Patent GB-145812-A (GB)
Title: Improvements in or relating to methods and apparatus for the detection and generation of sound or like waves
IPC: H04B11/00
Filed: 1918-12-31
Abstract: 145,812. Fessenden, R. A. Dec. 31, 1917, [Convention date]. Locating sounds; receiving and detecting audible signals; subaqueous audible signals.-In apparatus for detecting or producing sound waves, particularly for subaqueous signalling, a plurality of devices for detecting or producing sound are located in a liquid-containing tank, such as the oil tank of a ship, and acoustically insulated from each other. A pair of such devices may be mounted to rotate about a vertical axis. A system is also described which, in addition to means for converting received sound waves into electrical impulses, and means for indicating the presence of these impulses, such as a telephone receiver, comprises, either singly or in combination, a commutator for changing the frequency of the impulses with or without means which can be switched in to test the commutator, amplifiers which may be connected to the receivers directly or through commutators, and absorption coils for cutting out undesirable resonance effects. Fig. 5 shows four receivers 13 - - 16 mounted in the oil-tank of a vessel. The receivers may be of any suitable type such as microphones, telephone receivers, or Brocha tubes, but are preferably oscillators of the kind described in Specification 18765/13, which can be used either for reception or transmission. The oscillators are separated from each other by sound-insulating screws, shown as formed of plates connected to flanged strips 73 - - 76 to form a cruciform hollow chamber which is filled with air or sound insulating- material such as cork. A tube with a perforated lower end reaching to the bottom of the chamber, and its upper end discharging into the oil-tank, permits oil &c, which may leak into the chamber to be forced cut by air pressure. The outer edges of the plates may be joined together by corrugated strip 93, Fig. 7, and, to withstand internal pressure, the plates 65, 66 may be tethered by wires 96, 97 connected to lead balls 100 which prevent passage of sound vibrations. The complete system is shown diagrammatically in Fig. 2. Oscillators 13 - - 16 may be connected to a source 22 of alternating current, for producing sound, or to a telephone head-piece 25 for detecting. Absorption coils 34 - - 39, each provided with a switch for connecting-up or cutting-out, and of the type described in Specification 129,670, serve to cut cut undesirable resonance frequencies. Commutators 31, 32 may be put into circuit for changing the frequency of the electrical impulses, as described in Specification 22134/14. and are driven by a motor 46 with rheostat 47 for controlling speed. Amplifiers 52, 53 may be connected in circuit at will. A telephone switch 58 is provided so that either ear-piece may be used at will, or both together. The commutators may be tested by cutting-out the receivers 13 - - 16 and connecting up a battery 27<a> connected with resistances 28, 30, allowing a feeble current to be sent to the earpiece through the commutators, the condition of which is inferred from the sound produced. By comparing the sounds received in the different receivers, the direction of the source of sound may be estimated.