You need a conditioning circuit and a divide-by-ten logic chip. The conditioning circuit amplifies the signal to logic level and much more importantly isolates the local oscillator from the digital circuitry (you don't want digital hash leaking back into the local oscillator, the whole performance of a radio relies on a clean oscillator signal). Old fashioned unbuffered CD4xxx gates make good analog amplifiers btw - but not sure they go to 30MHz.
There are quite a few divide by ten chips in 74xx and 4xxx series. Once you've divided by 10 or 100 you can easily detect the frequency using a ATmega counter. Use timer1 as its got 16bits rather than 8.
Very good decoupling and a totally separate supply for the Arduino are pretty much mandatory to avoid injecting noise into the radio RF circuitry.