NIEDERFREQUENTZ SONARSTRAHLER

摘要

A low frequency sonar projector for use with a projector array having at least one ceramic stack comprised of lead magnesium niobate-lead titanate (PMN-PT) having a Curie temperature Tm approximately equal to the operating temperature of the projector. A mechanism is provided for applying heat to and for controlling the temperature of the ceramic stack to within a fixed operating range. A biasing circuit is included for providing a first electrical signal to polarize the ceramic stack. A driving circuit is also included for providing a second electrical signal to generate an output signal from the ceramic stack. Finally, a mechanism is included for transmitting the output signal from the ceramic stack to a fluid medium. In a preferred embodiment, a PMN-PT ceramic stack is in intimate enclosed contact with an elliptical-shaped outer projector shell. The Curie temperature Tm of the PMN-PT is selected to maximize the electrostrictive effects of the ceramic stack (102) for improving projector performance. The stack is surrounded by a heating coil which is controlled by a temperature/heater control mechanism to achieve and maintain the stack operating temperature within a fixed range. The ceramic stack is polarized by a d.c. biasing circuit signal and mechanical vibrations are generated within the stack by an a.c. driving circuit signal. The mechanical vibrations of the ceramic stack cause excursions in the outer projector shell which, in turn, produce acoustic signals in a body of water. First and second alternative embodiments are disclosed with each embodiment housing at least one PMN-PT ceramic stack.