A moist fart <| sep |> It was the beast <| sep |> Also good advice . <| sep |> Intrinsic value is a bullshit concept . <| sep |> FM long distance propagation acts different than AM skywave long distance propagation . AM signals bounce or skip at night time when ionosphere is reflective . FM signals can duct at any time if environmental conditions are just right . FM propagation is more line of sight in nature . A duct can open up between the troposphere and suck up a local FM station and carry it for hundreds of miles and dump it over a totally different area at the same time . Ducting doesn ' t happen constantly like AM skip or skywave can . And it may only last between a few minutes to hours , maybe longer . However , the duct effect can make that distant FM station appear as strong as a local station . HD carriers theoretically may also still be receivable at the distant area . I have certainly seen RDBS data recovered 50 miles away from an FM station that is ducting towards me . As a footnote . For FM HD , the power level of the HD signal vs the analog will be greatly different in amplitude level . HD signal may be 10 % of the power in watts or kilowatts of the analog carrier . In early HD standards , the max injection level was 1 % of analog power , this has been changed to 10 % to increase robustness of FM HD reception . Other considerations like transmission techniques have also reduced self interference HD signal interferes with its analog signal to justify injecting at higher levels . And to add to that , with AM this self interference is much worse . A station on 1310 KHZ with HD turned on can also interfere with its analog night coverage . It can also interfere with a local adjacent station on 1320 KHZ it will harm its own HD if turned on and spill over hash onto the analog 1320 KHZ . Most AM operators have voluntarily ceased AM HD transmission at night or all together for this reason . ALSO it adds a large delay to the audio for processing and the analog is purposely delayed to match it , this is no good for live sports