Hi list,
I just got started with GNU Radio Companion for use with my FCDPP and it's been great, already am decoding FM stereo and it sounds very good. However it probably isn't the most optimal way to do it:
My filters are the inbuilt bandpass - they're a bit hard on the CPU and was hoping to use the IIR filters as biquads instead but I can't seem to get them to work. Filter was designed with this applet (
http://www.earlevel.com/main/2010/12/20/biquad-calculator/ ) and I fed the A values into Feed-Forward of the IIR and B values to the Feed-Backward and it would not pass signal so I swapped A and B values and it apparently just passed the signal unaffected. Any ideas what I'm doing wrong?
What is the internal resolution for the IIRs? I am asking because some of my filter Q's are in the 10-60 range and am concerned about blowing them up.
Also, what would be the most efficient way (in GNU Radio) to get the absolute value of a signal? The best I've come up with so far was a Float->Complex feeding a Complex->Magnitude.