frd

The AN/FRD-10 Circularly Disposed Antenna Array (CDAA) was a United States Navy circular "Wullenweber" antenna array, built at a number of locations during the cold war for high frequency radio direction finding (HF/DF) and signals intelligence. In the Joint Electronics Type Designation System, FRD stands for fixed ground, radio, direction finding. 14 sites were originally constructed as a part of the "Classic Bullseye" program. Two AN/FRD-10 systems were also installed in Canada. AN/FRD-10 systems were originally constructed in the 1960s, but after the dissolution of the Soviet Union, the systems began to be shut down and demolished. The Naval Security Group operated and maintained the US Navy AN/FRD-10 systems. The system had several nicknames including Fred-10 and Elephant or Dinosaur cages. As of 2015, none of the US Navy AN/FRD-10 sites are extant, but the two Canadian sites remain in service. The AN/FLR-9 was a system with a similar design and function, but used by the US Air Force and Army.

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