ramtej/gpsrx

Reception of GPS signals from RTL-SDR and getting raw GPS data

GPSrx

##Reception of GPS signals from RTL-SDR and getting raw GPS data

• Using GNU radio software to realize the incoming data and plot its spectrum.
• GPS signals are well below the thermal noise, but can be received because it uses C/A signals which uses Spectrum spreading using PRN (Pseudo Random) Codes.
• By correlating the received signal (which looks like noise) by the C/A PRN code, GPS receivers receive data from satellites

##Results

• How PRN gold codes look like?, here are g5 and g17 C/A codes
• Results Yet, correlation of raw signal with all the 37 CA codes
• With self simulated data without noise, the power of correlation
• ####Check List!!!
• check the CA code correlation on the simulated noise!
• Correlate Code spreaded data with the cacode, simulation
• construct time domain sinc filtered signal from gold codes with data representation similar to GPS signal
• resample the signal simulating Doppler effect due to satellite and predict Doppler shift from GPS signal buried under noise

##Following links were referenced :

• C/A Code Generator in python MATLAB
• Information about CDMA band allocation
• Hobbyiest Guide to RTL-SDR an interesting read
• Soft GPS Project Page
• 1 bit ADC and a short video description here
• 1 bit processing of BOC
• GNSS SDR, contains specs about RTL-SDR
• A homemade GPS Receiver
• [Satellite Signal Acquisition, Tracking, and Data Demodulation] (http://www.artechhouse.com/uploads/public/documents/chapters/kaplan_894_CH05.pdf)
• A homemade receiver for GPS & GLONASS satellites
• GPS simulated signal Generation