Tektronix 2247A Operator's Manual page 68

Basic Applications
NOTE
For Increased resolution of the phase measurement, the
sweep many be Increased and both cursors repositioned to
the measurement points (see Figure 5-SC). The X10 MAG
feature may also be used In a similar manner by placing the
measurement points at the center vertical graticule line
before pressing the X10 MAG button (you may wan( lo re-
duce the A SEC/DIV setting prior to turning on the X10
MAG feature).
Frequency and Period Measurements
The 2247A has an eight-digit frequency counter/timer built In to make
accurate frequency and period measurements quickly and easily. Use the
procedure for making time-difference measurements to get a stable dis-
play. Then press the COUNTER/TIMER button and select the desired
measurement from the menu. The frequency (or period) will be displayed In
the upper right corner of the crt.
If you need to make a frequency or period measurement of a selected
portion of a complex waveform, you can make a gated measurement. Set
up the Instrument as before to get a stable display. Then use the followlng
additional procedure:
1. In the GATED MEASMT menu select the desired measurement.
2. Adjust the B INTEN and A INTEN controls to provide a good viewing
contrast of the Intensified zone that appears on th~ A Sweep trace.
3. Use the
I+-
OR DELAY control to position the Intensified zone to the
area of Interest on the waveform to be tracked.
4. The width of the gated zone Is controlled by the-+! control. Adjust
the width to define the gated measurement zone.
5. The frequency (or period) value that appears In the upper right
corner of the crt Is the value that occurs within the zone.
Time Delay Measurement
When using ALT Horizontal Mode, the TIME measurement mode provides
two Intensified zones on the A trace. There are also two associated B
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2247 A Operators
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Basic Applications
delayed traces matching the intensified zones. A direct readout of the delay
difference between the two zones is dis played in the top line of crt readout.
use the following procedure steps as a guideline for making delta-time
delay-time measurements.
1 . Apply the signals that measurements are tG be made on to the vertical
Input connectors. Turn on the VERTICAL MODE channels needed to
display the signals.
NOTE
Probes are the most convenient for in-circuit testing, and
coaxial cables are the most convenient when using signal
generators as the source of the test ·signals. Use correct
terminations to match the output impedance of any signal
generator used. The CH 1 and CH 2 vertical channels pro-
vide the widest range of signal conditioning, and the CH 3
and CH 4 vertical chan'.1~/s are most useful for digital signal
levels.
2. Use a VOL TS/DIV setting that produces a usable vertical display ampli-
tude for viewing ease; use an A SEC/DIV ~etting that produces two to -
five repetitions or cycles of the signal across the graticule area.
.., J
NOTE
When viewing multiple traces, it is bes' t to limit the vertical
amplitude to about two divisions so that -good · trace sepa-
ration may be obtained In the display.
3. Switch the Horizontal MODE to ALT. Advance the SEC/DIV setting at
least one position to obtain a faster B SEC_ I DIV setting.
4. Set the B Trigger MODE to RUNS AFTER.
5. Press the TIME button, then select the
I+-
SEC
-+I
menu choice. This
produces two Intensified zones on the A Sweep trace and two alternate
B Delay Sweeps. Use the TRACE SEP and VERTICAL POSITION con-
trols to position the B Delay Sweeps vertically in the graticule area for
ease of viewing the separate traces.
2247 A Operators
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