Patent GB-1406856-A (GB)
Title: Switching arrangement for controlling peripheral units in a time division multiplex common control system
IPC: H04Q3/545
Filed: 1972-10-31
Abstract: 1406856 Automatic exchange systems GTE AUTOMATIC ELECTRIC LABORATORIES Inc 31 Oct 1972 [24 Nov 1971 26 Jan 1972] 50191/72 Heading H4K In a system having a plurality of registers which communicate with a common logic via a multiplex arrangement, each register contains at least one pair of equipments that are each useable exclusively only during an originating i.e. dialling or a terminating, i.e. connecting portion of a call whereby both equipments of the pair can be connected to the multiplex over a single conductor each during its respective portion of a call by means of a switching device controlled by the logic. The system described effectively reduces the number of wires required in the register/sender complex disclosed in Specification 1,066,921 (USA Specification 3,301,963) General description. Fig. 3.-The system comprises a 1000 line group 110 formed of two stages of reed relay switches A, B for giving access between calling lines and originating junctors O, J, and three stages C, B and A for giving access between terminating junctors TJ and called lines. The originating junctors are initially connected by a register connector switch R to a register/sender group RS and are subsequently connected to a three stage selector group 120 which provides access to outgoing trunks 121 or to a line group in dependence on the nature of the call. Incoming trunks 152 have appearances on a selector group and also have access to the register/senders via a twostage bypath network. An originating marker performs path finding and path setting functions in the line group and the bypath network in respect only of originating calls (including those originating from a trunk) while a terminating marker performs these functions always in the selector groups and also in the line groups in respect of terminating calls. The register/sender group consists of 192 register junctors RRJ some of which are permanently allotted to local originating and some to trunk originating calls. The group accepts/ transmits digits in dial pulse form or multifrequency form, the latter requiring the services of a tone receiver 302-303 or a tone sender 301 reached via a reed network RSX. Each junctor has an associated block of a ferrite core memory RCM and has exclusive use of a processing wired logic and access to its memory block during a specific time slot. Overall control is vested in a duplicated stored programme controlled processor DPU which includes a magnetic drum on which directory/equipment number and routing code translation data is stored and a core memory acting as a call store. The originating junctors provide a line split function during call establishment. The terminating junctors provide ringing-control, battery-feed and line-supervision for both the calling and called sides. The register junctors, Fig. 2, are used for digit receiving and sending, tone application, initial battery feed to a calling station, party and coin testing, and, busy and idle indicating to the originating marker. They include discrete transistor drivers (triangles at base of figure) which serve to energize reed, HQA (small telephone type) and mercurywetted relays in dependence on control signals obtained from the local logic and sustained between recurrences of a register's time slot by flip-flops in a multiplexor RJM. The register sender memory is of ferrite core construction and has a sixteen word block in respect of each register junctor. It is read/ written non-destructively in a cycle of 202 time slots. Each time slot is divided into eleven subslots during most of which two words are read from store for processing. Each word has 26 bits of which 25 are for information. The function of the words, i.e. call processing commands, and digit storage, and the manner of accessing them during each register's time slot are described with reference to Fig. 5 (not shown). Register-junctor/local-logic access arrangements, Fig. 4.-The cable 310 from a junctor RRJ-0 is terminated by drivers 1124 and receivers 1101 in a so-called multiplex RJM. This groups the junctors initially into sets of three (c.f. gates 1103) and then into a group of twentyfour (c.f. eight input gates 1106). A total of eight such multiplexers are required for the 192 junctors of the embodiment. The multiplexers are normally connected to an A logic by a single conductor cable 313A but may be connected to an identical, but normally redundant B logic, by resetting flop-flip RJMCONE. Each single conductor is provided by one conductor of a twisted pair whose other conductor is grounded at each end. A clock provides address signals for gating each junctor to the logic, those signals in the case of junctors RRJ-0 being provided on leads RTG-ZAO, ZBO, ZCO which serve together to open gate 1166. The latter permits any signal from the junctor on scan leads PHM, TSDM to reach flip-flop PHL, TSDL and thus be extended to the logic on leads RJM-PH, -TSD on which the signals from all 192 junctors appear each during its own time slot. The flipflops PHL, TSDL are reset near the end of each time slot by a signal provided on lead RTGRRJ (to gate 1167) but most of the other flipflops, e.g. HRJL. active in the direction logic to junctor, are set by this signal provided that the logic is currently issuing a command relevant thereto. For example during the setting-up of a connection the originating line must remain connected to the junctor. In the latter a reed relay 10H (Fig. 2) effects the holding function by earthing lead H. Relay 10H itself is held by driver 1001 which is connected by lead HRJM to flip-flop HRJL. The latter is set during each time slot allotted to this register by the logic reissuing a command on lead RCB-HRJ. The temporary resetting of HRJL at the beginning of each of this register's time slots caused by the logic command appearing on lead RTG-RRJ is ineffective on the relay driver 1001. Repetitive use of multiplexer leads for different functions.-It will be appreciated that essentially the above disclosure follows that of Specification 1,066,921. One point of difference lies in the double usage of certain wires in cable 310 (Fig. 2) as will become apparent from Fig. 1. Therein a flip-flop TRL is provided in the multiplexer for conveying an originating-portion-of-call or terminating- portion-of-call indication over lead TRM to the junctor where a relay TR operates in the latter case. During the originating portion, flip-flops JCIL and CSTL are set in the register's time slot (see previous paragraph) so as to cause actuation of reed relays SP and 10CT respectively in the junctor. These relays serve respectively for coin testing in single slot touch calling key telephones and for coin testing or party testing when it operates for 10 msec. and so places a test relay TST in series with relay 10A and a subscriber's ground connection. During the terminating portion of thecall however the two flip-flops cause a ground signal to be applied to junctor lead C1 and a mercury wetted reed relay SD to be actuated. The ground signal on C1 provides a busy condition to a trunk or a cut-through signal to an originating junctor or an incoming trunk, the nature of the call preventing any ambiguity here. The SD relay is effective for recognizing that a terminating marker has seized an outgoing trunk or terminating junctor so that it can respond to, e.g. start dialling commands from a distant office. It should also be noted that relay TR as well as providing a steering junction has rest contacts which connect dial tone (normal or distinctive) via capacitors to the tip and ring pair TO, RO during the originating period of the call and make contacts for connecting busy or reorder tone during the terminating period of the call. Set-up of local call.-When a subscriber goes off hook, the subsequent operation of his line relay is noted by an originating marker which identifies the line and selects a path to an idle register junctor. The line and path identities are transmitted to the data processor whilst the path is actually being set up, pulsing reed relay 10H in the junctor coming up on cutthrough. The processor uses the register junctor identity as a call store address so as to place all the data relating to the call in the memory area allocated to this junctor. The marker meanwhile is informed by an earth signal over the lead ST (Fig. 2) that the junctor is seized and connected and in consequence it releases, usually within 75 msecs. The processor determines class of service, e.g. party, coin, dialling mode, dial tone type, billing method, special and digit pattern recognition, stores some of it in the junctor's call store area and passes some of it to the junctor's memory block in the register/sender group. If the subscriber has a call bar condition or cannot dial, the ensuing special actions required are conveyed to the memory block. The junctor (in the normal case) returns dial tone and the subsequent dialled digits are stored in its memory block. After three digits, the processor is accessed for a translation. In the local call case the processor's answer is that the register should await a further four digits and reapply. The first application to the processor marked the transfer from a call originating phase to a digit analysis phase. When the processor is reaccessed it adopts the terminating phase and instructs the terminating marker to set up a path and to supply ringing thereto. The marker checks the free/busy condition of the called party and attempts to set up a path thereto. If it is successful, the processor instructs the register/sender junctor to cut-through the originating junctor and to then release from the call otherwise, it commands it to revert busy tones. The processor clears its memory area allocated to the register junctor. Trunk calls are set up in similar manner except that only a first translation is usually required. This informs the reg