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Old 10-24-2007, 10:12 PM
Duane Clark
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Default Re: Paper about selecting fixed point bit widths?

[email protected] wrote:
> Hello all,
>
> Can anyone point me to a good general purpose paper about selecting
> appropriate bit-widths for a fixed point implementation of a signal
> processing algorithm? I've looked around and haven't found anything
> that describes a general methodology to use. I have implemented a
> design and it isn't performing as well as I would like. I suspect it
> has to do with some poor selection of bit slicing when it comes to
> multipiers and accumulators.


I don't know any papers. Personally, I do an implementation of an
algorithm in Matlab, first with floating point numbers, and then with
integers. I can then make quick changes and graph the two
implementations to compare the results. That allows me to determine how
many bits I need for various portions of the algorithm to get acceptable
results.

By the way, I tried the Matlab fixed point package, but found that the
performance was too poor to use on processing even a modest sized data
set, so I stick with using ordinary integers. Typically I stick a
comment at the end of most lines indicating the scaling of that
particular parameter.
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