RF code scanners

["Amit Deshmukh" <amit_deshmukh () bridgepoint com au>]

Has anyone had any experience with using radio frequency code scanners
and/or grabbers to try and grab codes for garage doors and things like
that?

What's the sort of hardware used for this? Surely it cant be a matter of
just cycling through the 2.4 Ghz (or appropriate) spectrum till u hit
the right frequency and the door pops open! There is probably also a
code burned into the firmware of the remote control device and the
receiver which may need to match up. 

I've heard of other devices which sort of "code hop" and use a different
code each time. Any vulnerabilities with those? (maybe they use an
"industry-standard" algorithm?)

Is it better to use a scanner or grabber with devices that use a static
non-changing code? 

Cheers,
Amit