Have you read op25/op25/gr-op25_repeater/apps/README?
Here is part of that file:
TERMINAL OPERATION
==================
After starting rx.py if plotting is in use a separate gnuplot window
should open. You must click on the terminal window to restore it to
focus, otherwise all keystrokes are consumed by gnuplot. Once in the
terminal window there are several keyboard commands:
h - hold
l - lockout
s - skip
q - quit program
, - decrease fine tune by 100Hz
. - increase fine tune by 100Hz
< - decrease fine tune by 1200Hz
- increase fine tune by 1200Hz
1 - toggle fft plot
2 - toggle constellation plot (cqpsk)
3 - toggle symbol plot
4 - toggle datascope plot (fsk4)
5 - toggle mixer plot
There are also two experimental commands (should not be used in -T mode)
f - manually change frequencies
t - if currently tuned to a CC, autostart scanning talkgroups
The "t" command allows trunk tracking without setting up a trunking TSV
file. However running with the -T <filename> command line option is
preferred as that allows use of white/black lists and talkgroup tags files.
If the terminal window freezes there may have been a crash. Press Ctrl-Z
to suspend the program and examine stderr.2 for error messages. If there
is a traceback please report the full traceback (and the command line) to
the mail list.