[Discuss-gnuradio] Basic IIR Filtering

[Robert Roberts]

Hello all,




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.


Thanks,
~Chris Roberts~
MS Student, Case Western Reserve University