Same Car - Multiple Drivers

[scrowner]

We are setting up the use of professional version and using the iPad to view and analyze collected data for multiple drivers. We run endurance races where drivers are exchanged every ~2 hours during the race with the pit time being about 3-5 minutes. We have the iPhone setup with the tom tom GPS ehancer and the iphone is plug into the cars DC supply. How do you propose we switch driver data collection while in the race? Ideally we want a simple way to change the data collection in a few seconds while in the pit - from one driver to another.

Is there a limit to the collected data size? We plan on running a minimum of 10 hours straight with collection active the whole time. Some races exceed 25 hours - that is continuous racing with 3-5 minute pit stops every 2 hours. What is your data set size collected per hour?

[Harry]

Hi,

I'd suggest to define two vehicles, e.g. "911Cup - D1" and "911Cup - D2". It is easy to switch the current car by pressing the little tool button in (e. g.) the Timer View and switch between cars here.

The number is laps is realistically not limited, but the number of GPS fixes in the database is limited to 64*1024. This means that with a completely empty database you have 18h to drive. With compression set to 'high', you will probably get 20 or 22h. This limitation has its origins in the original PalmOS implementation which is basis for the iPhone version. The reason I kept this implementation is both compatibility and speed - it is extremely fast!

To work around this, one can purge the GPS recordings from a lap recorded. The lap data remains, but the plot goes away. To purge GPS data from a lap, enter Lap Details and press the 'Purge' button.

- Harry

[bulls23]

What about one iPhone for each driver, preconfigured, easy swap during pit-stop, no problems with max amount of data

[scrowner]

I will tell everyone on the team to go get an iPod/iPhone for the race next weekend. Good for Harry - everyone buying a version of LapTimer Pro!

[mhane3]

Is the database size limitation ONLY a limitation for the number of GPS points or does it also get affected by other data? For example, would recording OBD II information shorten the maximum recording "time".

[Harry]

All fixes (GPS, OBD, Acceleration) are joined during recording, so OBD does not further reduce the recording time. I plan to break this 64k limitation in v15 anyway.

- Harry

[csmarx]

Harry, is the limit of data points per session or for the entire data base? I have a lot of laps already in the data base, and I'm going for 3 days to Laguna Seca. In addition I'll be testing the Emprum GPS device at 5 Hz - i.e. 5 times the data points per lap.

What happens when it's full?

Is there a way to determine how full the data base is?

Thanks,
Christian

[Harry]

Harry, is the limit of data points per session or for the entire data base? I have a lot of laps already in the data base, and I'm going for 3 days to Laguna Seca. In addition I'll be testing the Emprum GPS device at 5 Hz - i.e. 5 times the data points per lap.

What happens when it's full?

Is there a way to determine how full the data base is?

Thanks,
Christian

Goto Lap List and watch the table header. Here you see the # of fixes currently stored. You have 65535 overall. Version 15 will have 32 bit fix space - which is more than you will ever need. I currently work on this while still keeping the performance the current 16 bit system has (it is extremely fast). In case you really run into the limit soon, I'd suggest to export all data to the .hlptrl format, check that it has really arrived(!) as a backup, and purge the database completely. This can be done by killing the app (using the iPhones task list), going to the Settings app, selecting LapTimer -> Expert Settings and set the 'Clean Lap Database' switch. Start LapTimer again and the Lap List should be empty. Once LapTimer is 32bit (will be probably somewhere in autumn), you can import your data again and have everything in one place.

When the limit is reached, not further fixes are stored. There may be other side effects, so purge before arrive at the limit.

- Harry

[Btwyx]

I'm glad I found this thread, I just got an alert popping up saying I was critically low on space for GPS data, and that I should purge the GPS data, which I didn't want to do. I had about 333 laps in the data base, and I was planning on keeping them there. We had 2 more sessions at Laguna Seca to go.

My workaround was to download the non pro version of the lap timer which I'd previously bought and use that to record the laps. Now I've found the real solution is to upgrade the lap timer (I should have checked for updates before we left). I was stuck with a set of laps in the wrong ap. You reply also supplied the answer to that, export them in hlptrl format.

I was wondering what the problem was, I've got 32GB free on the iPhone and the lap timer is only using 38MB of it.

[Harry]

Background of the limitation to 65535 GPS fixes is rather technical. LapTimer's database implementation is based on a super fast, but a bit outdated network database used on the old PalmOS platform. This implementation used 16bit pointers for data sets making the limitation above. LapTimer v15 comes with a 32bit implementation which has been quite complicated - but is still super fast. Maintaining big numbers of data using the standard iOS mechanisms - or light weight SQL database will degrade performance too much. This is probably the reason most data loggers available on iOS reduce the number of fixes significantly. LapTimer is able to do the opposite and store update rates of 5 or 10 fixes per second and perform well nevertheless

- Harry