I have made some captures on the L-band uplink channels and tried to decode
the RACH messages. All four consecutive TCH channels (according to the spot
beam) were recorded and a call was made during the recording.
I am using the GRC block gmr_rach_scan.grc. I have removed the IQ swap from
the graph, as suggested in the mailing list. The sampling rate and
samples-per-symbol values have been set to 93.6k and 4, respectively.
It ran fine without any errors, but I couldn't see any results either on
the wireshark or under /tmp/rach.txt.
Maybe I overlooked something here. Any ideas or remarks?
Right now I am studing on osmGMR code and try to understand how it works. From the code my understanding and concerns are as below:
1. It looks like osmoGMR gmr1_rx only analyze and decode downlink(Satellite to MES) messages and data, am I right? If there any similar application that can decode both downlink and uplink(MES to Satellite)? Or osmoGMR needs input to implement downlink decode?
2. A plaintext-decrypt is mentioned in osmoGMR wiki but no detail about how to implement it. Is there a opensource code for A5-1-GMR? Or any other clue that can understand how plaintext decrypt A5-1-GMR? Does osmoGMR need input to implemen it?