Misled by online mapping or GPS?

"accurate to 100metres"
How old is your GPS willem? :-))

They have been accurate to under 10 metres for a long time now. I use the UBD street maps on Oziexplorer and they almost always have me on the correct side of the road! I use a Garmin GPS 11+ which is 6 years old.

I bet you wish you had one in the Suzuki in 1987!

Phil,
doesn't matter how old the GPS unit is. The yanks used to "intentionally", introduce an error to the network in order to put a stop to the civilian society (Terrorists), building a missile loaded with GPS navigation as a guidance system. By doing this no system would ever be accurate. The error was constantly changed so no GPS was ever very accurate. This particular project had a name but I cannot for the life of me think of it......it's Friday arvo and I've vaporised a few cordials. In Defence we developed DGPS which Triangulated a position and calculated a real position. Yes the error was that secret that defence did not know what the current programmed error was.

This error was removed....in the very late 90's I think which then introduced the ability for conventional GPS units to be much more accurate. Some advertise to within under 10 meters.

I know...I Project Manage the production of advanced weapons systems for Oz Defence and......other countries.

Toytruck

Interesting story that and have known about it for a long time. Funny thing is I am not sure the error was in the network I think it was programmed into the individual GPS. I know this sounds crazy because how do you licence all the GPS makers to program in the error all over the world. But the reason for me thinking this is because we were out bush and someone had an old machine which still produced the 100m error. This means it was getting correct info and then adding in the error internally. I would like to know more if anyone know better than this.

Hey Phil

LOL....4years of age...a Magellan 330

If you ever get to the Geo Centre of the Simpson you will find a 3-4 metre structure denoting the place. I found that my GPS was about 10 metres out of alignment with the structure according to the satellites.

About 20 metres away to the south there is another plaque stating NO!...THIS is the Geo Centre. Then a further 100 metres away another plaque stating THIS is the correct positioning for the Geo Centre......wait for it....some 20 metres to the west of that one yet another plaque.

Well, in the GeoCentre you can't go wrong as it is all flat earth(apart from a few bumps here and there....dunes) but imagine if you were driving along a steep mountain track in the mist, relying on your GPS...LOL

Cheers

ToyTruck,
hmmm I've had some SA red tonight too ( a nice Tatachilla cleanskin Shiraz), so I apologise if I'm a bit jovial.....Thanks for the info - I guess that means that GPS is only ever likely to be accurate when our US friends are no longer at war. :-))

Willem,
I'd love to go out there and help find your long lost Geographical Centre of the Simpson from 1987. Sounds like there's a heap more Centres out there now! I guess thats progress. But if this drought continues, the desert will be twice as big, the centre will move and you and Stephen L can go out there and redefine it again :-)))

Next issue will be global warming. With the icecaps melting, we have some great news - Lake Eyre will be full of water all the time - tourism will be booming - the Simpson Desert Resort Complex and Golf Course at Kallakoopah Creek will become the Gold Coast of the Centre. I guess they could then scrap the name "Lake Eyre" and rename it the "Great Inland Sea" - poor Charles Sturt would turn in his grave of he knew that he was 250 years ahead of his time.

I had better shut up now :-)))

Selective availability - or induced military error - was turned off in 2001 and spawned the birth of geocaching as a sport.

Even with only a 4 or 5 satellites you can reliably expect accuracy better than 15 metres if they are on a good spread.

The exception to the rule is deep in the valleys of the high country, the concrete canyons of the CBD or in other situations where you have a narrow spread of satellites directly overhead.

The 100m plus problem is a thing of the past.

Or geocaching wouldn't work. 27000 plus finds a week internationally is pretty compelling evidence.

www.geocaching.com

Dave

Allright I will rephrase what I meant to say.... lol

GPS are accurate up to 10 metres...dunno where the other 0 came from...typo?

Phil

Are you free mid July 07? Going out there again for the last time after the National Gathering. Hoping to do product test of suspension parts at the same time as well.

Yes the Red must be good as you are waxing lyrical...lol

Another red Willem?

It improves my pool game, might work on your typing...

:o)

Dave

Dave

To me RED=Gout....so no red for me...lol

Bundy and coke...Yes! or a VB or a good White or some Rocketfuel!!!

Ah, that's no good Willem. Gout's a bugger.

As for the Bundy, I'm with you there. Right now as a matter of fact. The cans of magic were on special for cod opening last weekend - and there's only a couple left.

Good weekend and lots of fish. Oh and cans...

Dave

F4Phantom,
I know this thread is getting pretty long but just in reply. I can guarantee that the error was in the network. This enabled the American Government to change the error on a regular basis to stop any unfriendly people working it out. There may have been an error programmed into individual units however I am unaware of this. If a terrorist had a unit that he or she (best be politically correct) wanted to use as a guidance system for a rocket of some kind and was able to work out the error that was programmed into the unit then you could allow for the error. By having it in the network no one ever knew what the error was and it was changed regularly.

Toytruck

Hey TTruck, what you say makes perfect sense and the idea that the error is in the unit itself is quite silly. But the problem is I dont know how to account for the fact that under 1 year ago (way after the error was taken away) we were in the bush with a pre-error correction unit, so basicly a very old one. It was hooked to a computer and maps. It was off around 100m all the time. Everyone just told me it was one of the old error units. never really made sense to me tho. The only think I can think of is if the map was raster and the unit was having trouble getting a good signal. Also the map calibration could have been off. but that would be on the basis that these guys calibrated their own map which I doubt.

re your second paragraph, probably correct Bilbo. In 91 a lot of units didn't have milspec GPS which could read the "P" code - the military encrypted signal which was accurate. The US and UK military went out and bought a whole pile of civilian GPS gear to outfit their ground units an turned off Selective Availability when needed.

Selective Availability was a satellite end fuzzing of the signal.

Cheers

Pete