Re: [Discuss-gnuradio] software implementation of GSM

[Joshua Lackey]

(Moving discuss-gnuradio to bcc.)

You can tell when it's working because of all the error messages you
get.

        address@hidden:~/src/gsm/gssm-v0.1/src/python$ ./file_gssm.py 
~/src/gsm/signal/signal.data 
        >>> gr_fir_fff: using SSE
        error: PCH, AGCH (0, 36)
        error: SACCH8 (0, 36)
        error: PCH, AGCH (0, 36)
        error: SACCH8 (0, 36)
        error: PCH, AGCH (0, 36)
        error: SACCH8 (0, 36)
        error: PCH, AGCH (0, 12)
        error: SDCCH8 (0, 12)
        error: PCH, AGCH (0, 46)
        error: PCH, AGCH (0, 36)
        error: SACCH8 (0, 36)
        error: PCH, AGCH (0, 22)
        error: PCH, AGCH (0, 26)
        error: PCH, AGCH (0, 36)
        [...]


So even if nothing is appearing in Wireshark, you should still be able
to tell if the radio demod path is working.

You can also add a few debug printf()'s in the code to see how far
you're getting.  Try adding a 'printf("fc found!\n");' at line 316 in
gssm_sink.cc and a 'printf("sch found!\n");' at line 360.  (It will be
line 361 if you first add line 316.)

Then you'll be able to see when you lock on the frequency correction
channel and the synchronization channel.


Quoting Eng. Firas (address@hidden):
> 
> Hi Joshua,
> 
> I followed installation instruction with almost no errors. But, when running
> Wireshark, I get nothing displayed with the GSM interface. My BTS signal is
> very high, and I located the offset of the frequency correction burst (which
> is by the way almost the same as your default one). Any suggested checking
> point ?
> 
> Firas,