Hey all,
I am currently working on a project creating a BPSK
modem through GNU radio and I am having issues with the
carrier tracking PLL block on my receive side. At first
I was getting a "beat" in my baseband signal, which is
shown here :
http://i.imgur.com/vuaVUs5.png?1
I discovered that i need to set the min/max frequency
within 0.1 Hz of the carrier frequency with a loop
bandwidth of ~100e-6 to get rid of the beat, but even then
it comes back occasionally. So basically this means that
the PLL cannot lock onto my exact carrier frequency for
whatever reason. Has anyone else had this issue with the
PLL? I can tweak it during run time, but I need it to be
able to lock on by itself.
My other option would be to create my own PLL block.
However, the PLL I would like to use has feedback loops so I
cannot create it in GRC. I have looked into programming a
block but my C++ skills are very sub-par. The biggest issue
being how to work with filters/feedback.