GB367878A - Improvements in or relating to sounding apparatus - Google Patents

Abstract

367,878. Echo-sounding apparatus; mercury switches. MARCONI INTERNATIONAL MARINE COMMUNICATION CO., Ltd., Marconi House, Strand, and SLEE, J. A., 16, Raphael Street, both in London. Nov. 15, 1930, No. 34447. [Class 118 (ii).] In echo-sounding apparatus for use on ships, means are provided to prevent an emission of pressure waves unless the vessel is in a position lying between predetermined limits of move. ment. Means are also described for preventing the emission when the vessel is rolling in a particular direction. Further, in order to remove air from the pocket in which the transmitter is situated, a pipe is led from the top of that pocket to a point above the water line. The invention is described as applied to an apparatus using the directional piezo-electric transmitter-receiver described in Specification 145,691, [Class 118 (ii), Signals], the time interval between the emitted and received sounds being measured by the means described in Specification 339,662, [Class 118 (ii), Signals]. The transmitting apparatus includes a switch comprising two inclined tubes C, D containing mercury normally completing a circuit between contacts C2, C1, D1, D2, as shown. If the vessel rolls more than a predetermined amount the circuit through this switch is broken. If desired, a second switch operated by pitching movements may be provided. A single inclined tube placed athwartships and containing mercury and two contacts forms a switch for preventing emission when the ship rolls in a direction away from the upper end of the tube, this switch action being due to the inertia of the mercury. Operation. At the beginning of the cycle a cam, not shown, on a shaft A closes certain contacts to prepare the time-measuring device for operation. It also closes contacts Y in circuit with a retaining winding J of a relay having an operating winding E and three pairs of contacts L, M, S. A second cam X of the shaft A closes a contact B and, provided the mercury switch CD is closed, operates the relay through the winding E. The retaining circuit is formed by the closing of contacts L, the closing of contacts M completes the anode circuit of a valve in the time-measuring device and the contacts S cause the discharge of a condenser U through a transformer T. The secondary of the transformer is connected to the transmitter and also to the time-measuring device. A pointer then commences to move in this device and it is arrested, by means not shown, on the return of the echo. The various circuits, including that containing the contacts Y, are finally opened by the first cam and a demagnetizing current is sent through the time-measuring device. The condenser U is " trickle " charged through a resistance Q.