How can I obtain the quantized filter coefficients as fixed-point objects in Filter Design Toolbox 4.0 (R2006b)?

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

Answer 1

[MathWorks Support Team]

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)