The document describes the Lissajous method for measuring frequency and phase using an oscilloscope. The Lissajous pattern results from applying sine waves simultaneously to the oscilloscope's horizontal and vertical deflection plates. If one frequency is an integral multiple of the other, the pattern will be stationary. The procedure involves setting up the oscilloscope, connecting signal sources, and noting how the pattern changes as the frequency or phase relationship between the signals is varied. Stationary patterns indicate integral frequency ratios, and phase shifts cause cyclic changes to the pattern.

1. LISSAJOUS METHOD FOR FREQUENCY
AND PHASE MEASUREMENT
CHIRANJEEVI E
RISE COLLEGE, ONGOLE

2. Measurement of Frequency by Lissajous method
The Oscilloscope is a Sensitive indicator for Frequency and
Phase Measurements.
The Lissajous Pattern Results ,when sine waves are applied
simultaneously to both pairs of deflection plates.
• If One frequency is an integral multiple of other ,the pattern will
be stationary and is called a Lissajous figure.

3. Measurement of Frequency by Lissajous method
 The Resulting Patterns depend on the integral and phase
relationship between two frequencies.

4. Measurement of Frequency by Lissajous method
Measurement Procedure
1. Set up the Oscilloscope and Switch off the Internal sweep(Change to Ext)
2. Switch off Sync. Control
3. Connect the Signal sources as shown in above fig.
4. Set the Horizontal and Vertical gain Control for desired width and height
of the Pattern
5. Keep freq fv Constant and Vary freq fh noting that the pattern spins in
alternate directions and changes shape.
6. The Pattern stands still when ever fv and fh are in an integral ratio(either
even or odd)
7. When fv=fh , the pattern stand still and is a single circle or ellipse
8. When fv=2fh ,a two loop horizontal pattern is obtained.

5. Measurement of Frequency by Lissajous method

6. Measurement of Frequency by Lissajous method

7. Measurement of Phase by Lissajous method
Procedure
1. Set up the Oscilloscope and Switch off the Internal sweep(Change to
Ext)
2. Switch off Sync. Control
3. Connect the Signal sources as shown in below fig.
4. Set the Horizontal and Vertical gain Control for desired width and
height of the Pattern

8. Cont….
5. Keep fV constant and vary frequency fh noting that the pattern
spins in alternate directions and changes shape.
6. When two frequencies are equal and in phase, The pattern appears
as a straight line at an angle of 450 with horizontal.
7. As the Phase between the two alternating signal changes, the
pattern changes cyclically as shown in below fig.

9. Cont….