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P U L S E R E P E T I T I O N TIME
Using the delayed sweep feature, reliable time measure-
ments can be made.
1 . Apply a signal to the INPUT jack and set the vertical
MODE to the channel to be used.
Adjust the VOLTS/DIV to obtain a normal easy to view
display of the waveform are displayed.
2. Adjust the A SWEEP TIME/DIV so that at least two
cycles of the waveform are displayed.
Select the HORIZ DISPLAY to A and set the B MODE to
affect the S T A R T S AFTER DELAY mode of operation.
Set the B SWEEP TIME/DIV as fast a sweep speed as
possible.
3. Adjust the w T R A C E SEP control to shift B sweep to
desired position. Using the DELAY TIME MULT, adjust
the intensified portion to coincide with the first pulse.
4. Using the DELAY TIME MULT, set the pulse to coincide
with one of the vertical graduation lines and record the
dial setting at this point.
5. Using the DELAY TIME MULT, adjust the second pulse
in the same manner to the vertical line used in step 4,
recording this dial setting as well. The pulse repetition
time is the second dial reading minus the first dial
reading multiplied by the A SWEEP TIME/DIV control
setting.
Using the formula:
Pulse
repetition
time = (2nd
reading) x Delayed sweep time (A SWEEP TIME/DIV set-
ting)
Read the dial setting when B sweep points of
DELAY TIME MULT © and © are in the same
position.
Fig. 32
[EXAMPLE]
For the example, the first dial reading is 0.76 and the se-
cond is 6.22 with the A SWEEP TIME/DIV set at 2 its.
We have, substituting the appropriate values. (See Fig. 32)
Pulse repetition time = ( 6 . 2 2 - 0 . 7 6 ) x 2 (*ts) = 10.92 ^ s
dial
reading — 1st
dial
USING DELAYED SWEEP FOR MEASUREMENT OF
RISETIMES AND FALLTIMES
Risetimes and falltimes are generally measured by using the
1 0 % and 9 0 % amplitude points as reference starting and
ending points for the rise or fall.
1. Apply the signal to the INPUT jack and set the vertical
MODE to the channel to be used.
Use the VOLTS/DIV and VARIABLE controls to obtain a
normal 6 divisions vertical amplitude waveform.
A
Using the w POSITION control, set the waveform posi-
tion in the central area of the screen vertically, that it to
coincide with the 1 0 0 % and 0 % lines on the C R T
screen.
Set the SWEEP TIME/DIV control to as high a speed as
possible consistent with observatin of both the 1 0 %
and 9 0 % points.
Set the A VARIABLE to C A L position.
2. Set the B MODE to initiate the S T A R T S AFTER DELAY
mode of operation and select the HORIZ DISPLAY to
ALT and adjust the B SWEEP TIME/DIV for as short as
possible an intensified section of waveform.
3. Using the DELAY TIME MULT, adjust the waveform
such that the 1 0 % point is intensified and record the
dial reading.
4. Similarly, using the DELAY TIME MULT, adjust the 9 0 %
point so that it is intensified and record that dial reading
as well.
The pulse risetime (or falltime) is simply the difference
between the two dial settings times the A SWEEP
TIME/DIV control setting.
Using the formula:
Risetime = (2nd dial reading — 1 s t dial reading) x Delayed
sweep time (A SWEEP TIME/DIV setting)
-Rise time
[EXAMPLE]
For the example, the first dial reading is 1.20 (10% point)
and the second is 7.38 (90% point) with the A SWEEP
TIME/DIV set at 2 us. (See Fig. 33)
Substituting the given value:
Risetime = (7.38 - 1 . 2 0 ) x 2 (jts) = 12.36 fis
Fig. 33
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