Австралияның көкжасықты радар желісі

Over the horizon radar network in Australia

The Jindalee Operational Radar Network (JORN) is an over the horizon radar (OHR) network operated by Royal Australian Air Force that can monitor air and sea movements across It has a normal operating range of to It is used in the defence of Australia, and can also monitor maritime operations, wave heights and wind directions. JORN's main ground stations comprise a control centre, known as the JORN Coordination Centre (JCC), at RAAF Base Edinburgh in South Australia and three transmission stations: Radar 1 near Longreach, Queensland, Radar 2 near Laverton, Western Australia and Radar 3 near Alice Springs, Northern Territory. beginning in the early 1950s. In 1969, The Technical Cooperation Program membership and papers by John Strath prompted development of a core "Over the Horizon" radar project.

Phase 1, Project Geebung, aimed to define operational requirements for an OHR 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 3 of the OTHR program was the design and construction of the JORN. The decision to build the JORN was announced in October 1986. Telstra, in association with GEC Marconi, became the prime contractor and a fixed price contract for the construction of the JORN was signed on 11 June 1991. The JORN was to be completed by 13 June 1997. Other unsuccessful tenderers for the project included experienced Australian software development and systems integration company, BHP IT, and experienced Australian defence contractor AWA Defence Industries (AWADI). Both of these companies are no longer in business. By 1996, the project was experiencing technical difficulties and cost overruns. Telstra reported an A$609 million loss and announced that it could not guarantee a delivery date. The failed Telstra contract prompted the project to enter a fourth phase.

Phase 4 involved the completion of the JORN and its subsequent maintenance using a new contractor. In February 1997 Lockheed Martin and Tenix received a contract to deliver and manage the JORN. Subsequently, during June 1997 Lockheed and Tenix formed the company RLM Group to handle the joint venture. An operational radar system was delivered in April 2003, with maintenance contracted to continue until February 2007. In August 2008 Lockheed Martin acquired Tenix Group's interest in RLM Holdings Pty Ltd.

As a consequence of the duration of its construction, the JORN delivered in 2003 was designed to a specification developed in the early 1990s. During this period the Alice Springs radar had evolved significantly under the guidance of the Defence Science and Technology Organisation (DSTO). In February 2004 a fifth phase of the JORN project was approved. Phase 5 aimed to upgrade the Laverton and Longreach radars to reflect over a decade of OTHR research and development. It was scheduled to run until approximately the year 2011,

In March 2018 it was announced that BAE Systems Australia would undertake the $1.2 billion upgrade to Australia’s Jindalee Operational Radar Network, which was expected to take 10 years to complete.

The JORN network is operated by No. 1 Remote Sensor Unit (1RSU). Data from the JORN sites is fed to the JORN Coordination Centre at RAAF Base Edinburgh where it is passed on to other agencies and military units. Officially the system allows the Australian Defence Force to observe air and sea activity north of Australia to distances up to 4000 km. This encompasses all of Java, Irian Jaya, Papua New Guinea and the Solomon Islands, and may include Singapore. However, in 1997, the prototype was able to detect missile launches by China over away. JORN is so sensitive it is able to track planes as small as a Cessna 172 taking off and landing in East Timor 2600 km away. Current research is anticipated to increase its sensitivity by a factor of ten beyond this level. It is also reportedly able to detect stealth aircraft, as typically these are designed only to avoid detection by microwave radar. was a cooperative research project, with American missile defence research, into using JORN to detect missiles. The JORN was anticipated to play a role in future Missile Defense Agency initiatives, detecting and tracking missile launches in Asia. As JORN is reliant on the interaction of signals with the ionosphere ('bouncing'), disturbances in the ionosphere adversely affect performance. The most significant factor influencing this is solar changes, which include sunrise, sunset and solar disturbances. The effectiveness of JORN is also reduced by extreme weather, including lightning and rough seas. As JORN uses the Doppler principle to detect objects, it cannot detect objects moving at a tangent to the system, or objects moving at a similar speed to their surroundings.