Controls, Connectors, and Indicators
(36) MODE B u tto ns (Up- and D ow n-A rrow s) and In d ica to rs—Select
the operating modes of the A and B trigger systems. Pressing the
Up-/Down-Arrow buttons selects the operating modes as shown by
the TRIGGER MODE lights.
Selections available for the A Trigger (A/B SELECT button lit) are:
AUTO LEVEL, AUTO, NORM, TV LINE, TV FIELD, and SGL SEQ.
Selections for the B Trigger (A/B SELECT button not lit) are: AUTO
LEVEL, RUNS AFTER, NORM, TV LINE FROM A SOURCE.
A T r ig g e r M o d e s
AUTO LEVEL—Automatically sets the range of the Trigger LEVEL
control to the peak-to-peak limits of an adequate A Trigger source
signal and triggers the sweep.
Autoleveling is repeated if triggering is lost, if the TRIGGER LEVEL
control is rotated to either end stop, or if AUTO LEVEL TRIGGER
MODE is selected again. AUTO LEVEL mode is useful for quickly
locating and maintaining an appropriate triggering level.
NOTE
When in AUTO LEVEL or AUTO triggering, the A sweep
free-runs to produce a baseline trace when the A trigger
source signal amplitude is too low or the frequency is below
10 Hz, Switch to NORM triggering if the repetition rate is
too slow for autoleveling.
AUTO—Triggers the same as the NORM Trigger MODE when an ade
quate trigger signal is applied. Flowever, the A sweep free-runs to
display a baseline trace when there is no trigger signal or the
frequency is below 10 Hz. The set triggering level changes only when
the TRIGGER LEVEL control is adjusted to a new level setting.
NO R M —Triggers the A sweep when the A Trigger LEVEL control is
set within the peak-to-peak limits of an adequate trigger signal. When
the A sweep is not triggered, no baseline trace is displayed.
2245A Operators
2-13
