The Ericsson Group 1968 - History of Ericsson - History of Ericsson

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32 For each programme a maximum of 20 test circuits can be connected to the traffic route tester. 10 as A test number and 10 as B test number. The programme comprises 100 connections, a test circuit being established from each A test number to each B test number. The traffic route tester is connected to an exchange as a telephone set. The reliability of the exchange equipment recorded by the traffic route tester will therefore be representative of the service offered to subscribers connected to the exchange. A failed attempt by the traffic route tester to set up a connection is immediately recorded on a centralograph and counter. The traffic route tester can be used in two ways • for checking the functional quality • as automatic fault tracer. When the traffic route tester is used for checking the functional quality, it sets up test connections between A and B test numbers. When a fault occurs during the test, the fact is recorded on the centralograph, after which the tester takes down the connection and continues to the next. In the course of the test the total number of attempted connections from A test numbers and the total number of satisfactorily completed connections are recorded on counters. By reading of these counters at the end of the test programme or after a given number of connections one obtains a measure of the quality within the exchange or exchanges on which the test was carried out. If, for example, the traffic route tester has made 5000 attempts at connection, of which 4995 were completed without fault, this means that 99.9 % of the connections were satisfactory or (expressed in a more conventional way) that the fault rate is 0.1 %. From the record on the centralograph char one can see between which A and B numbers the various faults have occurred and the type of fault in question. When the traffic route tester is used as automatic fault tracer, it constitutes a very valuable aid to the maintenance personnel. If the functional check shows that some part of the exchange or a given route has an unsatisfactory functional quality, the tests are concentrated to that point, with the tester set for fault tracing. When a wrong connection occurs, it is held, the tester stops and issues an alarm, and indicates on a lamp panel certain information for guidance in tracing of the fault. The tester starts on new connections only after manual release. Every established test connection is checked in respect of the following functions: • receipt of dial tone • transmission of ringing signals and ringing tone • switching to correct subscriber • no unwarranted tripping of signal • current feed • satisfactory communication • no third party on line or crosstalk • no short breaks • no incorrect metering • correct metering • correct clearing of test connection.
Fig. 2 Supervision of real traffic Supervision of Subscriber-Generated Traffic By means of RKR (register control relays) the A subscriber's line can be automatically measured in respect of leakage and the subscriber's meter circuit can be checked in respect of disconnection and leakage. RKR is connected to a normal register, usually one per 10,000-line group. This register must be accessible from all subsribers within the 10.000-line group. RKR can be strapped for three alternative leakage measurements on the subscriber's line: a) insulation resistance 30 kQ ± 20 % b) „ „ 100 „ ±20% c) „ „ 1MQ± 20 % If the insulation resistance is below the preset value, or if a fault is encountered in the metering circuit, the established connection can. if desired, be held for identification of the A subscriber. The result of the supervision of subscriber lines and subscriber meter wires is recorded on a number of counters. Manual Observation of Connections To permit an operator to supervise connection from subscriber to subscriber. two types of auxiliary equipment are required, KOB (relay set for connection of observation desk to RKR) and OBR (observation desk relays) (fig. 2). The operator can monitor the connection and, on a lamp panel, sees the digits dialled by the A subscriber. Even if the A subscriber replaces, the connection can be held from the observation desk. There is a 2-wire loop between KOB and OBR and the equipment works with up to 4000 ohms on this loop, so that in multi-exchange areas the observation desk can be placed at the main exchange. 33
Page 1: 2 1969
Page 4 and 5: Equipments for Maintenance of ARF 1
Page 8 and 9: 34 Supervision of Common Control Eq
Page 10 and 11: Fig. 4 Supervisory panel for exchan
Page 12 and 13: Fig. 8 Fault tracing «ith manual .
Page 14 and 15: Fig. 12 MFC tester Fig. 13 Electron
Page 16 and 17: Fig. 16 Test set AHP 1622 42 via a
Page 18 and 19: 44 The following tests can be made:
Page 20 and 21: Fig. 20 Transmission of alarm 46 A
Page 22 and 23: 48 Exchanges A—D attended. Mainte
Page 24 and 25: 50 result in wrong connection. With
Page 26 and 27: Fig. 2 Insertion of tone generator
Page 28 and 29: Fig. 4 Exploded view of the push-bu
Page 30 and 31: Fig. 7 Push-button mechanism with l
Page 32 and 33: 58 registered by the V.F. code sign
Page 34 and 35: 60 Description of a Junction Networ
Page 36 and 37: Fig. 4 Kxample of cable runs in a l
Page 38 and 39: 64 Data for Programming The calcula
Page 40 and 41: Interesting New LME Items at "Prote
Page 42 and 43: New Head of Telecommunication Grouo
Page 44: The Ericsson Group Associated and c

The Ericsson Group 1968 - History of Ericsson - History of Ericsson

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