Underwater military intelligence system - uses network of sea bed transponders which may be interrogated by sonar signals from surface vessels in transit

摘要

A submarine intelligence system incorporates a network of at least three transponders (10) mounted on the sea bed. Vessels passing the network may interrogate it by transmission of an interrogation signal through the water. The interrogation signal is used to trigger characteristic response signals to be transmitted by the transponders in response to it. A stationary surface interface buoy (52) may be used to allow access to the intelligence system by aircraft. The buoy is interrogated by radio signals and passes radio signals back to the aircraft.