Patent GB-665822-A (GB)
Title: Improvements in or relating to electric storage systems using electric discharge tubes
Inventor: REEVES ALEC HARLEY
IPC: H03K29/00
Filed: 1947-07-22
Abstract: 665,822. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. July 16, 1948 [July 22, 1947], No. 19618/47. Class 40 (iv). [Also in Groups XIX, XL (a). and XL (c)] A circuit comprising one or more cold cathode discharge tubes in used for storing information of the number ofpulses in a train and also the amplitude and/or duration of each pulse. Fig. 1 shows acounter circuit using a gas-filled sequence tube of the type described in Specification 639,827, [Group XL (a)], which comprises a cathode array 3, an anode rod 2, and an auxiliary cathode 9 with a starting gap projection 11. Negative-going input pulses are applied at terminal 21 of amplitudes A and B (B#A), the battery voltages and pulse amplitudes are such that except for cathode 4<SP>1</SP> which has a narrower gap no cathode fires until its gap has been ionized from a previouslyfired gap and by the spread of cathode glow along wire 9 from the end 10. A first A pulse fires gap 8<SP>1</SP> which continues discharging due to battery 13. If the second incoming pulse is of B amplitude gap 8<SP>11</SP> fires and the glow spreads to both 5<SP>11</SP> and 6<SP>11</SP>. By inspection the number of gaps which have fired and the extent of their glow spread can be ascertained which is indicative of the number of input pulses and the amplitude of each. Since the spread of discharge glow depends on both the amplitude and duration of the incoming pulses, the circuit may be used to record the number of incoming pulses and their respective durations if they are of constant amplitude or to record their respective energy contents if both their amplitudes and durations vary. In a modification, shown in Fig. 2, an additional "take-off" array 22 with its cooperating anode 23 enables the stored information to be extracted. Information is stored on array 3 as described in connection with Fig. 1 and negative pulses of equal amplitude from a distributer as described in Specification 665,819, are fed in turn to each terminal 28. These pulses fire either surface 25 or both surfaces 25, 26 of a given cathode depending upon the extent of ionization spread from the associated cathode of array 3 which depends upon whether this cathode had been fired by an A or B pulse. The output pulses are produced at transformer 27. In a further modification, shown in Fig. 3, input pulses are applied at terminal 21 and output pulses are produced at transformer 37 in response to extracting pulses of equal amplitude which are applied at terminal 39, as described in connection with Fig. 2. If the pulses applied to terminal 39 are of different amplitude levels A<SP>1</SP> and B<SP>1</SP> a process of addition takes place, e.g. if a stored A pulse occurs together with an A<SP>1</SP> pulse on terminal 39 so that cathode glow takes place from surface 32 then a B<SP>1</SP> pulse (B<SP>1</SP>#A<SP>1</SP>) applied at terminal 39 is equivalent to ionization from a ring 6<SP>1</SP> and an output pulse of amplitude B<SP>11</SP> is obtained. In general if r be the radix for the applied pulses and the storage array has r surfaces per cathode rod and the " take-off " array has 2r - 1 surfaces the output pulses will be in radix 2r. In a modification, shown in Fig. 4, the tube is enabled to store information continuously by the provision of two storage arrays 41, 43 and a " taking-off " array 42. The cathodes of arrays 41, 43 and of the array 42 may have the form shown in Fig. 5 at 67 and 66 respectively. Because of the finite ionization migration time, if array 41 has information stored on it this may be extracted by array 42 simultaneously with the registering of incoming pulses on array 43. Fig. 4 shows the application of such a sequence tube in a line-finder circuit for use with a multi-channel pulse modulation system. In this system each subscriber is allotted a given pulse in each train of successive trains of pulses the pulses being position-modulated to convey intelligence. Normally all pulses are of level A but when a subscriber lifts his receiver a B pulse is transmitted (B#A) and engages a line-finder for his channel. When the receiver is restored one or more C pulses (C#A) are transmitted to free the line-finder. As on calling only one B pulse is transmitted then if the linefinder is engaged the corresponding A pulse in succeeding trains must be converted to a B pulse. To ensure this sequence all the incoming pulses are applied to the " taking-off " array 42 and the output pulses at terminals 63 are fed to successive line-finders and finally after a delay of approximately one pulse train duration the returning pulses from the local line are applied to storage arrays 41, 43. The circuit is adjusted so that a stored A pulse and an A pulse applied to array 42 produces an A output pulse whilst a stored B pulse combined with an A " taking-off " pulse gives a B output pulse. A C pulse which can only be applied to array 42 produces a C output pulse. The sequence of events is illustrated in the pulse trains of a 10-channel system shown in Fig. 6 in which a positive extinguishing pulse occurs at the end of every train. It is assumed all linefinders are engaged and that channel 5 is calling (B pulse) and channel 8 is restoring (C pulse) so that the pulse trains shown at 73 (Fig. 6) are applied to array 42 and a train of pulses returning from the line-finders are applied to cathodes 41 and 43 as shown at 76 and 78 (Fig. 6) respectively. Array 41 which is storing information from a previous train has a positive gating pulse 75 (Fig. 6) applied to its glow spread wire 47 so that the present pulse train (shown dotted) is ineffective. Gating pulses 77 (Fig. 6) are applied to wire 49 to permit the pulse train 78 (Fig. 6) to fire the cathodes of array 43. As all the pulses applied to array 43 are at A level and all of the discharges at array 41 also are A pulses the outgoing pulses which are applied to the line-finders are as shown during the first train of graph 79 (Fig. 6). As no line-finder is free, channel Number 5 is still applied to array 41 as an A pulse, train 80 (Fig. 6). In the third pulse train shown at 85 (Fig. 6), channel 7 is shown ringing off (C pulse), channel 5 is still waiting for a line-finder and channel 9 is calling (B pulse) the output pulse train thus has the form shown at 86 (Fig. 6). The B pulse on channel 5 engages the line-finder set free by the C pulse on channel 8 and channel 9 engages the line-finder set free by channel 7. The returning pulses from the local line are fed to terminal 21 and the output pulses are taken from transformer 27. The incoming pulses from subscribers are applied to terminal 39, gating pulses are applied at terminals 52, 53 and extinguishing pulses are applied at terminals 56, 57.