Phase Difference - Tektronix 2221 Operator's Manual

Basic Applications- 2221 Operators
C
REFERENCE
SIGNAL
14. Use the CURSORS control to position the active
cursor to the first zero - crossover point of the phase
shifted signal ( see Figure 6-20B ).
U
A = 341.8ms
1 0 0
30
A
CURSOR
AT FIRST
ZERO
CROSSOVER
C
15. Note the phase - difference time (T2) from the crt
readout .
M
5
DIVISIONS
16. The amount of phase shift in degrees is calculated
from the following formula :
ACTIVE CURSOR AT
THIRD ZERO
Sms
CROSSOVER ( 360 ° )
T1
U
U
(A ) SINEWAVE PERIOD TIME ( T )
STORE MODE DISPLAY .
Phase shift ( degrees)
Tz x 360 °
TT
PHASE - SHIFTED
SIGNAL
A 6.30ms
ACTIVE
CURSOR
POSITIONED
AT FIRST
ZERO
CROSSOVER
OF SHIFTED
SIGNAL
EXAMPLE : The period ( T1) of the reference signal
shown in Figure 6-20 is 34.8 ms , and the phase
difference time ( T1) is 6.3 ms .
1 0 0
90
u
V
Substituting these values into the equation:
Phase
Shift
( degrees)
6.3 X 10-35
34.8 X 10 - S
x 360 °
65.17 °
.T2 Т ..
Sms
‫لا‬
( B) PHASE DIFFERENCE TIME (T2)
SAVE MODE DISPLAY .
4998-22
SLOPE
Figure 6-20. Phase difference between sinusoidal signals.
The slope of a particular portion of a waveform is the
rate of change of voltage with respect to time . The follow
ing procedure is useful for making the measurements
required for determining the slope of a portion of a
waveform .
10. Push the SAVE / CONT switch to activate SAVE
mode .
1. Preset instrument controls and obtain a baseline
trace .
11. Use the CURSORS control to move the active cur
sor to the sine wave's first zero - crossover point ( center
horizontal graticule line ).
2. Set the STORE /NON - STORE switch to the STORE
position (button in).
C
C
12. Push the SELECT C1 /C2 button to select the other
cursor, and use the CURSORS control to position the
active cursor to the sine wave's third zero - crossover point
( 360 ° ).
3. Set the VOLTS /DIV switch to obtain about five divi
sions of vertical amplitude .
13. Note the time of the sine-wave period (T1) from the
crt readout.
4. Set the SEC/ DIV switch to horizontally spread the
portion of the waveform to be measured across the width
of the graticule area ( see Figure 6-21 ).
C
C
6-20
u