TIS stations have low-pass filters from 3-20kHz, but it looks like most AM stations have low-pass filters from 5-20kHz anyways to avoid interference with neighb

TIS stations have low-pass filters from 3-20kHz, but it looks like most AM stations have low-pass filters from 5-20kHz anyways to avoid interference with neighboring channels: https://casetext.com/federal-register/audio-filtering-requirement-for-travelers-information-stations https://casetext.com/federal-register/audio-filtering-requir...