Applications; Time-Interval Measurements; Period And Frequency Measurements - Tektronix 7B80 Instruction Manual

Operating Instructions-7B80
APPLICATIONS
The following information describes procedures and techniques for making basic time measurements with the time-base unit
installed in a Tektronix 7700-, 7800-, or 7900-series oscilloscope. These procedures provide enough detail t o enable the
operator to adapt them to other related time measurements. Contact your Tektronix Field Office or representative for
assistance in making measurements that are not described in this manual.
TIME-INTERVAL MEASUREMENTS
Since time is a function of the sweep rate and the horizon-
tal distance (in divisions) that the sweep travels across the
graticule in a calibrated-sweep oscilloscope system, the time
interval between any two points on a waveform can be
accurately measured. The following procedures provide
methods to measure some of the more common time-
related definable characteristics of a waveform such as
period, frequency, rise time, fall time, and pulse width. The
procedure for each of these measurements is essentially the
same, except for the points between which the measure-
ments are made. The time interval between any two
selected points on a displayed waveform can be measured
with basically the same technique.
Period and Frequency Measurements
7. Measure the horizontal distance in divisions over 1 com-
plete cycle of the displayed waveform (see Figure 1-61.
8. Multiply the horizontal distance measured in Step 7 by
the TIME/DIV switch setting. (Divide the answer by 10 if
sweep magnification is used.)
Example: Assume that the horizontal distance over 1 com-
plete cycle i s 7 divisions, and the TIMEIDIV switch setting
is .1 ms (see Figure 1-6).
Using the formula:
Period
=
Horizontal distance X TIMEIDIV setting
Magnification
Perform the following procedure to measure the period and
determine the frequency of a displayed waveform:
Substituting values:
1. Install the time-base unit in a mainframe horizontal
Period
=
7 X 0.1 ms
=
0.7 millisecond
compartment (either A or B horizontal in a four-compart-
1
ment mainframe).
2. Connect the signal to be measured to the vertical unit
input.
3. Set the mainframe horizontal- and vertical-mode switch-
e s to display the time base and vertical units. (Check that
the time base VARIABLE (CAL IN) control is pushed in
and the HOLD OFF control i s in the MIN position.)
4. Set the TRIGGERING switches and LEVEL control for
a stable display (see General Operating Information for
selecting proper triggering).
5. Set the vertical deflection factor and position control
for about a 5-division display, vertically centered on the
graticule.
6. Set the TIMEIDIV switch and POSITION control for 1
complete cycle displayed within the center 8 graticule divi-
Fig. 1-6. Measuring the period and determining the frequency of a
sions as shown in Figure 1-6.
displayed waveform.
Scans by ArtekMedia O 2006