System and method for correcting satellite observations

Abstract

A system or method for determining a satellite observation for a virtual reference station can include: determining a virtual reference station location, receiving a set of satellite observations at a reference station located at a reference station location, determining a first GNSS correction for the virtual reference station location and a second GNSS correction for the reference station location, and determining the satellite observation for the virtual reference station by combining the set of satellite observations, the first GNSS correction, and the second GNSS correction.

1 . A method for determining a position of a mobile receiver comprising:
 determining a virtual reference station location associated with a virtual reference station;   receiving a set of satellite observations at a reference station located at a reference station location;   determining a first GNSS correction for the virtual reference station location and a second GNSS correction for the reference station location;   determining a satellite observation for the virtual reference station by combining the set of satellite observations, the first GNSS correction, and the second GNSS correction;   receiving a second set of satellite observations at the mobile receiver; and   correcting the second set of satellite observations using the satellite observation for the virtual reference station, wherein the position of the mobile receiver is determined using the corrected second set of satellite observations.   
     
     
         2 . The method of  claim 1 , wherein determining the virtual reference station location comprises setting the virtual reference station location to an initial locality of the mobile receiver. 
     
     
         3 . The method of  claim 1 , further comprising updating the virtual reference station location to a second virtual reference station location when a distance between the virtual reference station and the position of the mobile receiver exceeds a threshold distance. 
     
     
         4 . The method of  claim 3 , wherein the threshold distance is 10 kilometers. 
     
     
         5 . The method of  claim 3 , wherein the second virtual reference station location comprises the position of the mobile receiver when the distance exceeds the threshold distance. 
     
     
         6 . The method of  claim 1 , wherein combining the set of satellite observations, the first GNSS correction, and the second GNSS correction comprises:
 computing a first difference between the first GNSS correction and the set of satellite observations; and   computing a second difference between the second GNSS corrections and the first difference, wherein the satellite observation for the virtual reference station comprises the second difference.   
     
     
         7 . The method of  claim 1 , wherein determining the position of the mobile receiver comprises:
 determining a set of carrier phase ambiguity hypothesis for the second set of corrected satellite observations; and   selecting a carrier phase ambiguity of the set of carrier phase ambiguity hypotheses based on results of a hypothesis test comparing carrier phase ambiguities of the set of carrier phase ambiguity hypotheses.   
     
     
         8 . The method of  claim 7 , wherein the set of carrier phase ambiguity hypotheses comprises integer-valued carrier phase ambiguity hypotheses. 
     
     
         9 . The method of  claim 1 , further comprising 
 receiving a third set of satellite observations at a second reference station located at a second reference station location;   determining a third GNSS correction for the second reference station location; and   wherein determining the satellite observation for the virtual reference station comprises combining the set of satellite observations, the first GNSS correction, the second GNSS correction, the third set of satellite observations, and the third GNSS correction.   
     
     
         10 . The method of  claim 1 , wherein the first GNSS correction and the second GNSS correction comprises state space representation corrections, wherein the satellite observation for the virtual reference station comprises an observation space representation. 
     
     
         11 . A system comprising:
 a mobile GNSS receiver configured to:
 determine a locality of the mobile GNSS receiver; 
 transmit the locality to a remote computing server; and 
 determine a positioning solution associated with the mobile GNSS receiver based on a set of GNSS receiver satellite observations; and 
   the remote computing server, wherein the remote computing server is configured to:
 receive the locality of the mobile GNSS receiver; 
 generate a virtual reference station at a location that depends on the locality of the mobile GNSS receiver; 
 receive a set of reference station satellite observations associated with a reference station; 
 determine a first GNSS correction associated with the location of the virtual reference station; 
 determine a second GNSS correction associated with a location of the reference station; 
 determine an observation space representation correction by combining the set of reference station satellite observations, the first GNSS correction, and the second GNSS correction; and 
 transmitting the observation space representation corrections to the mobile GNSS receiver; 
 
wherein the mobile GNSS receiver is configured to use the observation space representation corrections to determine the positioning solution. 
     
     
         12 . The system of  claim 11 , wherein the remote computing system is further configured to:
 receiving a second set of reference station satellite observations associated with a second reference station located at a second reference station location;   determine a third GNSS correction for the second reference station location; and   wherein determining the observation space representation correction further comprises combining the set of reference station satellite observations, the first GNSS correction, the second GNSS correction, the second set of reference station satellite observations, and the third GNSS correction.   
     
     
         13 . The system of  claim 11 , wherein the first GNSS correction and the second GNSS correction comprise state space representation corrections. 
     
     
         14 . The system of  claim 11 , wherein the location of the virtual reference station is approximately the same as the locality of the GNSS receiver. 
     
     
         15 . The system of  claim 11 , wherein the remote computing system is further configured to update the virtual reference station location to a second virtual reference station location when a distance between the virtual reference station location and the position of the mobile receiver exceeds a threshold distance. 
     
     
         16 . The system of  claim 15 , wherein the threshold distance is 10 kilometers. 
     
     
         17 . The system of  claim 15 , wherein the second virtual reference station location comprises the position of the mobile receiver when the distance exceeds the threshold distance. 
     
     
         18 . The system of  claim 1 , wherein determining the position of the mobile GNSS receiver comprises:
 determining a set of carrier phase ambiguity hypothesis for the second set of corrected satellite observations; and   selecting a carrier phase ambiguity of the set of carrier phase ambiguity hypotheses based on results of a hypothesis test comparing carrier phase ambiguities of the set of carrier phase ambiguity hypotheses.   
     
     
         19 . The system of  claim 18 , wherein the set of carrier phase ambiguity hypotheses comprises integer-valued carrier phase ambiguity hypotheses. 
     
     
         20 . The system of  claim 11 , wherein the remote computing system is configured to determine the first GNSS correction or the second GNSS correction using a Gaussian process.