Bench Talk

There is no shortage of stories about bizarre Department of Defense programs, but this one is surely in the top tier. Extremely Low Frequency (ELF) signal propagation (we’re talking 3 to 30Hz) allows signals to pass through the earth and throughout the oceans to depths of several hundred feet, allowing a system at a single location to communicate nearly anywhere on the planet. This made it rather appealing for communicating with submerged submarines and might be able to function in the event of a nuclear strike. The idea was championed not just by the U.S., but by the Soviet Union and India as well. Signals degrade rapidly in the ocean, so when a submarine is submerged, it is less likely to receive communication. The purpose of Elf was to reach deeply submerged subs sufficiently to let them know to surface to receive communications through normal (and better) radio communications.