difficulty calibrat...
 
Notifications
Clear all

difficulty calibrating the logger

19 Posts
3 Users
0 Likes
40.3 K Views
(@johnscol)
Active Member
Joined: 9 years ago
Posts: 14
Topic starter  

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


   
ReplyQuote
 JonC
(@jonc)
Eminent Member
Joined: 9 years ago
Posts: 23
 

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.


   
ReplyQuote
(@johnscol)
Active Member
Joined: 9 years ago
Posts: 14
Topic starter  

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


   
ReplyQuote
(@moderator)
Noble Member Admin
Joined: 14 years ago
Posts: 1044
 

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

Snip


   
ReplyQuote
Page 2 / 2
Share: