GB172637A - Improvements in sound receivers, particularly for receiving sound waves in liquids - Google Patents

Abstract

172,637. Signal Ges. Dec. 7, 1920, [Convention date]. Subaqueous audible signals.-Receivers for sound signals, particularly for use in liquids, are so constructed that any oscillatory structures are so loosely coupled between themselves or with any detector that the degree of coupling is less than 40 per cent. When there are more than two oscillatory structures, the peaks of the resonance curve of one couple may be brought closer together by the coupling with the other structures. A formula is given for determining the degree of coupling between any pair of oscillatory, structures, but this may also be determined experimentally from the frequencies developed on couplings. In an example, Fig. 1 there are two diaphragms 1, 2 of which 1 only carries a microphone 4. The couplings are those between the diaphragm 1 and the diaphragm 2 through the casing 3, and between the diaphragm 1 and the microphone 4 through one electrode. In Fig. 2, a resonating chamber 9 is connected with the space behind each of the diaphragms 1, 2, by very small holes 7, 8. The resonator 9 is connected with a listening tube 10. In a further example, a ring acting as a detector is attached by a spring to the back of the casing and oscillates in a magnetic field. In each case the various structures which are loosely coupled are tuned independently to the signal frequency, which lies between the peaks of the resonance curves due to the coupling. Specification 150,322 is referred to. The Specification as open to inspection under Sect. 91 (3) (a) states that diaphragm 2, Fig. 2, can be replaced bv a rigid wall and the air chamber between diaphragm 1 and the hole 7 is then constructed as a resonator with less than 40 per cent coupling with the diaphragm 1. This subject-matter does not appear in the Specification as accepted.