This is a flowgraph that will calculate the signal-to-noise ratio (SNR) of a FM broadcast station using a RTL-SDR. This flowgraph demonstrates both measuring signal power and use of the '''Complex to Mag^2''' block.
This is the time domain (left) and constellation (Argand) diagram showing the phase shift of a complex sinusoid. The phase has been shifted +125 degrees (3π/4 radians).