# How can it be that my continuous relative phase exceeds 360 degrees?

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Hello,

For my research project I have to investigate the synchronicity between rowers in terms of the continuous relative phase. When the CRP is calculated based on phaseangle2-phaseangle1, this results in wrapping of the data, as can be seen in the graph below. But when I use the function unwrap to solve this problem, the CRP shifts and even exceeds 360 degrees, while it should be around 0 degrees.

How do I fix this?

##### 2 Comments

David Goodmanson
on 19 Mar 2024

### Answers (1)

David Goodmanson
on 14 Mar 2024

Edited: David Goodmanson
on 15 Mar 2024

Hello Suuz,

There is nothing inherently wrong with a phase angle of more than 360 degrees. In fact such a phase can be valuable. Given the mod 2pi ambiguity in the phase, you have two choices, which you showed above. You can either allow the phase be continuous, as in the lowest plot, or you can reset the phase to 0 every time it passes 360, and have discontinuous phase.

Sometimes one ends up taking the derivative of the phase, in which case the continuous function is obviously the choice. And the continuous function shows you a history, which is thrown away if you go to the discontinous version. If two cars are going head to head on the track, but one of them has been lapped twice, that is something you might want to know.

Also, it pays to remember that if you plug the continuous phase into a trig function, you get the same answer as you get from the discontinuous phase anyway.

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