difficulty calibrating the logger

Aaronia GPS and Data-Logger (also logging/including: Gyro, Tilt, Air Pressure, Height, Speed, Digital Compass)

Re: difficulty calibrating the logger

Postby johnscol » Monday 12. October 2015, 17:47

jon,

thanks, if you turn it on again tomorrow do you get similar values.

I'm often up northampton way.

i see some of those 256 values too, they need to be removed, but then you get to the what you replace them with, as i need all the updates for intergation, so i'm just averaging the reading either side of it, but i hate making data up (could never work for VW :-)

colin
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Re: difficulty calibrating the logger

Postby JonC » Tuesday 13. October 2015, 10:25

Ok,

So its the next day, the same GPS logger sitting at rest on the same table, without recalibration, gives the following data:

Gyro:
First varies from 12 to 16
Second varied from 18 to 22
Third steady again at 34

Accelerometer:
First varies from -127 to 769 Change in values at rest=(769--127)=896 (896/8192)*9.08655=0.012G
Second varies from -639 to 1025 Change in values at rest=(1025--639)=1664 (1664/8192)*9.08655=1.992G
Third varies from 7425 to 9025 Change in values at rest=(9025-7425)=1600 (1600/8192)*9.08655=1.915G

I'm struggling to see how the accelerometer can be of any use, it is too variable. Am I doing something wrong here?

As a comparison, my iPhone with a gyro recorder app is much better, with rest values only varying by about 0.01G. Unfortunately its range is not sufficient for my requirements.

Jon.
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Re: difficulty calibrating the logger

Postby johnscol » Tuesday 13. October 2015, 13:20

jon,

thanks for doing that,

i see similar, usually bigger diffs, but i dont think its as bad as your calcs, i think you dont need to * 9.8 to get G, that turns G into M/S2,

but its the G limit that is going to stop me making progress.

btw, I've sent you a pm with my email address, if you want to compare notes

colin
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Re: difficulty calibrating the logger

Postby Moderator » Friday 16. October 2015, 07:10

As a comparison, my iPhone with a gyro recorder app is much better, with rest values only varying by about 0.01G. Unfortunately its range is not sufficient for my requirements.

All mobile phone have quite the same IC installed as our GPS logger but the values you see on the mobile phone are allready data processed (high averaging) so you see very low value flicker.
So if you want to use RAW :!: data it is simply up to you to get the values usable and mormalized just as posted in viewtopic.php?f=39&t=1633
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