anyone used one of these? just wondering how easy and effective it would be.

 

http://www.qstarz.com/Products/GPS%20Products/BT-Q1000EXQR-F.htm

You may have problems with accuracy, GPS's are not too accurate sometimes

You may have problems with accuracy, GPS's are not too accurate sometimes

 

There's GPS and there's GPS. I have a QStarz 818XT and it's pretty impressive on 10hz.

 

This is the data from the GPS: http://i.imgur.com/a2Jwt.jpg

 

The gaps in the data down the straight isn't related to the GPS unit (software problems, driver perhaps) but you can see that it traces your line through the corner. I'm not interested in the data logging so much as more accurate lap time data.

thanks we just want it for lap time data too. So you get a google map of the track and somehow lay the data over the top? do the different colours (red/green) indicate a different lap and what if you do 10 laps how do you pick the different laps?

I'm not using that particular software anymore but IIRC the sessions are split into folders with individual laps as sub folders of each session within Google Earth. The export was just a KML file (and a few other formats if you wanted to do your own analysis).

 

Some of the software have preset layouts of the track with the start/finish line traced in already. Others you have to configure yourself but it's not terribly difficult depending on what software you're using.

 

That mapping is a single lap, was just a demonstration of the erratic data logging from this particular software. I think the red is supposed to represent braking but because this software was calculating speed internally coupled with erratic data feed problems resulted in some strange speed recordings. The 818XT has its own speed reading output but the software wasn't utilising it at the time.

If you have an android phone you could try -

Torque Pro - Does use a OBD2 connection for the data, but it also uses the gps and g-sensor in the phone.

and then download

Track Recorder - Its the Torque pro plug-in. If you have the phone setup on the windscreen you'll be able to video record the lap with an overlay of the google map and any gauges you have up on the screen.

 

There's GPS and there's GPS.

So very true on that, my garmin phone gets to about 1 - 2m accuracy, the girlfriends lg phone gets something like a 5m accuracy and the farther-inlaws gps hunk of junk can only get about 10m accuracy on a good day. The only good things about it is that its a big screen, takes a memory card, has bluetooth and it runs windows ce so i'm half tempted to nick it and see if i can get android on it.

Haven't seen it race car logging scenarios, but I know some GPS systems for surveying and positioning work use two aerials. A base aerial set up somewhere near the track and then an aerial mounted on the moving object. Knowing that one aerial is fixed and not moving, you can account for the error seen on the moving aerial. This is meant to be a lot more accurate, otherwise GPS is only 5m as a general rule, if you get any better than that, consider yourself lucky, it's not something they'll guarantee.