Here is an updated version of Kalibrator. Few things improved:
1) You can build it with GnuRadio 3.2 and 3.3. Just uncomment teh
correct option in the Makefile.
2) You can specify FPGA frequency (also known as ADC frequency or USRP
clock frequency) with "-F" command line option. So if you have 52MHz
clock, pass "-F 52000000".
3) With "-N" option you can set number of frames to listen before
"fcch not found" decision is made, and with "-O" option you can change
averaging window size.
4) I also changed that more cases are considered as "not found"
events. Otherwise kal used to stall when it is run without "-u" option
and offset is too high.
Also I wrote a small shell-script "scan900.sh" to scan the air for
FCCHs of existing base stations. It goes over the whole EGSM-900 and
logs all found frequencies to screen and a log file. This will help
you select the best base station to sync your USRP clocks to (if
you're using tunnable clock, like ClockTamer).
PS I should note here, that Kalibrator sensetivity is not very good,
so it will usually find less base stations then normal handset. So if
it doesn't detect FCCH on a particular frequency, it doesn't mean
there is no base station working at this frequency. We invite everyone
to write a better implementation for FCCH scan algorithm, as it is
very handy helper tool for every GSM developer/hacker.