stevensa

While I was helping a friend with his time attack car this weekend I decided to go ahead and mount my Droid X in his car using the Trackmaster App. The sat reception at the track was only showing accurate to 20ft, which is less accurate than the normal 8ft accuracy it reports. The car is also equipped with an AIM GPS lap timer and the official event timing and scoring using the tracks transponder system.

To my surprise, even with the not so great 20ft accuracy the cell phone read consistently within ~3 hundredths of a second of the track and AIM system.

This was using the cell phone only mounted to the windshield, and NO external antenna. Not bad for a $9 app.

geerookie

That's what I use and love it. I also have a 10Hz Bluetooth GPS that I use (left over from another timer) and haven't found that it makes any improvement on timing but helps for mapping and G's.
I have had the same results with accuracy, about 3 - 4 hundredths.

2MCHPWR

i used aLapRecorderHD on my Droid HTC incredible. Its a FREE app
It was also about dead on versus my race-keeper in-car video/data system.

Here is the video it takes (no data overlays though) when I put it on my friends supercharged M coupe following my car with a $5 ebay windshield mount:

http://www.youtube.com/watch?v=OQCDIhVPhjs

ScaryFast

The GPS accuracy for lap times is not particularly important. Your phone GPS antenna reads within 20 ft of absolute postion on the globe, but it's much more accurate in relation to itself. In other words, it may be 20 ft north of actual GPS postion on the earth, but all points within a lap are therefore 20 ft to the north so your laptimes will be pretty accurate (as you demonstrated). It's still reading an x,y position at all times. Throw in a lot of z (elevation), however, and you might not get an accurate distance or laptimes

For our vehicle testing, we use dual antennas (mounted a set distance apart along the x axis of the car), accurate to 10 cm. Among other things, this level of accuracy allows the measurement of actual vehicle rotation (to compare against a yaw sensor, for example). Of course these sensors can cost from $8k to $50k!

Mister_OT

OK...this might be a dumb question... but my Droid has the camera in the back of the phone. If I use the car mount, it blocks the video. How did you mount it so it can record videos at the same time? Which mount do you use?
Thanks,

Bills Z06

Anybody know of an app for Blackberry?

2MCHPWR

http://www.ebay.com/itm/180718823866...84.m1439.l2649

stevensa

Not sure which Droid you have, but this is the one I use for my Droid X

http://www.google.com/products/catal...d=0CIgBEPICMAA

GO_BLUE_VETTES

Yes! Blackberry please!

Or something that works on iOS?

Scooter70

I've seen iPeople use Harry's Lap Timer. It even does video overlay right in the app. (I wish Trackmaster would add that functionality.)

http://gps-laptimer.de/Home.html