What ejs said. Crosstalk would be across a broad range of DSL frequencies. By design, radio stations and radio-emitting devices use sharply defined narrow frequencies, firstly in order to get as much power as is appropriate into a particular frequency, and secondly so as not to be too greedy with the amount of frequency space (ie width in frequency terms) that they occupy, and so leave some room for other users. The frequency width or ‘bandwidth’ that a transmitter uses is proportional to the speed of transmission, disregarding mathematical tricks aimed at getting more speed, although these have their ultimate limits. So a faster transmission from a transmitting station, all other things being equal, means a wider frequency spike.
I have seen spikes myself which are, I suspect, from searching various websites giving frequency usage lists, to do with kit other than radio stations. Examples of such guesswork: One spike I have seen here might be from equipment at the airport in Tiree - highly speculative, but it is not incredibly far away, around 60 miles. Others could be to do with shipping and meteorological data. I once saw a spike which just possibly might have been associated with fish-finder equipment. But unless it’s one of the well documented radio stations this can be a dubious game.
