"Scott Gardner" wrote in message

On Mon, 29 Dec 2003 07:49:31 -0500, "Arny Krueger"
wrote:

Power isn't the only thing that is limited by a station license. The
license also stipulates a center frequency and a bandwidth. The
station has to stay within it's licensed radiated power, and
bandwidth usage limits. If it does that and meets a few other less
important limits, it is legally compliant.

I'm still a little bit confused. Here's a quote from a website
discussing the "loudness wars" and on-air compression:

"With great precision, modulation monitors display modulation on a
meter as a percentage of the FCC limit and via a "peak flasher" to
show peaks the meter does not catch. "Staying legal" is as simple as
keeping the light from flashing. Some monitors even provide a numeric
count of how many times the FCC limit has been exceeded. "

Yup, sounds about right. That's how stations monitor their legal compliance.


Here's a link to the page:

http://tinyurl.com/2zlda

What is the "FCC limit" that the author is discussing?

Typically, they are talking about the usual frequency or power limit,
depending on whether the station was FM (frequency modulation limit) or AM
(amplitude modulation limit). Over-modulation is possible in either case,
but the limits are stated differently, etc.

Does a
flashing light on the modulation monitor simply mean that the
station's licensed radiated power has been exceeded, or is there
another FCC-regulated characteristic of the signal that these monitors
are tracking?

If it's an FM station, they are monitoring maximum frequency deviation. For
FM, 100% modulation is +/- 75 KHz, but there is no technical limit to what
they COULD do. There are anecdotes about FM station where the red light just
stays on.