MOTU UltraLite-mk4, Руководство пользователя

Страница: 67 / 94

M O T U A U D I O T O O L S
67
Figure 9-13: Trigger settings.
Criteria
The criteria checkboxes (Figure 9-13) determine
the conditions that the trigger is looking for and
where it will look for them.
The
Left
checkbox causes the condition to be
looked for in the left channel of the signal; likewise,
the
Right checkbox looks for the condition in the
right channel. One or both of these can be enabled
simultaneously. If neither is enabled, the criteria
will not be found because the trigger is not looking
at any audio signal.
The
Pos
and
Neg
checkboxes determine the slope of
the event. When the
Pos
checkbox is enabled, the
trigger will look for an event where amplitude is
increasing; likewise, enabling the
Neg checkbox
tells the trigger to look for an event where
amplitude is decreasing. One or both of these can
be enabled simultaneously. If neither is enabled,
the criteria will not be found because the trigger is
not looking for any particular kind of event.
The
Level
setting defines the amplitude threshold
that the trigger is looking for. The Level is indicated
on the graph by a blue horizontal line (or two blue
horizontal lines, if
Magnitude
is enabled). Events
which cross this threshold using the enabled
slope(s) in the enabled channel(s) will activate the
trigger. The response of the trigger is set by the
Trigger mode (see “Trigger modes”, below).
Enabling the Magnitude checkbox tells the trigger
to look for both positive and negative Level values,
regardless of whether the Level value is positive or
negative. For example, if Level is set to +0.500 and
Magnitude is enabled, the trigger will look for both
+0.500 and -0.500. You will see a second blue line
appear in the display when
Magnitude
is enabled to
denote the second value.
Holdoff
Holdoff
defines a time interval during which the
oscilloscope does not trigger. The most recent trace
will be displayed during that period. When the
period is over, the trigger is “re-armed’, i.e. it will
begin looking for the criteria again.
Click and drag this value up or down to set it, or
double-click to return to the default value.
Trigger modes
The Trigger menu (Figure 9-13) provides four
modes:
Trigger indicator
Trigger menu
Criteria check boxes
Trigger mode What it does
None The Trigger is not active; this is the default mode.
The incoming audio signal will be displayed con-
tinuously as audio is received.
Auto The display is always updating, but when the con-
dition is met, the trigger event will be displayed
centered around the line marking time equals
zero.
Normal The display updates only when the condition is
met; the last trace will be displayed until the next
matching event is found.
Single
Sweep Similar to Normal mode, but the last trace will be
displayed until you manually arm the trigger by
clicking the Trigger indicator (Figure 9-13 on
page 67) or by pressing the spacebar.