MATLAB: How to obtain the quantized filter coefficients as fixed-point objects in Filter Design Toolbox 4.0 (R2006b)

Filter Design Toolbox

I create a filter using the FDATOOL or through command line functionality and would like the coefficients returned as fixed-point objects.

Best Answer

The ability to obtain the quantized filter coefficients as fixed-point objects is not available in the Filter Design Toolbox 4.0 (R2006b).
To work around this you can manually convert the coefficients to fixed-point objects as shown below:
d=fdesign.lowpass(0.40,0.54,0.05,50);
hd=design(d,'kaiserwin','filterstructure','dffir');
hd.Arithmetic='fixed';
set(hd,'filterInternals','specifyprecision');
hd.productWordLength = 16;
hd.accumwordLength = 40;
myfi = fimath('maxproductwordlength',16,'maxsumwordlength',40);
numerator = fi(hd.numerator,hd.signed,hd.inputwordlength,...
          hd.inputfracLength, 'fimath', myfi)
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