MOTU 828es, Руководство пользователя

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M O T U A U D I O T O O L S
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Type I recognition provides the most stable
display of the waveform. It is the most resistant to
change. Louder transients, such as those produced
by a snare drum, are not displayed inside of the
waveform window. Type I is best for observing the
shape of a signal produced by a synthesizer or
observing the tone of a guitar through a chain of
pedals.
Type II recognition is less resistant to change. It
will include loud transients within the waveform
recognition window. Type II is better for
observing percussive music where the beat itself is
to be centered within the waveform window.
Trigger
When the Trigger (Figure 10-12) is not enabled
(the Trigger menu is set to None ), the graph
updates based on time: after every n samples of the
monitored audio signal, the most recent samples
are displayed. When the Trigger is enabled (set to
any mode other than
None ), the graph updates in
response to specific conditions in the signal. The
Trigger section defines that criteria and how the
graph will display the events that match.
Figure 10-12:
Trigger settings.
Criteria
The criteria checkboxes (Figure 10-12) 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 indicator
Trigger menu
Criteria check boxes