[Discuss-gnuradio] GNU Radio IIR Filter Taps

[Keyur Parikh]

Hello,

I've been trying to move the fm De-emphasis (an IIR filter, I'm pretty sure) functionality of the WBFM_Receive block into an FPGA, and I'm a little confused as to how the taps work.

I'm in fm_emph.py and can see the taps listed as

btaps = [b0, b1]

ataps = [1, a1]

I had assumed this is a first-order IIR filter, and am basing my simple algorithm on a structure as seen in this link

http://www.mikroe.com/img/publication/various-electronic-books/digital-filter-design/chapter/ch3/fig3-2-20.gif

Is there something I'm missing? I don't seem to be getting the correct results based off my input data.

Thanks,

Keyur