Patent GB-190308508-A (GB)
Title: Improvements in Space Telegraphy
Inventor: THOMPSON WILLIAM PHILLIPS
Filed: 1903-04-14
Granted: 1903-12-17
Abstract: 8508. Thompson, W. P., [Stone, J. S.]. April 14. Telegraphs ; telephones.-Relates to systems of wireless telegraphy in which the signals are produced by the combined effects of two trains of electromagnetic waves of different frequencies, or of two trains having the same frequency but issuing from transmitting-conductors placed a multiple of a half-wave length apart, as described in Specification No. 27,739, A.D. 1902. The transmitting-station is shown diagrammatically in Fig. 1 and the receiving-station in Fig. 2. The transmitting - apraratus comprises the transmitting- conductors V, V<1>, transformers M, M', inductances L, condensers C, alternating-current generators A, and relays R<9>, R<10>. When a relay is energized, the corresponding train of waves is sent out. The relays are energized as follows :-The cylinders E', E' of insulating-n aterial carry on their surfaces contact strips x<1>, y<1> and x<2>, y<2> connected through brushes b<1>, b<2> with the battery B<9>. Brushes e', f<1> and e<2>, f<2> bear normally on the insulating material. When a cylinder is rotated, both relays are energized, the period of energization overlapping slightly in the case of the cylinder E', and to a greater extent in the case of the cylinder E<2>. Fig. 4 shows the means employed for turning the cylinders. A finger key k is depressed, and the ratchet-wheel I, on the shaft of the cylinder, is rotated. Several pairs of contact strips x<1>, y<1>, &c. are arranged on the periphery of each cylinder so that each partial rotation effects the transmission from the conductors V, V<1> of the two overlapping trains of waves. At the receiving-station, shown in Fig. 2, the trains of waves effect by means of the coherers K the energizing of the relays R, R', R<2>, R<3>, and during the overlap of the trains of waves the circuit 3 is closed, and the signal is received by the instrument T. Such signal is either a dot or a dash according as it is despatched by the cylinder E' or E<2>. Signals may also be sent automatically by the passage of a perforated strip of paper y<2>, Fig. 7, beneath the contact brushes e<1>, f<1> which alternately make and break contact with the metal block beneath the strip. In the diagram, Fig. 8, one train of waves is denoted by X, the other by Y, and the resultant signal by S. The strip may also be irregularly perforated for the purpose of giving out "blind " waves " from a third transmitting-conductor. Such waves have no signalling significance, and are intended only to prevent unauthorized tapping of the message. The signals may be received by means of a doubly-wound telephone, with one coil in each coherer circuit. The diaphragm is so adjusted that a current in one circuit alone is not sufficient to give a signal. When the transmitting conductors are disposed a multiple of a half-wave length apart, and waves of the same frequency are sent from both transmitting conductors, a quantitative wave-detector is used in the plane of the said conductors, and is so adjusted as to respond only to the energy of two trains of waves simultaneously received. The resonant condenser telephone receiving-circuit described in Specifications Nos. 27,253 and 27,272, A.D. 1902, may be used as the quantitative wave detector. A single transmitting-conductor with tuned branching circuits may be used for despatching or receiving the various trains of waves.