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crescentvenus / WALB

WALB is raspberry Pi and HackRF based Wireless Attack LaunchBox.
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Question about position fix #9

Closed petrovvlz closed 6 years ago

petrovvlz commented 6 years ago

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?

crescentvenus commented 6 years ago

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 ?

petrovvlz commented 6 years ago

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.

crescentvenus commented 6 years ago

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.

petrovvlz commented 6 years ago

Thank you for answers. If you didn't modify gps signal generating algorytm it help me to resolve my problem.