Questions about overlay data with XGPS160 and OBD

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atmosx
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Questions about overlay data with XGPS160 and OBD

Post by atmosx »

Hello, I'm using the GP edition on an iPhone 12 and iOs 15.1.1 with XGPS160 (SkyPro GPS Receiver) and GoPoint BT1A OBD and a GoPro Hero Silver 4. The car is a lotus Elise S2, 2002 model.

1. When using the XGPS160 the HLT doesn't seem to measure km/h (see screenshot). This is consistent in at least the 3 videos I tried. Is this a known issue, am I missing something? When I used the XGPS160 on track, the lap times were pretty accurate displayed (timer view).

2. It's not clear which data comes from the OBD and which is calculated. The gear No is often wrong (display says 4th but it is 3rd). My guess is that gear is calculated combining data from the car's gear ratio and RPM. I'm guessing kW fuel and temperature comes the OBD.

3. What exactly does the green dot display? Can we use it to measure suspension stiffness in fast corners, on track?

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If there are docs for all these questions please send a link. Thanks!
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Harry
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Re: Questions about overlay data with XGPS160 and OBD

Post by Harry »

Hello,

As long as an OBD adapter is connected to LapTimer, most values available from GPS and OBD will use OBD. So the speed displayed is OBD / wheel speed and obviously not delivered by the adapter / car. Please check whether speed is available from OBD at all (Sensor List ‣ you OBD adapter ‣ tap). In case it is not available, tick the Expert Settings "Video Tweaks" ‣ "Force Overlay GPS Speed" to pull the GPS value instead.

Gears are calculated from tire size, axle driven, drive and gear ratios, and rpm. You need to configure them for your vehicle. By default, some Porsche 911/997 parameters are used.

Fuel and temperatures are delivered by OBD, kW is calculated from MAF / MAP and some configurable engine parameters (see Vehicle Details again).

The green dot is part of the acceleration display. Search for "Kammscher Kreis" or see https://en.wikipedia.org/wiki/Circle_of_forces for details. In the sample above, there is both a minimal cornering to the left and slight acceleration detected. The dot may be green, yellow, red depending on thresholds you can define specifically for your car (Expert Settings). The yellow range should be the G's you want to corner with ideally, the red range should start at a G value when the car starts to slip or slightly before. Depends on what you want to analyze.

- Harry
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atmosx
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Re: Questions about overlay data with XGPS160 and OBD

Post by atmosx »

Harry wrote: Tue Jan 18, 2022 10:21 am Hello,

As long as an OBD adapter is connected to LapTimer, most values available from GPS and OBD will use OBD. So the speed displayed is OBD / wheel speed and obviously not delivered by the adapter / car. Please check whether speed is available from OBD at all (Sensor List ‣ you OBD adapter ‣ tap). In case it is not available, tick the Expert Settings "Video Tweaks" ‣ "Force Overlay GPS Speed" to pull the GPS value instead.

Gears are calculated from tire size, axle driven, drive and gear ratios, and rpm. You need to configure them for your vehicle. By default, some Porsche 911/997 parameters are used.

Fuel and temperatures are delivered by OBD, kW is calculated from MAF / MAP and some configurable engine parameters (see Vehicle Details again).

The green dot is part of the acceleration display. Search for "Kammscher Kreis" or see https://en.wikipedia.org/wiki/Circle_of_forces for details. In the sample above, there is both a minimal cornering to the left and slight acceleration detected. The dot may be green, yellow, red depending on thresholds you can define specifically for your car (Expert Settings). The yellow range should be the G's you want to corner with ideally, the red range should start at a G value when the car starts to slip or slightly before. Depends on what you want to analyze.

- Harry

Awesome! Thank you for taking the time to explain everything!

Kind Regards,

P.
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