thumb|upright=1.8|Typical GWEN relay node

The Ground Wave Emergency Network (GWEN) was a US Air Force command and control communications system, deployed briefly between 1992 and 1994, intended for use by the United States government to facilitate military communications before, during and after a nuclear war. Specifically, the GWEN network was intended to survive the effects of an electromagnetic pulse from a high-altitude nuclear explosion and ensure that the United States President or their survivors could issue a launch order to Strategic Air Command bombers by radio.

In accordance with the Joint Electronics Type Designation System (JETDS), the "AN/URC-117" designation represents the 117th design of an Army-Navy electronic device for general utility two-way radio system. The JETDS system also now is used to name all Department of Defense electronic systems.

Each GWEN Relay Node site featured a longwave transmitting tower, generally between tall, and emitting an RF output of between 2,000 and 3,000 watts. Of 240 planned GWEN towers, only 58 were built. In 1994, a defense appropriations bill banned the funding of new GWEN tower construction, and a few months later, the GWEN program was cancelled by the US Air Force.

History

GWEN was part of the Strategic Modernization Program designed to upgrade the nation's strategic communication system, thereby strengthening the value of nuclear deterrence. The GWEN communication system, established in the late 1980s, was designed to transmit critical Emergency Action Messages (EAM) to United States nuclear forces. EMP can produce a sudden power surge over a widespread area that could overload unprotected electronic equipment and render it inoperable. In addition, EMP could interfere with radio transmissions that use the ionosphere for propagation. It was thought that GWEN would use a ground-hugging wave for propagation and so be unaffected by the EMP. The first major phase of construction was called the "thin line" which began in 1985.

Operations

Command and control messages originating at various military installations were transmitted on the 225 to 400 MHz band and received by a network of unmanned relay stations, called "Relay Nodes", dispersed throughout the contiguous 48 states. The Relay Nodes would re-transmit these command and control messages to each other, and to Strategic Air Command operating locations and launch control centers using low frequencies in the 150-175 kHz range in order to take advantage of ground-hugging radio propagation similar to commercial AM radio stations.

Problems

Early in its lifetime, electrical interference problems caused by GWEN system operation began to surface. Since the stations were using LF, the chosen frequency was within 1 kHz of the operating frequency of nearby electrical carrier current systems. With GWEN handling constant voice, teletype and other data traffic, it caused interference to the power companies' diagnostic two kilohertz side carrier tone. When the side carrier tone disappeared due to interference from GWEN, the power grid would interpret that as a system fault.

Site layout

The overall area of a GWEN Relay Node was approximately , approximately × 700 feet. It was surrounded on the perimeter by locked, chain-link fences topped with barbed wire. Typical site features included:

  • Appleton, Washington
  • Austin, Nevada
  • Bakersfield, California
  • Billings, Montana
  • Bobo, Mississippi
  • Clark, South Dakota
  • Edinburg, North Dakota
  • Fenner, California
  • Flagstaff, Arizona
  • Gettysburg, Pennsylvania
  • Goodland, Kansas
  • Grady, Alabama
  • Great Falls, Montana
  • Hackleburg, Alabama
  • Hagerstown, Maryland
  • Hawk Run, Pennsylvania
  • Kirtland AFB, New Mexico
  • Klamath Falls, Oregon
  • Macon, Georgia
  • Medford, Wisconsin
  • Medora, North Dakota
  • Onondaga, Michigan
  • Penobscot, Maine
  • Pueblo, Colorado
  • Ronan, Montana
  • Savannah Beach, Georgia
  • Spokane, Washington
  • Summerfield, Texas
  • Whitney, Nebraska

Termination

Some of the initial towers had prompted groups of citizens in Massachusetts, Oregon, Pennsylvania, and California to organize to fight construction of GWEN towers in their areas. The groups believed that the presence of a GWEN node would increase the community's "strategic worth" in the eyes of the Soviet Union and thus invite attack. Responding to these groups, the Air Force repeatedly downplayed the importance of the towers, stating they were not worth that kind of attention by the Soviet Union.

In 1994, new construction of GWEN towers were banned after a defense appropriations bill eliminated any funding for the towers for one year. A few months later, the United States Air Force announced that they would terminate the construction contract to build the remaining 25 towers, except for the money used to dismantle the system.

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File:GWEN antenna tuning unit shelter and security fence.PNG|GWEN antenna shelter & security fence

File:GWEN equipment area.PNG|GWEN equipment area

File:Essex, CA GWEN site 1.jpg|Former GWEN tower, Essex, California

File:GWEN Essex CA updated GPD diff gear 1.jpg|GPS gear added to former GWEN tower at Essex, California

File:Essex CA, GWEN rf rad warning sign.jpg|RF radiation warning sign on former GWEN site at Essex, California

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See also

  • Command and Control (military)
  • Differential Global Positioning System
  • Post Attack Command and Control System (PACCS)
  • Minimum Essential Emergency Communications Network (MEECN)
  • Emergency Rocket Communications System (ERCS)
  • Survivable Low Frequency Communications System (SLFCS)
  • List of military electronics of the United States

References

;General

  • Closure of the Ground Wave Emergency Network (GWEN) Relay Nodes, USAF EAIP 1998.
  • FAS: Federation of American Scientists
  • USAF Installations