Federation to the End of the Second World War (continued)

In the 1925-27 period, expertise in radio field strength measurement techniques as applied to Medium Frequency (MF) broadcast transmitters, began to be established and measurement facilities and reference standards for the precise measurement of electrical quantities (voltage, current, resistance, capacitance, inductance) were established in 1927. The following year saw measurement facilities and reference standards for time interval and frequency, with accuracy traceable to national and international standards. Physical science activities commenced in 1931 and by 1932 the staff had grown from 1 in 1923 to 35. These expanding facilities were employed in a range of projects, including the installation of initial open wire carrier systems, the first submarine telephone coaxial cable to Tasmania and Australia's first 12 channel radio telephone system. The Laboratories also investigated a wide range of problems and in 1939 issued 213 Research Laboratory Reports on subjects ranging from cable corrosion at Sale, Victoria, to tests on ultra-high frequency navigational beacons.

Meanwhile attention here, as elsewhere, turned to the practicability of introducing automatic switching. Strowger, an American, first lodged a patent for an automatic exchange in 1889 and by 1912, after many changes, the switch mechanism had reached its final form, but the circuit details remained rather fluid, with frequent changes being made.[15] The first automatic exchange in Australia was opened on 6 July 1912, at Geelong, using equipment supplied by AEC, Chicago. It was in the nature of a field trial of automatic equipment and, although there was some public complaint concerning the standard of service in 1913, proved generally satisfactory. While the exchange was being installed, Hesketh, the Department's Chief Electrical Engineer, travelled abroad to review progress being made and to assess the merits of various automatic equipment designs. The outcome of this review, together with the performance of Geelong exchange, was that the 1912/13 Annual Report of the Department announced that automatic equipment would be used for new exchanges in capital city networks.

In retrospect this was a bold decision for, up to that time, most Strowger equipment had been installed as single exchanges, the only two large networks in the world being in Los Angeles and San Francisco, using main/branch networks, with most of the lines connected to the main exchanges. At the time the suitability of the equipment for large networks was still under question, while some doubted the ability of the public to remember five and six figure numbers.

The Australian automatic programmes had to have regard to the work which had been done after 1907 in upgrading the manual exchanges and as a result, the application of automatic equipment was patchy and limited, influenced also by the diversion of resources to the war effort after 1915. Although the switching equipment was imported, planning, building, maintaining and operating the networks were major tasks. When step by step equipment, the more general name for Strowger-type switches, was used in a multi-exchange network, the first one or two digits were used to select the exchange and, of necessity, the junction network was forced to comply with the numbering and switching arrangement adopted. Most networks in Australia used a main/branch exchange trunking scheme with five or six digit numbering, with the network divided into a number of areas, called main exchange areas, each having from one to ten exchanges.

Australian Academy of Technological Sciences and Engineering