Rise Time - Tektronix 2221 Operator's Manual

Basic Applications - 2221 Operators
NOTE
AV1F80.0 %
A1 = 1 01. Obnis
Pulses with fast rise times have only a few sample
points on the leading edge, and it may not be
possible to place the cursor at exactly the 10%,
80 % , 90 % , or 100 % points.
100
90
Л
П
П
П
П
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CURSOR
AT 90 % GRATICULE
5. Use the CURSORS control to move the active cur
sor to the minimum level of the waveform .
ACTIVE
CURSOR
AT 10 % GRATICULE
6. Push the SELECT C1 /C2 button to select the other
cursor, and use the CURSORS control to move the active
cursor to the maximum level of the waveform ,
10
%
2V
SAMPLE
5ns
7. Set the VOLTS /DIV switch and the VOLTS /DIV
Variable control (or signal amplitude) for a AV readout of
100% .
4998-18
Figure 6-16. Rise time, cursor method.
NOTE
П
П
The SAVE ACQUISITION mode button may be
pressed in at this time
to save the acquired
waveform for as long as desired. Voltage and time
measurements may be made on the SAVE waveform
with less trigger jitter.
3. Select a VOLTS /DIV switch setting that gives the
desired vertical deflection .
4. Set the SEC/ DIV switch to display the reference sig
nal with the desired sweep rate .
8. Use the CURSORS control to move the active cur
sor down the waveform's leading edge until the AV
readout is 90%.
5. Push the SAVE REF button .
3
П
9. Push the SELECT C1 /C2 button to select the other
cursor, and use the CURSORS control to move the active
cursor up the waveform's leading edge until the AV
readout is 80 % ( see Figure 6-16 ).
6. Acquire the waveform that is to be compared with
the reference waveform .
NOTE
10. Read the puise rise time from the crt delta time
readout.
WAVEFORM COMPARISON
A stored reference will remain displayed until the
DISPLAY ON /OFF button is pushed.
Switching the
instrument
to
NON - STORE removes stored
waveforms from the display, but the saved reference
waveforms remain in the digital storage memory for
use upon return to a storage mode. A new reference
waveform is saved when the SAVE REF button is
pushed .
Repeated comparisons of newly acquired signals with a
reference signal for amplitude, timing , or pulse - shaped
analysis may be easily and accurately made using the
SAVE REF function of the instrument.
1. Preset instrument controls and obtain a baseline
trace .
11
1
1
П
П
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7. Use the selected channel's Vertical POSITION con
trol to overlay the newly acquired waveform on the refer
ence waveform for making the comparison (see Figure
6-17) . The vertical deflection and sweep rate remain cali
brated to allow direct measurement from the graticule , or
cursors may be used to determine voltage or time
differences.
2. Set the STORE /NON -STORE switch to the STORE
position (button in) .
6-17