How to calculate the Phase difference between two signal sources in GNU Radio

Question

I am trying to calculate the phase difference between two signals, a sine wave and a cosine wave, using GNU Radio. I am using the following block configuration:

The problem is that I am not getting the desired output in the time sink block. I just see a constant signal with amplitude of 0 not changing over time.

Is my block configuration to calculate the phase difference between the two signals right?

Answer 1

As documented in the official Block documentation,

Sine

• Real-valued signal types: Amplitude·sin(2π·Frequency/Sample Rate·n) + Offset
• Complex-valued signal types: Amplitude·[cos(2π·Frequency/Sample Rate·n) + 1j·sin(2π·Frequency/Sample Rate·n)] + Offset

Cos

• Real-valued signal types: Amplitude·cos(2π·Frequency/Sample Rate·n) + Offset
• Complex-valued signal types (identical to Sin): Amplitude·cos(2π·Frequency/Sample Rate·n) + 1j·sin(2π·Frequency/Sample Rate·n) + Offset

(emphasis mine)

So, this isn't surprising - you're multiplying exp(j·something) with its own conjugate all the time, getting a constant exp(j·0) = 1, which has argument 0.

Try changing the initial phase of either of these!