I don't know exactly if/how this can help here , but I noticed how some stations broadcast alternate frequencies (belonging to that station in other areas in the country) in some specific areas and they don't in others.

To be more clear (I hope), I usually listen to "Radio24" wich broadcasts all over Italy and that has a number of different frequencies throughout the country, and they all are listed as alternate frequencies when I am in Rome. When I move to L'Aquila, a small town not far from Rome, I get "No AF information Available".
(In L'Aquila Radio24 occupies a different frequency than in Rome, just for the record).