Hi everybody I’m trying to find a frequency correction burst of gsm.
This Burst is due to GMSK Modulation 67,7 kHz obove the carrier and
I’ve got an older Nokia cell phone with some monitoring software where I
read out the arfcns the phone sees and thus the frequencies of the BCCH.
The phone sees a BCCH at 940MHz but if I use the usrp2/usrp1 and the
Constellation Sink in GRC I can’t see the phase shift of pi/2. But if I
the FFT sink I can see the BCCH, so it has to be there or am I mistaken?
The thing is if I use as file source the captured data from
it works fine and I can see thephase shift of pi/2.
I know they’re doing some processing before but it should be possible
my configuration too.
Setting is as follows:
30 db LNA in front of the usrp2
everything standard except
symbolrate: 270800 (gsm bitrate)
Hopefully somebody can help this is strange