8 - 1 3 Appl i c a t i o n s o f X-Y O p e r a t i on
When o p e r a t i n g t h e o s c i l l o s c o p e i n t h e X-Y mode, L i s s a j o u s p a t t e r n s can be d i s p l a y e d .
W i t h L i s s a j o u s p a t t e r n s , i t i s p o s s i b l e t o f i n d even t h e s l i g h t e s t phase d i f f e r e n c e or
s i g n a l d i s t o r t i o n and r e l a t i v e frequency p r o p o r t i o n s .
1) Apply the s i g n a l to be measured to the CHI INPUT t e r m i n a l . Apply the r e f e r e n c e s i g n a l
to the CH2 INPUT t e r m i n a l .
2) Set the H. MODE c o n t r o l to X-Y.
3 ) A d j u s t t h e VOLTS/DIV and V. VARI c o n t r o l s of b o t h c h a n n e l s t o o b t a i n an a c c e p t a b l e
d i s p l a y .
4 ) I n phase d i f f e r e n c e measurement w i t h L i s s a j o u s p a t t e r n s , measured v a l u e s w i 1 1 n o t
change by t u r n i n g the V. VARI c o n t r o l . Use an e a s y - t o - s e e d i s p l a y f o r measurement.
F i g u r e
21
Measuring Phase D i f f e r e n c e with L i s s a j o u s Patterns
The f o l l o w i n g r e p r e s e n t L i s s a j o u s p a t t e r n s i n d i c a t i n g t h e presence of s i g n a l d i s t o r t i o n or
phase d i f f e r e n c e .
Figure
22
Typical L i s s a j o u s P a t t e r n s
48
. B
<f> =
sm —
or
B
sin</> = —
A
where </> is the phase difference
Amplitude distortion, no
phase discrepancy
No amplitude distortion,
no phase discrepancy
No amplitude distortion,
1
8 0 ° phase discrepancy
A m p l i t u d e distortion,
phase discrepancy
No amplitude distortion,
9 0 ° phase discrepancy
No amplitude distortion,
phase discrepancy
