AN/URC-117 Ground Wave Emergency Network - Overview

Overview

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, over a large area, can produce a sudden power surge that would overload unprotected electronic equipment and render it inoperable. In addition, EMP would interfere with transmissions that use the ionosphere for propagation. GWEN would use a ground-hugging wave for propagation, being unaffected by the EMP.

The network was conceived as an array of approximately 300 radio transceivers distributed across the continental USA which operated in the Low frequency (LF) radio band. Later revised for 126 towers, plans again changed to include 56 radio towers linking 38 terminals; it was later expanded to 96 towers linking 49 terminals. Final network towers numbered 58.