[Hackrf-dev] scanning with HackRF

[Graham]

Hello to the list
I am new to HackRF and Gnu radio so bear with me if my question appears 
simple.

I am trying to get the HackRf to scan a range of freqs and stop at a 
signal that is greater than the squelch setting then continue scanning 
after a couple of seconds.  I cannot find any scanning blocks in Gnu 
Radio or any reference in any tutorials.

Any help gratefully received  :-)

Thanks Graham