Post-war and on to 1975 (continued)

Automatic routiners were increasingly used as a method of detecting defective apparatus. Available routiners of an early design, however, stopped and gave an audible alarm on detecting a situation which required attention, a feature which required staff in attendance. O'Mullane[51] has described an automatic recording scheme developed in Melbourne which enabled a routiner to test a group of selectors and record the necessary particulars of every switch failure disclosed during the test. The next development was to provide an installation in which the one recorder could serve all automatic routiners in the exchange.

Another requirement for determining the standard of service in the network was the ability to direct artificial traffic through the network. Initially this was done using equipment developed for use in the British Post Office, but this had several disadvantages. Petrie and Taylor[52] have given an account of work undertaken to adapt group selector routiners for artificial traffic generation and the design of a relay set which could be used at a remote location.

When ARF 102 crossbar was introduced into the network in 1963, a comprehensive approach to maintenance of the new equipment, built around the extensive use of supervisory and test equipment which the system incorporated, had to be developed. A. D. Pettersson, who was one of those closely involved, has given an account of the practices involved.[53] With the new equipment widely dispersed through the network, in order to obtain the advantages of common control facilities, there were many relatively small installations, a feature which led to work directed towards the development of facilities for centralising some aspects of crossbar maintenance. The APO, with Pettersson playing an important role, developed a supervisory system known as Automatic Disturbance Recording (ADR), using information obtained from experiments conducted in the relatively large Haymarket (Sydney) crossbar exchange. The development of ADR, involved equipment to give:[54]

• Interface equipment for conversion of the supervisory information to a form suitable for telemetering,


• storage and control units to handle the transmission of the information,


• the ability to decide the degree of urgency of the supervisory message,


• telemetry transmission and reception equipment for transmitting supervisory information from the exchange equipment to any desired location and for the reception of operational commands which may be used for control functions,


• supervisory messages transmitted in a form suitable for machine, including computer, processing.

25 Geelong Crossbar Exchange

Australian Academy of Technological Sciences and Engineering