View Full Version : Tasmanian multilateration

Dick Smith
24th Jul 2007, 03:44
What has happened in relation to the Airservices project to install multilateration outlets on mountain tops in Tasmania? This sounds like a pretty good system to me. It works with standard transponders, is highly accurate and not expensive. I would imagine it would be a better way to go in the short term whilst we wait for the world to sort out which ADS-B system is going to be accepted generally.

I would have thought that it would be a big saving for Airservices to replace the enroute secondary radars between Melbourne and Cairns with a multilateration system as per Tasmania.

I am looking for comments on this, and advice as to when the Tasmanian system will be up and going if it is not already going.

By the way, Ive been away driving from Moscow to Kazakhstan. On the 4,400km drive I did not see one general aviation aircraft at all. The only aircraft we saw were a couple of airliners leaving Moscow, and a couple of airliners landing at Almaty. Im sure things will change soon. There are many BMWs, Bentleys and Rolls Royces on the roads. The most popular new 4WD is a Lexus. I would imagine they will start moving their money into general aviation soon. Lets hope Australia does all the training.

Islander Jock
24th Jul 2007, 03:51
apologies for thread drift Driving in Kazakhstan:ooh::ooh:. You didn't have to drive during the local cops off pay weeks did you and get pulled over for the mandatory RTT? (Random Traffic Ticket). You're right about no GA. THe closest thing I saw when I was in Atyrau was a couple of old AN-2s. Gotta admit, it would be an amazing country to fly around.

24th Jul 2007, 05:30
... data assessment starts (hopefully) January, commissioning mooted July.
All subject to change of course!
Now I answered your question, how about answering/posting the stuff you send to the Task force on the other thread.
I will place a post in that thread to bring it back to the top of the page so you can find it easily :suspect:

man on the ground
24th Jul 2007, 11:54
And your real question, Dick, is.....?

24th Jul 2007, 12:04
The real question is:

Why did you shut down our Flight Service Units, Dick?

And why do we now listen to Joe Lighty taxiing in his 140 at West WupWup when we're flying at FL350?

My apologies, two questions.

Capn Bloggs
24th Jul 2007, 13:29
whilst we wait for the world to sort out which ADS-B system
According to the latest Flight, Europe HAS decided.

24th Jul 2007, 13:34
ScottyDoo, don't waste your breath.
Dick has much more important stuff to worry about like " how do we make airspace more difficult for jets around primary aerodromes "

24th Jul 2007, 14:30
Bloggs, me old, last I read in the last several weeks, the 1090 MHz technology was the way, p'raps we should all club together and buy Dick a subscription to AW & ST, Flight and a few others aviation journals so that he can stay in touch. There was even a lead article just recently starring Airservices and their ADSB intentions. It is clear that the international aviation community have a great deal of respect for Airsevices and their level of technical skills and professionalism, given the many references to them and their leadership.

But heck what would those evil, bonus crunching, union trog Airservices people know.:{

AND I cant put my finger on the article just now coz I lent the particular AW & ST to a colleague but a long serving Airservices chap was recently awarded a most prized gong for meritorious services to ICAO and if I recall correctly his involvement in the the development of the FANS technology.

Australia punches waaay above its weight in these forums.:ok: which is not surprising given our unique and very challenging aviation environment in one of the most isolated communities in the world.

Found this in one of my folders, it's a bit old but still very interesting and informative nonetheless.

24th Jul 2007, 23:21
Isn't Kazakhstan the number 1 exporter of Potassium?

I remember hearing that somwhere.

24th Jul 2007, 23:52
Dick is visiting his half brother Borat to give him some electronics.
And a Lexus Nano, with caravan.

Dick Smith
25th Jul 2007, 00:32
The thread is actually about Tasmanian multilateration. Hopefully we will be able to get back onto that track.

ScottyDoo, I thought the Flight Service units (especially the remote ones at places like Cooma, Coffs Harbour, Charleville and Longreach) were fantastic. It just so happened that the cost a fortune and the user was being forced to pay by the Government. Since the closure, over $1 billion has been saved by the industry, with no measurable affect on safety.

Imagine if that extra $1 billion had been charged by Airservices no doubt general aviation and the small commuter operators would be in an even worse condition.

In relation to the ADS-B system, it is pretty obvious that is hasnt been worked out. For example, Sweden has gone to a different system to the rest of Europe, and the United States still states that it will go ahead with a dual system (i.e. ADS-B Mode S squitter and Universal Access Transceiver UAT).

Many agree that we would want to be very careful in making a decision on this in too hasty a way, only to find out that the United States goes in a different direction, and the inevitable inexpensive Garmin/Honeywell units are not useable in Australia. The fantastic satellite based weather service that is available in the USA, which appears in real time (or within a few minutes) on the Garmin hand-helds, will never be useable in Australia because we have allocated the satellite frequency for another use. This means a $29 satellite receiver could cost thousands of dollars here.

Remember years ago we allocated a television channel (I think it was Channel 5A) to the international FM radio band. Fortunately, commonsense prevailed and this was changed. A similar situation existed with the AWA DME. In the end I paid a small fortune to remove the Van X DME from my Citation and put in an International DME.

Some may believe that 1090 MHz technology is the way to go. This would seem logical to me, but as stated above, at the present time the FAA has a different mindset. It will be interesting to see when and if they change.

Dick Smith
25th Jul 2007, 03:20
Getting back to the subject of the thread again, does anyone know if Airservices has considered using multilateration in place of the secondary surveillance radar between Melbourne and Cairns? Surely this would be a better way to go as they will not have to spend $100 million in funding ADS-B for GA aircraft.

I look forward to any comments.

25th Jul 2007, 07:17
Multilateration still requires precisly surveyed sites and I would believe a lot more stations to get coverage where an ADS-B groundstation with ADS-B equipped aircraft may only require one sited at a major regional airport in leu of the promised radar sites. To get coverage within the J curve I would be very very surprised if costs less than the equivalent in ADS-B stations. Total coverage would be way north of $100mill.

Do you honestly believe that over a billion dollars has been saved by shutting down the FSUs? No creative accounting allowed. Cost of staff and upkeep of facilities please! No adding values of infrastructure or real estate or charging of commercial rents and dividends to the shareholder allowed.

As for getting realtime wx for your nav system. I have been trying out a program on my GPS equipped PDA/Phone "POCKETFMS" I can download realtime radar from BOM that has aged no older than 15minutes and METAR?TAF whenever I am in 3G coverage from the ground and air. Seems to work OK so far.

We have no chance of getting satellite . However,as qouted a long while ago on this site, 3G network is expanding all the time. Maybe we will have to consider a use of that network for data uplink. Cost of a dedicated geostationary satellite purely for aviation use( even the yanks couldn't prove this case as economical for their uses and piggybacked on satellite radio network) vs a broadband connection from a 3G simcard

25th Jul 2007, 13:36
Re-multilateration as of 26/04/07-

RAPAC Report 26/04/07 (http://www.airservicesaustralia.com/customer/rapac/rapactas070426.pdf)

Go to the first subject of discussion. Still going with ADS-B. 19 sites all up.

The impression I got from other ASTRA sites was that multilateration was to be situated around regional and major airports as a fall back position for ADS-B. Multilateration will also work with a transponder response signal.

If 19 sites are required to cover TAS, how many sites will be required to get SSR like coverage for the J-curve?

26th Jul 2007, 00:25
Many agree that we would want to be very careful in making a decision on this in too hasty a way, only to find out that the United States goes in a different direction, Well that puts the complete kibosh on the Multilateration Dick. Each of the 18 WAAM sites is also a non-septic approved squitting ADS/B site. Why are you griping at Airservices for not delivering yet what you have already deemed inferior? Had you forgotten that all Tasmanian Terrorists will be able to track ADS/B equipped flights with their $2 scanner & a PC?

A better question would be if it will be commissioned, or even under trial before the LT radar is taken away...
Getting back to the subject of the thread again... Gee, sorry, you brought up Borat...

does anyone know if Airservices has considered using multilateration in place of the secondary surveillance radarErm, I think you claimed to have put a stop to this...

Dick Smith
27th Jul 2007, 00:21
JumpuFOKKERjump, the experts tell me that it is really easy to spoof a false position with ADS-B simply squit a false GPS position. In relation to multilateration, the experts tell me that it is a lot more difficult. This is because you really need the transmitter to be in the location that it is for it to give a position using multilateration. It works by timing and actually measures the distance from 3 or more stations.

The latest rumour is that the FAA is looking at a combined multilateration ADS-B system to reduce the chance of spoofing.

No, Im not griping about Airservices not delivering. Im simply asking when the Tasmanian system will be up and going.

In Tasmania a person with an ADS-B type receiver will not be able to detect the position of aircraft using Mode C and multilateration.

27th Jul 2007, 02:14
My experts tell me that whilst spoofing is always a possibility, with a low probability, there are sufficient defences within the system to render it a negligible risk, certainly below any other flight risks. At least, I understand, lower than Manpads.
Of course any defence can be defeated given a sufficiently sophisticated attack, to deal with that in any rational form, you get into high level encryption of everything radiating. And so it goes.(Hunter S Thompson)

Can anybody show me how Ockhams razor works here.

27th Jul 2007, 08:51

If the security concerns that you have in relation to 1090's are related to shoulder-launched, Ground-to-Air missiles then it might be worth spending a day with our beloved plane-spotters. You don't need an ADS-B receiver to achieve that particular aim... you just need the missile.

27th Jul 2007, 08:58
the experts tell me that it is really easy to spoof a false position with ADS-B simply squit a false GPS position.Then your "experts" don't know :mad:

You seem to surround youself with such "experts". Why?

28th Jul 2007, 07:16
Mr Smith, as a sceptic, prove it by demonstration. Or pack up your bags and go water devining! No demonstration on spoofing of an ADS-B signal has yet taken place anywhere in the world.

I know of a number of occasions where someone has spoofed the transmissions of ATC using handheld radios causing a lot of obvious problems, requiring an ATIS message to warn all users to change frequency and disregard transmissions on published frequency. Yet, there is no ban on handheld devices.

Come clean, Mr Smith. Why are you so against 1090ES ADS-B?

28th Jul 2007, 23:51
the experts tell me that it is really easy to spoof a false position with ADS-B If this is true, then the Multilateration sites, which are all ADS/B sites, can be spoofed, putting an ADS/B track on our screen. All sounds like bollocks to me.

29th Jul 2007, 09:24
Come clean, Mr Smith. Why are you so against 1090ES ADS-B?

I would have thought that much would be obvious. Whether it relates to surveillance technology or navigation technology (GRAS vs WAAS/SBAS), Dick is simply trying to minimise the cost to the GA/VFR user of those services.

I make no observation as to whether that is a good or bad thing other than to say that the wider industry may miss out on some significant safety or economic benefits for the sake of reducing the installation costs for the GA/VFR fleet.


My experts tell me that Multilat could prove to be a horrendously expensive piece of surveillance infrastructure relative to ADS-B.

But my guess is that you don't really care about that to the extent that VFR traffic does not pay the enroute charges that finances the investment in ground infrastructure.

As long as all you need to access multilateration is a transponder and don't have to pay for the extra ground equipment you don't really care do you?

29th Jul 2007, 10:14
By the way, Ive been away driving from Moscow to Kazakhstan.

Sorry Dick, couldn't help meself....


p.s why would anyone intentionally "spoof" a false position?

29th Jul 2007, 10:54

prolly just trying to claw back some ground from the really dumb "pay your own way have your own say" mantra he and his cohort stiffed GA with.

I see the US Reps have sent or are sending the FAA "user pays" bill to the dustbin of history. At least their GA reps represent, well GA not just the terry towellers.:ok:

30th Jul 2007, 00:40
My experts tell me that Multilat could prove to be a horrendously expensive piece of surveillance infrastructure relative to ADS-B. Your experts are no smarter than Dick's then. 18 sites for the MLAT in Tassie will give RADAR coverage better than half a dozen ADS/B sites, and put a return on ATC screens from a common or garden type Mode C transponder- equivalent to 2 SSR installations. It will also give precision monitoring of aircraft on the ground at LT (probly) and HB, using about 6 of the MLAT sites to do it.

All at a fraction of the cost of installation and a minute fraction of the cost of maintenance of a SSR. And only three times the ground cost of the 6 ADS/B sites I mentioned for much more capability. While it will not prevent ATC having Dick spoof on their screens (however unlikely that is) it would provide a cross check.

I believe another MLAT is now planned for Sydney to replace the PRM!

Going Boeing
31st Aug 2007, 21:19
(Reston, VA., August 30, 2007) -- Era has been awarded a patent covering fundamental attributes of network-centric management of surveillance system-wide information, including distributed timing and surveillance data bandwidth management. The patent includes methods of ADS-B tracking and multilateration, where aircraft transponder signals are received over local, regional and wide-area networks using a number of receivers designed to filter redundant transponder signals, time-stamp filtered signals and forward surveillance information to air traffic control and other users.

Conventional triangulation techniques on an aircraft's transponder signal have required decoding real-time transponder replies at several locations, time-stamping them and sending them to a central location for processing. Because each sensor has to time-stamp individual transponder signals, a relatively high bandwidth communications medium was required between each remote sensor and the central server. This is generally viewed as a barrier to large-scale implementation of wide area surveillance networks, especially in more remote regions where there may be limited communications infrastructure.

Era's patented techniques alleviate this problem, allowing users to manage massive amounts of real-time aircraft transponder information and use a variety of existing datalink and network implementations with various bandwidth constraints. Furthermore, the technique accommodates both passive and active surveillance systems for air traffic control, military, homeland security and commercial airport applications.

Era's solutions include hardware, software and systems for correlating flight identification data with aircraft registration numbers, including correlation of flight identification data from aircraft communications with the data from Mode S and ADS-B transponder transmissions. For some applications, this creates the same data as an air traffic controller would see, without the need for any active interrogation or connection to any Air Traffic Control equipment.

"Once again, Era has introduced truly ground-breaking solutions to facilitate the practical and early implementation of proven innovative surveillance solutions that will provide all users with tangible benefits," said Dave Ellison, President and CEO of Era Corporation. "This new technology allows for a myriad of opportunities, ranging from improving air traffic control efficiency and homeland security applications to aircraft noise mitigation and will help better serve all of our customers."

Source : Era Corporation