Patent GB-1110606-A (GB)
Title: Improvements in pulse sending apparatus
Inventor: RHODES JOHN GEORGE LAYCOCK
IPC: H04M1/272
Filed: 1964-06-11
Abstract: 1,110,606. Pulse sending apparatus. SHIPTON ELECTRONICS Ltd. 9 June, 1965 [11 June, 1964], No. 24281/64. Heading H4K. In a pulse-sending apparatus a pulse generator for sending pulse trains also feeds pulses into successive ones of a number of storage counters which have previously been set up to the digit sequence to be transmitted. The counter is advanced by the pulses fed to it to a predetermined state at which it operates a circuit to clamp the pulse generator to prevent the emission of pulses for a predetermined period of time, i.e. the interdigital pause, and also effects the connection of the pulse generator to the succeeding storage counter. The storage counters may be set up to the complement of the number to be transmitted either by operating the corresponding switches local to the apparatus or the apparatus may be centralized and each subscriber have a further pulsesender which operates at a high pulse rate to set up the storage counters remotely. In the pulse sender of Figs. 1 and 2 the subscriber closes one of switches 11 according to the digit he wishes to transmit first. Each switch is connected via a diode matrix 15 to apply a setting potential to the appropriate ones of lines 16, to set the binary counter stages 25, 26, 27 and 28 of one of the storage counters 17 to 24 to the complement of the digit selected. Each line 16 is connected to one of the terminals A, B, C and D of each of the storage counters 17 to 24, the particular storage counter which is set being selected by a sequence counter 34 which, via the diode matrix 35, applies an enabling potential to one of the terminals 36 to 43 which through transistors Tr3 and Tr4 in the selected storage counter unclamp the diodes D2 to allow the binary stages to be set. When the switch 11 is operated a potential also appears on line 44 via one of diodes D14 to operate the Sohmitt trigger stage 45. When the switch 11 is released capacitor C2 maintains the Schmitt trigger operated for a predetermined time after which it resets causing TR10, which was cutoff while the trigger was operated, to conduct and apply a stepping pulse to counter 34 which, via diode matrix 35, enables the following storage counter to be set by the next operation of one of the switches 11. A second sequence counter 53 is provided which via diode matrix 54 and lines 55 to 62 enables the counting function of each storage counters in turn, by unclamping the feed to the counter from the dial pulse generator 49 via line 52 and resistor R4. The two diode matrices 35 and 54 are interconnected via resistors R7 and diodes D6 and connected to a comparator circuit including resistors R8 and diode D7. The comparator circuit produces an output whenever the sequence counters 34 and 53 are at different counting stages and this output enables the dialling pulse generator 49 to produce dialling pulses to feed to the output line, via impulsing relays 50 and 51, and pulses to the storage counters via line 52. After the appropriate number of pulses have been produced by the generator 49, corresponding to the digit selected by the key 11, the storage counter will reach its zero count state and produce an output on its output terminal, i.e. the appropriate one of terminals 69 to 76. The output terminals 69 to 76 are connected via an OR circuit, including capacitors C5, resistors R11 and diodes D10, to a pause circuit 67 which comprises a monostable circuit which, when triggered by an output from a storage counter, blocks the dialling pulse generator, over line 65, for a predetermined time and also provides a signal to step on the sequence counter 53 so that the next storage counter has its dialling pulse input unblocked ready to count the pulses of the following digit. Eight storage counters are provided and immediately a digit value has been stored in one counter, by the operation of a key 11, the pulsing out begins and continues as detailed above, for each storage counter until the sequence counter 53 reaches the same count as sequence counter 34, i.e. all the stored digits have been sent. Should the keys 11 be operated so fast and for a number containing such a large number of digits that all the stores become filled all the output terminals of the storage counters will be exhibiting an " off zero " output and this fact is registered by a " store full " circuit 13, which is connected by terminals 77 to 84 to the output terminals 69 to 76 of the stores, and causes a lamp 85 to light and the keys 11 to be rendered inoperative until one of the storage counters has been pulsed out. When the apparatus is first switched on one side of each bi-stable stage in each of the counters 17 to 24, 34, and 53, is connected to the D.C. supply via a delay circuit so that all counters start in a predetermined condition. During operation, the sequence counters 34 and 53 are left, after each digit sequence has been sent, in a state dependent on the number of digits previously transmitted, resetting of these counters to any particular state being unnecessary. If desired, the pulse-sending equipment of Figs. 1 and 2 may be central to a number of subscribers, each of which is provided with the high speed pulsesending equipment of Fig. 3 (not shown), which comprises a set of keys which set up a counter which counts the impulses from a multivibrator and clamps the multivibrator off when the number of impulses corresponding to the key operated has been sent. The multivibrator operates at 1000 i.p.s. and a circuit is provided to give a 10 m. sec. gap between impulse trains. The high speed impulses are applied to the central equipment, Figs. 1 and 2, over a line 100, and are fed to the input circuit of the storage counters via a resistor, e.g. R18, the gating of the pulses to the appropriate storage counter being accomplished by connecting the diodes, e.g. D12 in counter 23, to the appropriate ones of the outputs of diode matrix 35. The sequence counter is stepped on by feeding the incoming pulse train on line 100 over line 44 to the Schmitt trigger circuit 45, the circuit remaining triggered during the pulse train and only resetting during the gaps between pulse trains to step on sequence counter 34. It is also suggested that the subscribers may use v.f. signalling to the central equipment.