SUBMARINE COMMUNICATIONS SYSTEMS

Why Sub Communications?

In one of the theories of the downing of flight 800, it is postulated that a coordinated attack was being tried, with a submarine launched missile against a target drone being painted by the distant Aegis.

This requires that the Aegis, or other command authority, be able to pass a launch command down to the submerged submarine.

These are some of the means by which submarines communicate with the surface.

ELF and VLF

The Navy maintains a typical VLF station (NAA) at Cutler, Maine, transmitting continuously on 17.8 kHz with power of 2,000,000 watts; and another (NLK) at Jim Creek, WA., on 18.6 kHz with 1,000,000 watts. (NOTE: These frequencies were provided by one military source, but are claimed to be inaccurate by another). These and others send a continuous string of data, which is phase modulated onto the carrier.

In all, a total of 7 U.S. ELV/VLF sites are known to be in operation.

In addition, the TACAMO command and control aircraft are able to directly transmit VLF messages using a trailing wire antenna.

At the frequencies, a quarter wave is, indeed, about five miles, but that's just a red herring. Neither a surface ship nor a sub could trail an antenna in the water and try to transmit a signal; you'd just have a dead short to ground! A surface ship could, however, easily send a signal to a sub, simply by sending the message to Cutler, ME or Jim Creek, WA, by satellite. There, the message could be slipped into the data stream and arrive at the sub within a couple of seconds.

Submarines don't require long wire antennas to receive these transmissions. They sometimes use faraday shielded loops on remote buoys, although the connection wires to the buoy can vibrate in the water flow, revealing a sub's location to enemy sonar.

LASERS

The following picture is from a book on submarine warfare printed in 1987.

There is an optical window in the blue-green part of the spectrum which enables laser transmissions to penetrate the ocean a substantial distance.

According to this source, in 1987, the United States was developing laser based communications systems for high speed communications with submarines. One must assume a certain progress after 9 years.

Laser communications offer many advantages in addition to high speed.

While surfaced in clear weather, a submarine enjoys high speed, unjammable communications which cannot be used to locate the sub itself.

When submerged, the system is one way to the sub, like VLF/ELF, but (based on the surface conditions refracting entering laser light) would operate at 300 times the data rate of VLF/ELF.

XSTAT

XSTAT is an expendable radio transceiver deployed on an 8000 foot wire tether. It allows a submerged submarine to deploy a short high band radio antenna above the water more than a mile from its true position

LASERS CONFIRMED

The existence of a two way laser based aircraft to submarine communications system is confirmed by the following article from the Office Of Naval Research on the accomplishments of USS Dolphin.


                            USS DOLPHIN (AGSS 555)
                                       
   A picture of the USS Dolphin USS DOLPHIN is the Navy's deep diving
   submarine designed to test advanced submarine structures, sensors,
   weapons, communications, and machinery systems. USS DOLPHIN serves as
   a scientific platform capable of operations at unprecedented depths
   greatly exceeding that of any known operational submarine. In November
   1968, she set a depth record for operating submarines that still
   stands. In August 1969, she launched a torpedo from the deepest depth
   that one has ever been fired.
   
   Utilizing a large payload (over 12 metric tons) and a highly versatile
   instrumentation suite, civilian and Naval activities employ USS
   DOLPHIN for testing a multitude of technologically advanced and
   complex equipment. Presently configured to conduct extensively deep
   water acoustic research, oceanic survey work, sensor trials, and
   engineering evaluations, USS DOLPHIN operates as a Unit of the U.S.
   Naval Submarine Force, U.S. Pacific Fleet, under Commander, Submarine
   Development Group One.
   
   In over twenty years of operations, USS DOLPHIN has proven most
   successful in assessing "the overall Anti-Submarine Warfare (ASW)
   significance of deep diving submarines" and exploiting "the limits of
   present technology in designing for deep depths." Her operations have
   been broad based and far reaching, and they include development of
   operational concepts and testing of advanced engineering design
   features, weapons, launcher and fire control systems, and deep ocean
   acoustics. Much of this work is necessarily classified, but examples
   of USS DOLPHIN's specific achievements are listed in the following
   list.
   
   The Dolphin's Crest
     * First successful submarine-to-aircraft optical communications
     * Development of a Laser Imaging system of photographic clarity
     * Development of an Extreme Low Frequency (ELF) antenna for TRIDENT
     * Evaluation of various non-acoustic ASW techniques
     * Evaluation of various low probability of interception active
       sonars
     * First submarine launch of a MOSS system
     * First successful submarine test of BQS-15 sonar system
     * Development of highly accurate (10 cm) towed body position
       monitoring system
     * deepest launching of a torpedo
     * Development of a new Obstacle Avoidance Sonar system
     * Development of a highly accurate target management system
     * Evaluation of a possible "fifth force of nature"
     * First successful submarine-to-aircraft two-way laser communication
       
   The USS DOLPHIN has achieved a great deal of success in each of her
   endeavors and has many firsts added to her record. She has indeed
   proved the feasibility of operating deep in the ocean.
   
   The single most significant technical achievement in the development
   of the USS DOLPHIN is the pressure hull itself. It is a constant
   diameter cylinder, closed at its ends with hemispherical heads, and
   utilizes deep frames instead of bulkheads. The entire design of the
   pressure hull has been kept as simple as possible to facilitate its
   use in structural experiments and trails. Hull openings have been
   minimized for structural strength and minimum hull weight, in addition
   to eliminating possible sources for flooding casualties.
   
   The USS DOLPHIN 's unique capabilities allow her to conduct
   independent deep ocean research missions. She is a unique blend of the
   lessons learned of the past and the most advanced technology of the
   present. The USS DOLPHIN's continuing contributions to research and
   development will significantly influence the design of 21st century
   submarine sonar, weapon, communications, and engineering systems.
   
   Information from USS DOLPHIN's Welcome Aboard pamphlet.
     _________________________________________________________________
   
   The USS DOLPHIN is the second submarine of the name. The first USS
   Dolphin (SS 169) was a forerunner of the "Fleet Boat" class of
   submarines - the work horses of WWII.
     _________________________________________________________________
   
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     _________________________________________________________________
   
   Last updated on 18 September 1995 by LCDR P J Hoffman,
   
   
    hoffman@nadn.navy.mil

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