GPS as lap timer

[JustenGT8]

I know there are some GPS lap timers available and software to turn your GPS capable phone into one but what about your average GPS?

I can access a work GPS that i know works well and i used to calibrate my speedo......anyone know of an equiv software package to RaceChrono that will enable me to run the GPS as a lap timer? either in real time (preferable) or as a downloadable log file i can play with on the PC?

[takai]

ChronoGPS (http://www.chronogps.com/) is what i use, and it makes a pretty damn good lap timer.

Much better if used with a 5hz GPS, but the 1hz i have for just navigation works ok too.
Does both live timing, plus logging, and has the ability to be connected to a WiiMote for G-sensor input.

Im currently running one off an EeePC, and mucking around with it for timing my route to work etc, works a charm.
Had a chance to chuck it in someone elses car a while back on the track and it worked beautifully, albeit i only had a 1hz GPS at the time, so it wasnt updating as fast as it could have.

Still waiting for WiiMote prices to drop a bit so i can pick up one of those.

[JustenGT8]

Pardon my lack of gizmo tech but this still needs a PC of some type?

I was hoping there's something out there you can load into your GPS

[takai]

Depends on what GPS you have. That one will run on a WindowsCE based device (although entering in the details can be a bit hard on the built in keyboard).

My one of these: http://www.dealextreme.com/details.dx/sku.8545 will run it fine.

[JustenGT8]

I believe it's a Garmen of some description, i'll go dig it out.

[takai]

Hm, it all depends on whether the GPS can run other programs at all, or whether its locked to the navigation program.

Might be a better idea to grab a 5hz GPS and an old PDA.

[JustenGT8]

It's all dollars at the end of the day. You can pick up a IR sensor style timer off ebay for sub $300 so at worst i'll grab one of those. It's a bit pointless just hitting the track with good rubber etc if the sessions aren't timed....i can have as much (if not more) fun on street rubber but it becomes more about hooning then than 'racing' ?

[takai]

Yeah, i know the feeling. The GPS style i think gives you a lot more information about where you are braking and where you could be braking more.

An EeePC currently goes for like $400, and a 5hz GPS for about $50-60. Thats cheap enough for me to go with that option, plus the EeePC is useful for more than just lap timing. When i get the race car back out on the track ill have the EeePC logging everything from the ECU, as well as the laptiming and g-sensor data, which will probably just leave me swimming in data.

[Bananaman]

For those who read this and are wondering what the software for your phone is, it is this:

http://www.racechrono.com/

I will be tryign it on the track day thats coming up. The track thats on the site for wakefield only has the single timing point though, if i can be bothered i might work out how to do my own.

[Bored?]

If you just had a gps that could do position logging (like a typical garmin handheld), you could download the data and postprocess it to figure out lap times. Probably not as useful as having it in real time though.

[MWP]

I cant see how a GPS is going to be accurate enough for lap timing.
In Aus you cant get any better than 4m accuracy. That along with GPS position lag will make for some rather random timing.

[Viper]

I've used a driftbox for abit.
They do fairly good job.
Found it has issues with continuous chained tight radius corners.
Otherwise its a nice bit of kit.
Software that comes with it also isnt too bad.
Costs about $300-$400 i think.

Just depends where you want to spend your money

[Bored?]

I cant see how a GPS is going to be accurate enough for lap timing.
In Aus you cant get any better than 4m accuracy. That along with GPS position lag will make for some rather random timing.

4m at 120kph = 0.12 seconds, but hopefully you're going faster than that over the start/finish line.

On top of that, GPS error is not temporally random, nearby samples have similar error, which makes it possible to get nice smooth interpolation of speed.

[skiddz]

I cant see how a GPS is going to be accurate enough for lap timing.
In Aus you cant get any better than 4m accuracy. That along with GPS position lag will make for some rather random timing.

4m you are talking about hand held correct?

cos when using gps to get co-ordinates for constrained centres (PSM's and OIP's etc) they have an accuracy better than +/-10mm

also you only really get positional lag when in an urban canyon( reflection and distortion of the signal) or with thick cloud as the cloud attenuates the signal.

[JustenGT8]

Yeah pretty well established that the GPS systems are good to within 0.2 secs of natsoft timing,, good enough for me.

Where did you find a Driftbox for $300, would take it at that price ?