receiver comprises high-sensitivity radio frequency front-end and navigation processor associated with a client CPU. The client CPU runs an operating system that serially communicates with the navigation processor. The client CPU is also able to obtain navigation data system transmissions from a network server and provides such when the direct satellite signals in the high-sensitivity environment are too weak to be demodulated directly. A low power, low frequency oscillator with a watch-type crystal and counter are used as a real time clock to keep time uncertainty under fifty milliseconds when the receiver is hibernating. If the time uncertainty and position uncertainty are below certain maximums when the receiver is re-awakened, then a minimum number of satellites will be needed and making a preliminary z-count to each can be avoided.

Abstract: A navigation-satellite receiver support data network comprises a server connected to the Internet to provide initialization information to clients for faster cold starts. The server includes a GPS receiver that provides for tracking of a constellation of navigation satellites. When a client is started cold, time and frequency are initially unknown to it. Test messages are sent back and forth over the Internet and a path delay time is computed from the average of the quickest transit times. This yields the offset time between the server's time system and the client's time system. The server sends current time information to the client, and the computed path delay is added. The client can then compute correct time from the server and path delay information, and thereby select much sooner which satellites are correct to search.

Abstract: A cellphone system comprises a GPS reference station located with a telephone cell site. Such GPS reference station tracks the GPS satellites visible to its local area and estimates the Doppler for each such GPS satellite. The system also includes mobile GPS receivers and cellphones that move around and through the operational area of the cell site. It is assumed that the satellite Dopplers seen by the GPS reference station will have insubstantial differences with the true Dopplers observed by other GPS receivers operating within the cell site's service area. The Doppler estimates are thus routinely communicated over a wireless telephone channel to the mobile GPS receivers and cellphones that register locally. Such mobile GPS receivers then can confidently adopt the surrogate Doppler estimates as a center starting point for their initialization frequency searches. The time required for such mobile GPS receivers and cellphones to initialize and provide a first fix is thereby substantially reduced.

Abstract: A navigation-satellite receiver comprises a real-time clock that can be slaved to the highly accurate time base of the GPS system. During such times, the amount of correction and the operating temperature are both tracked. It is assumed the operating temperature will has the greatest influence of frequency errors later when the real-time clock cannot be slaved to the GPS time base. When the receiver is powered-down, the real time clock is nevertheless kept alive. Its free-running frequency is corrected for temperature. The next time the receiver is powered up, time accurate to better than one millisecond in a day can be obtained instantly for use in other receiver initialization procedures.

Abstract: A navigation satellite receiver method determines what navData is on-hand, what level of time uncertainty exists, and what position uncertainty there is for the receiver at turn-on. Indoor and outdoor search engines are used that can vary their search windows and dwell times to increase receiver sensitivity. Received signals are stored in several playback loops that can be operated in parallel to increase search sensitivity in the face of large uncertainties in time ad frequency, and still reduce the time-to-first-fix. Satellite acquisition can be achieved even when the navData is too weak to be read by requesting help from a server.

Abstract: A navigation receiver comprises a digital sampler that precedes digital signal processing which can operate at a high rate and a low rate. If the high rate is selected for noise reduction by non-coherent averaging, the samples are averaged over time and transformed to the low rate. The digital signal processor is fed only low-rate samples in either case.

Abstract: A navigation-satellite receiver comprises means for initialization that gets a head start by knowing time to within a few seconds and position to within 150 kilometers. A two-dimensional grid of points is setup with constant altitude that represents solution starting points within the 150 kilometer area. Fractional pseudoranges from each satellite in a constellation are inspected for a best initial fit with the points in the grid. A variety of time bias adjustments within the time bounds are also tried against the points to find a best fitting point. That point then is used in a drive to find the final solution and to produce the first fix from cold start.

Abstract: An SPS receiver comprises a radio receiver for measuring pseudoranges to orbiting SPS satellites, a local real time clock accurate within three seconds of true SPS system time, and a communication channel to receive NAV-data rebroadcasts from a server. Such server is associated with its own private navigation receiver that has direct satellite signal reception that is strong enough to reliably demodulate the SPS system NAV-data. The SPS receiver synthesizes its own NAV-data from time information provided by the local real time clock and almanac and ephemeris data provided by the server in the rebroadcast. Thus the SPS receiver can operate in weak signal environments that would otherwise be impossible.

Abstract: A navigation-satellite receiver uses a reference station accessible over a network to store NAV data subframes for pattern matching at a network client. Alternatively, the pattern matching is performed by the server when per-byte communication costs are high. The stored NAV data repeats ephemeris data every thirty seconds, and full almanac data every 12.5 minutes. This permits the client to instantly recognize where in the NAV data sequence its own received signals are, and it need not actually wait to receive the preambles in the TLM words. Several precious seconds are therefore saved in producing a rapid time-to-first-fix.

Abstract: A reference station system comprises a plurality of GPS reference stations that are distributed in different parts of the world to be able to simultaneously gather a complete set of satellite vehicle ephemeredes. Each reference station is associated with a network server connected to the Internet. Each network server posts ephemeredes, NAV-data, and other useful information for clients derived from its corresponding reference station. All such network servers inject their information in all the other servers in the system Each server validates and authenticates any injected data. Each client is also qualified as a subscriber before being able to access the complete ephemeredes database and other GPS system information.