HD Radio

This is a response to a letter to Radio World by Daniel Brown, Zebra Radio who was responding to Michelle Bradley of REC's previous letter to Radio World.

REC has filed comments in response to Bryan Broadcasting Corporation's Petition for Rulemaking to allow AM broadcast stations to voluntarily discontinue all AM analog broadcasting and convert to the HD Radio MA3 mode.  MA3 is an all-digital operation.  Two variants of MA3 will allow AM stations to operate in a 20 kHz wide channel where secondary and teritary sidebands more than 5 kHz from the center frequency are either reduced by 15 kHz or they are completely suppressed.  The MA3 mode is a far departure from the "hybrid" MA1 mode which involves the use of a 30 kHz wide channel.  In the past, the MA1 hybrid digital mode on AM, especially at night, has resulted in substantial first and second adjacent interference to analog AM stations forcing many stations to turn off the digital mode and leaving a bad taste in the mouths of AM listeners and radio enthusiasts across the nation.  MA3 mode uses a narrower channel and therefore reduces the chances of digital to analog interference.