Abstract: A charging circuit for a helicopter dipped sonar system in which a single ble conducts sonar and command signals in either direction along with a DC charging current from the helicopter to a storage battery in a submersible sensor unit. A multiplexer and power supply in the helicopter respectively provide simultaneous transmission of command data and charging current over a common conductor to the sensor unit. A filter and demultiplexer positioned in the sensor unit passes only the data for control of a sonar transmitter. The storage battery is charged directly from the conductor and a battery charge indication as well as hydrophone information is combined by a multiplexer at the sensor and returned to the helicopter by the common conductor for data display and power supply control.

Abstract: An acoustic detection system comprising two arrays of omnidirectional sensors or hydrophones wherein the sensors in each array are disposed along a curved line, such as an arc of a cylindrical surface. Accordingly an acoustic signal or wavefront propagating along any vector within the arc is registered by the respective sensors as phase lags determined by the locations thereof. The respective sensor output signals are each connected to a preselected electrical delay circuit such that the registered phase lags are further increased. The delayed sensor signals are then summed for each array, forming two directional beams and the signal sum for each array is then connected to identical narrow bandpass filters. The output of each filter is fed to a hard limiter, then to a differentiator and the output signals of the differentiators control a bistable flip-flop producing a pulse train where the width of each pulse corresponds to the phase lag difference between the beam signals.