Patent GB-146192-A (GB)
Title: Improvements in and relating to apparatus for the determination of wave energy direction
IPC: A61C5/12
Filed: 1920-06-25
Abstract: 146,192. Steward Davit & Equipment Corporation, (Assignees of Mason, M.). June 25, 1919, [Convention date]. Locating subaqueous. sounds. - Time - compensating devices are used for bringing into phase the effects of two or more groups of receivers affected by energy arriving from a given direction. The invention is described with special reference to determining the direction of subaqueous sounds. In the arrangements illustrated in the figures, the receivers consist of rubber diaphragms or nipples which transfer the sound direct from the water to air-tubes connected to a stethoscope, and variable time-compensation is effected by varying the lengths of the airtubes. By this means the effects of a number of fixed receivers may be added together in phase, as regards sounds arriving from any given direction, while sounds from any other direction give interfering components and a weaker resultant. The effects of two groups of receivers may be compensated and delivered separately to the two ears, so as to bring the binaural sense into play. The invention is not limited, however, to arrangements of this type; the air-tubes may be of fixed length, to give compensation in a particular direction, a sound being located by swing- ing the system of receivers; the sound may be picked up in the first place by microphones, which are connected individually to telephones, which transmit the sound through compensating airtubes to a stethoscope; or compensation may be effected by electric time-lag circuits; moreover, the invention is applicable to determining the direction of wireless signals. In the simple binaural apparatus shown in Fig. 4, which is merely explanatory and forms no part of the invention, fixed receivers 21, 22 are connected to ear-pieces 27, 28 through sliding connexions 25, 26. When the slide is adjusted so that the sound reaches both ears in phase, the sound appears to be binaurally centred, while movement of the slide in one or other direction makes it appear to come from left or right of the listener's head. The direction of the sound is read from a scale 29. A row of receivers may be compensated in the same way by a series of sliding " trombones," but it is preferred to use a rotary form of compensator, as shown diagrammatically in Figs. 9 and 10. The receivers 101 - - 106 are connected to the ear-piece 163 through air-channels such as 121, 141. 161, and the receivers 107 - - 112 are similarly connected to the ear-piece 164. With the compensator in its central position, as in Fig. 9, the paths from the receivers to the ear-pieces are arranged to be all of equal length, but by turning the compensator, as in Fig. 10, the length of each path can be made greater or less than that of the previous path by any desired amount. The compensator is rotated until the sound appears to be binaurally centred and is heard with maximum intensity, and the angular position of the compensator indicates the direction of the sound. By joining the channels 161, 162 the binaural effect may be dispensed with, direction being determined entirely by the maximum effect. A constructional form of rotary compensator, for a row of 28 receivers, is shown in Figs. 11 and 12. It consists of a fixed bottom plate 202, with 14 arcuate ridges 211 &c., and a rotatable upper plate 201 with 14 circular grooves 271 &c., which fit over the ridges 211 &c. The plates are lubricated with castor oil, which also serves to seal each groove from its neighbours. The grooves are filled in over the segment 285 and open into radial grooves 286, 287 which communicate through apertures 288, 289 with the ear-pieces of a stethoscope. The first 14 receivers are connected to apertures 231 - - 244 at one side of the ridges in the fixed disk, and the other 14 receivers are connected to apertures 245 - - 258 at the other side of the ridges. It will be seen that as the plate 201 is rotated the paths from the receivers to the stethoscope are varied in length as described in connexion with Figs. 9 and 10. Another form of rotary compensator, for a row of 12 receivers, is shown diagrammatically in Fig 34. The receivers are connected to apertures 1 - - 12 in the lower plate of the compensator, which is also pierced with fourteen other apertures and with connecting channels, as shown. The eight loop-shaped lines, however, represent grooves cut in the bottom face of the upper plate of the compensator, which is rotatable on the lower plate. These grooves are formed as complete loops, but are interrupted between the apertures 1 and 3, 4 and 6, &c. by wedges which project from the lower plate. With the compensator in its central position, as represented in Fig. 34, the branching paths from all the receivers to the stethoscope leads 732, 733 are of equal length, but by rotating the groove-plate of the compensator the path from each receiver can be made longer or shorter than that from the previous receiver by any desired amount. For example, a clockwise movement of the groove-plate will lengthen the paths of receivers 1, 4, 7, 10 and shorten the paths of receivers 3, 6, 9, 12 relatively to the paths of receivers 2, 5, 8, 11; at the same time, bv the action of the loop grooves shown at the left and right of the figure, the common paths from the groups 1, 2, 3 and 7, 8, 9 are lengthened relatively to those from the groups 4, 5, 6 and 10, 11, 12; and, by the action of the loop grooves shown at the top and bottom of the figure, the common path of the double grip 1 - - 6 is lengthened relatively to the common path of the double group 7 - - 12. This form of compensator is combined with a valve for switching it into connexion with either a port or starboard row of receivers. Each row of receivers is mounted in a water-filled sheet-metal " blister " 1023, Fig. 30, exterior to the hull, and is backed by a thick metal inertia-plate 1021 and a sound-screen 1022, consisting of a sheet-metal box filled with felt. The inertia-plate 1021 diminishes the pressure-release effect of a thin hull. Alternatively, a heavy metal backing or a layer of concrete may be applied inside the hull, or the hull may be locally stiffened by ribs &c. The receivers may be inset, as shown in Fig. 30<B>, or mounted in the water-filled space between outer and inner hulls, or in oil or water tanks. Each tube from the compensator may lead to a group of eight receivers, Fig. 31, which are permanently compensated, as described in Specification 147,669, to favour sounds from a forward direction. The Specification describes precautions which should be observed to avoid disturbances of compensation due to temperature effects.