Patent GB-856130-A (GB)
Title: Improvements in or relating to signalling systems
Inventor: KEATING JOHN HENRY
IPC: H04M15/08
Filed: 1956-06-27
Abstract: 856,130. Automatic - exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. May 17, 1957 [June 27, 1956], No. 19835/56. Class 40 (4). In a calling line identification system of the kind disclosed in Specification 615,271, the digits of the calling line number are sent in a 5-unit code in which each unit consists of a pulse of 900 c.p.s., followed by either a pulse of 600 c.p.s. or one of 750 c.p.s., the code signal for each digit having two 600 c.p.s. pulses and three 750 c.p.s. pulses. The 900 c.p.s. pulses are employed as synchronizing pulses to prepare the receiver for operation by the 600 c.p.s. " code " pulses and the 750 c.p.s. " complementary " pulses. If the correct numbers of pulses of each type are not received no digital display takes place. General arrangement and operation of sender, (Figs. 1-4).-A 10,000 line automatic exchange is associated with a manual board over which long distance calls are routed. As in the prior Specification, each line circuit has a pair of discs ARA, ARB of non-linear resistance material the junction of which is connected to one of the speech conductors. The other sides of the discs are connected to signalling leads from the send control relay set SCRS of which leads there are two sets, each of 100 leads. Each lead of the first set extends from contacts of a relay MA to 100 discs ARB associated with line circuits having a particular thousands/ tens digit combination, and each lead of the second set from contacts of a relay CA to 100 discs ARA associated with line circuits having a particular hundreds/units digit combination. There are ten MA and ten CA relays of which only 1MA and 2CA, concerned with lines having the thousands digit " 1 " and lines having the hundreds digit " 2," respectively, are shown. All lines of the exchange have a prefix digit " 5 " and the leads associated with the typical line circuit SLC of line " 51234 " are designated " 5-2-4 " and " 1-3 " indicative of the digital signals they are to carry. An identification cycle is divided into five periods PD, MD, CD, TD and UD (Fig. 5), during which the prefix, thousands, hundreds, tens, and units digits, respectively, are signalled. In period PD relays LA, 1CA to 10CA and 1MA to 10MA are back and V.F. signals are produced at terminals PCU1 to PCUO. As the prefix digit is " 5," PCU5 is strapped to back contacts LA1 to LA10 so that digit " 5 " signals are extended to the hundred contacts of 1CA to 10CA. One contact set of each of these relays is strapped (as shown for 2CA2) so that the prefix " 5 signals are impressed upon the 100 common leads and thence to the discs ARA of all 10,000 lines. In period MD, LA is up and signals are generated at the terminals MT1 to MT0, each of which is common to a make-before-break contact set in each of relays 1MA to 10MA. Since 1MA is associated with all lines in the " 1 " thousands group, MT1 is strapped to all its back contacts and the thousands digit " 1 " signals are thus applied to the discs ARB of the 1000 line circuits having that thousands digit. Similar strappings provided for the other MA relays (not shown) perform similar functions for the other thousands groups. In period CD the relays 1MA to 10MA also are operated and signals again appear at PCU1 to PCUO, each of which is extended over a front contact of LA to a make-before-break contact set of each of relays 1CA to 10CA. The U.F. signals for hundreds digit " 2 " are connected by the strap at 2CA2 to all the 2CA back contacts and thence to the ten signalling leads serving discs ARA of the 1000 line circuits having hundreds digit " 2," similar straps across 1CA1 ... 10CA10 (not shown) performing similar functions for the other hundreds groups. During the fourth period TD, when 1CA to 10CA also are operated, signals again appear at MT1 to MT0 and the relevant tens digit signals are extended over the corresponding contacts of 1MA to 10MA each contact extending signals to the discs ARB of 100 line circuits. Finally in period UD the units digit signals from PCU1 to PCUO are extended by the contacts of 1CA to 10CA to the discs ARA of the corresponding line circuits. Initiation of identification.-A subscriber having initiated a trunk call is routed to a manual board relay set MBRS terminating in multiple jacks AJ. Relay 1L and 1B pull up, the calling lamps LP are lit, and the operator answers; operation of S and SS extinguishing the calling lamps. Operation of a calling line identification key at the manual position extends positive battery over the tip of the jack to bring up CS which offers a batteryconnected winding of S1 to lead SE of the send control relay set SCRS. If or when the latter is free (ST and UV down), ground on this lead brings up S1 which releases 1L, connects +75V to the incoming speech conductors, thus biasing the discs ARA, ARB of the calling line into the conductive condition, operates 1ST in SCRS, and connects - 50V to the non-linear resistors ARC, ARD to prepare for the transmission of 900 c.p.s. synchronizing pulses from transformer TRC. In the subsequent identification cycle each of the relay sets MBRS which has been conditioned as described will receive identification signals appropriate to the line circuit extended thereto. The operation of 1ST brings up SA, followed by SB, which grounds the secondary of TRC to extend a long-duration pulse of 900 c.p.s. via each of the associated cord circuits to the V.F. receiver associated therewith, and releases SA. Capacitor C1 charges until the voltage across the upper winding of DR is sufficient to operate that relay, whereupon C1 discharges and then charges in the reverse sense until the lower winding of DR becomes operative to release DR. This process continues, the values of C1 and of the resistors RV2 and R18 being such that DR is up for 22 m.s. and down for 11 m.s., of each 33 m.s. period. Relays DRA and DRB are actuated in time with DR and during their 22 m.s. operated period relays A and B (under control of SO) are operated for successive 11 m.s. periods. With DRB down, A up, and B up respectively, output paths are completed in successive 11 m.s. periods from the sources of 900 c.p.s., 750 c.p.s. and 600 c.p.s. connected to TRC, TRA and TRB, respectively. The extension of 750 c.p.s. and 600 c.p.s. to the line marking transformers TR1 to TR5 and TR6 to TR10 is determined by the condition of marking relays VA to ZA; a second set of relays 1VA to 1ZA (not shown) performing similar functions for a second set of marking transformers (not shown) associated with terminals MT1 to MT0. Each of the main periods PD, MD, CD, TD and UD is nominally 165 m.s. and consists of five 33 m.s. periods, and, as shown in Fig. 5, during each main period one set of marking relays (VA to VZ for periods PD, CD and UD or relays 1VA to 1VZ for periods MD and TD) are operated for successive 33 m.s. periods. These are designated, for convenience, V, W, X, Y and Z periods and for the first 11 m.s. portion of each a 900 c.p.s. synchronizing signal is transmitted, whereas a 600 c.p.s. " code " signal or a 750 c.p.s. " complementary " signal is produced in the 3rd or 2nd 11 m.s. portion, respectively, at each of the terminals PCU1 to PCU0 or MT1 to MT0. The 5-unit code used (Fig. 5A), is such that for each digit to be signalled two " code " pulses and three " complementary " pulses are sent. The appropriate code and complementary pulses are extended (via discs ARA and ARB) only to those line circuits which are to be identified and thence to the relevant manual board relay sets where they are interlaced with the 900 c.p.s. synchronizing pulses. The complete series of pulses transmitted from MBRS for any five-digit number consists of ten code pulses, fifteen complementary pulses and twenty-six synchronizing pulses, as indicated at the foot of Fig. 5. A " count-of-five " circuit comprising high-speed relays SV, PC, SW, PA, SX, SY, PV and SZ, which operate at the times indicated in Fig. 5, controls the operation of marking relays VA to ZA successively for 33 m.s. periods during the digit periods PD, CD and UD, and the similar operation of 1VA to 1ZA during MD and TD. The set of marking relays to be controlled is determined by the operated or released condition of TA and TB, operation of which relays, together with that of LA, 1MA to 10MA, and 1CA to 10CA, is also controlled by the count-of-five relays. At the end of the cycle relay UV comes up and relay S1 in each manual board relay set concerned is released, together with DR in SCRS. In MBRS the release of S1 reconnects the speaking path, reoperates 1L, removes the bias from ARC and ARD, and disconnects 1ST in SCRS. The latter releases slowly to initiate release of that relay set. Reception and display of calling line number, (Figs. 6-13).-Operator's position equipments PE are multipled over four non-homing positions finders PF, each of which is associated with a separate receive control relay set RCRS, of which the first 1RCRS is shown in full. Each RCRS is connected to the wipers of a separate position display finder DF (also non-homing) which provides over wipers DF1 to DF15 access to a five-digit display means (preferably of the type described in Specification 742,254) at each operator's position. Each such means includes five indicators of which the three (PD1, MD1 and UD1) for the prefix, hundreds, and units digits are shown. Momentary operation of the identification key KLA brings up 1DR which extends the ring and tip of the answering plug to bank contacts of PF3 and PF2, marks the position outlet in PF8, and extends ground to the start terminal (in this case 1FS) of the first choice control relay set of the position. If 1RCRS is idle (CO and IA up) its start relay ST is operated and starts the position finder. Test relay HH (connected up by ST) pulls up to the marked outlet, stops the finder and allows H to operate in series with the finder motor. The latter relay connects the tip and ring