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

Abstract

An 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.

What is claimed is:  
     
         1 . A method for locating position comprising: 
 receiving satellite telemetry data from all of the satellites in a global positioning system constellation of satellites using a network of tracking stations, where the network includes enough tracking stations to observe only a portion of an orbital sphere for the global positioning system constellation, the portion selected to include all of the orbits of the satellites;    communicating the received satellite telemetry data to a central processing site;    propagating selected satellite telemetry data to a mobile receiver; and    acquiring at least one satellite signal at said mobile receiver using said selected satellite telemetry data.    
     
     
         2 . The method of  claim 1  wherein the portion of the orbital sphere observed by the tracking stations is between plus and minus 55 degrees relative to the equator of the earth.  
     
     
         3 . The method of  claim 1  wherein the selected satellite telemetry data comprises the ephemeris data for each satellite in view of the mobile receiver.  
     
     
         4 . The method of  claim 3  wherein the selected satellite data comprises a pseudo-range model, derived from the ephemeris data, that represents a relative position of each satellite in view of the mobile receiver.  
     
     
         5 . The method of  claim 3  wherein the selected satellite telemetry data comprises a Doppler measurement derived from the satellite ephemeris data.  
     
     
         6 . The method of  claim 1  wherein said acquiring step further comprises: 
 using the selected satellite telemetry data to narrow a frequency uncertainty and a code uncertainty.  
 
     
     
         7 . The method of  claim 1  further comprising: 
 computing a position of said mobile receiver using said selected satellite data.  
 
     
     
         8 . The method of  claim 7  wherein said computing step is performed within the mobile receiver.  
     
     
         9 . The method of  claim 7  wherein said computing step is performed at a location that is remote from said mobile receiver.  
     
     
         10 . The method of  claim 1  wherein said at least on satellite signal is a signal having a high signal strength and said acquiring step further comprises: 
 using the at least one acquired satellite signal to aid in receiving other satellite signals having low signal strength.  
 
     
     
         11 . The method of  claim 10  wherein said at least one acquired satellite signal is used to generate a clock and a correlator delay offset.  
     
     
         12 . The method of  claim 10  wherein said at least one acquired satellite signal is used to improve an estimated pseudo-range computation for satellite signals having low signal strength.  
     
     
         13 . Apparatus for locating a position of a mobile receiver comprising: 
 a network of satellite signal receivers for receiving satellite signals from all satellites in a constellation of global positioning satellites, where the network includes enough satellite signal receivers to observe only a portion of an orbital sphere for the constellation of global positioning satellites, the portion selected to include all of the orbits of the satellites;    a communications network, coupled to each of said satellite signal receivers in said plurality of satellite signal receivers;    a satellite data processor, coupled to said communications network; and    a mobile receiver, coupled to said satellite data processor.    
     
     
         14 . The apparatus of  claim 13  wherein the portion of the orbital sphere observed by the satellite signal receivers is between plus and minus 55 degrees relative to the equator of the earth.  
     
     
         15 . The apparatus of  claim 13  further comprising 
 a wireless network for communicating said satellite data to said mobile receiver.  
 
     
     
         16 . The apparatus of  claim 13  wherein said satellite data processor generates a pseudo-range model for each mobile receiver and communicates the pseudo-range model to the mobile receiver.  
     
     
         17 . The apparatus of  claim 13  wherein said satellite constellation is a global positioning system (GPS) satellite constellation.  
     
     
         18 . Apparatus for providing satellite data to a mobile receiver comprising: 
 a network of tracking stations for receiving telemetry data from satellites in a constellation, where the network includes enough tracking stations to observe only a portion of an orbital sphere for the constellation, the portion selected to include all of the orbits of the satellites; and    a communication network for propagating the telemetry data from all the satellites to a data processor.    
     
     
         19 . The apparatus of  claim 18  wherein the portion of the orbital sphere observed by the tracking stations is between plus and minus 55 degrees relative to the equator of the earth.  
     
     
         20 . The apparatus of  claim 18  wherein said data processor transmits said data to a mobile receiver.  
     
     
         21 . The apparatus of  claim 18  wherein said data processor produces a pseudo-range model using said telemetry data.  
     
     
         22 . A method for locating position comprising: 
 receiving satellite telemetry data from all of the satellites in a global positioning system constellation of satellites using a plurality of tracking stations, where the plurality of tracking stations are positioned to observe only a portion of an orbital sphere for the global positioning system constellation, the portion selected to include all of the orbits of the satellites;    communicating the received satellite telemetry data to a central processing site;    propagating selected satellite telemetry data to a mobile receiver; and acquiring at least one satellite signal at said mobile receiver using said selected satellite telemetry data.    
     
     
         23 . The method of  claim 22  wherein the portion of the orbital sphere observed by the tracking stations is between plus and minus 55 degrees relative to the equator of the earth.