Re: [Discuss-gnuradio] GMSK at 768kb/sec and other good stuff

[Dawei Shen]

Hi Eric and other dudes

I am studying the GMSK2 code now. The code is very clean and obviously designed sophisticatedly. I feel excited to read the code. Could you please help explain the following code to me?

    alpha = 0.0002   # FIXME, maybe 0.0008/spb
    self.freq_offset = gr.single_pole_iir_filter_ff(alpha)
    self.sub = gr.sub_ff()

    fg.connect(self.fmdemod, (self.sub, 0))
    fg.connect(self.fmdemod, 
self.freq_offset, (self.sub, 1))

This part is following the FM demodulator.  My guess is you are going to remove the DC offset, is that right? But why do you use an IIR filter?

I plan to add comments to the codes and put them on my website once I finish studying them.

Thanks for your time

Dawei