"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
.170...
Garrett Fulton fired this volley in
:

Is this similar to the control head?
http://ciphermachines.com/Gallery/in...8-Voice-Scramb
ler That was the only voice scrambler I saw used on Marine aircraft
in
Vietnam. I figured the Navy used the same one but maybe the river
boats were different? Had to change the codes at midnight every
night.
Code books were locked in a safe with two thermite grenades inside.
If
we got overrun, were supposed to set the grenades on top of the
safe
and set them off.


That doesn't ring any bells, mentally. I don't know. It was a long
time
ago in a land far, far away! I thought I remembered it being about
half
as big as the radar head.

I remember that we had TWO forms of encryption. First was the box
itself. Then, when we had to convey specific coordinates (say, for
a
strike, but NOT while under fire), we used a paper code-scrambler
wheel,
which they changed-out every week.

They weren't taking any chances that Charlie could figure us out
from our
radio comms.

Lloyd

Radio Intercept was a very important weapon in the fight against
U-boots, which were required to frequently report their position so
they could be vectored toward Allied shipping.

https://en.wikipedia.org/wiki/High-f...ection_finding
Although the position report was strongly encrypted, the direction
they transmitted it from told the anti-sub forces all they needed to
hunt it down. The Germans were well aware they could be located the
same way they tracked down spy transmitters in France, but they didn't
realize the British system could find them instantaneously using a
method they had dismissed as inaccurate. It -was- inaccurate from
distant land bases, but good enough when the HF/DF direction finder
was on a destroyer trailing the sub.

I heard about Spread Spectrum in 1970, though not if we used it in
small tactical radios. It makes a radio transmission indistinguishable
from static.

--jsw