On 3/8/2015 11:58 PM, Wayne.B wrote:
On Sun, 8 Mar 2015 17:08:19 -0700 (PDT), True North
wrote:

We used to read stories of our previous class of diesel electric submarines getting within torpedo range of 'merican carriers. Didn't realize the newer Upholder class did the same thing.

BTW ..it was four submarines we took off British hands. Three are based in Halifax in various stages of operational readiness.

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Those guys are so good at submarine tracking and identification that
they probably knew they were coming 100 miles away. The propellor
and hull noise of every ship and sub is totally unique, just like a
finger print or DNA sample. There are world wide networks of
underwater microphones that track ships and subs everywhere. The
noise signature of every one is in a database.



The US military system was called SOSUS. The stationary, land based
SOSUS systems have been phased out in favor of a ship and sub mounted
towed array system that can be used anywhere. It's a passive system and
compares noise signatures to a library of signatures contained it it's
computer system. It can detect and identify a vessel by name, it's
location, speed, course, etc., and like other systems the data is
networked via high speed communication links to many ships.

I was assigned to a project group in the Navy that had the first
operational towed array system installed. At the time it was called
"Interim Towed Array Surveillance System" (ITASS) and the first ship to
receive the equipment was the USS Van Voorhis, followed by two other
DE's of the same class. This was back in 1970. The system has evolved
and has been improved and is now standard equipment on most Navy combat
vessels and subs.

It's one of several methods for detecting and locating surface ships and
submarines. There are others currently deployed and being developed.
Blue/Green laser technology continues to be explored for sub detection
and communication purposes.