Calibration question

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ottacat
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Calibration question

Post by ottacat »

As per my earlier (and still pending moderation post), I have some questions about calibration.

1. I've seen a reference that the phone cannot be used completely flat - is this true? I prefer to keep the phone in a compartment on the centre console. I can build an insert but I'd need to know the minimum tilt necessary.

2. Can I use the motorcycle setting (70 degree tilt) in a car or should I do an individual calibration?

2. Can you give me a bigger picture on the preparations and steps for individual calibration, specifically:
  • How much straight and flat road will I need? I will obviously need to find a location to do the calibration and I need to know how long and straight it needs to be.
  • There are three activities - standstill, drive straight line and gear calibration - what is the difference between drive straight line and gear calibration? What activities will I need to do? It is hard to read the phone's prompts while doing the calibration and it would be nice to know in advance what I should be prepared to do.
Thanks in advance!
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Harry
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Re: Calibration question

Post by Harry »

In case you haven't seen it, please have a look into "Acceleration Handling" available from www.gps-laptimer.de/documentation. 1) True, flat doesn't work - except you calculate acceleration from GPS after the fact instead of measuring it. 2) No, motorbike preset has both a different mounting angle, and a different approach to derive lateral acceleration. So you need to use individual calibration. 3) For individual calibration, mount the device in whatever position (except flat) first. Switch to individual calibration if not done already. Goto Timer View and verify you get displays +- 0 G for both longitudinal and lateral acceleration. In case it is off (i.e. calibrated wrong), touch the "Last G" gadget to reset calibration. That's actually all you need to do. The rest will work automatically on track. Once you see calibration worked fine, use the lock function to memorize the calibration for the future - provided you do not change the mounting position ever. I do not recommend to calibrate the device off track, you will need high longitudinal forces and speeds to make it work. It is designed to work on track, not public roads ;-) In case you want to ignore the recommendation, select the Acceleration View from Analysis ‣ Realtime and touch the acceleration circle. You will get an assistant guiding you through all steps.

- Harry
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ottacat
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Re: Calibration question

Post by ottacat »

Thanks very much for the detailed answer - much appreciated.
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rbpeirce
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Re: Calibration question

Post by rbpeirce »

Harry wrote:True, flat doesn't work - except you calculate acceleration from GPS after the fact instead of measuring it.
- Harry
I, too, place my phone flat. I don't do videos on top of which I don't trust window mounts. I put it under a net behind my seat with a view of the sky (Porsche Cayman). So, what will I get or not get by doing this? What happens if I "force" the calibration? Overall, is the software even useable with the phone in this position?

I just downloaded it planning to use it on Monday. However, if it won't work very well or at all, I can use the software I have been using.
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Harry
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Re: Calibration question

Post by Harry »

Have you checked the doc linked?

In case you do not use one of the mounting presets or use a position not supported, LapTimer will not record valid acceleration values. It will record other data and work nevertheless. To derive acceleration data from GPS, select a lap, press Recalculate and Acceleration. This will calculate lateral and longitudinal acceleration from corner radius and speeds.

Actually I strongly recommend to use a mount instead of placing the device in a position not in view and generating other issues. Quality mounts do not fall off for street going cars.

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rbpeirce
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Re: Calibration question

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Harry wrote:Have you checked the doc linked?
Actually I strongly recommend to use a mount instead of placing the device in a position not in view and generating other issues. Quality mounts do not fall off for street going cars.

Harry
I agree they shouldn't but I have had problems with several suction cup mounts for various devices like nav and radar detection devices. I have a RAM iPhone mount which is supposed to be very good. I will investigate whether it is possible to tether it somehow, just in case.
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Harry
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Re: Calibration question

Post by Harry »

The recommended RAM mount is listed on www.gps-laptimer.de/compatibility/ios and www.gps-laptimer.de/compatibility/android.

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rbpeirce
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Re: Calibration question

Post by rbpeirce »

That's the one I have with the four prong spring-loaded phone mount. Unfortunately, the only way I could tether it satisfactorily was to mount it low on the windshield. You can see a tiny edge of the mount from the camera but mostly it is pretty clear.

I checked trying to tether the mount to the mirror but couldn't make it work. I'll play with it some more when I have time.

The problem is the rake of the windshield prevents getting a completely satisfactory angle between the phone and the mount when the mount is low. The ball needs to be able to move in different planes at each end of the connecting piece but that would require individual clamping at each end. This would not be a problem with the phone below the mount.
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Re: Calibration question

Post by Harry »

The Cayman will not be too different to a 911... Attach the suction cup in the top directly below the mirror. Point the mount down and turn the XGrip into your direction again. This works pretty well and allows you to point the smartphone as required and - when using video - in a way it has no mount parts in the field of view.

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rbpeirce
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Re: Calibration question

Post by rbpeirce »

Harry wrote:The Cayman will not be too different to a 911... Attach the suction cup in the top directly below the mirror.
Harry
I tried that but felt like it obscured my view so last night I tried positioning it behind the mirror to the right of the mirror mount. After playing with it a bit I found a location where I could still adjust the mirror and tether the mount to the mirror mount. I don't know how strong that is but it is better than nothing. With any luck it will never be tested.

Thanks for the help. I think I am okay now.
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