Jindalee Operational Radar Network
The Jindalee Operational Radar Network (JORN) is an over-the-horizon radar (OTHR) network that can monitor air and sea movements across 37,000 km2. It has a normal operating range of 1,000 km to 3,000 km. It is used in the defence of Australia, and can also monitor maritime operations, wave heights and wind directions.
The roots of the JORN can be traced back to post World War II experiments in the United States and a series of Australian experiments beginning in the early 1950s. From July 1970 a study was undertaken; this resulted in a proposal for a program to be carried out, in three phases, to develop an over-the-horizon-radar system.
Phase 1, Project Geebung, aimed to define operational requirements for an over-the-horizon-radar (OTHR), and study applicable technologies and techniques. The project carried out a series of ionospheric soundings evaluating the suitability of the ionosphere for the operation of an OTHR.
Phase 2, Project Jindalee, aimed at proving the feasibility and costing of OTHR. This second phase was carried out by the Radar Division, (later, the High Frequency Radar Division), of the Defence Science and Technology Organisation (DSTO). Project Jindalee came into being during the period 1972-1974 and was divided into three stages.
Stage 'A' commenced in April 1974. It involved the construction of a prototype radar receiver at Mount Everard, (near Alice Springs), a transmitter (at Harts Range, 160 km away) and a beacon in Derby. When completed (in October 1976) the Stage A radar ran for two years, closing in December 1978. Stage A formally ended in February 1979, having achieved its mission of proving the feasibility of OTHR. The success of stage A resulted in the construction of a larger stage 'B' radar, drawing on the knowledge gained from stage A.
Stage 'B' commenced on 6 July 1978. The new radar was constructed next to the stage A radar. Developments during stage B included real time signal processing, custom built processors, larger antenna arrays, and higher power transmitters, which resulted in a more sensitive and capable radar.
Trials were carried out with the Royal Australian Air Force during April 1984, substantially fulfilling the mission of stage B, to demonstrate an OTHR operating in Australia. Another two years of trials were carried out before the Jindalee project officially finished in December 1985.
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