crap radio or maybe even crap generator onboard producing rubbish AC waves.
else its hetrodyning with another local transmitter.
why dont you bung up an mp3 of it somewhere and we could listen to it.
might even be a birdie in you scanner IF.
mike
 wrote in message 
...
 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.
 _______________________________________________
 Ken Kuzenski AC4RD atsign mindspring dotsign com
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 All disclaimers apply, see?  www.duke.edu/~kuzen001