Patent GB-722777-A (GB)
Title: Automatic telegraph switching system
IPC: H04L12/54
Filed: 1952-11-24
Abstract: 722,777. Telegraph exchange systems. AUTOMATIC ELECTRIC LABORATORIES, Inc. Nov. 24, 1952 [Dec. 10, 1951], No. 29667/52. Class 40 (3). In an automatic telegraph exchange having a number of incoming lines each with an individual circuit, a number of outgoing lines, and a number of cross office units, each having access to each of the outgoing lines and being accessible to each of the incoming line circuits, means are provided in each line circuit for recording a message received, and also for capturing a directing circuit, the latter registering the address portion of the message, and then capturing a cross office unit, the message being then produced in the line circuit and recorded for a second time in the cross office unit. The cross office unit is then connected to the desired outgoing line and the directing circuit and line circuit disconnected. The message is then transmitted from the second record over the outgoing line when the latter becomes free from previous messages. The general arrangement of the system is shown in Fig. 1. Four relay switching centres UWP, JLX, UAC and UEP are shown together with tributary stations and also connected to further relay centres BAC, JAC, and JWP. The tributary stations are identified by four or five-letter codes consisting of the three-letter code of their relay centre together with an individual letter or letters. The lay-out of a relay centre is shown in Fig. 2 in a simplified form giving only one input and one output line. The former is connected to an input circuit 400 which has a director assignor 800 which picks up, when required, one of a pool of directors 200A, 200B, &c., and the line selector 801 then associates the director with the appropriate incoming line circuit. Each director can control a common routing translator 2900, temporarily associated with the director, and having a patch panel 3200 for effecting some variations in operation manually. Each incoming line circuit is individually associated with a cross office selector 3300, which has access to each of the cross office units 3400, also the multiple call position 3340, and the intercept operator position 3330. Each cross office unit is individually associated with an outgoing selector 4300 which in turn has access to each of the outgoing lines. Each outgoing line has a timer T4495 (Fig. 44), a number transmitter 4430, a send relay R4440, and a monitor unit 4450. There is also a cancel transmission unit 3450 common to all the cross office units which is provided to break and cancel transmission of a low-class precedence message over an outgoing line to permit the immediate transmission of a high-class precedence message. The tape reader 340 detects start of message and end of message indicators, and the channel number comparator checks the received number of the message with that shown on a local counter. The director includes the following arrangements operated by reader 340 and given in more detail later. Means to detect and register the routing indicator, means to detect and register the degrees of precedence, and means to register the identity of the outgoing line required for a message. Lastly a relay group and testing circuit which engages selector 3300 with a cross office unit 3400 and also controls outgoing selector 4300. The cross office unit may store a number of the same low-class precedence messages for a particular outgoing line or it may be selected from a pool to store and transmit a high precedence message. The cancel transmission unit 3450 may be used by any cross office unit to break in and cancel the transmission of a low precedence message whenever a high precedence message requires the line. Each message should comprise a start of message indicator, a channel number indicator, a precedence indicator, an address indicator, perhaps a multiple message indicator, the body of the message, and an end of message indicator and the tape reader 340 operates control or indicating apparatus in accordance with these indicators. The incoming line circuit 400 in centre UAC is shown in detail in Figs. 3 to 8, Fig. 7 (not shown). The line from relay centre UEP first passes a slow release relay R305 that gives an alarm on a long break in the message and then reaches the driving magnet M331 of perforator 330. Slackening of tape 333 due to operation of the perforator operates switch 341 and puts sensing magnet M344 into operation. The contacts 350 to 355 of this magnet have connections A, B, C, D, E, and PPC to the sensing relay arrangement 401 in Figs. 4 and 5. As each character of the start of message indicator comes in relays R410 to R450 operate and set up connections to operate and lock a pair of relays of the set R490-1 to R490-14 and at the end of the start-of-message indicator all these relays are left locked. If any character of the indicator is incorrect the locking circuits are not completed and relays R490-1 to R490-14 all release. A circuit is also provided to give an alarm if the start of message indicator is omitted. Relay R460 (Fig. 4) is operated at each character sensing and steps a magnet M690 (Fig. 6) of a counting switch 690A. The first movement of this prepares a circuit for its return to zero on actuation of relay R490-14. If this counting switch reaches its twenty-fifth contact without relay R490-14 showing the completion of the start of message indicator, an alarm R601 is actuated and the attendant, after examining the message can restart operation by moving key K668. He also has to operate K825 (Fig. 8) to operate channel number relays as though the correct channel number has been received. The channel number indicator, which is the next part of the message on tape 333 consists of a " figures shift " character followed by three digit characters. When the " figures shift " character is sensed, relay R490-14 has already operated and prepared a circuit for the channel number connecting relay R830 (Fig. 8). Relay R480 in the sensing relay system completes this circuit and relay R830 on operating prepares locking circuits for itself and relay R850. When the relay R470 restores at the end of the " figure shift " sensing cycle, R850 is left locked and the channel number sensing relays R860A to R860E are connected to the sensing relays 401 and are ready for operation to indicate the digits of the channel number. The channel number comparator 900 counts the messages received on the incoming line and compares the channel number indicator of each message with its own reading. If these do not agree it stops transmission of the message and causes an alarm. It is manually returned to zero at the commencement of the operational day. When a digit of the channel number is sensed R860A-R860C are operated to mark the appropriate one of the ten conductors of cable 870 which is connected to the comparator 900. If this conductor is also marked by the wiper of the number register in the comparator, R840 completes a circuit for magnet M820 (Fig. 8) which moves its wiper 822 to prepare a circuit for testing the next digit. When the last digit has been sensed and tested wiper 824 makes a contact that operates " channel number complete " relay R810 which advances the number register in comparator 900 by a unit. Manual means are provided for an operator to vary the number register if required. A director seize relay R660 (Fig. 6) is energized by R810 and switch wipers of line selector 810 are then started on a step-by-step search for an incoming line and, when found, this is seized by the director. The precedence indicator which forms the next part of the message consists of one of six different possible signals indicating consecutive degrees of precedence. The three highest precedences will cause the transmission of their message to interrupt a lower precedence message but the remaining degrees only ensure that their message follows at once on a lower priority message that is in course of transmission. As shown in Figs. 23-25 the two highest priorities, " flash " and "emergency," have a single detector circuit 2300FE, the next " operation immediate " has a circuit 2300-OP, the next " priority " has a detector 2300-PP, the next " routine " has a detector 2300-RR and the last " deferred # has a detector 2300-NM. There may also be a detector which detects an indicator stating that the message should go to more than one station. After the previous message operations, the sensing relay group 401 is connected to the precedence sensing group 1901 (Fig. 19) and the first character of the precedence indicator operates an appropriate combination of relays R1910A to R1910E in series with relay R1970 which controls a slave relay R1980, the latter sending signals to the precedence detector 2300 (Figs. 23 and 25) and also locking those of the precedence registering relays 2000 (Fig. 20) which have been actuated from group 1901. The indicator for deferred precedence is "NMNM." When relay R2035 for N (Fig. 20) operates, it energizes relays R2560 followed by R2565 (Fig. 25). These relays prepare circuits so that the next signal " M " operates R2570 and R2575. R2580 and R2585 operate under the second N and R2590 and R2595 under the second M. When a space character follows the precedence indicator, all the relays release except R2590 and R2595 which remain locked to indicate the successful detection of a deferred precedence indicator. The indicator for routine precedence is " RR " and the first operation of the R relay R2040 (Fig. 20) energizes R2380 (Fig. 23) followed by R2385. This prepares matters so that the next " R " received operates R2390 and R2395 and these last two relays remain locked to indicate a successful detection of routine precedence. A precedence selector switch (Fig. 22, not shown) bears six banks of contacts corresponding to the degrees of precedence and the relays of each detector mark the appropriate bank by removing ground therefrom. The priority preference indicator " PP operat