Method and apparatus for locating mobile receivers using a wide area reference network for propagating ephemeris

Abstract

A method and apparatus for distribution and delivery of global positioning system (GPS) satellite telemetry data using a communication link between a central site and a mobile GPS receiver. The central site is coupled to a network of reference satellite receivers that send telemetry data from all satellites to the central site. The mobile GPS receiver uses the delivered telemetry data to aid its acquisition of the GPS satellite signal. The availability of the satellite telemetry data enhances the mobile receiver's signal reception sensitivity.

1 . A method of distributing satellite-navigation data, comprising:
 processing satellite signals at each of a plurality of reference stations to receive a respective plurality of satellite-navigation-data streams;   forming packets in response to said plurality of satellite-navigation-data streams to generate a plurality of packetized satellite-navigation-data streams;   sending each of said plurality of packetized-satellite-navigation-data streams to a processing system;   removing, at said processing system, duplicate packets within said plurality of packetized satellite-navigation-data streams to generate a combined packet stream; and   sending said combined packet stream into a communication network.   
     
     
         2 . The method of  claim 1 , further comprising: decoding satellite-navigation-data within said combined packet stream to generate satellite data. 
     
     
         3 . The method of  claim 2 , wherein said satellite data comprises at least one of ephemeris data, almanac data, ionosphere data, universal time offset data, satellite health data, and raw data bits. 
     
     
         4 . The method of  claim 1 , wherein said plurality of satellite-navigation-data streams comprises global positioning system (GPS) satellite navigation messages, and wherein each of said packets includes a sub-frame of said GPS satellite navigation messages. 
     
     
         5 . The method of  claim 4 , wherein removing said duplicate satellite-navigation-data streams comprises removing said satellite-navigation-data streams as a function of a satellite identifier. 
     
     
         6 . The method of  claim 5 , wherein removing said duplicate satellite-navigation-data streams comprises removing said satellite-navigation-data streams as a function of said satellite identifier and a time-of-week value. 
     
     
         7 . The method of  claim 1 , wherein said processing system comprises a position-processing site, and the method further comprises: receiving said combined packet stream from said communication network at the position-processing site. 
     
     
         8 . The method of  claim 7 , further comprising:
 decoding satellite-navigation data within said combined packet stream to generate satellite data; and   storing said satellite data at said position-processing site.   
     
     
         9 . The method of  claim 7 , further comprising:
 receiving, at said position-processing site, at least one additional packetized satellite-navigation-data stream;   removing duplicate packets within said combined packet stream and said at least one additional packetized satellite-navigation-data stream to generate another combined packet stream;   decoding satellite-navigation-data within said other combined packet stream to generate satellite data; and   storing said satellite data at said position-processing site.   
     
     
         10 . The method of  claim 9 , wherein said at least one additional packetized satellite-navigation-data stream is generated by at least one reference station disposed proximate to said position-processing site. 
     
     
         11 . A system for distributing satellite-navigation data, comprising:
 a plurality of reference stations operable to process satellite signals to receive a respective plurality of satellite-navigation-data streams, and to form packets in response to said plurality of satellite-navigation-data streams so as to generate a plurality of packetized-satellite-navigation-data streams; and   a processing system operable to receive each of said plurality of packetized-satellite-navigation-data streams, to remove duplicate satellite-navigation-data streams within said plurality of packetized satellite-navigation-data streams so as to generate a combined packet stream, and to send said combined packet stream into a communication network.   
     
     
         12 . The system of  claim 11 , wherein said processing system includes a processor operable to decode satellite-navigation data within said combined packet stream to generate satellite data. 
     
     
         13 . The system of  claim 12 , wherein said satellite data comprises at least one of ephemeris data, almanac data, ionosphere data, universal time offset data, satellite health data, and raw data bits. 
     
     
         14 . The system of  claim 11 , wherein said plurality of satellite-navigation-data streams comprises global positioning system (GPS) satellite navigation messages, and wherein each of said packets includes a sub-frame of said GPS satellite navigation messages. 
     
     
         15 . The system of  claim 14 , wherein the processor is operable to remove said duplicative satellite-navigation-data streams as a function of a satellite identifier. 
     
     
         16 . The system of  claim 15 , wherein the processor is operable to remove said duplicative satellite-navigation-data streams as a function of any of said satellite identifier and a time-of-week value. 
     
     
         17 . The system of  claim 11 , further comprising: a position-processing site operable to receive said combined packet stream. 
     
     
         18 . The system of  claim 17 , wherein said position-processing site comprises:
 a processor for decoding satellite-navigation data within said combined packet stream to generate satellite data, and   a memory for storing said satellite data.   
     
     
         19 . The system of  claim 17 , further comprising: an additional reference station disposed proximate to said position-processing site and operable to provide at least one additional packetized-satellite-navigation-data stream; wherein said position-processing site comprises:
 a processor operable to remove duplicate satellite-navigation-data streams within said combined packet stream and said at least one additional packetized satellite-navigation-data stream to generate another combined packet stream, and to decode satellite-navigation-data within said other combined packet stream to generate satellite data; and   a memory for storing said satellite data.   
     
     
         20 . An apparatus for distributing satellite-navigation data, comprising:
 means for processing satellite signals at each of a plurality of reference stations to receive a respective plurality of satellite-navigation-data streams;   means for forming packets in response to said plurality of satellite-navigation-data streams to generate a plurality of packetized satellite-navigation-data streams;   means for sending each of said plurality of packetized satellite-navigation-data streams to a processing system;   means for removing, at said processing system, duplicate packets within said plurality of packetized satellite-navigation-data streams to generate a combined packet stream; and   means for sending said combined packet stream into a communication network.