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Altera_Forum's avatar
Altera_Forum
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16 years ago

Band Pass filter output data

Hi everyone,

I use FIR compiler v8.1 to generate a band pass filter 50hz

Configuration :

- Input Data unsigned width : 8 bits

- I use a coef file generated by Matlab

- coefficients scaling : Auto ... Bit Width : 8

--- Quote Start ---

-0.03758602

-0.04600525

-0.05416903

-0.05998012

-0.05842221

-0.04470215

-0.01824851

0.01576782

0.04887938

0.07399496

0.08870862

0.09481480

0.09481480

0.08870862

0.07399496

0.04887938

0.01576782

-0.01824851

-0.04470215

-0.05842221

-0.05998012

-0.05416903

-0.04600525

-0.03758602

--- Quote End ---

and I try to undestand why i have a signed data out ( see image )

fir data in/out (http://img190.imageshack.us/img190/9161/firbp.jpg)

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  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    16 years ago

    If the frequency response is O.K. for your application, no problem to use it. So you basically have to cut the extra LS bits from the 20 bit output. There seem to be some some confusion with the sampling rate of the simulation file, but you should be able to clarify the point when including the filter in a real design.

    I remember, that some FIR compiler users previously had problems with the usage of source/sink handshake signals. I hope, that the meaning of these signals is said clear enough in the FIR users guide.