Abstract: A global positioning receiver unit utilizes a temperature compensated oscillator and a unit controller. The temperature compensated oscillator generates a clock signal, and the unit controller is configured to track GPS time based on the clock signal while the receiver unit is in a sleep state. The unit controller is further configured to perform a position fix based on a satellite signal and the GPS time tracked by the unit controller.

Abstract: A method for detecting a positioning signal includes (a) correlating a segment of a received positioning signal with a reference signal of a selected code phase and frequency to obtain a correlation value, (b) if the correlation value is less than a predetermined minimum, assigning the correlation value to the predetermined minimum, and (c) accumulating the correlation value in a sum of correlation values obtained using other segments of the received positioning signal. In addition, the correlation value may be reduced by a predetermined value, which is preferably an expected mean value for a noise component in the segment of the received positioning signal.

Abstract: The present invention discloses a system for determining the position of a GPS terminal. The system comprises a GPS terminal, a location aiding server, and a communications system. Messages are passed between the GPS terminal and the server, as well as within the GPS terminal, to determine the mode of operation of the GPS portion of the system. Decisions are made based on availability of aiding data and Quality of Service requirements.

Abstract: A GPS receiver system determines the presence of trackable signals at code delays less than the prompt delay being tracked for a particular, signal and changes the prompt delay to correspond to the smallest code delay having a trackable signal. Trackable signals at large code delays are multipath signals and may be separately tracked to aid in dead reckoning. The trackable signals at code delays not adjacent to the current tracked prompt delay may be tracked in the same channel as the prompt delay so that all satellite channels are continuously evaluated for multipath signals being tracked or a non-satellite specific channel may be used to sequentially step through the satellite signals to evaluate multipath on a satellite by satellite basis.

Abstract: In a mobile communication device, a method for compensating for a frequency adjustment in an oscillator shared between a communication circuit and a positioning signal receiver is provided. In one embodiment, a method for determining the operating frequency of an oscillator detects a beginning time point of a reference signal received by the mobile communication device and enables a counter to count in step with a clock signal derived from the oscillator. When an ending time point of the reference signal is received by the mobile communication device, the count is stopped, and the frequency of the oscillator is determined based on the count in the counter and an expected time that elapsed between the beginning time point and the ending time point.

Abstract: A GPS car navigation system derives GPS position update information from motion of the car along the actual track. Turns along the track are detected when they actually occur and are compared with the predicted turns so that the time and position at the actual turn can be used to update the then current GPS derived position of the vehicle. Updating position information with actual turn data improves the accuracy of GPS navigation especially during single satellite navigation.

Abstract: Techniques are provided for synthesizing a long coherent I and Q correlation integral at a particular frequency by synthetically combining a sequence of shorter correlation integrals at the same or different frequency. Techniques are also provided for acquiring a carrier-modulated signal with an unknown shift of the carrier frequency, and possibly some additional unknown signal parameters. These techniques involve synthesizing coherent correlation sums at a fine frequency resolution, using coherent correlation sums that are calculated at a coarse frequency resolution. This approach allows for coherent processing of the received signal over an arbitrarily long time interval, while avoiding the excessive computational requirements of traditional methods.

Abstract: A data detection circuit within a global positioning system (GPS) satellite receiver operates to detect and decode data sent in a spread spectrum signal. The data detection circuit receives input from a radio receiver, the information containing data from a plurality of satellites. The data is supplied to a circular memory device, which determines which data corresponds to which satellite. The memory device sends the received signal to a matched filter, which decodes the signal received from each satellite. This signal is analyzed to determine whether a phase inversion due to data modulation on the received signal is present. The phase inversion can occur at boundaries, known as data epochs, in the received signal, and corresponds to data in the received signal. This data contains information relating to the position of each satellite and is collected by the data detection circuit for use by the GPS receiver.

Abstract: A satellite based positioning method and system including storing satellite sub-almanac data on a mobile station. Embodiments include using the sub-almanac data to take measurements and calculate a coarse position of the mobile station. Embodiments further include a location server calculating a correction to the coarse position, and the location server determining whether any sub-almanacs used to calculate the coarse position require replacement.

Abstract: The invention comprises a set of pseudolites deployed throughout an area of interest in which the GPS constellation visibility may be limited, such as in and around some high-rise buildings in an urban setting, and a database of these installed pseudolite locations with their PRN numbers indexed by cell-site. When the cellular telephone is in communication with a particular tower or transceiver, the PRN numbers of all local pseudolites are transmitted to the cellular telephone. If the cellular telephone has a position solution which has been transmitted to the cell tower, prepositioning information for a code search can be transmitted to the phone as well. The phone can then augment the phone's normal acquisition list with the pseudolites in the area and track the pseudolites to augment navigation capabilities in a harsh environment.

Abstract: A two part signal acquisition process includes a parallel signal detection process and signal verification/false alarm rejection process. A massively parallel architecture of acquisition correlators search a large region of the time-frequency uncertainty during the parallel signal detection process to identify the most likely detections for each search dwell. Concurrent with the parallel signal detection process performed by the acquisition correlators, the current list of most likely detections is examined with additional search dwells in the verification/false alarm rejection process. The verification/false alarm rejection process is performed by a plurality of independent correlators or tracking channels. Under software control, the tracking channels perform repeated dwells on the most likely detections until they can be dismissed as false alarms or verified as the desired signal.

Abstract: A partial almanac collection system is disclosed. The partial almanac collection system includes a global positioning system (“GPS”) module, and a controller in signal communication with the GPS module and the call processor, the controller instructing the GPS module to collect piecewise almanac data in response to a request from the call processor.

Abstract: A protocol independent interface for processing, within a mobile device, protocol aiding data received at a call processor with a Global Positioning System (“GPS”) interface, where the protocol aiding data is produced according to a Geolocation Server Station protocol is disclosed. The protocol independent interface may include a means for receiving, at the GPS interface, the protocol aiding data received at the call processor, means for converting the received protocol aiding data to interface data that is transparent to the Geolocation Server Station protocol, and means for passing the interface data to a GPS module.

Abstract: The invention relates to an aided Global Positioning System (GPS) subsystem within a wireless device. The wireless device includes a wireless processing section capable of receiving signals from a wireless network and a GPS subsystem having a radio frequency (RF) front-end capable of receiving a GPS satellite signal. The wireless processing section of the wireless device receives an external clock and determines the offset between the clock in the wireless processing section and that of the external clock. The GPS subsystem then receives the offset information from the wireless processing section, information related to the nominal frequency of the wireless processing section clock and the wireless processing section clock. Using this information and the GPS clock in the GPS subsystem, the GPS subsystem determines an acquiring signal, which is related to a frequency offset between the GPS clock and the network clock.

Abstract: A multi-function device with a positioning function and a real time positioning engine is disclosed. The device contains also a shared processor used by the positioning function and other functions of the device, such as a mobile radio-communication function. The positioning engine performs in real time the most computational intensive calculations of the positioning function, such as downsampling, Doppler mixing and correlation calculations. Since the received signal need not be stored, the memory requirements of the positioning function are significantly reduced if aiding data is available.

Abstract: The present invention discloses methods, apparatuses, and systems for eliminating auto- and cross-correlation in weak signal CDMA systems, such as GPS systems. The invention uses parallel data paths that allow standard correlation of signals in parallel with verification of the lock signal to determine whether the system has locked onto the proper signal within the scanned signal window. The invention can be made with multiple CPUs, a single CPU with dual input modes, on multiple IC chips, or as a single IC chip solution for small, low cost reception, downconversion, correlation, and verification systems.

Abstract: A receiver in receipt of a plurality of pseudo noise codes, where each of the pseudo noise codes originates from a GPS transmitter and a plurality of chips make tip each pseudo noise code with an offset between 511 chips before a pseudo noise code boundary and 512 chips after the pseudo noise code boundary, and a local clock having an error of less than 0.5 ms relative to a GPS time and synchronized to a GPS signal that is able to be decoded with a decoder connected to the receiver and the local clock and by simultaneously solving the four pseudo range equations for at least four GPS transmitters a determination of the location of the receiver occurs.

Abstract: The present invention discloses methods, apparatuses, and systems for eliminating auto- and cross-correlation in weak signal CDMA systems, such as GPS systems. The invention uses parallel data paths that allow standard correlation of signals in parallel with verification of the lock signal to determine whether the system has locked onto the proper signal within the scanned signal window. The invention can be made with multiple CPUs, a single CPU with dual input modes, on multiple IC chips, or as a single IC chip solution for small, low cost reception, downconversion, correlation, and verification systems.

Abstract: System and method for mitigating the effects of narrowband noise in a location-determining signal are provided, wherein the location-determining signal is associated with a periodic reference signal, the embodiments include identifying a set of noisy frequencies in the signal, determining a set of frequencies to be removed, and removing the set of frequencies from either the location-determining signal or the reference signal, thereby removing the effects of narrowband noise from the location-determining signal.

Abstract: Techniques are provided for synthesizing a long coherent I and Q correlation integral at a particular frequency by synthetically combining a sequence of shorter correlation integrals at the same or different frequency. Techniques are also provided for acquiring a carrier-modulated signal with an unknown shift of the carrier frequency, and possibly some additional unknown signal parameters. These techniques involve synthesizing coherent correlation sums at a fine frequency resolution, using coherent correlation sums that are calculated at a coarse frequency resolution. This approach allows for coherent processing of the received signal over an arbitrarily long time interval, while avoiding the excessive computational requirements of traditional methods.