RACH intercepting

This is merely a historical archive of years 2008-2021, before the migration to mailman3.

A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/gmr@lists.osmocom.org/.

Sylvain Munaut 246tnt at gmail.com
Wed Sep 11 15:48:37 UTC 2019


Hi,

> I'm interested in intercepting L band up-link RACH channel
> I found the BCCH channel of the spot beam I'm currently in then scan the same ARFCN but in uplink
> I had a cfile and I tried to read it using gr-gmr1 in the branch sylvain/gr
> but i have no results , may be I don't know how to use the read utility in sylvain/gr

Although the method should work to detect the RACH burst on L-band, it
has only ever been tested on C-band wideband captures, so YMMV.
Note that the example .grc graph that's provided does an IQ swap
because usually when you get samples from a C-band LNB they underwent
a spectrum inversion due to the high-side LO mixing inside the LNB. If
you're working off a direct capture off L-band you need to remove that
swap from the graph.

Also, are you sure you actually _have_ RACH requests in your file and
they don't saturate your receiver ?
If you have an example capture to post, put it online somewhere and
post the link.


> I also have another question about the file test.pcap in http://people.osmocom.org/tnt/gmr/
> how can I have a file like it and is it l band RACH data or C band.

This was captured on C-band.

Cheers,

     Sylvain Munaut



More information about the gmr mailing list