An Aided Location Communication System (“ALCS”) is described that may include a geolocation server and a wireless communication device having a GPS section where the GPS receiver section is capable of being selectively switched between a standalone mode and at least one other mode for determining a geolocation of the wireless communications device. An Aided Location Communication Device (“ALCD”) is also described. The ALCD includes a position-determination section having a GPS receiver and a communication section where the position-determination section is selectively switchable between a GPS-standalone mode and at least one other mode for determining a geolocation of the ALCD.

Aided location communication system

In a satellite global positioning system, satellite acquisition and location assistance is based upon shared information between a GPS receiver and a remote server. Satellite position is predicted by satellite almanac data.

Method and apparatus for determining global position using almanac information

In a method for providing location-based information over a network, a plurality of GPS reference data sets, corresponding to a plurality of respective local areas, are acquired at intervals such that each GPS reference data set is updated on a continuous basis. A plurality of aiding data sets are generated at intervals based on the respective GPS data sets, whereby each aiding data set is updated on a continuous basis. The generated aiding data sets are stored at intervals on a data-storing network server, whereby updated aiding data sets are available on a continuous basis for access by a requesting entity via communication with the data-storing network server.

System and method for providing location based services over a network

The present invention provides methods and systems for keeping the ephemeris in a navigational receiver current to achieve fast TTFF without the need for connecting to an aiding network or remote server. In an embodiment, the receiver keeps the ephemeris current by downloading the ephemeris in the background. In the preferred embodiment, the receiver uses a background sleep/wake up process to download current ephemeris with minimal power drain. In this embodiment, the receiver alternates between a sleep mode and a wake up mode. During the wake up mode, the receiver attempts to download current ephemeris. The receiver then goes back to the sleep mode until the next wake up to conserve power. The receiver may wake up from the sleep mode to download the ephemeris when the stored ephemeris is no longer current or the ephemeris broadcasted from a satellite has been updated or based on receiver usage patterns.

Background ephemeris download in navigational receivers

To provide sub-meter accuracy in a local positioning system, ranging signals with a high modulation rate of code, such as 30 MHz, or more are transmitted. Code phase measurements may be used to obtain the accuracy without requiring relative motion or real time kinematic processing. The ISM or X-band is used for the carrier of the code to provide sufficient bandwidth within available spectrums. The length of codes used is less than or about a longest length across the region of operation, such as less than 15 kilometers in an open pit mine. The spread spectrum codes from different land-based transmitters are transmitted in time slots pursuant to a time division multiple access scheme for an increase in dynamic range. To avoid overlapping of code from different transmitters, each time slot includes or is separated by a blanking period. The blanking period is selected to allow the transmitted signal to traverse a region of operation. Differential measurements of signals received at a base station and a mobile receiver may improve accuracy.

Land-based local ranging signal methods and systems

A differential global positioning system (DGPS) using coarse data for the locations-in-space of GPS satellites for ranging to the GPS satellites and then determining a precise differentially corrected GPS location of a GPS user receiver. The coarse GPS data can be GPS almanac data or non-current GPS ephemeris data as long as the same data is used by both a GPS reference receiver and the GPS user receiver.

Ralph F. Eschenbach

Papers

Differential global positioning system using coarse GPS data for a fast time to a precise first fix