Tektronix 2221A, User Manual

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Displaying.Signals
Current
Data
Capturing Random Events
Infrequent or random events can be “captured” by using the single-sweep
trigger mode in combination with either the Scan or the Roll mode. These
two modes are called “Scan-roii-scan" and “Triggered Roll" respectively.
These two modes are only available at sweep speeds of 0.1 ms and slower.
Triggered Roll:
F I S tepl: Set the Trigger Mode to P-P AUTO.
f"1
Step 2: Press the Acquisition TRIG POS button to select the position on
the screen where the trigger event (“T”) will be displayed.
H Step 3: Press the Setup ACQ button to call up the Acquisition Menu.
F I Step 4: Select Roll and press the ACQ menu button again to exit the
menu.
f l Step 5: Press the SGL SWP button.
Note that the trace moves across the screen continuously from right to left.
Also, the READY light is on indicating the oscilloscope is waiting for a trigger
signal. (If the READY light is not on, press the SGL SWP button again.)
When the trigger event occurs, the acquisition continues across the screen
from right to left until it reaches the trigger point indicator. The oscilloscope
then records the event coincident with the trigger, completes the record, and
freezes the display.
Scan-roll-scan:
f~l S tepl: Set the Trigger Mode to P-P AUTO.
f l Step 2: Press the Acquisition TRIG POS button to select the position on
the screen where the trigger event (“T”) will be displayed.
f l Step 3: Press the Setup ACQ button to call up the Acquisition Menu.
3-12 In Detail