12
Jan
10

The New Sosus: Optical ASW

  Well, I try and keep up on what's going on, and I must say that this completely caught me unawares. I found the original through a blog I visit entitled Molten Eagle. It written by a submariner and has a LOT of interesting stuff. Anyway, the original article appeared in Military and Aerospace Electronics in February, 2002. Because it's relatively short, I'm posting it all here. I am VERY interested in learning more about this system, and would like to hear from anyone with information they are willing to share.
———————————————————————-

Navy using optical sonar sensors to enhance submarine detection and alleviate maintenance problems

By John Keller

WOODLAND
HILLS, Calif. — Sonar experts from the Northrop Grumman Navigation
Systems Division in Woodland Hills, Calif., envision a vast ocean-floor
optical sensor array that can detect and track some of the world's
quietest submarines through minute phase shifts of light.

This array, which U.S. Navy leaders call the All Optical Underwater
Segment — or AO-UWS — is to be deployed in strategic ocean areas that
either funnel heavy submarine traffic, or where pinpointing hostile
submarines is crucial.

The
AO-UWS could go on line as early as 2004, says Jim Andersen, director
of business development for fiber optic acoustic systems at Northrop
Grumman Navigation Systems.

Northrop
Grumman engineers are designing the AO-UWS optical sensor array under
terms of an $8.9 million contract from the U.S. Space and Naval Warfare
Systems Command (SPAWAR) in San Diego. The 24-month development program
will culminate in an at-sea demonstration of the system sometime in
2003.

Among
the chief advantages of underwater optical sensors are sensitivity and
reliability, Andersen says. Optical sensors are to augment or replace
existing underwater arrays of electronic hydrophones that are part of
the U.S. Navy's Integrated Undersea Surveillance System — better known
as the IUSS.

"This
system is for deep water, so you could deploy it anywhere," Andersen
says. "It will be large fields of sensors — hundreds to thousands of
sensors — that are used for ASW- [anti-submarine warfare] type
detection."

The
sensor array and signal-transmission media will be all-optical
components — manufactured from plastic or silica, which is not
susceptible to the corrosive influences of saltwater, Andersen says.
Electronic components, on the other hand, can suffer corrosion or
short-circuits in seawater, which present the Navy with a persistent
maintenance headache.

"The
advantage is there is no electronics in the water, or on the 'wet end',
so the stuff we put in the water is very reliable" Andersen explains.
"All the electronics is on shore or on a ship, which can be mounted in
COTS [commercial off-the-shelf] versions; you don't have to package
electronics for the water, and you can rely much more on standard COTS
electronics."

The
AO-UWS sensor array detects phase shifts in light waves caused by the
sounds of submarines. "We put a carrier frequency on the light beam,
and at the sensor the acoustic pressure signal will shift the phase of
the light," Andersen says. "It is these phase shifts that we pick up."

The
AO-UWS works by connecting arrays of optical sensors with optical
fiber. These interconnected arrays, in turn, connect via optical fiber
with signal-processing gear on shore, aboard ships, or inside
submarines.

"Once
we convert the optical signal back into a voltage signal, we format it
to whatever someone might want, such as fast Ethernet," Andersen says.
"We rely on the signal-processing people to process it however they
want. We just give it to them in the right format for the processing."

Two
subcontractors are working with Northrop Grumman to develop the AO-UWS
— MariPro Inc. of Goleta, Calif., which is concentrating on mechanical
wet-end junctions, terminations, and packaging; and Digital System
Resources (DSR) Inc. of Fairfax, Va., which concentrates on interfacing
to existing Navy sonar processing systems.

The
AO-UWS is to become part of the Navy's Integrated Undersea Surveillance
System, which includes the Sound Surveillance System (SOSUS), Fixed
Surveillance System (FSS), the Fixed Distributed System (FDS), the
Surveillance Towed Array Sensor System (SURTASS), and the Advanced
Deployable System (ADS).

Northrop
Grumman sonar experts envision the AO-UWS as a complement or
replacement for the Fixed Distributed System, Andersen says. The FDS is
a fork-shaped array of ocean-floor sensors that not only detect the
sounds of submarines, but also help analysts use triangulation to
gather range and bearing information.

Northrop
Grumman is also using optical sonar sensors on submarines such as the
future Virginia-class new attack submarine to enhance
submarine-detection capabilities, and also to reduce maintenance tasks.

With
optical sensors on submarines, "the beauty is the previous system had
electronics external to the pressure hull," Andersen explains. "It is
difficult to maintain them, even in port. We had to dry-dock them. Now
we have optical fiber outboard and the electronic maintenance issues
involve simply changing out a printed circuit card. They can do that
even underway."

Military & Aerospace Electronics February, 2002

Author(s) :

  John Keller

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2 Responses to “The New Sosus: Optical ASW”


  1. January 15, 2010 at 03:44

    Tim, IIRC, after the fall of the wall, didn't we foolishly dismantle/mothball a large part of our SOSUS sensors up in Iceland monitoring the Faroe Gap? Also some in Newfoundland as well? Or was it considered to becoming obsolete and something like the above was planned to replace it? Zoomie me knows little of these arcane Spy vs Spy ASW submariner matters, so what's the deal?

  2. January 15, 2010 at 06:40

    VX, Wikipedia says it in fewer words than I would:SOSUS was gradually condensed into a smaller number of monitoring
    stations during the 1970s and 80s. However, the SOSUS arrays themselves
    were based upon technology that could only be upgraded irregularly.
    With the ending of the Cold War
    in the 1990s, the immediate need for SOSUS decreased, and the focus of
    the US Navy also turned toward a system that was deployable on a
    theater basis. The SOSUS components are now used for scientific
    projects, such as tracking the vocalizations of whales and other ocean
    mammals in various study projects, as a data network for undersea
    instrumentation packages, and for acoustic thermometry. The SOSUS system was declassified in 1991, although by that time it had long been an open secret.
    Commander Undersea Surveillance (CUS), head of the IUSS, was elevated to an echelon IV command 28 February 2007. [1] CUS at NAS Oceana Dam Neck Annex operates under the operational guidance of COMPACFLT.
    Naval Ocean Processing Facilities in Oak Harbor, Washington, and
    Virginia Beach, Virginia, still monitor SOSUS and FDS, and they provide
    SURTASS connectivity around the world.


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