Patent GB-1079038-A (GB)
Title: Improvements relating to automatic telecommunication switching systems
Inventor: WARMAN BLOOMFIELD JAMES
IPC: H04M3/08
Filed: 1963-10-25
Abstract: 1,079,038. Automatic exchange systems. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Oct. 12, 1964 [Oct. 25, 1963], No. 42222/63. Heading H4K. A line and equipment identifier in an exchange system comprises a marker (usable for setting up a call) which is connected to an established connection and which applies a marking over the switch train of the connection to the marking wires normally extending between the marker and the switches and usable for initially setting up the connection and means for connecting these wires to an identifier which can identify an equipment involved in the connection from the markings appearing on the wires. The identifier is used in conjunction with a sectionalized exchange system of the type described in Specifications 989,336 and 999,945. Setting up a call.-A calling line LG1 is connected via A, B and C switches to a register REG in which dialled digits are recorded. A route selector determines a free path between LG1 and a link circuit LC and between the called line LD1 and the link LC and then calls-in a calling-side marker MG and a called-side marker MD. The latter apply the relevant markings to wires MG1-MG4 (and similar wires on the called side) for causing operation of the selected cross-points (cross-bar, reedrelay or electronic). When the call is established metering takes place by means of 245 m.sec. positive pulses on the P wire. Call tracing.-This may be required in respect of delayed release, testing or malicious calls. If the called number is known, e.g. in the case of a malicious call, an operator TC keys-up the number into a test register T/REG whereafter a connection is set up between the "busy" called line and an access marker MTA. The latter seizes an identifier ID and this then transmits a 5 m.sec. positive pulse over the called-side P-wire during a gap in the metering cycle period of 500 m.secs. (X, Y party metering) when the meters are inoperative. The pulse is thus extended into LC where a relay responds so as to effectively identify the link circuit and to bring-up markers MG and MD. The latter apply positive marking potential to the holdwires on the calling and called sides of the link whereby signals appear on the marking wires MG1 to MG3 after transmission through the operated cross-points. The identifier connects itself in turn to the markers and stores the signals on relays. The identities of the calling and called lines and the equipments used for the call which are all derivable from the signals on the marking wires may then be displayed at the test console. Forced release of identifier.-If the calling-side of the connection is not completely identified within a specified time, a monostable circuit in the identifier relapses and causes the identifier to connect to the called side marker MD in order to determine the identities of the called side equipment. If the latter identification is not completed within the specified time, the identifier is released and an alarm is given to the operator. Established connection not accessible to marker. This may arise if the connection is under observation or is being tested for trunkoffering purposes. In this case the positive pulse on the P-wire brings-up a relay in the testing circuit whereby a corresponding lamp in the test console is operated. Call-tracing if link circuit is served by more than one calling- or called-side markers.-This type of link is discussed in Specification 999, 945 and is used for interconnecting non- adjacent sections of the exchange (i.e. for interconnecting corresponding sub-units of all sections). In this case all the markers must be free before identification can take place. One of the markers is seized and this then busies the others. Identification then takes place as before. Fault conditions.-If a permanent positive potential occurs on the P-wire, a relay in the identifier responds thereto and energizes an indicator lamp.