Averaging 16 bit values without using 32 bit math


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  1. #1
    Join Date
    Jan 2007
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    Brazil
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    Default Averaging 16 bit values without using 32 bit math

    Hello everyone..

    I am trying keep a running average of the last 400 samples of signal. This signal's range is 500~1200. Is Darrel's Taylor Running Average routine (thanks Darrel) going to work? Should I increase the range of my signal, for example, for 10000~24000? ( x 20)

    Thanks in advance!

    Regards..
    Sylvio,

  2. #2
    Join Date
    Jul 2003
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    Colorado Springs
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    Default

    That averaging routine doesn't work so well with LARGE sample sizes.

    Scaling the values up will help some, but it will still suffer on the low end.

    A couple years ago, there was another guy that wanted to average 8,000 samples.
    I wrote the attached program for him, and like normal, never heard from him again.
    Usually that means it worked.

    No guarantees, but you might give it a try...
    <br>
    Attached Files Attached Files
    DT

  3. #3
    Join Date
    Oct 2004
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    Talking

    Maybe you can use 256 samples.
    You only have to add the highbytes of the samples!


    (a1+a2+...+a256)/256 is the same as: a1/256+a2/256+...+a256/256

    The problem is rounding! I would add the MSB of the low-bytes and divide this sum by 2 and add it to the first result.

    Just think a little about it !

    ($1270+$1280+$1290+...)/256 = $12+$12+$12+...
    and: (0+1+1+...)/2=1.0
    so you get: $36+1.0= 55 !!!
    PBP 2.50C, MCS+ 3.0.0.5, MPLAB 8, MPASM 5.14, ASIX Presto, PoScope, mE mikroBasic V7.2, PICKIT2

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