GB129120A - Improved Means for Detecting and Locating Sub-aqueous Sounds. Towing Hydrophones. - Google Patents

Abstract

129,120. Sykes, A. F. July 6, 1918. Locating subaqueous sounds; subaqueous audible signals.-Relates to sound detecting and locating devices of the kind described in Specifications 15320/15 and 131,038. The element which is adapted to vibrate as a whole is made of material of density comparable with that of water and preferably of stream line form, and the microphone is contained within a cavity in the vibrating element. In one simple form, the vibrating member (which may be of wood impregnated with paraffin wax, is in two parts 1, 2 providing an air chamber 3, the microphone 5 being mounted at the apex of a hollow cone 4. In another form, the microphone is mounted on a diaphragm. Preferably, however, an hydraulic arrangement is provided to amplify the vibrations. As shown, this comprises a chamber 10 closed by diaphragms 8 and mounted within the air space so as to receive vibrations through a ring 11. The chamber 10 contains liquid, (water, oil, carbon tetrachloride, and mercury are mentioned) and an acoustically insulated mass 14. Provision is made to allow for expansion &c. of the liquid by a tube 16 communicating with the exterior water or with a flexible bag or equivalent. The microphone 5 is mounted on one diaphragm 8. In a modification, the mass 14 is omitted, and the diaphragms are connected by a strut on which the microphone is mounted immersed in the liquid. Fig. 5 shows a modification in which the liquid chamber is divided by a thick partition supporting an air chamber within the liquid, the ends of the chamber formed as diaphragms connected by a strut 18 carrying the microphone (not shown). This form collects vibrations from a large area before transference to the microphone. In a further modification, the chamber containing the liquid extends the full length of the air chamber, being surrounded by an annular air space, and the outer surface of the parts 1, 2 is covered with rubber. The device may he towed by a cable 6, a weight of stream-line form (not shown) being connected to the cable ahead of the towed body. A tail float, (not shown), may be attached to a cable 7. Fins may be fitted to the towed body to regulate depth of immersion, and these mav be automatically controlled by the pressure due to immersion, acting on a diaphragm or flexible chamber 43 connected to the fin 42 so as to vary its inclination. Depth of immersion may also be controlled by adjusting the angle at which the towing cable leaves the towed body, the cable being attached to a pivoted arm the angular position of which may be controlled by an automatic device of the above described type.