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Lissajous Patterns Explained

 

Lissajous Patterns

Lissajous Patterns

Definition

Lissajous patterns are the shapes formed on an oscilloscope screen when two sinusoidal signals are applied:

  • One signal to the X-axis (horizontal)
  • Another signal to the Y-axis (vertical)

What They Show

  • Frequency ratio of two signals
  • Phase difference between signals

Common Shapes

  • Straight line → signals are in phase
  • Circle → 90° phase difference
  • Ellipse → general phase difference
  • Complex loops → different frequency ratios

Examples

  • If fx = fy → simple shapes (line, circle, ellipse)
  • If fx : fy = 1 : 2 → figure with 2 loops

Applications

  • Oscilloscope analysis
  • Signal comparison
  • Frequency measurement

It is a graph of one signal versus another, instead of versus time.

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