Abstract: GPS assistance message and data issue identifiers for transmission to GPS enabled mobile stations in cellular communications networks and methods therefor. The GPS data issue identifiers indicate whether GPS data, for example corresponding ephemeris and almanac data, stored at the mobile station requires updating. In the exemplary 3rd generation (W-CDMA/UMTS) architecture, the GPS assistance message is a System Information Block (SIB), and the GPS ephemeris data identifier and corresponding satellite identifier is encoded in a value tag included in a Master Information Block (MIB).

Abstract: A flowchart (400) includes the step (402) of collecting a predetermined number of TOA measurements arriving at the assisted satellite positioning mobile station from a base station, the step of (406) simultaneously collecting a corresponding number of GPS position measurements of a position of the GPS receiver, and the step (410) of computing the base station location and/or the step (414) of computing a perceived time bias offset required for a message to travel between the base station and the mobile station using the predetermined number of TOA measurements and the predetermined number of GPS position measurements.

Abstract: A cellular network protocol which maintains the reliability of assisted GPS based positioning is taught. An Integrity Monitor (IM) informs mobile stations, their users, or networks of measurement quality and it warns them of failing and failed GPS satellites by isolating them from the effects of these failures. Whenever an unhealthy satellite is detected, its corresponding assistance data will be excluded for delivery or for position determination. In other words, there are two specific aspects to the Integrity Monitor (IM). For DGPS users, it predicts the reliability or quality of the DGPS corrections. For all users, it isolats the mobile position calculation from the effects of GPS satellite failures. The UDRE parameter, nominally output by a reference DGPS receiver, is used to communicate the DGPS quality information, and DGPS corrections are simply excluded for failed satellites.

Abstract: An assisted global positioning satellite (Assisted GPS) system has a GPS reference network node (260) that collects GPS satellite broadcast messages and prepares separate GPS assistance messages to be modulated by a base transceiver station (BTS) (202) on a cellular carrier signal (201) and sent to single or multiple handset (204). In a first preferred embodiment, instead of the handset (204) receiving standard ephemeris and clock correction data elements in a GPS assistance message, a compressed GPS assistance message containing XYZ information contains a GPS satellite's coordinate position modified according to the satellite clock correction. In a second preferred embodiment, there is a first type of compressed GPS assistance message containing subframe 1, 2, 3 data of a GPS satellite broadcast message and a second type of compressed GPS assistance message containing subframe 4, 5 data of a GPS satellite broadcast message.

Abstract: The present invention provides methods and devices that enable correction of gyroscope bias and gyroscope bias drift in low-cost, vehicular navigation and positioning systems without using estimates of position and heading, and subsequent correction of heading and position errors resulting from gyroscope bias and bias drift, without relying on assumptions regarding gyroscope bias or predetermined time-dependent gyroscope bias drift profiles. The invention improves over existing GPS/DR systems that do not compensate for actual gyroscope bias instability, but instead correct the heading and position error that is induced by the bias instability and then correct estimates of gyroscope bias based on the corrected position and heading. The inventive methods provided herein can be used with any DR vehicle positioning system that uses a gyroscope.

Abstract: A cellular network protocol which minimizes the required data flow between the cellular infrastructure and each mobile handset supporting a GPS based positioning capability is taught. Four specific innovations are introduced which together minimize the number of bits required to be transferred to each handset: a method for reducing or removing the requirement for GPS ephemeris updates to each mobile; a method for compression of the differential correction broadcast message; a method for controlling the rate at which the network updates each handset's ephemeris based on an ephemeris age limit; and, finally, a method which each mobile can use to determine when an ephemeris update is needed, based on an accuracy prediction and a threshold which is unique to each mobile.

Abstract: A method for substantially reducing the error that accumulates in dead reckoning systems. The method includes determining heading changes from a dead reckoning system (10), testing for improbable heading changes (20), and setting to zero any invalid heading change (40). Testing for improbable heading changes (20) in differential odometry systems includes checking the sign of both prior (60) and next pulse count differences (70) and setting an invalid heading change flag (80) if either or both differ in sign. In systems using a heading rate sensor, testing for improbable heading changes (20) includes checking whether a heading change is below a minimum turn rate (90) and, if so, setting an invalid heading change flag (100).

Abstract: A method of recovering the heading of a terrestrial vehicle navigation system having a GPS receiver integrated with a dead reckoning system. After determining that a current estimate of the heading may be in error (12, 14), Doppler measurement double difference observables are computed for all GPS satellites whose L band carriers are in phase or frequency track, available distance traveled and heading change information is extracted, and the results are combined and processed (20) to produce a new current heading estimate. A recursive estimator is used to guarantee convergence to an accurate result. Conventional GPS/dead reckoning combined systems generally reset to the first available GPS position following a heading loss. Gross positioning errors can accumulate up to this point, however. The methods described can recover the dead reckoning system heading by processing Doppler information from a single GPS satellite, and thus reduce position error growth occurring when the heading is unknown.

Abstract: An odometer assisted global positioning system (GPS) method operates in a vehicle to indicate the position of the vehicle. The vehicle has an odometer, a processor, and a GPS receiver. The method knows the last position of the vehicle and finds a measured Doppler and a measured pseudo range for each satellite of the GPS which is in line of sight with the vehicle. The processor determines the Doppler compensation to the measured Doppler. The processor combines the speed of the vehicle with the Doppler compensation to the measured Doppler in order to produce a new heading of the vehicle. The processor combines the last known position of the vehicle with the new heading and with the Doppler compensation and the measured pseudo range to provide a new position of the vehicle.

Abstract: An embodiment of the present invention is a combined GPS and dead-reckoning (DR) navigation sensor for a vehicle in which a pair of modifications are made to an otherwise conventional Kalman filter. Process noise is adapted to cope with scale factor errors associated with odometer and turning rate sensors, and correlated measurement error processing is added. When only two Doppler measurements (PRRs), or three with an awkward three-satellite geometry, are available, DR error growth can nevertheless be controlled. The measurement error correlations in the conventional Kalman filter covariance propagation and update equations are explicitly accounted for. Errors induced by selective availability periods are minimized by these two modifications.

Abstract: An embodiment of the present invention is a shipboard GPS positioning system having data links to outlying tailbuoys equipped with respective GPS receivers. On ship, an Intel 386-based microcomputer system collects data from various ship's equipment including the ship's GPS receiver and data from the several tailbuoy units. A computer-implemented process located in the microcomputer system controls the following processes. Periodically each GPS receiver produces updated pseudo ranges (PRs) and these are time-tagged. The time-tagged PRs for the ship are aligned according to their time tags with their counterpart PRs from the tailbuoys. The raw PRs are then passed through a Kalman mathematical filter to produce filtered pseudo-ranges (PRs). A position solution is then attempted for each GPS receiver using the PRs. The filters provide statistical data that is used to rate the quality of each PR in a weighted least squares solution process.