A system to mitigate errors in GPS corrections and ephemeris uncertainty data broadcast to a vehicle is presented. The system includes reference receivers in a first ground subsystem and a processor. The processor: receives, from reference receivers in a wide area network of reference receivers, satellite measurement data for a first plurality of satellites and receives, from the reference receivers in the first ground subsystem, satellite measurement data and ephemeris data from a second plurality of satellites; evaluate the satellite measurement data to determine if the GPS corrections are degraded by a current ionosphere disturbance activity; determine a current quality metric of the ionosphere; adjust a Vertical Ionosphere Gradient standard deviation sigma-vig; evaluate the ephemeris data to determine if the GPS corrections provided to the vehicle are degraded by ephemeris errors; and establish ephemeris uncertainty to protect integrity based on the evaluation of the ephemeris data.

A Global Positioning System (GPS) receiver, a control method of the GPS receiver, and a GPS system are provided, which are capable of reducing an initial position check time using an SBAS signal transmitted from a SBAS satellite. The control method of a GPS receiver includes receiving an SBAS signal from a SBAS satellite and calculating a satellite clock and a satellite position of the GPS receiver using the received SBAS signal. The SBAS signal may contain a difference value between the ephemeris data and the almanac data of the GPS satellite. The difference value between the ephemeris data and the almanac data may include a satellite clock difference value and a satellite position difference value for the GPS satellite. Accordingly, it is possible to acquire the current position and time information more quickly and accurately, by shortening the initial position check time using the difference value between the ephemeris data and the almanac data included in the SBAS signal.

A ground-based system to reduce the effect of interference, comprising a plurality of reference receivers, wherein the reference receivers are spaced a distance apart such that a single source of interference is unable to substantially interfere with a subset of the plurality of reference receivers, wherein the subset of the plurality of reference receivers includes at least two reference receivers; and a processing module communicatively coupled to the plurality of reference receivers and configured to receive data from each of the plurality of reference receivers, wherein the processing module is further configured to perform differential calculations on the data to calculate measurement corrections and estimated errors.

GBAS includes reference receivers, processing module, and communication device. Processing module checks GNSS satellite measurements to determine proximity of GNSS satellite measurement's IPP to IGPs derived from SBAS geostationary satellites. Processing module determines that GNSS satellite measurement is safe for mitigation using overbounded Vertical Ionosphere Gradient standard deviation sigma-vig (.sub.vig) when IGPs possess acceptable GIVE values. Processing module determines whether number of GNSS satellite measurements determined safe for mitigation using .sub.vig are able to produce VPL that meets VAL required for precision approach. Communication device communicates overbounded .sub.vig along with differential corrections and indication of which GNSS satellite measurements that are safe for mitigation using at least one overbounded .sub.vig are able to produce VPL that meets VAL required for precision approach to GNSS receiver when number of GNSS satellite measurements determined safe for mitigation using overbounded .sub.vig are able to produce VPL that meets VAL required for precision approach.

Techniques and apparatus for satellite-based determination of a position of a mobile device are disclosed. In some embodiments, such techniques include: obtaining a plurality of first satellite measurements in a first frequency, and a plurality of second satellite measurements in a second frequency; using at least qualified or consistent satellite measurements to determine the position of the mobile device, sending at least the qualified or consistent satellite measurements to a network device, or disabling usage of first satellite measurements in the first frequency or second satellite measurements in the second frequency.

Systems and methods for sharing convergence data between GNSS receivers are disclosed. Convergence data received at a GNSS receiver via a communication connection may be utilized to determine a position of the GNSS receiver.

A navigation satellite system, one or more NSS reference station is set out for providing information to one or more rover receivers. The NSS reference station comprises a processing unit configured to determine one or more first range intervals representing first ambiguity windows based on estimated atmospheric effects, and determine one or more second range intervals representing a second ambiguity window smaller than each of the first ambiguity windows based on uncertainties of range measurements within a predetermined previous period. The NSS reference station further comprises a transmission unit configured to transmit, to the NSS rover receivers, first messages each comprising a modulo a first ambiguity window, and transmission of two first messages, to range measurement transmit between the NSS rover receiver, a plurality of second messages, each second message comprising a range measurement modulo one of the second ambiguity windows.

Systems and methods for averaging satellite sigmas and readmitting excluded satellite measurements into differential corrections and integrity monitors are provided. In one embodiment, a method comprises: calculating a first RFI based averaged sigma and a second RFI based averaged sigma, wherein the first RFI based averaged sigma includes a sigma for the excluded satellite measurement and wherein the second RFI based averaged sigma does not include the sigma for the excluded satellite measurement; and, readmitting the excluded satellite measurement into either a differential correction broadcast or a respective integrity monitor when the first RFI based averaged sigma is less than or equal to the second RFI based averaged sigma.

An error correcting location system includes a ground station with fixed reference coordinates. The ground station may receive satellite broadcast messages from a plurality of location system satellites. Further, the ground station may determine location coordinates based on the satellite broadcast messages, and compare the location coordinates to the fixed reference coordinates to determine a compensation value. In addition, the ground station may send the compensation value to location system devices. Upon receipt of the compensation value, the location system devices may utilize the compensation value to generate highly accurate location coordinates.

A system is provided for tracking an asset within a geographic area. The system includes an antenna mast supportable by, and extending upward from, an object configured to move or facilitate movement of the asset. The antenna mast is capable of supporting a plurality of wireless locating units of a plurality of geo-spatial positioning systems, which are configured to locate a respective one or more locating units, and thereby the asset, within the geographic area. The system also includes a controller positionable on the object and configured to control operation of the wireless locating units. The controller is further configured to direct transmission of data to a host via one of the locating units or another wireless transmitter, and in a manner that accounts for a wireless link between the respective locating unit or other wireless transmitter and the host.