• aardA
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    6
    edit-2
    16 days ago

    RDS and related protocols like TMC have specifications for both FM and AM transmitters. Those are used to stop playback if an urgent message comes. I’m assuming you have AM stations with such signals in the US (I don’t think we have in the EU) - otherwise the AM radio mandate would indeed be stupid.

    edit: did some digging (it’s been almost 30 years since I cared about that stuff) - seems the US was pretty late to the party for radio data channels, and side channels for AM (which wasn’t of that much interest here due to the FM heavy radio landscape in Europe) only was discussed in the early 90s for the US specific variants. I couldn’t find any details if that actually ever got implemented. Given that most documentation available on that topic is heavily focusing on EU I’d guess it never got that much use in the US.