onefastviking

I do now, I did see you on Saturday tho, didn't I ?

V

Texas RS

Yes, I was there yesterday. You were busy on Stein's car when I came by.

onefastviking

Cool, I had to make sure I wasn't imagining things.
Yep, still sorting out a few things on his "Pumpkin" new car, it's a nice car tho and once sorted all out it should be fast. I believe he qualified 16th out of 40 or so in SPB, it was his third lap in the car and his first ever PCA CR event, so pretty damn good in my opinion.

mglobe

Michael is a very good driver. Congrats to both of you.

onefastviking

Thanks, from myself and Michael.
It sure was nice to be back at the track !

Texas RS

Viking,

It was good to see you back. Stay away from those eight legged creepy crawlers!

mglobe

I've been looking into this some. I'm finding from session to session my AIM data is relatively consistent, but it is off from Google Earth coordinates, while the Vbox data is correct. I don't see a whole lot of issues with the AIM data within the files, just relative to Vbox and GE. After some experimentation, I've found that if you subtract .0001 degrees from the Longitude, the data matches up pretty damn accurately. Seems like some sort of firmware issue, but that's a SWAG.

Matt Romanowski

Interesting. I can't find the excerpt, but Roger had a section on GPS where he overlays the AiM data on Google Earth maps from various years and you can see where the GE data changes from year to year. Very interesting about the longitude looking like it's shifted.

ProCoach

Anyone who has compared Traqmate at the same track from year to year has seen that shift/drift.

MoTeC has some interesting information about refining the accuracy of their RaceGrade GPS module information that I have found useful. That configurability is not offered in TM, AiM or VVB.

I think same day/session line comparison can be useful, but have found timing coordinates comparable across wide stretches of time.

mglobe

I've got data from tow SOLOs on the same day, and an Evo4 from several weeks earlier, and they all show the same longitude "error" relative to GE and Vbox. It's not gps drift I don't think given that it persists. Once you shift the data .0001 drug to the west, it looks fine.

tabasco

Mike,

If the shift is constant, it sounds more like a GPS datum problem.
The AIM might be giving positions on a different grid.

Check if there's anything in the preferences of the AIM software to change the datum.
Google maps uses WGS84.

-Guillaume

mglobe

Good point. I'll look into it.

Texas RS

Mike,

The data you sent me also seems to have a bias to the north as well.

T

mglobe

You are correct. It actually appears to be of about the same magnitude. I will have to look at my other data to see if that is the case there as well.

ShakeNBake

I had lots of trouble with my AIM Solo DL at COTA recognizing start/finish on the smartycam, and when I looked at the GPS data it was off by hundreds of feet. Lots of 20min laps

TexasRS printed out some nice 11x17 laminated COTA maps with reference lines from his VBOX on them - turned out perfect. Great teaching tool.

I'm not sure if people know this but Racelogic (company behind the Video VBOX) makes some of the world most accurate GPS data acquisition devices for automotive engineers. Here's an excerpt of a description of the GPS tech in the Video VBOX:

"Velocity and heading data are calculated from Doppler Shift in the GPS carrier signal, providing users with unparalleled accuracy. For example, over 10 tests between two light barriers placed exactly 1000m apart, the VBOX will report a distance within ±2-3cm, on every test, and the average comes out to within less than 1cm. Impressive for a device using satellites 18,000kms away!".

For the first time I have been able to compare lines via overlays. Could never do this with AIM, Traqmate, or G2X.