Abstract: An acoustic transducer system for acoustic signals in water has at least one hollow spherically-shaped shell for vibrating in response to acoustic signals impinging from the water. The hollow spherically-shaped shell has one or more portions that are reflective of impinging radiation, and a resilient matrix in contact with the water resiliently supports the responsive hollow shell. A laser Doppler velocimeter transmits radiation onto the reflective portion (portions) and receives reflected radiation from the reflective portion (portions). The reflected radiation generates signals in the laser Doppler velocimeter that are representative of the acoustic signals from the water medium. A computer receives the representative signals from the laser Doppler velocimeter and displays them on an interconnected display to determine direction and range to a target. The acoustic signals can originate from the target or can be reflected portions of acoustic energy transmitted from an acoustic projector.

Abstract: A region of water is insonifed with a series of pulses. A synthetic apeture radar (SAR) is flown about the region and images the water surface above the sonified area. The radar has a carrier frequency (Fr) the acoustic source has a nominal carrier frequency of Fa. This acoustic frequency Fa is selected such that the acoustic wavelength is nearly, or exactly, half the wavelength of the radar carrier Fr where modified by the Sine of the incident of angle. Also practical are those acoustic wavelengths that are integer multiples of the wavelength that is half the radar wavelength. This arrangement will result in the Bragg condition in portions of the radar image of the water surface. The pulse repetition frequency (PRF) of the radar and the acoustic sources are equal (or can be such that the acoustic PRF is an integer multiple of the radar PRF), and locked in phase together by a radio frequency link between the SAR and the sonar transmitter. The sonar signal is repeatable and coherent with the radar signal.