On Thu, 22 Feb 2007 11:02:54 -0500, lsmyer wrote:

Maybe that explains what I've been hearing on WTAM lately. For the past
few nights, I've heard a weird warbling sound at times. Last night, it
was gone. Since WTAM is also a Clear Channel station, maybe that
explains why they sounded normal last night. I hope the sound stays away.

That's not what IBOC sounds like.

IBOC is a loud hissing noise on adjacent channels. (generally on the
first channel either side of the IBOC station. Many receivers will also
hear it on the second channel either side.) So if WTAM were running IBOC
I'd expect a hiss on 1090 and 1110, maybe also on 1080 and 1120 depending
on your radio. I've heard rumors that some poorly-adjusted stations (or
radios) will hear the hissing noise on the station's own frequency as well.

The FCC only authorizes IBOC operation between 6am and 6pm. (if sunrise
is earlier than 6, IBOC may begin at sunrise; and if sunset is after 6,
IBOC may continue until sunset) It is rare (but not unheardof) for large
stations to violate these times. I have to suspect most such "violations"
are the result of FCC-authorized tests.