XY plotting

Oscilloscopes generally plots time X-axis. They also provide and X-Y mode, where one input is plotted on the X-axis. This feature is used for showing lissajou’s figures and also for measuring the phase difference of two input waveforms.

Objective

Plot two signals in the X-Y mode and find out their phase difference. The phase difference is be generated by CR circuit.

_images/RCsteadystate.svg _images/phase-from-xy-screen.png

Procedure

  • Make the connections as shown in the figure. Use 1K and 1uF
  • Note down the maximum value and the y-intercept

The phase difference is given by the equation \theta = sin^{-1}\Bigg(\frac{y_{int}}{y_{max}}\Bigg)

_images/xyplot-screen.png

Discussion There is an option to plot (A1-A2) against A2. In the above circuit, this plots the voltage across the capacitor against the voltage across the resistor.

  • Select C = 1uF, R = 1 kOhm and plot (A1-A2) vs A2. A
  • Adjust the frequency to make them equal.