Patent GB-723148-A (GB)
Title: Improvements in or relating to telephone or like systems
Inventor: BAKER GEORGE THOMAS
IPC: H04M15/04
Filed: 1953-05-27
Abstract: 723,148. Automatic exchange systems. BRITISH TELECOMMUNICATIONS RESEARCH, Ltd. May 21, 1953 [May 27, 1952], No. 13435/52. Class 40 (4). A magnetic drum of the type described in Specifications 717,687, 717,689, 718,924 and 723,147 is used to register metering pulses for each of a number of subscribers' lines, which are scanned continuously in synchronism with the rotation of the drum. The registrations individual to the different subscribers can be extracted and displayed on a common indicating device. The drum is divided into portions, each portion dealing with 100 subscribers and comprising (1) an address track bearing representations of the numbers 1-100 relating to the subscribers; (2) a first transfer track on which a dialled number is stored and subsequently compared with the numbers on the address track ; (3) a second transfer track to which a meter registration is transferred while it is being extracted: and (4) a meter track on which the meter registrations for the various lines are registered. On the meter track each storage area corresponding to a line has 18 areas, the first 2 for control purposes and the others for storing the meter registrations in binary code. Clock pulses TX1-18 correspond to areas, TZ1-100 to individual meters, and TW1-7 to the different meter tracks. Strobe pulses also occur at the end of the TX pulses to operate memory circuits as required. Registration of metering pulses. The first subscriber's position on the first meter track is used for control purposes, the others being assigned to the different subscribers. When a pulse is detected on meter wire PM, Fig. 6, during the time corresponding to the first area for any meter (PM, TX1), memory circuit MA operates and writes a dot in the second area of the meter track (TX2) by operating V11 and momentarily marking lead BM1. MA then adds 1 to the registration in areas 3-18 by applying potential to the grids of V10 and V11 until the registration in one of these areas changes from 0 to 1 when an output on the inverse meter sampling lead SLM together with the appropriate clock pulse #TX3-18 restores MA. On the succeeding scan if potential is still on the meter lead PM, MA is again operated but is immediately reset by the busy mark in area 2 (TX2, SLM). When the marking on lead PM disappears MA is not operated and the busy mark in area 2 is erased by operation of V10. Extraction of meter registration. Dialling digits into first transfer track. To ascertain the meter reading of a particular subscriber, a key KT1, Fig. 5, is set to select the appropriate meter track and key KA is operated, followed by dialling of the two digits necessary to identify the position on the meter track. On the first break of impulse springs IP, MI operates in area 1 of the control portion (TX1, TZ1) of the first meter track to enter a busy dot in position 2 by marking lead BM1. M1 also clears the count in areas 3-6 by marking lead AM1. For the first digit M1 operates M2 in position 8 if the first transfer track is clear (TX8, SLT1). M2 restores M1 and enters 1 in the area of the first transfer track (TX9-12) corresponding to the first digit by operating valves V6, V7 to reverse the registrations in successive areas until a 0 has changed to 1 when M2 is reset (SLT1, TX9-12). Each closure of contacts IP causes M3 to operate in position 2 and add 1 to the timing count in positions 3-5 of the control portion of the first meter track (SLS, TX3-6), M3 then being restored. Each reopening of IP reoperates M1 to clear the timing count and operates M2 to add 1 to the digit recorded on the first transfer track. At the interdigital pause M3 fills positions 3-6 in the control portion of the first meter track and enters a dot in position 7 of the first transfer track (BT1) and then in position 8 to serve as a busy control for the first digit. M3 is then reset (SLS, TX8). The second digit is entered in positions 15-18, M2 operating in position 14. Comparison of first transfer track and address track. The record in the first transfer track is repeated over the whole track and the dot in position 7 operates M4. M4 is repeatedly reset until coincidence of readings on the two tracks occurs, when M4 remains operated and by marking lead BS enters a dot in position 1 of the required registration on the appropriate meter track as a reading-off control. Contacts KA2 now permit the inserted dot (SLS, TX1) to operate M5 which is reset if the second transfer track is not clear (SLT2). If it is clear, M5 inserts a dot in position 2 of the second transfer track, transfers the number stored in the register on the meter track to the second transfer track and erases the busy dot in position 7 of the second transfer track, transfers the number stored in the register on the meter track to the second transfer track and erases the busy dot in position 7 of the first transfer track. Transfer of meter reading to printing apparatus. M5 is reset on the next scan and M6 operates to subtract 1 from the registration on the second transfer track. On each occasion a pulse is sent out on lead PO to a high-speed counter whereby the meter registration is transferred. M6 is reset at each subtraction but when transfer is complete M6 remains operated and M7 operates in position 18. M7 erases the registration on the second transfer track (AT2), holds M5 and M6 inoperative and operates M8. M8 pulses out the address stored on the first transfer track over leads TP, UP until the two digits have been cleared when M9 and M10 operate to mark lead PR to cause printing, at the end of which potential on lead PC resets M7, M9, M10. Successive readings. If key KB is also operated, to give a step-on facility, M5 while operated inserts a dot in position 1 of the next meter registration so that M5 is re-operated and the extraction operation repeats for the next meter position. M5 connects SLA to BT1 to enter the subscriber's number on the first transfer track and the process continues as described above. Automatic read-off. When a meter is halffull a dot is inserted in position 18. With contacts KA1 open, this operates M5 using an auxiliary reading head SLS<1> one meter ahead of the normal head in the manner described in Specification 718,924. An auxiliary address reading head SLA is set one meter position behind normal to pick up the address under the control of M5. The identity of the track on which the registration is stored is provided by MT1, MT2 . . . which are selectively operated under control of track clock pulses TW1, TW2 . . . when M5 operates. These memory circuits are reset by potential on lead PC when printing is completed.