Method and System for Integrated GLONASS and GPS Processing

Abstract

An integrated global navigation satellite system (GNSS) receiver may be operable to decompose GNSS IF signals associated with GPS satellites and/or GLONASS satellites into a constituent narrowband GPS data stream and/or a plurality of constituent narrowband GLONASS data streams utilizing, for example, a GPS IF tuner and/or one or more GLONASS IF tuners. The narrowband GLONASS data streams and/or the narrowband GPS data stream may be processed at reduced sampling rates utilizing a shared sample memory in the integrated GNSS receiver. The narrowband GLONASS data streams and/or the narrowband GPS data stream may be stored in allocated sections of the shared sample memory. The stored narrowband GLONASS data streams and/or the stored narrowband GPS data stream may be processed using a correlation such as a fast Fourier transform (FFT) correlation.

What is claimed is: 
     
         1 . A global navigation satellite system (GNSS) receiver, comprising:
 a processor configured to store a first and a second downsampled GNSS datastream corresponding to a first and a second received GNSS signal, respectively, in a corresponding first and second allocated portion of a shared sample Memory; and   a correlation engine configured to access the shared sample memory to process the first and second downsampled GNSS datastreams.   
     
     
         2 . The GNSS receiver of  claim 1 , further comprising:
 a first tuner configured to sample the first received GNSS signal according to a first sampling rate to provide a first narrowband GNSS datastream, and   a second tuner configured to sample the second received GNSS signal according to a second sampling rate to provide a second narrowband GNSS datastream.   
     
     
         3 . The GNSS receiver of  claim 2 , further comprising:
 a first decimator configured to sample the first downsampled GNSS datastream according to a first decimation rate to provide the first narrowband GNSS datastream; and   a second decimator configured to sample the second downsampled GNSS datastream according to a second decimation rate to provide the second narrowband GNSS datastream.   
     
     
         4 . The GNSS receiver of  claim 3 , wherein the first and second decimation rates are less than the first and second sampling rates, respectively. 
     
     
         5 . The GNSS receiver of  claim 1 , wherein the correlation engine is further configured to process the first and second downsampled GNSS datastreams using a fast Fourier transform (FFT) correlation, a matched filter correlation, or a correlator. 
     
     
         6 . The GNSS receiver of  claim 2 , wherein the processor is further configured to adjust an allocated size of the first and second allocated portions based on changes in the first or the second received GNSS signal. 
     
     
         7 . The GNSS receiver of  claim 1 , wherein the correlation engine is further configured to store a generated output in the shared sample memory. 
     
     
         8 . A global navigation satellite system (GNSS) receiver, comprising:
 a processor configured to store a first and a second decimated narrowband GNSS datastream corresponding to a first and a second narrowband GNSS datastream, respectively, in a corresponding first and second allocated portion of a shared sample memory; and   a correlation engine configured to access the shared sample memory to process the first and second decimated narrowband GNSS datastreams.   
     
     
         9 . The GNSS receiver of  claim 8  , further comprising:
 a first tuner configured to sample a first received GNSS signal according to a first sampling rate to provide the first narrowband GNSS datastream, and a second tuner configured to sample a second received GNSS signal according to a second sampling rate to provide the second narrowband GNSS datastream. 
 
     
     
         10 . The GNSS receiver of  claim 9 , further comprising:
 a first decimator configured to decimate the first narrowband GNSS datastream according to a first decimation rate to provide the first decimated narrowband GNSS datastream; and   a second decimator configured to decimate the second narrowband GNSS datastream according to a second decimation rate to provide the second decimated narrowband GNSS datastream.   
     
     
         11 . The GNSS receiver of  claim 10 , wherein the first and second decimation rates are less than the first and second sampling rates, respectively. 
     
     
         12 . The GNSS receiver of  claim 10 , wherein the first and second decimation rates are substantially the same as a signal chip rate corresponding to the first and second received GNSS signals, respectively. 
     
     
         13 . The GNSS receiver of  claim 8 , wherein the correlation engine is further configured to process the first and second decimated narrowband GNSS datastreams using a fast Fourier transform (HT) correlation, a matched filter correlation, or a correlator. 
     
     
         14 . The GNSS receiver of  claim 9 , wherein the processor is further configured to adjust an allocated size of the first and second allocated portions based on changes in the first or the second received GNSS signal. 
     
     
         15 . The GNSS receiver of  claim 8 , wherein the correlation engine is further configured to store a generated output in the shared sample memory. 
     
     
         16 . In a global navigation satellite system (GNSS) receiver, a method comprising:
 storing a first and second downsampled GNSS datastream corresponding to a first and second received GNSS signal, respectively, in a corresponding first and second allocated portion of a shared sample memory; and   processing the first and second downsampled GNSS datastreams from the shared sample memory.   
     
     
         17 . The method of  claim 16 , further comprising:
 sampling the first received GNSS signal according to a first sampling rate to provide a first narrowband GNSS datastream, and   sampling the second received GNSS signal according to a second sampling rate to provide a second narrowband GNSS datastream.   
     
     
         18 . The method of  claim 17 , further comprising:
 decimating the first narrowband GNSS datastream according to a first decimation rate to provide the first downsampled GNSS datastream; and   decimating the second narrowband GNSS datastream according to a second decimation rate to provide the second downsampled GNSS datastream, wherein the first and second decimation rates are less than the first and second sampling rates, respectively.   
     
     
         19 . The method of  claim 16 , wherein the processing comprises:
 processing the first and second downsampled GNSS datastreams using a fast Fourier transform (FFT) correlation, a matched filter correlation, or a correlator.   
     
     
         20 . The method of  claim 16 , further comprising:
 adjusting an allocated size of the first and second allocated portions based on changes in the first or the second received GNSS signal.