Tektronix 422, Instruction Manual

Page: 34 / 213

Operating Instructions—Type 422 AC-DC
Then, w ith a T IM E /D IV 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 V A R IA B LE T IM E /D IV
control is set to CAL.
9. M ultiply the distance measured in step 8 by the set­
ting o f the T IM E /D IV switch. If sweep magnification is
used, divide this answer by 10.
This answer can by converted to frequency by taking the
reciprocal o f the repetition rate (see applications on
Determining Frequency).
Time Duration Measurements
To measure time between tw o points on a waveform, use
the following procedure:
1. Connect the signal to one o f the INPUT connectors.
2 Set the vertical Mode switch to display the channel
used.
3. Set the VO LTS/DIV switch to display about fo ur
divisions o f the waveform.
EXAMPLE. Assume that the horizontal distance be­
tween the time measurement points is five divisions (see
Fig. 2 16) and the T IM E /D IV switch is set to .1 ms w ith the
magnifier off.
Using the formula:
Time duration
horizontal
distance X
(divisions)
T IM E /D IV
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 T IM E /D IV 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 o f first and last
divisions o f 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 w ithin the center eight divi­
sions o f the graticule.
The time duration is 0.5 milliseconds.
Determining Frequency
The time measurement technique can also be used to
determine the frequency o f a signal. The frequency of a
periodically recurrent signal is the reciprocal o f the time
duration (period) o f one cycle.
Use the follow ing procedure:
1. Measure the tim e duration o f one cycle o f the wave­
form as described in the previous application.
2. Take the reciprocal o f the tim e duration to determine
the frequency.
EXAMPLE. The frequency o f the signal shown in Fig.
2-16, which has a tim e duration o f 0.5 milliseconds, is:
Frequency tim e 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 o f 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 V O LTS/D IV switch and V A R IA B LE control
to produce a display an exact number of divisions in ampli­
tude.
i
H i
2 -2 4
{