[Hallicrafters] "Airplane" Noise on Short Waves

[Tony Martin W4FOA]

Scott,
I think you will find that those were HF Multiplex signals which are now 
almost never heard since microwave multichannels came on the scene.  The HF 
MUX can still be heard in some of the lesser developed areas of the world, 
as can HF relays of long distance telephone calls.  Rare, but still 
operational even in this day of modern technology.

The woodpecker was a completely different animal...it was OTOH (Over the 
horizon HF radar) mostly coming from the USSR at that time. Signals were 
incredibly strong and makes one wonder just how much power were they 
running, anyway.

73
Tony, W4FOA



----- Original Message ----- 
From: "Freeberg, Scott (STP)" <Scott.Freeberg at guidant.com>
To: <Hallicrafters at mailman.qth.net>
Sent: Monday, May 02, 2005 1:54 PM
Subject: RE: [Hallicrafters] "Airplane" Noise on Short Waves


I remember hearing airplane noise as well as a kid with my shortwave.  I 
wonder if it was RTTY broadcast.  When I was a radioman in the Navy during 
Viet Nam, I used copy RTTY fleet broadcast.  I sounded like an airplane I 
guess.  It consisted of a many individual RTTY channels with super narrow 
shifts, transmitting in that bandwidth.  With a really good receiver you 
could slowly tune up the frequency and pick out the individual mark/spaces 
for each RTTY channel within in 3 Khz or whatever bandwidth.  Do you think 
thats what the airplane noise is?
73, Scott WA9WFA
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