RIGOL MSO/DS2000A Series - Manual (Page 71)

Chapter 3 To Set the Horizontal System RIGOL
MSO2000A/DS2000A User’s Guide 3-5
According to sinθ=A/B or C/D (wherein, θ is the phase deviation angle between
the two channels and the definitions of A, B, C and D are as shown in the figure
above), the phase deviation angle is obtained, that is:
θ=±arcsin (A/B) or ±arcsin( C/D)
If the principal axis of the ellipse is within quadrant I and III, the phase deviation
angle obtained should be within quadrant I and IV, namely within (0 to π/2) or (3π/2
to 2π). If the principal axis of the ellipse is within quadrant II and IV, the phase
deviation angle obtained should be within quadrant II and III, namely within (π/2 to
π) or (π to 3π/2).
X-Y function can be used to measure the phase deviation occurred when the signal
under test passes through a circuit network. Connect the oscilloscope to the circuit to
monitor the input and output signals of the circuit.
Application example: measure the phase deviation of the input signals of two
channels.
Method 1: Use Lissajous method
1. Connect a sine signal to CH1 and then connect a sine signal with the same
frequency and amplitude but a 90° phase deviation to CH2.
2. Press AUTO and enable X-Y mode. Rotate Horizontal SCALE to adjust the
sample rate properly to get better Lissajous figure for better observation and
measurement.
3. Rotate VERTICAL POSITION of CH1 and CH2 to display the signals at the
center of the screen and rotate VERTICAL SCALE of CH1 and CH2 to make
the signals easy to observe. At this point, the circle as shown in the figure below
should be displayed.