Best lap timing app?

[dcramer]

Interesting, how are you going to put it in the car so it can see the sky ?

[T.Dot_E30]

I have a windshield mount. I usually position it towards the top behind the rearview mirror on the passenger side.

[dcramer]

Ah, ok, so one of the things that I found important was the GPS sample rate.

Most of them do 1/second, which isn't quite enough for tracking a car. Does this GPS unit do more ?

The one I have does 10/second which is a little too much, 5/second is about right.

[kamus]

So far I've just been reading my lap times off my video footage at the end of the day. From your screenshot I'm liking the speed display and lap count (assuming those will be more accurate when coupled to your external gps).. is there anything else you use the app for? And.. I'm guessing the app works by running while your phone camera is filming? Is there a way it could work using footage from a dedicated camera?

Originally Posted by T.Dot_E30

I have a few videos up on youtube.

Harry's lap timer is cool because it does video overlay. At mosport GPS signal wasn't that great so speed readings are off. An external GPS receiver would improve the signal alot, im looking into it for next year.


http://www.youtube.com/user/tdottme#p/u/2/Py1f4Q8hwD4
There are more that i've uploaded under the same account.

[T.Dot_E30]

Originally Posted by dcramer

Ah, ok, so one of the things that I found important was the GPS sample rate.

Most of them do 1/second, which isn't quite enough for tracking a car. Does this GPS unit do more ?

The one I have does 10/second which is a little too much, 5/second is about right.

The Emprum UltiMate GPS add-on I bought has a 5hz update rate, wheras the iPhone internal gps is 1hz. The Ultimate also supports passing NMEA data to the app, which as I understand it makes the timing more accurate.

For more tech talk, read this: http://www.gps-laptimer-forum.de/vie...a957db271ce315

Originally Posted by kamus

So far I've just been reading my lap times off my video footage at the end of the day. From your screenshot I'm liking the speed display and lap count (assuming those will be more accurate when coupled to your external gps).. is there anything else you use the app for? And.. I'm guessing the app works by running while your phone camera is filming? Is there a way it could work using footage from a dedicated camera?

It is possible to use the app only for data acquisition. You can then output the data and overlay it onto another video. Not exactly sure how it is done, but it is possible. Probably not as easy as letting the app do it.

Another add on that you can buy is an OBDII doggle, which allows the app to overlay RMP, Trottle, Brake, Current Gear, etc.

Can't wait to try it out, there has been a update to the app with some new features.

[2bmw2]

Having a 5Hz or 10Hz NMEA update rate does not make the systems more accurate. What you really need is either a dead reckoning system using a gyro and accelerometer to extrapolate the points in between the one second samples, or you need to process the RAW binary data from the GPS and write your own algorithms to process the data for better resolution. (or use a combination of RAW data and additional sensors. That's how we do it on the GPS products I work on.

And there is absolutely no reason that the GPS signal at Mosport would be weaker than anywhere else. If you want to read about the sort of module I use, here's a link: http://www.u-blox.com/images/downloa...W-10018%29.pdf

Just a module like that is more then the price of those external receivers that plug into your phone.

Here is one solution for an external GPS/GSM antenna that mounts on the inside of your windshield http://search.digikey.com/scripts/Dk...893cs926574116