[Hallicrafters] "Airplane" Noise on Short Waves

[howard holden]

The "airplane noise" is (was) indeed multiplexed RTTY. Used by all all 
branches of the armed forces. Some was fleet broadcast, and some even 
dedicated to one ship especially if that ship was a flag command, but most 
was point-to-point stuff. Normally 16 but as many as 64 channels of RTTY 
jammed into one sideband, the other sideband used for voice links. They used 
time-division-multiplexing, and the tuning of the signal was extremely 
critical to get all the channels to decode. The FRR-59 and FRR-60 were often 
used for receiving, but a good op could tune an R-390 well enough to decode 
the signals. Land stations usually used the FRT-39 and FRT-40 for XMIT.

Howie WB2AWQ ex NGR, NAW

----- 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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