Raverdave
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JORN assures early warning for Australia
29 February 2000
By Michael Sinclair-Jones
Introduction
Australia is using a sophisticated new radar network that can detect stealth bombers, curb illegal immigration and spy on neighbouring nations from at least 3000 kilometres away. The $A1.8 billion Jindalee Operational Radar Network (JORN) has taken more than 30 years to complete but is now undergoing final trials.
JORN is designed to monitor air and sea movements across 37,000km of largely unprotected coastline and 9 million square kilometres of ocean. It is being used to cast a security shield across Australia's remote northern approaches without the high cost of maintaining constant maritime and air patrols.
Operational Use
Jindalee over-the-horizon radar was used to track military aircraft landing and taking off from Dili Airport, in East Timor, on 20 September 1999, when Australia-led Interfet forces began securing the former Indonesian province from militia violence. Australian Hercules C130 transports were detected from 1500 kilometres away by a 6 kilometres-long radar array at Longreach (Queensland), and at a similar site at Alice Springs (Northern Territory).
Aircraft images were displayed on radar consoles in Adelaide and Melbourne, 2600 kilometres from the action. Royal Australian Air Force commanders said the radar was accurate enough to show aircraft turning on their landing approach to Dili Airport.
Radar 2 (blue arc) is located at Laverton
IRSU (pink arc) is the Jindalee Alice Springs Facility
Radar 1 (yellow arc) is located at Longreach
The new radar has also been used to track illegal immigrants approaching Australia by boat through the region's largely unguarded northern waters. Although designed primarily for air detection, JORN was reconfigured last year at Australian Government request to scan for marine intruders. More than 500 illegal immigrants have been arrested and detained in recent weeks, largely as a result of JORN intelligence passed to civilian customs authorities. JORN can also measure wave height and wind direction for meteorological reports. 
Jindalee radar at Longreach, Alice Springs and Laverton (Western Australia) enables Australian military commanders to observe all air and sea activity north of Australia to distances of at least 3000 kilometers. This takes in all of Java, Irian Jaya, Papua New Guinea and the Solomon Islands, and halfway across the Indian Ocean.
JORN underpins Australian long-term military defence planning based on repelling an invader that attacks southwards through the Indonesian Islands, as did Japan in World War 2.
RAAF Group Captain Greg Hockings, who heads the new Jindalee Operational Radar Network, describes Jindalee as a "tripwire" in Australia's northern surveillance system.
JORN project manager Gordon McElroy, who previously directed Lockheed Martin's US battlefield defence programs, says of JORN: "There is none like it anywhere on the planet."
The JORN System
Lockheed Martin is the major partner in an Australian joint venture company, RLM Systems, which took over the project from the Australian Government's partly privatised telecommunications company, Telstra, in 1997. RLM performed a rescue operation after Telstra reported a $609 million loss on the project and could not guarantee a delivery date.
JORN uses two high frequency radio transmitters located 2300 kilometres apart, at Longreach and Laverton. The transmitter arrays are about one kilometre long and can generate a 20 kilowatt signal, which is stronger than most radio station signals.
The signal is said to be strong enough to blow up nearby re-fuelling depots, which are equipped with metal "faraday" shields to stop accidental sparks.
Signals are aimed at the ionosphere, where the beam is reflected over the horizon to targets up to 3000km away. A weak return signal from over the horizon is captured by a highly sensitive receiver that uses advanced software to separate background "clutter" from selected targets.
The receivers consist of two "arms", each 3.4 kilometers long, and each site consists of 960 individual antenna masts that must not be more than 10mm out of line along the whole length.
Transmitter and receiver sites near Longreach and Laverton are located about 100km apart to prevent electronic interference. The system is linked to 17 beacon stations across northern Australia, which are used to measure ionospheric conditions and calibrate transmissions from Longreach and Laverton.
The RAAF admits the system can operate well beyond its "unclassified" range of 3000 kilometres when radar signals become trapped inside the ionosphere and bounce twice before emerging over the horizon. However, unofficial reports that JORN can see as far as Singapore Harbour, Hong Kong and the Russian border are described by the RAAF as "highly optimistic".
More than a million lines of software code were written to integrate the constantly changing electronic data in what is described by RLM Systems as the biggest software development project in the southern hemisphere. The whole network is linked to a test command centre in Melbourne and, via a duplicate link, to the RAAF's high frequency surveillance command headquarters at Edinburg base, near Adelaide.
Stealth Aircraft not Immune
Edinburg is also linked to a third Jindalee transmitter and receiver at Alice Springs, which has operated as a JORN test site since 1993. McElroy says the Jindalee radar is very difficult to jam because of the way the signal is propagated over the ionosphere. "It can also detect stealth bombers, which are not designed to defeat the characteristics of Jindalee's high frequency radar," he said.
Stealth aircraft, such as the US Nighthawk F117A, are designed with sharp leading edges and a flat belly to minimise reflections back towards conventional ground-based radars. However, Jindalee radar bounces down from the ionosphere onto upper surfaces that include radar-reflecting protrusions for a cockpit, engine housings and other equipment.
Group Captain Hockings says stealth aircraft are coated with special radar absorbing material to avoid detection by conventional microwave radar. But the Jindalee radar uses high frequency radio waves, which have a much longer frequency than microwave radar. "Unless designed to be stealthy to both microwave and HF radars, (stealth) aircraft would not evade detection by JORN," he said.
Defence contractors are due to hand JORN over to the RAAF at the end of next year.
http://defence-data.com/features/fpage37.htm
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