Tektronix 2445B - Page 80

Applications
Without Parametric Measurements
The Delta Time (At) function also can measure the percent ratio between
two different time intervals, such as the period and width of a pulse, which
define duty factor.
1. Display the signal with SEC/DIV and VAR set for one cycle over exactly
five horizontal divisions.
2. Activate At and align the two vertical cursors with the beginning and
end of the high portion of the pulse. Measure the low portion of the
pulse if you want to measure the portion of the cycle that is low (see
Figure 3-5).
If the portion of the pulse you are measuring is less than 1 division wide (20%),
you can improve the accuracy of the measurement. Activate the X10 MAG, without
changing SEC/DIV or VAR, and align the cursors with the magnified pulse. The
RATIO reading will be 10 times the actual ratio.
The CRT readout displays the ratio, in percent, between the separation of the
two cursors and the five-division reference interval. When the two cursors are
separated by five divisions, the readout indicates 100%.
A1
0.0 V
REFERENCE
CURSOR
2 V
TIME RATIO
X RATIO 32.9%
■i-T-
-DELTA
CURSOR
i 'I
__.!_.
20.1 us
TEST
SIGNAL
REFERENCE
-INTERVAL -
(5 DIVISIONS)
(3832-18) 5854-16
Figure 3-5. Time ratio (duty factor).
3-14
2465B/2455B/2445B Operators