Can you switch frequency on the fly?

Hello
I have just started to play with the USRP2 and am a little bit curious
if it is possible to start listening on one frequency - say 1575.42MHz
and then switch to say 1226MHz without restarting the recording of data
(I want to switch frequency as fast as possible)

Is it possible?
How long time will the frequency change take? (order of magnitude 1uS,
100uS or 10ms )

Thanks!
Oscar j