Patent GB-373180-A (GB)
Title: Improvements relating to the sending and receiving of distance controls or secret communications by wire or by radio
IPC: H04L27/26
Filed: 1930-11-12
Abstract: 373,180. Type-printing telegraphy. SEMPRINI, F., Via Oberdan, Pirano, Italy. Nov. 12, 1930, No. 34125. Convention date, Oct. 22. [Class 40 (iii).] The invention relates to a signalling system for the purpose of type-printing telegraphy or of effecting controls at a distance, in which the signals consist of currents of two frequencies, selected from a number of available frequencies, and are transmitted in succession. At the receiving end, the frequency is applied to a series of tuned relays, each of which is associated with a particular group of printing members and also with one member of each of the particular groups individually associated with the other tuned relays. In operation, the actuation of the appropriate relay by the first frequency of a signal controls electromagnetic means through which a circuit is momentarily prepared for all the members of the particular group, and a temporary circuit is prepared to one member of each of the remaining groups. When the second frequency is received similar circuit preparing is effected, and the momentary connection of the printing devices of the particular group completes a current circuit for one of the devices for which a circuit has been temporarily prepared by the first frequency. Receiving arrangements, (Fig. 10). The tuned relays, to each of which the incoming signal impulse is applied in series, comprise electromagnets 8, 9 .. 14 associated with tuned plates 15, 16 .. 21 which, when set into resonance by the appropriate frequency, open corresponding contacts 22 .. 28. Assuming the relay 1 to be operated, the opened contact 22 releases the spring-biased core of the magnet 29 which, at contact 36, prepares a circuit for each of the printing members 57 .. 62, and energizes the relay 43 actuating a member 50 to prepare a circuit for the members 68, 74, 80 .. 98 of the other groups. The contact member 50 remains in the set position until positively restored by the relay 100. If the second frequency operates relay 4, the release of the magnet 32 connects a momentary circuit to each of the printing members 75 .. 80, and this partial circuit will, in conjunction with the circuit prepared by the contact member 50, effect the energization of the printing member 80. The actuation of any printing member closes a contact 99 energizing the restoring magnets 100 .. 106, through which the operated members 50 .. 56 are positively returned to the normal position. The actuating members 57 .. 98 may be utilized for controlling a typewriter or for effecting controls. Transmitting arrangements. A frequency generator comprises a permanent-field electromagnet connected to the line and associated with a vibrating plate 6 set into operation by an exciter electromagnet 5. As shown in Fig. 2, when a key 4 is depressed, the magnet 5 is energized, attracting the plate 6, and at the same time causing the pivoted contact lever 7 to move on to a contact sector 8 connecting the magnet 9 to the line. On the release of the key 4, the plate 6 releases and vibrates at its natural frequency, inducing in the field of the electromagnet 9 fluctuations which are transmitted to the line until the arm 7 passes off the contact sector 8 under the action of the spring 10. An arrangement for the transmission of two successive frequencies by the depression of a single key is shown in Fig. 4. On the operation of the key 1, a conducting brush 2 successively engages contacts 3, 4 carried on a pivoted member 8 and connected to exciter electromagnets 11, 12. On the full depression of the key, a nose 7 engages a shoulder 9 rotating the member 8 in an anticlockwise direction to a position in which it is latched by a pivoted pawl 6.. On the return movement of the key 1, the brush 2 will be out of engagement with the contacts 3, 4, but the nose 7 will engage the end of the lever 8 to rotate it to its normal position in which it is latched by a pivoted pawl 5. Calling and secret signalling arrangements. In order to condition for reception a station with which it is desired to communicate, the transmitting station is arranged to send a definite succession of frequencies. A receiving station will be conditioned for reception if the relays are tuned to the transmitted frequencies and if they are arranged and operated in the same order as the sequence of transmitted frequencies. As shown in Fig. 3, the sequence of the frequencies for obtaining selective connection with a receiving station is obtained by a series of plugs 2 and sockets 1, through which the keys are connected to the exciter magnets 22 .. 28 of the line electromagnets 8 .. 14. By means of a combinator 5, the frequencies constituting a signal may be varied on the depression of a special key or of certain or all of the signal keys 29 .. 70, so that electromagnets 6, 7 are energized and step forward a contact carrying drum 5 with reference to fixed rows of contacts 3, 4. At the receiving station a recombinator is actuated in conformity with the combinator at the transmitting end. Arrangements for conditioning a station for reception. In the arrangement shown in Fig. 11, the frequencies utilized for conditioning a receiving station are different from those employed in the message transmission, and are arranged to actuate tuned relays 1 .. 7. On the assumption that the frequencies forming the call signal actuate the relays 1 .. 7 in sequence, the opening of contact 29 will release the core 22 of the electromagnet 15, which at contact 36 will energize the winding 43, and operate an electromagnet 50 which releases a time switch 51. When the second frequency is received the core 23 drops, and extends the circuit over contact 37. On the reception of the final frequency the core 28 falls, and closes contact 42 which over the arm a of the switch 58 energizes an electromagnet 55 moving a rod 57 and a contact arm b to place the receiving relays 8 .. 14 and the magnets 59 .. 65 (corresponding to the magnets 29 .. 35 of Fig. 10) into a receiving condition. The relay 55 will not be energized if the calling signal is not received within the time of revolution of the wheel 51 even if the frequencies arrive in the correct sequence, since the tooth 53 will open the circuit of the electromagnets 43 .. 49 at the contact 54. At the end of the message a signal is transmitted which energizes in a manner analogous to the operation of a printing magnet, a restoring magnet 68 by which the rod 57 is moved to the right and the system is returned to its normal condition. If a correct calling signal is received within the predetermined time whilst the station is already engaged in reception, an electromagnet 67 energized over contact 42 and contact 66 engaged by the arm a of the switch 58, transmits (in a manner similar to the operation of the exciter magnets 22 .. 28, Fig. 10) a signal indicative of the engaged condition. In an alternative arrangement, Fig. 12 (not shown), the frequencies for conditioning the receiving station are the same as those utilized for the transmission of the message. Specification 1899/86, [Class 40, Electric telegraphs &c.], is referred to.