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Similar intervvorking exists with the international transit centres of Type ARM in Ireland. Spain and Yugoslavia. References 1. CCITT. IIIrd Plenary Assembly, Geneva, 1964. Blue Book - Telegraph Technique. 2. MCKINNON, R. K.: Aiitomatisation of the Australian Telex Network-Part I. Telecomm. J. Aust. 75(1965): 2, pp. 108—115. 3. MCKINNON, R. K., CRANE, N- R. & KROL, J. R.: Aiitomatisation of the Australian Telex Network - Part II. Telecomm. J. Aust. /5(I965): 3, pp. 208—222. 4. SHARP, K. V.: Mercury-Wetted Contact Telegraph Relays. Telecomm. J. Aust. I5(\ 965): 2, pp. 116—119. 5. CRISPIN, J. S.: Intercontinental Telephone and Telex Exchanges. Ericsson Rev. 44(1967): 3, pp. 111—117. 6. STRINDLUND, E.: Telex - a General Survey. Ericsson Rev. 44(1967): 2, pp. 65—76. 18
Automatisation of the Australian Telex Network R. K. McKINNON, AUSTRALIAN POST OFFICE, MELBOURNE, AUSTRALIA Technical and operating features of the automatic telex network, installed throughout Australia, are outlined. UDC 621.394.34 621.397.74 LME XI5 recently The new automatic network uses the keyboard of the subscriber's teleprinter to send digit information for selection of the required number. Printed service codes are used in the system to inform the calling subscriber of the progress of his call, that is, a short printed indication is given on the calling subscriber's machine. The system uses a fast trunk signalling technique employing 5-unit start/ stop code transmission for selection and rate-setting information. A simple numbering and charging basis has been employed. The characteristics of telex traffic differ significantly from telephone traffic, making less complex numbering and charging arrangements possible. A feature of telegraph traffic since World War II has been the shift from public telegraph networks operated by telecommunication administrations, such as the Australian Post Office, to telegraph services in which the administration simply provides the necessary facilities, which subscribers themselves operate. Subscribers with a closely defined sphere of interest and a heavy volume of traffic have, in general, chosen custom-engineered private-wire leased teleprinter services, and these were developed during and after the war. An obvious need developed for a general switching network which would cater economically for subscriber's more widely dispersed communication requirements, and for traffic loads lighter than those occurring on leased privatewire service. Further, such a network should permit efficient international connection and allow easy transfer of traffic, to and from the extensive Australian public telegraph network. As a result, a service known internationally as telex was introduced on a manual switching basis in 1954 and phenomenal rates of growth in subscribers and in traffic developed in following years. In the telex service the subscriber uses a teleprinter as the basic subscriber's instrument. Calls are then switched from teleprinter to teleprinter on a comparable basis to the switched telephone system. There are, of course, some significant differences in technique between a telex and a telephone switching system. The telex system uses direct current signalling from the subscriber's terminal unit, and this has an important influence upon the transmission path through an exchange. Unattended reception at the subscriber's terminal is employed and affects exchange calling, clearing and holding conditions. 19
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Page 8 and 9: On physical subscriber lines other
Page 10 and 11: In a new Recommendation U 11, CCITT
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Page 20 and 21: In this case, after receipt of the
Page 24 and 25: The capital cost of the telex syste
Page 26 and 27: Fig. 1 Traffic distribution by dist
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Page 32 and 33: A variety of special subscriber mar
Page 34 and 35: to be tripped. The calling subscrib
Page 36 and 37: References 1. C.C.T.T. Illrd Plenar
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