An elongated hydrophone array of the type adapted to be towed behind a marine vessel includes a flexible tubular casing in which a chain of acoustic sensors is mounted. A drogue attached to the trailing end of the array serves to maintain the array in a streamer-like horizontal attitude during normal use. An acoustically transparent sheath of open-pore polyurethane foam surrounds the portion of the array in which the sensors are mounted so as to maintain the noise-producing turbulent boundary layer of water that occurs at the array-water interface at a considerable distance from the actual sensors.
An improved hydrophone body, suitable for forming an array of towed hydrophone bodies or "fish", formed by placing an acoustic shield or scatterer in the nose and tail sections of the hydrophone body to reduce noise coupling from the cable into the hydrophone sensor. This resulting hydrophone has significantly reduced background noise interference.
A marine acoustic array employs a plurality of sections connected together sequentially with the outer surfaces of said sections having a non-smooth configuration to create a water flow along the length of the array as it is towed through a water layer that causes sensors within the array to provide outputs having improved signal-to-noise ratios.
Hydrophone streamer apparatus embodying concentric tube construction for achieving improved low noise operation is disclosed. A plurality of hydrophone elements are supported within a compliant inner tube at spaced intervals therealong by compliant mounting means. The inner tube is supported within an elongated outer jacket by compliant support means between the outer surface of the inner tube and the inner surface of the jacket. Suitable support means may comprise a plurality of trilobate devices each formed of three tubular sections equally spaced around the inner tube, the trilobate devices being located along the inner tube at positions between adjacent transducer elements.
An expandable sensor array including at least one expandable member movable between an unexpanded stowed state and an expanded deployed state and a plurality of sensors interconnected with the at least one inflatable member and operatively connected to form a sensor array.
A technique for a vibration isolation module (VIM) used for towed arrays is disclosed. The VIM has a stretchable cable on which is mounted one or more rigid spacers which make contact with an outer hose formed of a flexible material having a selected vibration attenuation characteristic. The spacer transmits energy between the parts of the VIM which contact the spacer for attenuation purposes. The spacer is "soft mounted" on the stretchable cable so that it may be moved by a limited amount along the cable in response to forces of a specified minimum magnitude. This ability to move allows adjustment of the internal parts of the VIM during use to avoid concentrating stress at any one particular contacting area. Disclosed is an embodiment where two sleeves are used to abut the spacer at opposing ends thereof. The sleeves are clamped to the stretchable cable with a limited clamping force such that they remain stationary until the spacer is exposed to the predetermined breakaway force and/or the stretchable cable cross-sectional size decreases by a predetermined amount.