Patent GB-190704125-A (GB)
Title: Improvements in or in connection with Wireless Electric Signaling
Inventor: CABOT SEWALL
Filed: 1907-02-19
Granted: 1908-02-13
Abstract: 4125. Cabot, S. March 10, 1906, [date applied for under Patents Act, 1901]. Telegraphs.-Relates to the use of wireless telegraphy in conjunction with wire telegraph lines for the purpose of bridging rivers, or communicating with ships, &c. In the systems described, 'front-stroke' Morse signals are sent over the land lines, and are repeated as 'back-stroke' Morse wireless signals, which are practically unreadable. The received ' back-stroke' wireless signals are then retransformed into 'front- 'stroke' land line signals for further transmission, or for the purpose of being read at the wireless receiving-station. Fig. 6 shows a wire telegraph line I connected on the one side with a wire telegraph station having a transmitting key K<1> and sounder 14, and on the other hand with a repeating station for converting 'front-stroke' Morse line signals into back-stroke' wireless signals, or conversely, and capable also of the direct despatch of wireless signals. If the switch N is on the contact n, the circuit of the electro-magnet L is broken, the key K being then available for direct manual wireless transmission instead of as a repeating-device. By means of the switch U, the telephone T may be placed in circuit with the battery B and wave responsive device P, for the direct reading of wireless signals received through the antenna V, or the relay 5 may take the place of the telephone for the purpose of retransmission on the line I. If the switch N is open and the telephone T in use, signals may be sent from the antenna V by depressing the key K. The first effect of such depression is to open the circuit of the wave-responsive device P at k<11>. The receiving-circuit I<11>, C<11> is then short-circuited by the earth at o, o<1>, E, and finally the power circuit is closed at k<1> so as to set up oscillations in the circuit S, C, M and in the antenna V. The signals thus despatched are front-stroke' Morse signals. Signals received while the key K is not in use, or `break' signals received during the moments when it is not depressed, set up oscillations in the circuits V, I<11>, I", C<11>, o<1>, E, and, in the circuit I2<111>, k<11>, P, and thus cause variations in the current flowing from the battery B through the telephone. When the wireless station is used for repeating purposes, the switch N is closed, and the relay 5 is in circuit with the wave-responsive device. The key K<1> at the wire telegraph station is normally closed by its lever switch, the relays 2, 11 being thus normally energized. When signals are to be depatched from the wire telegraph station, the lever switch is removed from beneath the key K<1> to open the line, and the key is then depressed to transmit the signals. Each depression of the key energizes the local relay 11 and produces 'front-stroke' signals on the local sounder 14. It also energizes the relay 2 and opens the circuit of the electro-magnet 1, thus producing a momentary break in the train of oscillations which are being despatched from the antenna V. The wireless signals are therefore of ' back-stroke ' type. These signals are received by a distant station identical in character with that shown in Fig. 6. Oscillations set up in the antenna V cause the energization of the relay 5, thus introducing additional resistance R<1> into the line I. The reduction of current in the line is not sufficient to de-energize the relay 2, but the relay 11 is de-energized and the armature of the sounder 14 is released. Every break in the received train of waves is consequently represented by an increase of current in the line I and by energization of the sounder, so that the ' back-stroke' wireless signals become front-stroke' signals in the line, and are read as such on the sounder. The receiving - operator can break' the message by opening his key K<1>, thereby sending a train of waves from the antenna V which he controls. The effect of this is to de-energize the relay 11 at the transmitting station at the moments when the key K<1> is depressed, the transmitting operator being thus notified of the ' break' by the silence of his own instruments. In a modified system, an additional key is provided at the wireless stations, by the use of which the direct manual transmission of ' back-stroke ' wireless signals can be effected. When the key K, Fig. 6, resumes its normal or raised position, a sudden impulse of current from the battery B may flow through the relay 5 and cause a fluttering of the relay 11. To prevent this, a relay 8 is connected across the terminals of the resistance R<11>, in the circuit of the magnet 1, so that when the relay 2 is energized, the inductive kick from the winding of the relay 8 maintains the shunt f, 10, f<1> across the relay 5 until the contact at k<11> has been made and the current impulse in the circuit, which includes the battery B, contact k<11>, wave responsive device P, and relay 5, is over. This device may be dispensed with if potassium hydroxide be employed as the electrolyte for the oscillation detector.