I
would like to recognize and distinguish between FM and QPSK
signal by analyzing its properties.
I
have a general idea about their main distinguishing
feature:
-
FM has continuous phase;
-
PSK has phase disruptions (gaps).
I
can get phase for every sample since they are complex.
But
I am lost in the implementation because I have many ideas
how to find the phase differences but not so much practice
with gnuradio blocks.
I
tried to implement some kind of phase derivative function by
measuring the phase difference between consecutive samples.
But the problem is the following - I do no know exactly
symbol rate. Can I do this by trying variable delay between
samples or are there any other better alternatives in
Gnuradio?
Thank
you in advance for any suggestions! Of course, some channel
noise exists and impairs phase measurements.