gmr April 2021

gmr@lists.osmocom.org

2 discussions

RACH scan
by Johann T. 06 Feb '23

06 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

Few questions about Osmo-GMR
by Anton Minchev 26 May '21

26 May '21

Hello , last week i worked with osmo-gmr projest ,but still have some questions: 1. I need some more info about S band GMR - what sat is this , az / el , what trafic etc. 2. About gmr1 ambe decode - i tried about dozens of .dat files from gmr1 rx live , some give me ! codec errors , some not , but all .wav audio files are scrambled ,speesh is not recognized at all .. is there some clear traffic at all, or all is A5/2 coded ? 3. If all is scrambled where i may find offline tables / H n matrix/,any source that may generate them ? And if i have tables how they will be integrated with existing osmo-gmr ? I see gmr1_gen_mat that generates G/g matrix .. some more info about that .. .G and .g files seems so small .. Thanks in advance !

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gmr April 2021