GB403119A - Improvements in or relating to pressure wave transmitters and receivers incorporating magneto-strictive devices - Google Patents

Abstract

403,119. Subaqueous signalling and echo-sounding apparatus. MARCONI INTERNATIONAL MARINE COMMUNICATION CO., Ltd., Marconi House, Strand, and HINTON, N. P., 57, Broughton Avenue, Finchley, both in London. June 10, 1932, No. 16475. [Class 118 (ii).] In a subaqueous pressure wave signalling, echo-sounding, or similar system wherein the transmitting or receiving device comprises a magnetostrictive body having windings arranged in a tuned circuit, the circuits are arranged so that the long leads connecting the device to the controlling or receiving equipment are without effect on the tuning of the circuit. In the system shown in Fig. 1, the energizing winding L of the magnetostrictive body is arranged in the tuned circuit L, C which is connected over leads l<1>, l<2> respectively to the receiving amplifier V and the battery B for controlling transmission. A transmitting key K controls a relay R, located near the tuned circuit L,C, over lead l<3>, the contact of the relay being arranged in the lead l<2> so as to control the energization of the tuned circuit. The relay R is adapted to isolate the lead l<2> from the circuit L, C so as to prevent alteration of tuning. Compensation for different lengths of lead l<1> is effected by the tuned circuit L<1>, C<1>. An alternative method of exciting the tuned circuit involves the provision of a condenser of large capacity connected in series with the condenser C and charged and discharged under the control of a key at the control point ; the large condenser may be provided at the control point. In these arrangements the large capacity prevents alteration of the tuning by the connecting leads. The receiving equipment may be protected against the transmitted impulses by a large impedance Z and a spark gap or oppositely connected diodes connected across the receiving circuit. The Provisional Specification states that the transmitting coil may be excited by damped wave trains set up by a spark gap and fed through a transformer. Specifications 402,123,402,828,402,829,402,830; and 402,831, [Group XXXIX], are referred to.