Locking into a frequency

Hi,
I am currently working on a project were i have to detect a frequency,
lock
into it and then decode the signal. I tried to use gnuradio but i faced
a
lot of problems such as the speed of scanning the signal or the accuracy
of
detecting the signal. I am now trying to implement that into a python
code.
Could anyone help me with this code ??

Many thanks in advance,
Tasos