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For the below figure of 8 Lissajous pattern, it is clear that the frequency of the Y input is half the X input. However how to conclude about the phase difference relation. The answer is option D, is it because the sense of direction is clockwise? How to conclude the phase difference for figure of 8. Is there a generalised method like in the case of ellipse where the phase difference is Sin inverse of intercept value by maximum value.

enter image description here

Fawaz
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  • It's both of them: http://www.pitt.edu/~tjs98/misc.html – Andy aka Dec 05 '20 at 11:53
  • But the answer is actually D. – Fawaz Dec 05 '20 at 11:58
  • @Andyaka both B and D draw the same image, yes, but only one of them draws the image in the order the arrows given. – Justme Dec 05 '20 at 12:10
  • At the top, X starts at 0 and increases, Y starts at 1 and decreases... –  Dec 05 '20 at 12:13
  • Honest curiosity: Where do I apply the knowledge / skill asked about here? Doesn't seem to be a buildup to a control theory root locus problem, and I'm not quite sure what I'm demonstrating elegantly by this measurement method. Following OP's approach, this also doesn't seem to be a case of testing student's abilities to creatively find solutions, but some method that's been taught – but for what purpose? – Marcus Müller Dec 05 '20 at 13:02

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Yes, you simply need to determine the starting XY coordinate and in which direction the XY coordinates start to move as time increases. And then check if the direction matches the diagram you are given.

Justme
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