On Wed, Apr 24, 2013 at 8:56 AM, Chuck Ritola <cjrit...@gmail.com> wrote: > 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:
There are FM receivers/demod blocks already that you can play and experiment with. In 3.6, they are located in gnuradio-core/src/python/gnuradio/blks2impl, look for wfm_rcv blocks. Obviously, though, nothing stopping you from building and experimenting on your own. > 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? I think this has already been addressed in another email thread, but try negating the A vector. And try using the gr_filter_design tool. > 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. The taps are passed in as double-precision floating point. > 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. Well, you could always write a block to do that yourself. There's also the blocks::transcendental block that you can use. Should be able to pass it "fabsf" and "float" as the arguments. > Thanks! > > Chuck Tom _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
