Helicopter detector for submarine - uses heat sensor and sonar on periscope to differentiate aircraft from surface ship

摘要

The periscope of the submarine is fitted with a scanning heat detector and a scanning sonar. The heat detector picks up all types of craft, while the sonar identifies surface vessels, which can be separated from the signals. The presence of only the heat signal signifies an aircraft. The helicopter type of aircraft is identified by electronic processing of the heat signal, to pick out the cyclic beat of the rotors, on the thermal pattern. Both sonar and thermal patterns can be displayed on the same CRT for rapid identification of possible submarine hunting helicoptors.