[BC] iBiquity was Digital Radio Express

[Kevin Tekel]

Phil Alexander wrote:
> It is now possible to make radios that select the correct demodulation
> for digital using more than one standard. The old AMS argument doesn't
> hold up.

It never held up.  In 1983, Sony and Sansui both introduced receivers
which could automatically switch between four different AM Stereo systems,
depending on which pilot tone was received (5 Hz for Magnavox, 15 Hz for
Kahn, 25 Hz for Motorola, or 55 Hz for Harris).  I've tested my Sony
receiver with a multi-system AM Stereo generator, and even if a station
switches to a different AM Stereo system without dropping their carrier,
it will automatically change to the correct decoding method within one
second.

p.s. Even today some Kahn POWER-Side stations still transmit a 15 Hz Kahn
AM Stereo pilot tone.  That's fully legal because the FCC does not
consider POWER-Side to be an "AM stereo" method, regardless if it is
transmitted with a pilot tone or not.  IBOC also uses a pilot tone of
sorts -- around
150 Hz if I remember correctly; it's quadrature-modulated, so it is
(mostly) inaudible on conventional AM receivers.




		
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