lap time error

[terryo]

i am using ECU manager 3.5.4.2 to extract data and i2 standard (latest update) to try to analyse stored data from my M800. i have an on-board GPS receiver

when i review the generated data, the lap times are always a few seconds at variance from the official timing for the event.

i have no idea how to investigate this

any hints or tips would be appreciated

thanks, Terry

[David Ferguson]

How are you generating the lap times? Using I2 Standard Tools->Lap Generator?

Can you post a logged data file (the .ld), that demonstrates the issue?

[terryo]

yes, i ask it to generate laps, then times are shown . i can enter the lap length

i'll try to work out how to extract/post a file

you wont be able to see the difference with official times. the track uses "mylaps" system

[David Ferguson]

OK, there is the problem. Often the lap length used is not the actual distance you traveled in a lap. When inserting laps, what I do is using a graph with the speed channel, find the main straight where the start/finish would be located. Determine the approximate speed when you cross the start/finish line (in my cars this is typically about 100 mph (160 kph). Insert a beacon at this point. Note the distance for this point -- now go forward to the next lap (same shape on the speed trace), and put the cursor at the same speed. First, note the distance, and subtract the first distance to find a typical lap length (I prefer to set the distance channel to either feet or meters for accuracy). You can now insert a second beacon.

With the lap distance determined, (and at one good reference beacon set) you can now use Generate laps, and I think the results should be much better.

Hope that explanation helps, if not, I can prepare a short video showing you this in action.

[terryo]

that makes sense , but i still need to try what you suggest. thanks again

i thought Motec software had in-built co-ordinates for the start/finish line. in fact they publish that info for the track i last used and there is a red mark automatically appears on the track map which looks about right .

[David Ferguson]

The GPS laptiming is a feature of the dash logger products, or it can be done in I2 if you have logged the GPS coordinates logged. But in I2 you need to manually enter the coordinates if you want the beacons inserted at a specific location (or move the cursor to that location before starting Lap Generation using GPS).