Detection device for underwater objects

Abstract

Abstract An Omega station transmits radio signals and at least one underwater aerial with connected receiver (1) is tuned to the signal frequency. An electronic changeover unit has an input for an above-water aerial, and one for each of these below water level. It also has an output connected to the receiver aerial input. Changeover between the receiver input from the two aerials occurs on a short time period basis, and a phase-sensitive circuit is provided which compares the phases of the signals from the aerials above and below water. An alarm circuit is activated when the phase of the signal, received from the underwater aerial varies in relation to that received from the above water aerial. The below-water aerial is of the long loop type which with its end turned towards the radio receiver is connected to an adjuster for turning purposes. Thus, signals received from this aerial have the same phase as those from the above-water aerial when no object passes within the vicinity of the underwater aerial.

Inventors

• 👤 Sven Ramstrom

Bibliographic Details