Question about position fix
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Hello.
When I compile original gps-sdr-sim my devices can't fix position (I use HackRF with TCXO). If I start your binary, tablets got gps-position in several seconds. May be something wrong in 8-bit signal of original gps-sdr-sim? I see in GPS-test application stronger signal generated by your binary. May be I need to remove anthenna gain code from my project?
There are two ways to generate GPS signal.
a) Make a binary I/Q file at first using gps-sdr-sim, then transmit using hackrf_transfer.
b) Generate GPS signal in real time using named pipe(FIFO).
Which way did you try ?
I try both variants. But devices can not lock gps-signal even generated i/q file transmited via hackrf_transfer. They display in GPS Test app about 10 satellites but GNSS Status "No Fix" 5 minutes and more. I have no critical CPU load. When I start your gps-sdr-sim binary and transfer output data via named pipe all my devices get GPS location in seconds.
Original gps-sdr-sim should be no problem if you follow the link. https://github.com/osqzss/gps-sdr-sim
I modified original gps-sdr-sim.c to make it possible to utilize multiple core of Pi3 using threading and other minor performance optimization.
Thank you for answers. If you didn't modify gps signal generating algorytm it help me to resolve my problem.