Patent GB-190717264-A (GB)
Title: Improvements in and relating to Apparatus for Receiving Sound in Submarine Signalling and the like.
Inventor: DONNITHORNE VYVYAN HENRY
Filed: 1907-07-29
Granted: 1908-07-29
Abstract: 17,264. Donnithorne, V. H., and Donnithorne, H. E. A. C. July 29. Sounds, locating distance or direction of.-The direction of a source of sound-signals is indicated by an instrument which measures the difference of the effects produced by the sound waves in the circuits of two telephone transmitters, and the distance may be indicated, if signals of known intensity are used, by a second instrument which measures the sum of the effects in the two circuits. In submarine signalling, to which the invention is specially applicable, the transmitters may be on opposite sides of a vessel below the water line and inside or outside the hull, and the indicating- instruments, which may be graduated to give direct readings of the direction and distance, may be on the bridge. (1) In one arrangement, each transmitter T, Fig. 2, is in circuit with a ring-shaped electro-magnet Q, which is preferably made of coiled wire and is formed with a spiral air-gap R containing two resistances of a material such as bismuth, tellurium, or mercury vapour, the resistance of which is affected by a magnetic field. These resistances may be in the form of flat coils or strips, or wires connected in parallel and their values change when the transmitter T is affected by sound-waves. The pairs of resistances L', L' and K', K', which are thus affected by the two transmitters, are connected in a bridge arrangement, as shown in Fig. 1, and the difference of the effects in the two transmitter circuits-is indicated by a galvanometer J. The sum of the effects is indicated by a differential galvanometer D, the two coils of which are in parallel circuits, containing respectively the bridge arrangement and an adjustable resistance C, which is preferably of the same material'as the resistances L<1> &c. The galvanometers J, D may be provided with damping-devices and with loose pointers for registering maximum deflexions, and their readings are normally adjusted to zero by variable resistances. The two circuits of the galvanometer D may contain windings differentially arranged on an electromagnetic device for closing an alarm-bell circuit when a sound is received. An ordinary telephone receiver W, Fig. 2, can be put in circuit with the transmitter T when desired. (2) In another arrangement, the two transmitters act inductively on circuits containing a unilaterally conductive substance such as carborundum, and the rectified currents from these circuits are passed through separate windings of two galvanometers which measure respectively their sum and difference. (3) In a third arrangement, the currents in the circuits of the two transmitters act on plungers suspended from the end of a pivoted beam, which may be of aluminium and may be floated on a liquid such as mercury, and a pointer is moved by the beam, or a separate pointer by each of the plungers, when the currents in the two circuits become unequal. One or the other of two alarm circuits is closed, according to the direction in which the beam is tilted. The sum of the effects in the two circuits may be indicated by a differential galvanometer, or, according to the Provisional Specification, by a modification of the balanced beam arrangement. (4) To prevent waste of battery current, the circuit of each transmitter may normally include a high-resistance winding which forms the primary of a transformer and is automatically short-circuited when the current becomes variable, the secondary of the transformer being in circuit with an electromagnetic device for this purpose. A catch may be provided to maintain the short-circuit till opened by hand. Or the transmitter circuits may be normally open and may be closed by electro-magnetic switches, or, according to the Provisional Specification, by electro-magnetic devices operated by auxiliary telephone transmitters. (5) The above receiving-arrangements may be made selective to sounds of a particular pitch by connecting adjustable capacities and inductances in the circuits.