Operating Instructions—Type 422 AC-DC
Then, with a TIME/DIV switch setting of 50 jus the repeti
tion rate of an unknown signal which completes one cycle
in seven horizontal divisions can be determined by using the
repetition rate formula (step 6):
Repetition
Rate
50 [is X 1.37 X 7 = 480 [is
8. Measure the horizontal distance between the time
measurement points. Be sure the VARIABLE TIME/DIV
control is set to CAL.
9. Multiply the distance measured in step 8 by the set
ting of the TIME/DIV switch. If sweep magnification is
used, divide this answer by 10.
This answer can by converted to frequency by taking the
reciprocal of the repetition rate (see applications on
Determining Frequency).
Time Duration Measurements
To measure time between two points on a waveform, use
the following procedure:
1. Connect the signal to one of the INPUT connectors.
2 Set the vertical Mode switch to display the channel
used.
3. Set the VOLTS/DIV switch to display about four
divisions of the waveform.
EXAMPLE. Assume that the horizontal distance be
tween the time measurement points is five divisions (see
Fig. 2 16) and the TIM E/DIV switch is set to .1 ms with the
magnifier off.
Using the formula:
Time duration
horizontal
distance X
(divisions)
TIME/DIV
setting
magnification
Substituting the given values:
-p* I .• 5 X 0.1 ms
Time duration =
--------
-
-----------
4. Set the TRIGGERING controls to obtain a stable
display.
5. Set the TIME/DIV switch to the fastest sweep rate
that displays less than eight divisions between the time
measurement points (see Fig. 2-16). See Horizontal Sweep
Rate in this section concerning nonlinearity of first and last
divisions of display.
Fig. 2-16. Measuring time duration between points on a waveform.
6. Adjust the vertical POSITION control to move the
points between which the time measurement is made to the
center horizontal line.
7. Adjust the horizontal POSITION control to center
the time-measurement points within the center eight divi
sions of the graticule.
The time duration is 0.5 milliseconds.
Determining Frequency
The time measurement technique can also be used to
determine the frequency of a signal. The frequency of a
periodically recurrent signal is the reciprocal of the time
duration (period) of one cycle.
Use the following procedure:
1. Measure the time duration of one cycle of the wave
form as described in the previous application.
2. Take the reciprocal of the time duration to determine
the frequency.
EXAMPLE. The frequency of the signal shown in Fig.
2-16, which has a time duration of 0.5 milliseconds, is:
Frequency time duration 0.5 ms 2 kHz
Risetime Measurements
Risetime measurements employ basically the same tech
niques as time-duration measurements. The main difference
is the points between which the measurement is made. The
following procedure gives the basic method of measuring
risetime between the 10% and 90% points of the waveform.
1. Connect the signal to either INPUT connector.
2. Set the vertical Mode switch to display the channel
used.
3. Set the VOLTS/DIV switch and VARIABLE control
to produce a display an exact number of divisions in ampli
tude.
i
H i
2-24
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