For many years I've kept a scanner at work to listen to the air-ambulance
helicopters come and go--I just find the choppers interesting.

Moved to a new job last month in Louisville, KY. Just out of curiosity, I
added the listed frequency (464.1375) for the excursion boat _The Belle of
Louisville_ to my scanner. (I took the two-hour ride this weekend and it
was a lot of fun.)

So I do hear activity from the _Belle_, but there's a warbling sort of
audio tone on all their transmissions. Sounds like someone blowing a
slide-whistle while working the slide up and down. Don't know that I've
ever heard that before.

Is this something designed to discourage listening? (In my case,
sometimes the warbling isn't very loud in the audio stream, and at other
times it's loud enough to make it difficult to hear what they're saying--I
have no idea why it varies like this.) Or is the warbling for some other
reason? TIA.


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Ken Kuzenski AC4RD atsign mindspring dotsign com
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All disclaimers apply, see? www.duke.edu/~kuzen001