Stanley, (with apologies to everyone else that already knows this) GPS
satellites are in geosynchronous orbit. This means they orbit at the same speed
as the earth's rotation. This allows them to remain over a fixed point over the
earth. But the ocean is like a Faraday shield. It blocks any RF from
penetrating very far beneath the surface, especially in the uhf band the
satellites operate at. That's why a nuke boat has to surface to transmit. It
can however (as DR mentioned) receive a message via ELF which has severe
limitations. The frequency used is 75 Hertz. I'll let you calculate the
wavelength. But its so long, they have had to build enormous buried antenna
system to make it work. The coding used for US military ELF transmissions
employed a Reed-Solomon error correction code using 64 symbols, each
represented by a very long pseudo-random sequence. The entire transmission was
then encrypted. The advantages of such a technique are that by correlating
multiple transmissions, a message could be completed even with very low
signal-to-noise ratios, and because only a very few pseudo-random sequences
represented actual message characters, there was a very high probability that
if a message was successfully received, it was a valid message
(anti-spoofing).The communication link is one-way. No submarine could have its
own ELF transmitter on board, due to the sheer size of such a device. Attempts
to design a transmitter which can be immersed in the sea or flown on an
aircraft were soon abandoned.Due to the limited bandwidth, information can only
be transmitted very slowly, on the order of a few characters per minute (see
Shannon's coding theorem). Thus it is reasonable to assume that the actual
messages were mostly generic instructions or requests to establish a different
form of two-way communication with the relevant authority. The way we know the
position of Russian submarines is pretty simple. We simply assign one of our
fast attack boats to shadow the Russian boomer when it leaves port. The theory
being that if nuclear war was imminent, our boat would immediately sink the
Russian. But this is the ONLY way we can currently know a Russian submarine's
location while submerged. GPS doesn't enter into to it. Hope this clears it up
for you. JS
---------- Original Message ----------
From: "" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "sblumen123@xxxxxxx"
for DMARC)
To: sparkscoffee@xxxxxxxxxxxxx
Subject: [sparkscoffee] How to track submarines
Date: Sat, 1 Aug 2015 15:48:17 -0400
JS, Lee pixiehat and to whom it may concern Now I remember, no ifs. ands, or
buts, a network of ocean bottom sensors were placed and terminated at a central
monitor stationmanned by Russian and American techs. How come you fellers with
comic book mentalities couldn't figure it out? tsk, tsk, tsk,Senile Stanley
wins again and again and again. Great to be 90, hope you fellers can make it
and enjoy the benefits.
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