Vai tämmöinen systeemi on Gwen?
Milläs se Kapanazden systeemi pelaa, ellei juurikin samoilla energioilla?
http://www.nap.edu/read/2046/chapter/4DESCRIPTION OF GWEN SYSTEM
The Ground Wave Emergency Network (GWEN) system was designed to protect U.S. communications during a high-altitude nuclear explosion. Such an explosion could affect strategic communications in two important ways. First, the electromagnetic pulse (EMP) produced by a high-altitude nuclear detonation could, over a large area, produce a sudden power surge that would overload unprotected electronic equipment and render it inoperable; in recent years, the Air Force has pursued an extensive program to protect critical electrical components by making them immune to the effects of the EMP-produced power surge. Second, the EMP could interfere with radio transmissions that use the ionosphere for propagation of signals. GWEN uses a ground-hugging wave for propagation, not the ionosphere, and so would be unaffected by high-altitude nuclear detonations. It should be recognized that this ground-hugging wave propagation of the GWEN LF transmitter is no different than that for normal AM radio stations. For the latter sources, the electromagnetic fields also propagate with electric fields that are nearly vertical relative to the ground.
GWEN, developed by the Air Force Electronic Systems Division, calls for three types of stations: input/output stations (I/Os), receive-only stations (ROs), and relay nodes (RNs). I/O stations can both send and receive messages. ROs only receive messages transmitted through I/Os. Unmanned RNs, which would be dispersed throughout the conterminous 48 states, would provide continuous relay links between I/Os and ROs. I/Os and ROs would be at strategic Air Force locations, and RNs would be either on government land or on private land leased by the government. The ground wave used to transmit through the network requires RNs at intervals of approximately 150 - 200 miles.
I/Os would use 50-W transmitters to drive antennae mounted on 20-to 100-ft towers. They would broadcast ultra-high-frequency (UHF) signals in the 224- to 400-MHz band. I/O terminals would enter messages into the RNs by line-of-sight UHF radio links. Airborne I/Os would use the same basic equipment sets and operate at the same power and frequency band as fixed I/Os.
ROs would use 48-in. loop low-frequency (LF) receiving antennae, which would be generally on or near the roofs of existing military communication facilities as would fixed I/Os. Airborne I/Os and portable RO terminals would also use the system. ROs would be installed at fixed locations, and portable units would be stationed at alternate Strategic Air Command (SAC) operating locations. Launch control centers (LCCs) would also be equipped with RO terminals.
Most of the RNs would communicate primarily with other RNs, transmitting with LF antennae at 150 - 175 kHz. Eight of the RNs would receive messages from I/Os