Initial purchase

I have been tracking my cars for a couple of years now and this year I decided to take up Hill Climbs and sprints. I want to add some analysis of my activities so I decided to buy a GPS Lap Timer.

Budgets are tight so I have been looking at what is available and came across a product called Pit King GPS and is marketed by JJC and Demon Tweeks in the UK at £150 + VAT + Delivery. I subsequently found out this is an OEM product from Beijing China called Tutor GPS lap timer from a company called Sumomoto and can be purchased via Paypal for $180 inc delivery.

The product is a no nonsense GPS lap timer with all the software either provided or built into the firmware in the unit. It has a 10hz GPS resolution and produces a csv formatted file in a memory card. The basic data is Time stamp, Position XYZ, Speed and acceleration X,Y,Z.

The built in firmware needs to learn the track with a dummy run to define the Start/Stop point in the track. After that all the subsequent runs are referenced to that. The PC application depends on the previous adherence to the process.

Sprints and hill climbs are not always a loop. Forrestburn track of 1030m is no exception. I decided to take the Tutor GPS to a test/track night at Forrestburn to try it out. I did not analyse the data while at the track night but merely downloaded it when I got home. With  a lap top and some knowledge of the file that Tutor GPS hardware produces it is possible to extract the data you want.

As predicted the Tutor hardware display was very little use to analyse the data on track but importing the data to Open Office reveals some hidden treasure. I cannot see at this point doing this at the track side esp in the rain.

The key to using Tutor GPS hardware on a sprint is to Cycle the power every time as this is the only way I have found to reset it for my purposes. Then press the up/down buttons simultaneously such that the top left lap display reads 00.Then as you are about to set off for a timed run press Start/Stop once, the timer should start to display duration numbers. At the end of the run press Start/Stop again. At this point press up/down buttons simultaneously to save the file.

Here is the initial results.

Forrestburn by GPS

Distance vs time

Speed vs time

The above inconsistency is brought about by a poor decision by me to place the ariel away from any metalwork of the car.

References

Sumomoto: http://www.sumomoto.com/GPSLapTimers/index.html

Demo Tweeks: http://www.demon-tweeks.co.uk/karting/lap-timers/pitking-products-gps-lap-timer

Forrestburn track: http://www.mscc.org.uk/forrestburn/track-layout