gmr May 2022

gmr@lists.osmocom.org

1 participants
2 discussions

RACH scan
by Johann T. 05 Feb '23

05 Feb '23

Hi, 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? Many thanks, Johann

3 8

MES to Satellite decoding and A5-1-GMR decrypt
by Tiger Yi 24 May '22

24 May '22

Dear all, 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? Best Regards, Tiger

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gmr May 2022