A project called RaceChrono – GPS lap timer
It all began as my idea of a mobile phone based lap timing software. Using GPS is nothing new in the lap timing business, but what made the idea exciting to many, was the possibility to use a commonly available smart phone together with a cheap Bluetooth GPS instead of expensive purpose made hardware. I made a proof-of-concept in a few weeks, which inspired a few other Carfreaks and quite soon RaceChrono was born.
About a month ago, after several hundreds of hours of work, extensive testing and many laps driven, we finally felt that our project was ready enough to go public.
The main feature is of course the Live Timer, which shows your lap- and sector-times in real-time. Also included are a scalable graphical display of traveled path, satellite reception display, speedometer and a compass:
When you’re back at the pits, you can also browse through your lap and sector times, or view your trap speeds:
Or maybe analyze your laps by graphs of time, speed and altitude compared to any another lap:
All lap timing sessions are logged, and the results can be viewed afterwards. The raw NMEA-output from the GPS is also saved, so you can use that in other compatible software if you wish.
And yes, there’s always the question of accuracy when it comes to timing anything. After extensive testing, we feel really confident on RaceChrono’s accuracy. Our tests together with commercial lap timers have showed an accuracy of between +- 0.03-0.10 seconds with a cheap 5 Hz receiver. Switching to an ordinary 1 Hz SirfStar3 receiver RaceChrono was still very accurate – on the level of +- 0.10-0.15 seconds. Keep in mind however that accuracy is fully dependent on the quality of your GPS receiver and signal reception. There is also an experimental performance testing feature in RaceChrono, but at the moment we would not rely too much on the individual results it gives.
Note that if the signal from the satellites is too weak, your lap times can be inaccurate and in worst case you can even miss some laps. So take care to position your receiver properly on your dash close to the windshield, or maybe even outside the car! Use the satellite reception display to help you find the best location in your car.
Currently supported phones are almost all Series 60 smart phones (specifically Series 60 2nd edition and 3rd edition). This means that tens of Nokia smart phone models are supported, and some LG and Samsung models as well. Nearly all Bluetooth GPS models are supported, but we recommend either a 5 Hz MTK chipset based or a common 1 Hz SirfStar3 based receiver.
I guess that’s all for now. Please visit the project web site at www.racechrono.com!