Method and apparatus for decompression of compressed long-term-orbit data

Abstract

A method and apparatus for processing long-term-orbit data that is valid for an extended period of time into the future (i.e., long-term-orbit data). The long-term-orbit data is processed by reducing redundant information from the data to form compressed long-term-orbit data that is subsequently decompressed or reconstructed for use in a GNSS receiver.

1 . A method for processing long-term-orbit data comprising:
 receiving compressed long-term-orbit data; and   performing at least one of decompressing or reconstructing long-term-orbit data from the compressed long-term-orbit data.   
   
   
       2 . The method of  claim 1 , wherein the step of performing at least one of decompressing or reconstructing of the compressed long-term-orbit data comprises extracting a reference long-term-orbit data from the compressed long-term-orbit data. 
   
   
       3 . The method of  claim 1 , wherein the step of performing at least one of decompressing or reconstructing of the compressed long-term-orbit data comprises selecting a current long-term-orbit data. 
   
   
       4 . The method of  claim 1 , wherein the step of performing at least one of decompressing or reconstructing of the compressed long-term-orbit data comprises: applying a delta long-term-orbit data to a reference long-term-orbit data to determine a current long-term-orbit data. 
   
   
       5 . The method of  claim 4 , wherein the delta long-term-orbit data is determined on a field-by-field basis. 
   
   
       6 . The method of  claim 4 , wherein the current value is at least one of selected, received or computed. 
   
   
       7 . The method of  claim 4 , wherein the step of performing at least one of decompressing or reconstructing of the compressed long-term-orbit data further comprises adding the reference long-term-orbit data to the delta long-term-orbit data. 
   
   
       8 . The method of  claim 4  further comprising utilizing a dynamic map for at least one of identifying where the data is located within the delta long-term-orbit data or identifying the bit sizes of each parameter within the long-term-orbit data. 
   
   
       9 . The method of  claim 8 , further comprising arranging at least one of the decompressed or the reconstructed long-term-orbit data according to a determined requirement. 
   
   
       10 . The method of  claim 1 , wherein at least one of the compressed, the decompressed or the reconstructed long-term-orbit data comprises: long-term-orbit data for each satellite of a plurality of satellites forming a set of long-term-orbit data. 
   
   
       11 . The method of  claim 1 , wherein the step of performing at least one of decompressing or reconstructing comprises:
 identifying a first long-term-orbit data for at least one satellite as a reference data for said at least one satellite; and   subtracting a second long-term-orbit data from the reference data to form a delta data, for said at least one satellite.   
   
   
       12 . The method of  claim 11 , wherein the first long term satellite orbit data is selected from the set of long term satellite orbit data. 
   
   
       13 . The method of  claim 11 , wherein the first long term satellite orbit data is derived by using information from the set of long term satellite orbit data. 
   
   
       14 . The method of  claim 11 , wherein the first long term satellite orbit data is arbitrary. 
   
   
       15 . The method of  claim 1 , wherein at least one of the compressed, decompressed or reconstructed long-term-orbit data comprises a dynamic range map. 
   
   
       16 . The method of  claim 1 , wherein the compressed long-term-orbit data comprises an indicator of whether a field is at least one of compressed, decompressed or reconstructed. 
   
   
       17 . The method of  claim 1 , wherein the compressed long-term-orbit data comprises scale factors of the delta data. 
   
   
       18 . The method of  claim 1 , wherein the step performing at least one of decompressing or reconstructing compressed long term data comprises:
 generating satellite orbit data for a past period of time; and   extending the satellite orbit data into the future.   
   
   
       19 . The method of  claim 1  further comprising: transmitting the uncompressed long term bit data to a global-navigation-satellite-system receiver using a wireless communications link. 
   
   
       20 . The method of  claim 1 , further comprising: transmitting the compressed long-term-data to a global-navigation-satellite-system receives using a wireless communications link. 
   
   
       21 . A method for decompressing long-term-orbit data comprising:
 receiving compressed long-term-orbit data;   determining a reference long-term-orbit data; and   determining at least one delta long-term-orbit data representing differences between the reference long-term-orbit data or other long-term-orbit data.   
   
   
       22 . The method of  claim 21 , wherein the reference long-term-orbit data is actual long-term-orbit data selected from a set of long-term-orbit data or arbitrary long-term-orbit data. 
   
   
       23 . The method of  claim 21 , wherein the creating a plurality of delta long-term-orbit data further comprises: computing a difference between at least one term of one of the other long-term-orbit data or at least one term of the reference long-term-orbit data. 
   
   
       24 . The method of  claim 20 , further comprising utilizing a dynamic map for at least one of identifying where the data is located within the delta long-term-orbit data or identifying the bit sizes of each parameter within the long-term-orbit data. 
   
   
       25 . The method of  claim 21 , further comprising generating a bitmask that indicates whether a term of the other long-term-orbit data is at least one of compressed, decompressed or reconstructed. 
   
   
       26 . The method of  claim 21 , further comprising omitting terms from the delta long-term-orbit data when said terms can be reconstructed from the remaining data. 
   
   
       27 . The method of  claim 21 , further comprising arranging the reference long-term-orbit data and the delta long-term-orbit data to form a compressed data set. 
   
   
       28 . The method of  claim 21 , further comprising reconstructing a set of long-term-orbit data using the reference long-term-orbit data and the delta long-term-orbit data. 
   
   
       29 . The method of  claim 28 , wherein the reconstructing step further comprises: adding a delta term to a reference term. 
   
   
       30 . The method of  claim 28 , wherein the reconstructing step further comprises using a rate term. 
   
   
       31 . The method of  claim 30 , wherein the rate term is multiplied by a time difference. 
   
   
       32 . Apparatus for at least one of decompressing or reconstructing long-term-orbit data comprising:
 means for receiving compressed long-term-orbit data; and   means for at least one of decompressing or reconstructing long-term-orbit data from the compressed long-term-orbit data.