This is a new gps transmitter that replays files created with
https://github.com/osqzss/gps-sdr-sim

All the code was written by @jamesshao8

Instructions for creating an example file

https://blog.csdn.net/shukebeta008/article/details/103270214

Using that tool,
gps-sdr-sim -e brdc3540.14n -l 30.286502,120.032669,100 -b 8

That will create a gpssim.bin file that you rename to BBD_NNNN.C8 and then create BBD_NNNN.TXT with:

sample_rate=2600000
center_frequency=1575420000