GB148988A - - Google Patents

Abstract

148,988. Signal Ges. May 19, 1917, [Convention date]. Addition to 1995/13. Subaqueous audible signals.-Relates to receiving-apparatus in which the damping of the system due to work done on the microphone or other detector is made equal to the damping due to radiation of energy from the diaphragm, as in the parent Specification, and consists in designing the system so that it comprises only one, or at most two, resonant structures, the other parts of the apparatus being made aperiodic, or with natural frequencies far removed from the working frequencies. A tuned diaphragm 1; Fig. 1, may carry an aperiodic microphone 2, consisting of a casing 4, acting as one electrode, and an insulated inner electrode 5, the two electrodes forming a rigid system. Or an aperiodic diaphragm 1, Fig. 2, may carry a tuned microphone 2, consisting of electrodes 7, 8 connected by spring bows 9, 10, the granules being kept in place by a ring 11 of soft material, such as silk. Or a tuned microphone, as in Fig. 2, may be mounted on a tuned diaphragm, as in Fig. 1, by an adjustable coupling consisting of a pin 5, Fig. 3, engaging a friction collar 14. Or the tuned structure 7, 8, 9, 10, Fig. 3, instead of acting itself as a microphone, may carry a separate aperiodic microphone of the kind shown in Fig. 1.