[CW] 10mhz signals?

[Donald Chester]

>Covered (encrypted) 100wpm RTTY.

>Probably military.

I recall back about 1960 the short wave bands were filled with signals that
sounded kind of like the old Soviet jammers, but were outside the SWBC
bands. They were about 3 kHz wide, as I recall. Once, I was playing around
with the  old phasing type crystal filter and got the bandwidth down to
about 100 Hz. When I tuned through one of those signals, I could pick out
about two dozen individual signals that sounded like regular narrow-shift
RTTY. It was some kind of multiplexing that allowed a large number of
signals to be transmitted simultaneously. I never operated RTTY, so never
tried to decode it. Don't know if each individual carrier was regular
Baudot, or some  non-standard method of encoding.

Also about that same time, one winter evening I was listening to WSM in
Nashville, 650 kHz. They used to run a wide variety of programming, not just
country music. I could hear a clicking sound beneath their modulation, which
was right at the threshold of being annoying.  I turned on the BFO. Their
carrier was being frequency-shift keyed just like a RTTY signal. I called
the station, told them what I was  hearing and asked  what it was. At first,
the guy who answered the phone denied knowing what I was talking about, so I
told him to listen, and I put the phone up to the speaker of the receiver
and let him hear the FSK tone. His response was "Oh you must be listening on
a short wave receiver. It's an experiment we are  running for the Air
Force."

Both diamond shaped Blaw-Knox towers at WSM and WLW each have a brick wall
built round the base of the tower, whereas most AMBC stations merely use a
white picket fence. They said the reason was that the stations  were
transmitting strategic information embedded in their regular programming
during WWII, and the brick walls were built to prevent possible Nazi or
Japanese agents from taking pot shots at the tower base insulator.


Don k4kyv