Patent GB-383659-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1931-07-29
Abstract: 383,659. Automatic exchange systems. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, Liverpool, and BAKER, G. T., Blackbrook, Caerphilly, Glamorgan. July 29, 1931, No. 21712. [Class 40 (iv).] A code translating register controller at a satellite on receiving the name code that it shares with the main office holds up the transmission of impulses until the thousands digit has been received and then, if the call is local, changes the circuits of the 1st code selector to make it act over a 2nd set of wipers as a digitabsorbing final selector. If the call is from a coin-box sub-station, such sub-stations appearing in a particular level of the finder, the register controller sends out a route code depending on the name code dialled but different from that which would be sent in the case of a call from an ordinary line. A similar arrangement is made in the case of calls from party lines. It may however be arranged that all the calls of these two kinds are routed in the same direction whatever name code is dialled. All the junctions can be reached over any of the 1st 7 levels of the 1st code selector, the position to which it is set determining the numbers of times the meter is to be operated. ' The register controller is similar to those described in Specifications 358,043 and 377,236. Call-finder. Line relay LK, which carries a high resistance included in its initial circuit to make it suitable for different lengths of line, attracts only its armatures lk1, lk2 when the subscriber calls to mark the line and energize starting relay S which energizes V. The vertical and rotary magnets VM, RM of the allotted call-finder, Fig. 2, then interact in turn with a common stepping relay G, the changeover being effected by R, and when the line is reached, 1H switches through, shunts out V and energizes G to kick off the allotter. The line relay LK now attracts its remaining armatures to cut itself out of the line circuit and look to the private wire. Association of register controller with call. The next register controller to be used is preselected by an allotting switch RBS except when all register controllers are busy when the allotter stops on terminals associated with the busy common wire 35. When a connecting circuit is taken into use its relays L, B, BB, C are energized and as a result, ST, Fig. 10, is energized and the link is marked calling to the switches SFS of the register controllers. ST energizes K and the magnet SFM of the switch SFS interacts with 3G in the allotter until the calling circuit is reached, whereupon KA switches through and energizes KB which kicks off the allotter. Normal operation of register controller. Dialled digits are recorded on an office register BC (which energizes an off-normal relay BP on its 2nd level) and digit registers TH .. U, the units register acting as digit distributor. Provided the code dialled is not that shared by the local and the main office, the switch U in position S connects ground to one end of the sending switch stepping relay 1G which is shunted by springs SPS driven by an individual pendulum interrupter IP. The sending switch then removes a shunt from the loop springs OPS driven by the same interrupter and translated and numerical digits are sent in known manner under control of the stop relay ZS and control switch CNT. Zero and enquiry calls. When 0 is dialled, the office register energizes MB, which sets up the manual board code, starts its transmission immediately and arranges for the operation of CO to free the register controller as soon as it has been sent. When 90 is dialled, MC is operated and routes the call in a similar manner (except that it only controls directly the value of the 1st digit) to the enquiry operator. Calls to test clerk. When 99 is dialled, TC is operated and routes the call to a test clerk, the first digit value being controlled directly by TC, the next 4 in the usual manner and a 6th directly by TC. Discriminating between local and main office calls. When the common code is dialled, the marking potential over 1a of the BC switch energizes 1LO which prevents the operation of the sending switch. If the thousands digit indicates a local call, a current is made over LO, Figs. 7 and 6, for LO in the connecting circuit, to release the register controller. If not, sending is initiated over an alternative circuit involving wiper 3k of the thousands register. Special routing of coin-box and party lines. When the finder switches through on level 9 (coin boxes) or level 0 (party lines) CB or CB and PL in the register controller pull up, connect the sending starting wire to wiper 6a of the BC switch instead of to the control switch wiper 2e, shunt the loop springs and energize BR. Consequently when sending would normally begin, no impulses are sent out, but the sending switch moves to a position marked by wiper 6a. On the operation of the stop relay, BR falls back and releases the BC switch unless the call is for a manual office, in which case 2R is energized over wiper 7f and releases CB, whereupon the sending switch goes home and sending begins with the normal routing. The restoration of the BC switch re-energizes BR which now energizes AR. AR energizes 2R which disables the spare code feature, since special routing codes are found in the spare positions of the BC switch, and energizes the vertical magnet of the BC switch which then interacts with 2G until the vertical wiper BCVW encounters earth over 5f or 6f of the sending switch. 2G then locks and BR falls after an interval to unlock 2G, which then interacts with the rotary magnet until wiper 6a reaches the position marked by 7f or 8f, whereupon 2G is locked and AR falls after an interval followed, by 2G, CB. The sending switch then goes home and sending begins. Incoming calls. These are extended by the same connecting currents as other calls but, to save time a separate allotter is provided. All the junctions appear on the same level of the finders (level 1 in the case shown) and when the finder switches through a circuit is made for LO in the connecting circuit to prevent operation of the register controller. Operation of switch, Figs. 4 and 5, as digitabsorbing final selector. With the local call relay LO operated, the hundreds digit which in this system always has the value 7 is repeated via C to the vertical magnet 2VM, L, B, BB, C having been operated on seizure of the connecting circuit. On the relapse of C after this digit, the release magnet 2ZM is energized over vertical bank contacts VB. 2ZM locks over off-normal springs and arranges for the operation of DA when restoration is complete. DA locks up and, switches over from the lower to the upper set of wipers. At the conclusion of the next (tens) train, E pulls up to transfer the impulse circuit to the rotary magnet and energize C. At the end of the units digit, C and E fall in succession to provide the testing interval. If the line is idle, 2H pulls up followed by CO to initiate ringing. If not, 2H is unaffected and M starts the busy tone equipment, sends back a tone signal and flashes LP. Normal ringing current is connected to terminal CDR1 and to the terminals engaged by the lower + wiper when a call is made to an individual line in the top three levels, post springs NP having then changed over. When the called party replies, F completes the connection. Party line systems ; code ringing. Party line subscribers appear in the upper three levels of the final selector and the required code, generated as described in the paragraph on " current supply equipment," is picked up by the lower + wiper which is connected by post springs to the ring cut-off relay in place of the normal ringing lead. Party line systems; reverting calls. The meter terminals of party lines (of which there are 3 in the system shown) are connected to vertical terminals of the selector. In a reverting call, the selector finds the line busy and accordingly on the relapse of C a circuit exists from battery picked up by the lower - wiper over RC to ground at dz4. RC prevents the operation of M when E falls. The calling subscriber now hangs up and L, B fall back, BB however being held by RC. The switching relay 2H now operates in series with A and the appropriate ringing code is sent out. When the called party replies, F releases 2H, RC, and L, B pull up again, L subsequently acting as feed relay for both parties. Metering. When a local subscriber replies, 11 energizes D which connects DS to ground pulses on MPS from the switch MPS, Fig. 12. DS on operating locks and connects ground pulses on MPZ to DZ which after an interval connects up metering battery and locks up. DS holds while MPZ is grounded and then opens the metering circuit. In the case of external calls, all of which go over the same set of junctions which however are reached over any of the 1st 7 levels of the 1st code selector, DA is not operated and when D pulls up (this time over the junction) the metering wire is connected (after a suitable delay as in single metering) via the vertical wiper 1VW to one of the wires MP1 .. MP6 which derive appropriate numbers of metering impulses from the switch MPS. Operation of switch as 1st code selector. When the register controller switches through, relay A is energized over the impulsing loop and energizes BA. As a result, the first digit received from the register controller raises the switch, which then hunts with its lower set of wipers for an idle junction, A now acting as the stepping relay, under control of 2H which on switching through energizes the ring cut-off relay F. The remaining digits are repeated over the junction and when the register controller has run down, CO is energized, releases the register controller and extends the talking circuit back to the relays I, D, of which I pulls up at once and D when the subscriber replies. Release in outgoing calls. To provide plenty of time for the far end to release, th