GPS racechrono

I've used one of these and they are not bad. Sometimes the GPS can drop out nullifying your time. But having said that, a very cool little add on for a mobile phone.

Just gave the racechrono a test in our Astra SRi, works well and also has a tracker that maps out a track after the first lap pretty cool stuff!

I've had it for a little while and only used it on the odd occasion. They state on the website that it can be up to .5seconds off when going from a standing start, makes it only really good for lap times and 80-120.

gps only updates a few times per second, and is only accurate to within like 5 - 10 metres, how can this be accurate?

if you travel say 1/4 mile (400 meters for arguments sake) and the GPS is accurate to 10m assuming the internal clock is bang on then its accurate to 2.5% (10/400)*100=2.5% correct me if my maths is wrong.

mhale71 said:

gps only updates a few times per second, and is only accurate to within like 5 - 10 metres, how can this be accurate?

Click to expand...

I would imagine the software corrects anomalous readings by averaging acceleration between updates, and interpolates the exact time / speed / location between two measuring points when crossing the target parameter. The lack of precision of launches compared to lap times and 80-120km/h performance is also attributable to this method. *EDIT* Damn too slow response!

I do have N95, and though I really haven't used it yet, track mapping does look pretty average (I recorded my commute as a Special Stage..:angel and at least is well worth the cost Qstarz receiver would do better, it's supposed to have 5Hz update and are also much more accurate. Internal GPS is on the ballpark, though.

You are locked to around 8 satilites at a time so they are all working together to keep it up to date.

For what it is and what it costs its great!
I'm sure there is better units out there but for the aveage street tuner I does a great job