'Debugging' a wireless alarm....

Hi!

I'm trying to intercept the signal from a PIR in a cheap alarm unit - I want to see the 'data traffic' from the RF receiver to the microcontroller (an em78p447sap).

I've tried to use a simple arduinoscope to detect the signal coming out of the RF circuit on the alarm unit board but I think the sample rate is not high enough.

I guess my two questions are:

1 Is the signal coming from the RF unit in the alarm unit likely to be in MHz range?
(I believe the microcontroller can handle 4.5Mhz+)

2 Is there any way to view the traffic using an arduino?
(My pockets aren't deep enough for a quality digital storage scope )

Thanks!