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jyh
Advanced User
Joined: 23 Nov 2005
Posts: 14
Location: CERN (Geneva)
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 Posted: Wed Nov 23, 2005 4:46 pm Post subject: Decimal Places & Averaging (DrDAQ,PICOLOG) |
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A)
the decimal places are there but always displayed as "0"
http://hemery.sytes.net/DecPlace_Averaging.jpg
Is the "decimal places" feature in PICOLOG still under development?
B)
The steps are too flat to be true
http://hemery.sytes.net/Averaging.jpg
How can I get measurements only base on averaging
excluding any other kind of hidden signal data processing?
Thank you for your advice 
Typical wave form of the signal with Picoscope
http://hemery.sytes.net/PicoScope_Averaging.jpg
I never encounter these sort of flat steps observed with PICOLOG
n.b. the above comments do apply to all versions up to the latest available (5.12.7) |
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Michael
Guru
Joined: 07 Jul 2005
Posts: 93
Location: St Neots, Cambridgeshire
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| Posted: Fri Nov 25, 2005 11:32 am Post subject: |
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Hello,
I shall answer your questions in order:
a)
We will look into this anomoly, we have not seen this error here.
b)
PicoLog is a data logging system which instruct the instrument to get samples at set intervals. If you wish to view averages, you can use PicoScope or write your own software.
I have never seen these flat spots on the graph before. It may be processor loading that has reduced the sampling interval for parallel devices. Although this should never happen.
Best regards,
Michael |
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Guest
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| Posted: Sat Nov 26, 2005 12:16 am Post subject: |
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Hello,
Thank you for your interest in these 2 preceeding comments.
For "A", it is straight forward to reproduce.
For "B", whenever the trailing digits will no longer be ".00" on the PLW
window, the flat spots may also disappear.
PICOLOG applies a rounding rather than an averaging
on measurements taken during every 1 second interval.
Since PICOLOG performs several readings every 1 second,
an averaging would supply a better accuracy for free.
In this context, any truncation or rounding introduces a systematic
error on all values and leads to artefacts such as stepping function
rather than a smooth ascending or descending curve.
n.b. the above demonstration is irrelevant if PICOLOG performs only 1 reading per second. Furthermore, no chance to have the trailing digits different from ".00"
Best regards,
Hemery |
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