Hi,
some time ago I got interested in receiving GSM with GnuRadio.
I attach a block that does rough timing estimation and frequency
correction based on FCCH blocks.
Just put it in your gr-howto directory and modify Makefile.am and
howto.i accordingly.
Also attached is a python code that I used to test it.
I have not tested it with real data from the usrp yet (no DBSRX db in
the lab), but with some online files (Robert’s samples):
http://www.segfault.net/gsm/resources/
I would be interested to hear how the block performs with real-time
data from the usrp.
Next step (if/when I get some time) is to do fine timing estimation
jointly with channel estimation based on the Normal burst training
sequence.
Best,
Achilleas