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Cool!  I appreciate the code.  I will give it a try.  Very elegant and simple.

Regards, Bob

Andrew Warren <aiw@CYPRESS.COM> wrote ..
> Bob Japundza <PICLIST@mitvma.mit.edu> wrote:
>
> > I have been thinking about the tanks sloshing around as being
> > noisy signal, and that is one of the reasons why I've been
> > contemplating the median filter.  Do you have a better suggestion?
>
>     Seems to me that a straight low-pass filter would work well.
>
> > I tried an analog low-pass RC filter, and didn't have good luck
> > with it, because of the low resistance of the senders (30-240 ohm
> > Stewart-Warner float types) and not to mention it made me nervous
> > to have large caps tied to the fuel senders, in an airplane, no
> > less.
>
>     Try a digital low-pass filter.  Given a series of input samples
>     in the range 0-255, this code (all 7 words of it) should perform
>     a 256-sample moving-window average and give you the filtered
>     result in AVEHI.
>
>     ; Run this on every input sample.  Enter with the new input
>     ; sample in NEW.  Exits with filtered result in AVEHI, and
>     ; NEW unchanged.
>     ;
>     ; Might want to initialize AVEHI to something reasonable at
>     ; program start; if it were me, I'd probably just initialize
>     ; AVEHI to the first input sample.
>     ;
>     ;          (WIDTH-1)*AVE + NEW
>     ;    AVE = -------------------
>     ;                 WIDTH
>
>     AVEHI   EQU     [ANY FILE REGISTER]   ;Holds the average [0-255].
>     AVELO   EQU     [ANY FILE REGISTER]   ;Holds the fractional part
>                                           ;of the average.
>     NEW     EQU     [ANY FILE REGISTER]   ;Holds the new sample.
>
>     FILTER256:
>
>         MOVF    AVEHI,W
>         SUBWF   NEW,W
>         SKPC
>         DECF    AVEHI
>         ADDWF   AVELO
>         SKPNC
>         INCF    AVEHI
>
>     -Andy
>
> === Andrew Warren -- aiw@cypress.com
> === Principal Design Engineer
> === Cypress Semiconductor Corporation
> ===
> === Opinions expressed above do not
> === necessarily represent those of
> === Cypress Semiconductor Corporation
>
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