High speed travelling

[+apersson850]

Yesterday, something weird occured to me.

Although my Vista was located inside a window, in the same building

all the time here in south Sweden, it suddenly started a journey of

its own. I happened to have it connected to MapSource in logging mode

at the moment, so I could follow the flight on the PC screen.

 

First, it began in the Atlantic outside Norway. Then it made a 570 km

trip in over Norway, passed Oslo and almost reached the Swedish

border before that trip was finished. The speed was reasonable for

todays passenger aircrafts. The speed varied between 830 and 380

km/h. Except for the first part of the journey, when it logged a

speed of 55176 km/h. The altitude was all the time at about 153

meters, which means that, considering the topography of Norway, it

was probably more tunneling than flying, at least when it came in

over the coastline.

 

It should be said that there were very few satellites that could be

received at this particular moment, since most of those available

were obscured by the building. At this moment I got a message from

MapSource that it was transmitting in NMEA mode (which it was) and

that the map datum was unknown, which could cause errors in the

positioning. I checked the datum in the Vista. It was still WGS 84. I

also switched mode to Garmin format, but that didn't change anything.

Then I put the unit outside the window, to make it possible to get

better signals. It did then start receiving Egnos signals, and after

a while MapSource reported that it had a 2D differential position.

Still traversing Norway at high speed, though.

 

Then it lost navigation. But after a while it re-appeared over

Scotland, making a 270 km dash towards Germany, like a de Havilland

Mosquito of WW2 vintage. About the right speed too, 520 km/h. Except

the first part of that journey, when it completed 233 km in six (6!)

seconds, equivalent to 140057 km/h!

 

After that, it once again lost navigation. After a while, it

reappeared over south Sweden, although not where it ought to be. But

suddenly it was longing for home, and moved to the correct position

at 3552 km/h.

 

Notice that I did nothing to correct the unit, i.e. didn't turn it

off or so. It came back to its senses by itself, and has worked

normally since then. No problem before this occured either.

 

Previously, I have seen occasional glitches in the position

calculation, which may be indicated by a ridicoulus top speed stored

in the unit, but this is the first time that I've been able to sit

and watch the whole episode on a connected PC. This was definitely

not a temporary glitch. Since I have it all recorded, I can see that

it started at 15:08:36 and ended at 16:20:31. A total of one hour and

twelve minutes, that is.

 

The final conclusion is of course: "Don't trust your GPS blindly".

All the time during this voyage, the unit reported normal EPE values,

like 20 meters or so. That's quite ordinary, considering the effect

of the building blocking most of the satellites.

Had it not been so obviously wrong, I may not have noticed at all.

 

I've also posted this text to the Vista group at Yahoo.

 

Anders

[Vacman]

Moulder and Scully are on their way to check it out. Everyone, please go back your homes and offices and do NOT look up into the sky. I repeat, do NOT look up into the sky.

 

If you ever catch on fire, try to avoid looking in a mirror, because I bet that will really throw you into a panic.

[+pizzachef]

Hehehehe....

Garmins

 

Actually I'm a little jealous...I wish mine would do something cool like that once in a while. Knowing EXACTLY where I am is getting kinda boring.

 

-pizzachef

[+GOT GPS?]

Couple things:

 

Up there in Sweden the GPS needs to be in a South facing window.

 

Also I wonder about WAAS there in Europe.

 

It could be other things like This that or the other thing, but one thing, is he pulling our legs?

[+apersson850]

The only one pulling legs here is my Vista, I can assure you.

 

I do have the track log saved as evidence, if anyone would like to have a look. A track can be faked, I know that, but that's as good as it gets.

 

I agree that a window facing south is the best window to use here. Unfortunately that requires, in this particular case, to turn the building around about 90º. Since it's a rather big building, I'll skip that idea. Besides, at this particular moment a window facing east would have been even better, but that means turning the building around a full 180º, sooo...

 

Most of the time the Vista couldn't see any Egnos satellite at all. It wasn't until I placed it just outside the window when it got hold of #33. But even with a postition reported as 2D differential, it was still on this wild trip.

 

Still, if it can't get enought satellites to tell where it is, that's no excuse for the GPS making it all up, is it?

 

Now I wasn't harmed by this thing, but one could perhaps be if it would have been a small error. Otherwise, I'm mostly sorry for not being able to join the Vista on this trip!

 

Anders

[leifnel]

I have logged "fantasy trips", while my eMap was mounted in the car in the parking lot. Several days it went from Copenhagen to Sweden and Norway. Unfortunately, it is now on a real trip; somebody broke into the car and stole it.

 

Two weeks ago, I drove a couple of Km's 800meters below ground level...

 

Leif

[+nincehelser]

My Vista did something like that a couple weeks ago, but it wasn't nearly as long in duration as yours.

 

I was driving, and the Vista was in the map view. All of a sudden it was showing I was moving backward at a pretty good clip...much faster than I was moving forward. After about a minute it was about a mile off-track, but then it corrected itself.

 

I'm guessing there's a bug in the software. (I'm running the latest)

 

George

[+Bloencustoms]

I wonder if you had a GPS guided weapon, and instead of steering the weapon by having it goto a position, you could steer it by telling it to remain at a position, then change the prc from the sattelite to make it think it's moving.

 

"Searching with my good eye closed"

[briancm]

I've seen something similar on my walks with my Garmin Geko. When I put it in my pocket and walk briskly, the unit will on occasion record me as making wild jumps about the place, like a deranged kangaroo. These jumps occur in situations where the signal is obstructed by buildings or heavy foliage.

 

I think the problem is that the GPS is getting very marginal signals, trying to make sense of them, and then producing coordinates with no sense of the limits of physics. Maybe the programmers were watching Star Trek when they wrote the code....

[+jtice]

My Vista makes crazy tracks also, if i am hiking and not holding it out in front of me. Most all the track is fine,,, but all of a sudden it will have a line on the track that shoots off in a straight line somewhere,, then back to where im actually at. It must make a track mark that is from its messed up signals, and then regain signal. Its driving me nuts,,, BUT,, ive never had it do anything like that while riding my bike, or in the car.

[+Brian - Team A.I.]

My Vista currently shows me as having achieved a top speed of 220mph, courtesy of my 4-cylinder 4x2 Nissan pickup.

 

However, prior to the upgrade to v3.10, I had achieved an astounding 494mph on land.

 

Brian

Team A.I.

[freeside]

I have observed on several occasions the Vista will lock on to six or seven satellites, with strong signal, and then say "Weak GPS signal", as though it had no sats at all. For a while I thought maybe it could be due to a pathological satellite configuration, where the birds are too close together to be really useful; but the last time this happened they were quite spread out. Each outage lasts for about fifteen seconds. The last time this happened the Rinos were able to tell location just fine. Has anybody else seen this problem? I do not recall it happening before the upgrade to 3.10.

[+mcdefjef]

I didn't know aliens knew how to make Alien GPS Drawings.

[+Renegade Knight]

A bad signal with "correct" differential information would cause that. So your GPS goes on a trip but so far as it can calculate it's only 20' off.

 

I've never seen it happen though, that would be cool.

 

Maybe your vista was practicating astral projection.

 

=====================

Wherever you go there you are.

[BeDoggy]

I noticed wierd stuff with my new geko, too. Several times now it has shown a top speed as though I were travelling at supersonic speeds. As well, the directional arrow seems to "freeze" if I change direction. It will point behind me, but as I advance the distance to the waypoint will decrease. Weird. But I guess these posts are evidence that the the more expensive units do stuff like this too. Glad I didn't spend TOO much on my GPSr.