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osqzss / gps-sdr-sim

Software-Defined GPS Signal Simulator

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NI USRP No GPS Satellites Viewed

mebekturk opened this issue · comments

commented

Hello everyone!

I'm trying this software with NI-USRP 2950R and got a problem. SDR transmits something at 1575.42 MHz(I analyzed with a spectrum analyzer) but none ofmy device can see any GPS satellite info. Here is what I tried:

  1. Downloaded the latest brdc file from NASA website.
  2. I build the gpssim.c code with gcc gpssim.c -lm -O3 -o gps-sdr-sim
  3. I generated the gpssim.bin file with gps-sdr-sim -e brdc3540.14n -l 30.286502,120.032669,100
  4. To transmit samples from USRP, I used tx_from_file example ./tx_samples_from_file --file gpssim.bin --type short --rate 2500000 --freq 1575420000 --gain 0
  5. USRP starts transmit signals but none of my devices can receive any GPS signal. I tried with ublox receiver and with my iphone.

What could be the problem ? I appreciate any help.

commented

Set a proper sample rate: gps-sdr-sim -e brdc3540.14n -s 2500000 -l 30.286502,120.032669,100