Harry's GPS Suite Forum

Yesterday, I videoed a road driving session and when I played it back it's obvious that the calibration is out as the green dot sits North of the line when the car is stationary. Do I need to manually calibrate before each session and what is the correct procedure. I look but couldn't find any details in the documentation.

Thanks.

Hi,

Actually LapTimer is designed in a way it should auto-recalibrate for you when necessary (i.e. after rotation and in case a wrong calibration is detected). As people have different using patterns, it may fail nevertheless. The approach the design should work for is as follows:

• Start LapTimer and turn to the orientation desired
• Mount the device
• You may see an alert asking you for confirmation of changed orientation now - confirm if mounted correctly
• The important thing is you should do all of the above while standing still, not while driving

In case you want to get exact / guided directions, change to Acceleration View and bring up the calibration assistant (wrench button). Another well kept secret is you can manually start recalibration both in Video View by tapping the acceleration circle, and by tapping the Las Max gadget in other views.

To be sure you are fine, check you get near zero lateral and longitudinal acceleration (point centered in acceleration circles) while standing still (in the pits).

- Harry

Thanks. I've got the auto-calibration now.
When I go to the "More" tab the "Acceleration" menu shows a small white "c" on a grey background. Does that mean that it needs calibrating? There is sometimes also a red "c" badge superimposed on the "More" tab. Tapping the red car in the centre brings up a calibration window prompting the user to drive in a straight line. Is this an alternative method? Not sure when this should be used.

Edit: I've just done an auto recalibrate, the green is dot is bang on centre but the red badge is still displayed.

Calibration requires several steps to complete. The most important is the first one as it eliminates gravity and device pitch. The second one eliminates the device yaw (compared to driving direction) and requires a straight line driven plus massive acceleration / deceleration. The red C is shown as long as not all steps have been completed. All of this is working in background, the Acceleration Assistant is mainly for displaying the status. The step #2 above is typically done once you are on track. As long as step #1 is fine (and the dot centered), just drive. It will mostly work just fine (repeated: To be sure you are fine, check you get near zero lateral and longitudinal acceleration (point centered in acceleration circles) while standing still in the pits).

- Harry

Ok, thanks.