Rebroadcasting method and system for navigation signals

Abstract

A “synchrolite” or rebroadcasting device allows GPS or GNSS navigation signals received at one or several locations to be processed at a separate location. The signals received by the synchrolite are added to a pilot tone and then encoded with a superimposed spread-spectrum code before being rebroadcast. The superimposed code allows signals from different synchrolites to be distinguished during the navigation process.

1 . A method for receiving rebroadcast ranging signals, the method comprising:
 (a) receiving a spread spectrum ranging signal;   (b) despreading the spread spectrum ranging signal as a function of a first spreading code;   (c) despreading a despread ranging signal output of (b) as a function of a second spreading code; and   (d) determining a range as a function of an output of (c).   
     
     
         2 . The method of  claim 1  further comprising:
 (e) isolating a pilot tone in the output of (b); 
 (f) performing (b) as a function of the pilot tone. 
 
     
     
         3 . The method of  claim 1  further comprising:
 (e) despreading the spread spectrum ranging signal as a function of the a third spreading code different than the first spreading code; and 
 (f) despreading an output of (e) as a function of a fourth spreading code; 
 wherein (d) comprises determining the range as a function of the output of (c) and an output of (d). 
 
     
     
         4 . A system for receiving rebroadcast ranging signals, the system comprising:
 a receive antenna;   a first despreading demodulator connected with the receive antenna, the first despreading demodulator responsive to a first spreading code;   a ranging signal receiver connected with an output of the first despreading demodulator for receiving a despread ranging signals despread with the first spreading code, the ranging signal receiver operable to despread the despread ranging signal from the output and determine a range.   
     
     
         5 . The system of  claim 4  further comprising:
 a first filter connected with the despreading demodulator, the first filter operable to isolate a pilot signal from the output of the despreading demodulator, the first spreading code responsive to the pilot signal. 
 
     
     
         6 . The system of  claim 4  further comprising:
 a second despreading demodulator connected with the receive antenna, the second despreading demodulator responsive to a second spreading code different than the first despreading code. 
 
     
     
         7 . The system of  claim 6  wherein the second spreading code comprises a code for a different synchrolite. 
     
     
         8 . The system of  claim 6  wherein the second spreading code comprises a code for different signals from a same synchrolite. 
     
     
         9 . The method of  claim 1  further comprising repeating (a), (b), and (c) for different ranging signals from a same synchrolite. 
     
     
         10 . The method of  claim 1  further comprising repeating (a), (b), and (c) for different ranging signals from a different synchrolite.