1975 ONWARDS (continued)

Because the AXE switching system had no version suitable for use as a small autonomous rural exchange and as the ARK crossbar system could no longer provide an adequate level of customer and network facilities, attention turned to obtaining a suitable system either by using equipment from a different manufacturer or requesting LME to develop a small rural version of AXE. Studies resulted in a decision to develop a new Ericsson design suitable for use both in Australia and elsewhere, to be known as AXE 104 (rural), as a joint Ericsson/Telecom effort, with Telecom staff included in the design team, adding an important new dimension to Australian practices.

System studies showed the need for an exchange optimised for small rural terminal applications typically in the range of 40 to 600 lines but the design concept adopted will permit up to 2048 lines to be connected with, in addition, some transit switching capacity, but in all configurations the overall traffic limit will be 200 erlangs. Although initially most installations will be connected to the analogue network, the aim is for AXE rural to be capable of inclusion in the IDN, thus requiring the facility to connect to either digital or analogue transmission networks.[65]

Design focused on the elements of AXE102 which, in a small exchange, make the cost per line unacceptably high. This has resulted in deletion of the group selector stage, with the subscribers' stage providing group selector functions, and required the design of a new small central processor. First installations of AXE104 were planned for 1987, after trials in 1986. As with the DRCS, design of a suitable transportable equipment shelter to house the switching, transmission and ancillary equipment, has been undertaken by Telecom to provide low energy consumption with highly reliable thermal performance under an extreme range of temperature conditions.

When phase seven TV was completed, a large low population density segment of Australia was still without a live TV service. Within this extensive area were a number of small centres of population acting as service centres for pastoral, fishing and mining industries and a series of aboriginal communities, together with widely scattered pastoral homesteads. In the late nineteen seventies, the Government decided to use INTELSAT satellite services to provide programme relays to small population centres and Telecom was requested to provide receive only TV satellite terminals and low powered transmitters at these locations.

V. L. Cavallucci[66] has given an account of the logistic and technical approaches to the problems. This was, for instance, the first occasion in the world where a communications satellite was used as a relay station to serve a network of ground TV stations, requiring:

• Extensive use of 6.5 to 7.5 m non-tracking earth stations;


• mains station quality low priced, low noise, amplifiers and receivers;


• new designs of television transmitters;


• new supervisory system;

Readers are referred to Cavallucci's paper for details.

Australian Academy of Technological Sciences and Engineering