Query regarding phase of analytic signal.

Question

Using the following matlab commands, phase of analytic signal can be obtained.

sig_a = hilbert ( sig ) ; ph = atan(angle(sig_a)) ;

As for as my understanding is angle(sig_a) will give phase of sig_a. I am not understanding why tan inverse of angle(sig_a) is required? Please help.

Answer 1

As stated in comments, applying atan after angle makes no sense, since the angle command outputs the phase in radians. It would be appropriate to have either

• ph = angle(sig_a);
• ph = unwrap(angle(sig_a));

Unwrap is a useful command that eliminates unnecessary breaks in the phase plot by picking a continuous branch of argument.