The World’s Largest "Radio" Station [pdf]

The US Navy’s Project ELF, also known as Project Sanguine, is an Extremely Low Frequency communications project designed to communicate with deeply-submerged submarines. It uses low-frequency waves to signal one-way coded messages to submarines, alerting them to surface for more detailed communication. The project consists of two transmitters located in Wisconsin and Michigan, with huge antennas that can produce a usable signal at the low frequency of 76 Hz. [summary] [comments]

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