I’ve been doing some experimentation with some very basic IIR filtering.
I am creating sinusoidal float sources with a sampling rate of 32Khz,
connecting them through the gr.iif_filter_ffd() block, and then output
the result to an audio sink and a spectrum scope. For my taps, I am
designing them in MATLAB, negating them appropriately, and entering them
into the GNURadio script.
I am finding that if I use a tap vector length of greater than 4 the
code stops working. Instead of a tone I get no noise.
Has anyone experimented with IIR filters of a longer length? The only
other IIR code I have seen is in the emph/demph filters, but that is a
low order filter.
MS Student, Case Western Reserve University