[CW] 10mhz signals?

Fri Jul 26 10:07:29 EDT 2013

Yes, Hans is correct. One of the reasons for using these types of 
signals was that you could transmit with just one transmitter and 
antenna system, to several outlying stations ( less cost for equipment 
and frequency spectrum at the base station).  The US dept of State, 
amongst other US communications facilities used this method.  A weakness 
of it was that the signal strength was shared amongst the several 
communications links, thus showing lower input at each station.  Another 
problem was that your were tied to one frequency to each set of targets, 
and when propagation changed for one, and he wanted a  QSY,  that was 
not necessarily a good thing for the other station(s) receiving the 
transmission.  Eventually, the system was abandoned due to those 
problems.  My understanding is that hf is pretty much gone from the 
diplomatic telecommunications system.  They apparently couldn't run it 
viably after my retirement.  hehe
> Mike Manship <mailto:mjmanship at iquest.net>
> Thursday, July 25, 2013 11:26 PM
> 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
>
>
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> Hans Brakob <mailto:kzerohb at gmail.com>
> Thursday, July 25, 2013 2:54 PM
> 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
>
>
>
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> Donald Chester <mailto:k4kyv at charter.net>
> Thursday, July 25, 2013 11:58 AM
>> 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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>
> ------------------------------------------------------------------------


-- 
Danny Douglas
N7DC
ex WN5QMX ET2US WA5UKR ET3USA SV0WPP VS6DD N7DC/YV5 G5CTB    all 2 years 
or more (except Novice)  Short stints at: 
DA/PA/SU/HZ/7X/DU/CR9/7Y/KH7/5A/GW/GM/F
Pls QSL Direct, buro or LOTW -preferred
I do not use, but as a courtesy do upload to eQSL for those who do.

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