Tektronix 47E5A

divisions . Substituting these values in the horizontal
conversion factor formula :
Horizontal
Conversion
Factor
2. 19ms
8 X 0.2 ms
1.37
Then with a TI ME/DIV switch setting of 50 jJS, the time
duration of an unknown signal that completes one cycle in
seven
horizontal divisions , can be determined by using the
time duration formula:
Time Duration = 1.37 X 50 jJs X 7 = 480 jJs
This answer can be converted to frequency by taking
the r
eciprocal of the time duration (see applications on
Determ ining Frequency) .
PHASE DIFFERENCE
MEASUREMENTS
Use either the CHOP or AL T mode . Set the A TRIGGER
SOURCE switch to CH 1. The reference signal should
precede the comparison signal in time . Use coax ial cables
or probes that have equal time delay to connect the signals
to the
input connectors .
If the signals are of opposite polarity , set the INVERT
pushbutton to invert the Channel2 display (signals may be
of opposite polarity due to 180
0
phase difference ; if so,
take this
into account in the final calculation) . Set the CH 1
and CH 2 VOL TS/DIV switches and the CH 1 and CH 2
VAR
controls so the displays are equal in amplitude .
Set the TIME / DIV switch for about a one-cycle
waveform. Position the display and turn the A VAR
TIME / DIV control for 1 reference signal cycle in exactly
eight divisions (see Fig. 21) . Each division of the graticule
represents 45° of the cycle (360° -:-- 8 divisions =
45 ° Idivision). The sweep rate can be stated in terms of
degrees as 45° I division .
Measure the
horizontal difference between correspon-
ding pOints on the waveforms and multiply the distance
measured (in divisions) by 45° I division (sweep rate) to
obta in the amount of phase difference.
EXAMPLE: The horizontal difference is 0.6 divi sion
with a sweep rate of 45° I division as shown in Fig. 21 .
42
475A/OM44 Operators
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