I have experimented with the wfm_rcv_pll.py for broadcast FM, and have som questions regarding it:
- what is the purpose of using the gr_pll_carriertracking_cc on the pilot tone? The way I understand the funtion of gr_pll_carriertreacking_cc is to baseband a signal which lies on a carrier and therefore it should be used on the stereo channel instead.
- is there any particular reason why the alpha i set to 0.25*bandwith*pi/demodrate? I found out that setting this parameter to 0.8*bandwith*pi/demodrate the noise floor drops considerably, which makes the stereo channel appaear more clearly.