Patent GB-613084-A (GB)
Title: Improvements in telegraph apparatus
IPC: H04J3/04
Filed: 1946-05-27
Abstract: 613,084. Type-printing telegraphy; thermionic distributers. TELETYPE CORPORATION. May 27, 1946, No. 16048. Convention date, May 28, 1945. [Class 40 (iii)] A telegraphic signalling system has at the transmitting station a series of electronic tubes adapted to be conditioned by signal - initiating means according to the signal to be transmitted and an electronic distributer comprising a plurality of tubes operating in tuned succession for operating successively conditioned ones of said series; and has at the receiving station signal-receiving means, a similar electronic distributer and electronic means under the joint control of the signal-receiving means and the distributer tubes for causing the received signals to be recorded. The transmitted signals are mpltiplexed. Transmitter (Figs. 3, 4 and 5). The generator 21 applies a sine wave to the grid 38 of the double triode amplifier 22 to produce an amplified output 39 (Fig. 10) which is rectified by the left-hand diode of a rectifier 23 and the output 44 (Fig. 10) fed to the grid 47 of amplifier 22 so biassed that the output is a square wave 49. This is differentiated by a condenser 52 and its associated cathode resistor to produce pulses 50 which are rectified by the right-hand diode of rectifier 23, the output 53 being passed to the grid 58 of a triode amplifier 24 to produce positive pulses 63 which are applied over conductor 67 to the control grid of each of the thyratrons 75 ... 84 of a closed chain distributer. Owing to their too-negative bias, none of the thyratrons fire. A momentary depression of start key 146, however, earths the grid of thyratron 84 and this fires, preparing the grid of the next tube 75 for firing. On the arrival of the next pulse over conductor 67, tube 75 therefore fires, extinguishing tube 84 and preparing the next tube 76. All the ten thyratrons 75 ... 84 now continue to fire in turn, and permit the transmission of a fiveunit code character in each of two channels. The operating current of each thyratron 75 ... 84 raises a corresponding grid 167 or 171 of relay triodes 153a ... 157b to its operating potential. The ten anodes 168 or 172 are connected by means of plugs 261 and sockets 181, 188 to five tape contacts 263 ... 267 of a tape transmitter 151 or of a second transmitter 152. For each mark (i.e. perforation) beneath the tape feelers, a contact 263 ... 267 will close and apply battery 26 via plug and socket pins 8 to the anode 168 or 172 of the corresponding triodes 153a ... 157b. Each relay triode 153a ... 157b so conditioned by a mark on the tapes will conduct when it receives its pulse from the distributer 75 ... 84 and the consequent potential drop across resistor 197 lowers the grid' potential of a transmitting triode 159 sufficiently for the valve to be non- conducting and, with switch 250 in the position shown, no current is sent to the output jack 257. Spaces, which do not permit the relay triodes 153a ... 167b to conduct, do not lower the grid potential of the transmitting triode 159 which therefore conducts and battery 243 sends a negative pulse to the output jack 257. With the switch 250 in its alternative position, marks cause positive signals to be transmitted to provide double - current working. When a character has been transmitted from the first tape transmitter 151, the distributer conditions the second five relay 'tubes 155b ... 157b and the character set up in the second tape transmitter 152 is transmitted. Two-channel multiplex working is thus obtained. Tape stepping. The stepping-on of the tape of transmitters 151, 152 is accomplished by means of valves 161, 162 or 163, 164 respectively. For instance, when at the end of a character thyratron 79 fires, the consequent fall of potential across resistor 207 extinguishes the normally conducting valve 161 and allows the second valve 162 to conduct. A battery 192 energizes a tape stepping solenoid 272 via plug and socket pins 7, the return path being via pins 6 and the valve 162 to earth. The subsequent firing of thyratron 80 causes energization of the solenoid 272 in the same way, the joint control by both thyratrons 79, 80 being necessary because of the time required for the tape-stepping mechanism to function. Receiver (Figs. 7, 8 and 9). Incoming signals are fed to a corrector network 302 where they are compared with the sine-wave output of the frequency generator 301 in order to automatically adjust the generator frequency to maintain synchronism with the transmitter. Pulses 63 (Fig. 10) are produced at the output of triode amplifier 311 in the same way that similar pulses are produced in the transmitter and are applied over conductor 314 to the control grid of each thyratron of a closed chain distributer 316 ... 325. These fire in turn and produce a square wave output which is differentiated by the ten condensers 349. The resultant positive pulses sequentially raise to zero potential the control grids of selector tubes 331 ... 340 and so condition them for firing. If a mark is being received over the signal input jack 361, then the screen grids of the selector tubes 331 ... 340 are positively biassed and the one whose control grid is at that moment conditioned as above will fire. A space will not raise the screen grid potential and no selector tube will fire when a space is being received. Manual adjustment of a phase network 306 varies the phase of the sine wave output from the generator 301 to permit the positive pulses applied to the selector tube control-grids to occur during the most advantageous portion of the incoming signal. When a selector tube 331 ... 335 fires, battery 382 energizes a corresponding relay 448 ... 452 of a multiplex printer 453, which may be of the type described in Specification 235,561, [Class 40 (iii)], over armature contacts 434, plug and socket contacts 7, the appropriate relay and its associated plug and socket contacts, the conducting selector tube, and earth at 354. After the five distributer tubes 316 ... 320 have fired, and the multiplex relays 448 ... 452 have been selectively operated in accordance with the received character signals from the first transmitter, distributer tube 321 fires and via condenser 398 sends a positive pulse to the control-grid of a valve 343. This grid is connected also to the potentiometer 406 through which battery 413 sends current. The normal negative bias thus supplied by the potentiometer 406 to the grid of valve 343 is cancelled out by the pulse from distributer tube 321 and the valve 343 conducts, energizing a printing magnet 457 from battery 382 over the armature 432 of a relay 346. After a time determined by the resistance-capacity network 427, 431, the relay 346 operates and de-energizes the printing magnet 457 and any energized multiplex magnets 448 ... 452, and also removes battery 382 from the anodes of selector tubes 331 ... 340, thus quenching those that have fired. As at the transmitter, two-channel multiplex working is provided by employing ten distributer tubes, ten selector tubes, two " printing " valves 342, 343 and two recorders 453, 459. The recorder 459 is a multiplex to start-stop converter and is connected to a start-stop printer 462 which may be of the type described in Specification 365,975.