Interpolated FIR filter from filter specification
hd = ifir(d)
hd = design(d,'ifir',designoption,value,designoption,...value,...)
hd = ifir(d) designs an FIR filter from design object d, using the interpolated FIR method. ifir returns hd as a cascade of two filters that act together to meet the specifications in d. The resulting filter is particularly efficient, having a low number of multipliers. However, if ifir determines that a single-stage filter would be more efficient than the default two-stage design, it returns hd as a single-stage filter. ifir only creates linear phase filters. Generally, ifir uses an advanced optimization algorithm to create highly efficient FIR filters.
ifir returns hd as either a single-rate dfilt object or a multirate mfilt object (when you have DSP System Toolbox™ software installed), based on the specifications you provide in d, the filter specification object.
specifications supplied in the object h.
To determine the available design options, use designopts with the specification object and the design method as input arguments as shown.
For complete help about using ifir, refer to the command line help system. For example, to get specific information about using ifir with d, the specification object, enter the following at the MATLAB prompt.
fpass = 0.2; fstop = 0.24; d1 = fdesign.lowpass(fpass, fstop); hd1 = design(d1,'ifir'); fstop = 0.2; fpass = 0.25; astop = 40; apass = 1; d2 = fdesign.highpass(fstop,fpass,astop,apass); hd2 = design(d2,'ifir'); fvtool(hd1,hd2)