[CW] 10mhz signals?

[Mike Manship]

That is one of my earliest memories of short wave - hearing those 
roaring rtty mux stations on my dad's S-38B as a little kid.
My little kid imagination thought I was hearing the roar of airplane 
engines or generators. It wasn't until 20 years later that I tuned
them in with narrow selectivity as Don did and realized they were rtty 
signals. I haven't heard them in quite a while. I guess they
went the way of the dodo and LORAN as they were replaced by 
satellite/fiber/whatever.

73 de Mike W9OJ


On 7/25/2013 2:54 PM, Hans Brakob wrote:
> What you were listening to was 16 channels of frequency division 
> multiplexed RTTY.  The equipment most commonly used was the 
> AN/FGC-60-series which accepted up to 16 channels of 100WPM baudot 
> RTTY.  The output was a nominal 3kc wide audio signal transmitted over 
> SSB.  The individual channels were typically individually encrypted in 
> Jason or Orestes.  The system could run dual- or quad-diversity to 
> combat selective fading.  Then, of course, the capacity was reduced to 
> eight or four channels.
>
> 73, de Hans, K0HB
>
>
> On Thu, Jul 25, 2013 at 10:58 AM, Donald Chester <k4kyv at charter.net 
> <mailto:k4kyv at charter.net>> wrote:
>
>     >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
>
>
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