Feasibility of recovering radio transmission carrier frequency
You can use a PLL to track the incoming signal's frequency. As long as the loop remains in lock &mdash; i.e., the phase error does not "wrap" beyond the phase detector's ability to deal with it &mdash; you can select the loop parameters to attenuate the modulation to a fairly arbitrary degree. The mean frequency of the PLL output will be the same as the mean frequency of the incoming signal, so it then becomes a question of how much deviation you can tolerate in the output.