B. Source
Choose a single trigger source to correctly display the timing relationships between
two channels. Choose the channel with the lowest-frequency signal to avoid
ambiguous displays.
With VERT MODE TRIGGER SOURCE and either P-P AUTO TRIGGER MODE or
CHOP VERTICAL MODE, the triggering signal is the algebraic sum of the Channel 1
and Channel 2 input signals.
Use a composite trigger source only to compare asynchronous signals. To generate a
composite trigger: select VERT MODE TRIGGER SOURCE, BOTH-ALT VERTICAL
MODE, and any TRIGGER MODE except P-P AUTO.
C. Coupling
For signals with strongly interfering components, HF Reject and LF Reject coupling
give added selectivity. When AC coupling is selected, triggering continues as the dc
level of the signal changes.
D. Slope
Use the SLOPE control to select either the rising (/) or the falling (\) edge of the signal
to trigger the sweep.
E. Level
The LEVEL control gives you complete freedom to choose the most appropriate
threshold voltage on a signal to initiate sweeps whenever any trigger mode except P-
P AUTO is selected.
F. Holdoff
With irregular signals such as bursts, the HOLDOFF setting can improve display
stability. Also, if the signal has a fixed pattern of variation from cycle to cycle, some
modes of the signal may be omitted from the display. Changing the HOLDOFF setting
can force the instrument to display all the modes of the signal. Normally, the
HOLDOFF control should be set at MIN.
7. Calibration Summary
Calibrate the voltage (vertical) and time (horizontal) scales of the scope as follows:
1) Connect a wire from the PROBE ADJUST to CH1 or CH2.
2) Adjust the trace using the position controls until the square wave is located at
aconvenient position on the screen.
3) Measure the height of the square wave in volts. You should find that it is 0.5
Voltspeak-to-peak so that the 0.1 V/div scale is appropriate. Make certain that the
Variable
(CAL) knob is in its calibrated (detent) position. If the square wave does not measure
0.5 V ask your TA for help.
4) Measure the period of the square wave in seconds. Use a time scale setting that
displays several cycles of the square wave. In order to obtain the best accuracy,
measure the time for several cycles and divide by the number of cycles. Again make
certain that the Variable (Cal) knob for the horizontal sweep (SEC/DIV) is in the
calibrated (detent) position. The period should be 10~
3
seconds.
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