"Michael Rathbun" wrote in message
news:3f6b7748.19395909@localhost...


The "open mike in an airplane cockpit" sound, when found in the middle of
the
ute bands, is actually multi-channel teletype. If you can find one of
them,
and if you have a sufficiently narrow filter, you can pull individual
channels
out and hear very narrow shift FSK.

Yeah, I could zero beat the BFO on several carriers across the channel.
There's a wider one now, which sounds more hissy. With a ringing single
crystal filter on it's most selective position and the BFO I can now make
some way cool "Open Mike In The Flying Saucer" sounds.

Anyway, thanks for confirming my guess about the transmissions.


Those of us who were SWLs and who worked on AN/TCC-4 TT multiplex
equipment in
the military all had "aha, that's what that is" moments the first time we
listened to a carrier channel that had one of these connected to it.

As far as the bagpipe sounds, I figured it might have been some sort of
automated signal to switch between either different terminals or customers.
Commercial radio used dial tone like signals at the start and finish of
network feeds. Westinghouse/Group W was the worst for that racket. Heard
alot of that stuff on low VHF, too.

The only reason I suspected that was sometimes I'd hear the B-17 sound or
inverted sideband between the bagpipe riffs. They usually went on and on as
if they were just marking the channel. Like the RTTY stations transmitting
the same endless pattern. Of course, the bagpiper could have been piping
out actual information, I sure don't know for sure.

Frank Dresser