PAVE PAWS -long range radar

Long Range Radar under the spotlight



 Long Range Radar, Early Warning Systems, Over The Horizon Radar

 

With missing flight MH370 being topic A at everyone’s dinner party these days it comes as no surprise that the press, plus a few learned individuals are crying out for an overhaul of our aviation communication and radar systems. Of course as most professional pilots flying international routes will tell you is that there are always blind spots and if you really want to take your aircraft out of sight, know your territory, get out to sea as quickly as possible and rely on satellite’s not picking you up.

PAVE PAWS -long range radar
PAVE PAWS operator Staff Sgt Paul Brawner -Service Depicted: Air Force
Source: Wiki/Credit CMSGT. Don Sutherland

Satellites are great at picking up things when it knows where to look – like the OTH radar systems used by the military.

Radar, here we look at secondary radar, sends out a signal, activates a transponder in an aircraft which in turn radiates necessary data to the receiving station.

Primary Radar – PAVE PAWS, DUGA-3 and JINDALEE long range systems

Now we have primary radar, our hot topic of the day. I read that this radar system is basically a pretty dumb machine – in what sense this article was written I don’t know but military radar nowadays comes out in many shapes and sizes. It can be continuous wave, modulated continuous wave, pulsed, rotating aerials, fixed arrays, high power, very high power and of course low power etc, etc. And of course when you need to find a surface to air missile or intercontinental continental ballistic missile or ICBM they had better be darn accurate. PAVE PAWS (Phase Array Warning System) is just that.

The Australian Jindalee radar system is used to detect aircraft and sea vessels up to 3000km north of Australia and deep into the Indian ocean, is shrouded in mystery and not surprising too as it is after all a military installation. Theoretically the radar can pick up sea vessels over 16m in length, or supposedly a 737 taking off from Singapore airport – How well it does this is anybody’s guess unless you were the installation or design engineer. What I do know is that theoretically it is very possible with modern technology. The Jindalee system would be pretty much a white elephant if it could not walk the talk.

Long Range Radar – Safety at Sea and in the Air

We can sit and concoct as many theories as we’d like but one thing is certain, nobody bullies any military organisation into revealing their latest technology – rightfully so. Whether the Australian government is holding secret top level information is anybody’s guess. Mine is a simple no. The Australians, in my honest opinion, hold the track record for having the most sophisticated search and rescue systems on planet earth – one being due to their AUSREP service. The US Coastguard have their AMVER system which although is an international system, seafarers are at the mercy of the territory they are in, unlike the AUSREP system. Having been to many Australian ports, the Aussies hold a very no-nonsense approach to mischief. Therefore I do not believe the Australians would be bullied into giving any information away with regard to the Jindalee system but neither would they hold information back if they had it if we had to look at the extent they value human lives on ships at sea. (or aircraft for that matter – their national airline has an impeccable record). This extent has no boundaries. This extent also covers civilian life.

OTH or over the horizon radar has been with us for the last fifty or so years and like most early warning systems the Jindalee system was on the drawing board in the 70s and 80s. The key to Jindalee’s success is an extremely powerful  digital signal processing system. The drawbacks are, however, a typical OTH scenario – the inconsistent Ionosphere: night effect, poor weather, high seas and anything else which would either increase noise or reduce the backscatter (reflections). The JORN system (Jindalee Operational Radar Network), like all OTH, uses the Doppler effect to range and this also has a typical downside, it will not detect a target moving tangentially to the transmission. Looking at this we must realise that JORN therefore is not totally reliable under adverse conditions, neither in other frequency spectrums which may or may not be line of sight. Was the JORN even pointing in the right direction – the HF transmission focuses on the area, (called tiling), where it needs to capture the data from, not like the rotating antenna system which uses line of sight microwave energy. JORN electronically steers a transmission – operators scan a specific tile which covers a designated area and cannot scan multiple areas such as altitude as in sea and air simultaneously. Or at least that is what we have been informed. JORN, although quite capable of picking up vessels in the ocean thereby stopping illegal entry has been failing to do just that. So what’s up?

OTHR is not unlike conventional microwave radar which requires a sizable window area of metal to be reflected – wooden craft will just not be seen. The Jindalee system requires a vessel class such as the Armidale to return useful input. OTHR on the other hand will detect conventional stealth aircraft because of the frequencies used.

Long Range Radar – Worldwide Coverage

To have a system so powerful to cover the entire globe it would need hosting countries or partnerships to exist. This will never happen from a military aspect and from a civilian aspect, these systems are hugely expensive which cannot be justified only based on the loss without trace of one or two aircraft or ships over the last few years. So what solutions do we have?

Long Range Radar – Military Objective

We have absolutely no control over what the military can or cannot do, as seems the case now, so we need to focus on international law overseeing civilian craft. Don’t hold a foreign government responsible if your own laws are lax – with this in mind modern communication and transponder systems must be designed to communicate with or without satellite assistance. The inertial navigation system and HF transmissions seems like a likely choice and for many this may be the first step to moving forward. HF communication, through the radiation of a suppressed sideband still has only ‘x’ amount of useable channels. Using an OTH system one could still interrogate the vessel or aircraft but again the installation would be manned by the military.

With MH370 missing the news media has been complaining about the fact that a cell phone location be obtained easily, why not the aircraft. Fact is that this means of recovery is based on triangulating microwave energy from three towers to detect location – this cannot be used on an aircraft.

Without all countries complying to an internationally agreed upon system for radio detection and ranging the Jindalee project is probably the best and only choice we do have for long range detection. Read more on the vulnerability of Aussie radar here.

The facts speak for themselves, OTH was not primarily designed for civilian aircraft search and rescue just as the satellite system we have is not designed for monitoring the movement of every civilian aircraft in the sky or on the ground. Sure enough, even technology from the 1950s and 1960s was sophisticated enough to detect targets through OTHR techniques, 21st century computer data processing just made it more powerful in the receiving end, which after all is the fundamental weakness of OTH. (actually all radar – both uWave and HF receivers are extremely complex devices).

From the first early warning devices in Alaska to the Russian Duga-3 OTH of the 80s, long range radar using Doppler shift has become strategically important in military defence. For all it’s sophistication, it is still a military installation and is used exactly for that purpose – defence. Not search and rescue.

Long Range Radar – in Conclusion

Although, for the average Joe a lot of what military radar can and cannot do is speculative, one thing is certain – they can detect aircraft from a long range off and based on design and usage, do not need to be manned.  The long range radar needs to be designed for a specific purpose – tiling and signature recording is nothing new, neither phase array systems. Not releasing what may be deemed as classified information is also not new – the mystery of missing flight MH370 has opened up a can of worms which for the naive lest be left alone. Unless there is a convention we are not certain about, all countries are fiercely protective over their defence installations.

 

 

 

 

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