Project Sanguine - Wikipedia

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2021-05-29 21:30:03

Project Sanguine was a U.S. Navy project, proposed in 1968 for communication with submerged submarines using extremely low frequency (ELF) radio waves. The originally proposed system, hardened to survive a nuclear attack, would have required a giant antenna covering two fifths of the state of Wisconsin. Because of protests and potential environmental impact, the proposed system was never implemented. A smaller, less hardened system called Project ELF consisting of two linked ELF transmitters located at Clam Lake, Wisconsin and Republic, Michigan was built beginning in 1982 and operated from 1989 until 2004. The system transmitted at a frequency of 76 Hz. At ELF frequencies the bandwidth of the transmission is very small, so the system could only send short coded text messages at a very low data rate. These signals were used to summon specific vessels to the surface to receive longer operational orders by ordinary radio or satellite communication.

The originally proposed system would have had a giant "antenna" consisting of 6,000 miles (9,700 km) of buried cables in a rectangular grid covering 22,500 square miles (58,000 km2), two fifths of the state of Wisconsin,[1] powered by 100 underground power plants in concrete bunkers.[2][3] The cables were grounded at their ends, and loops of AC electric current flowed deep in the ground between the ends of the cable, generating ELF waves; this is called a ground dipole. The original design was projected to cost billions[4] and consume 800 megawatts of power.[1][5] The goal was a system that could transmit tactical orders one-way to U.S. nuclear submarines anywhere in the world, and survive a direct nuclear attack.[2]