Waveform recognition, Trigger – MOTU UltraLite-mk3 - Hybrid FireWire/USB 2.0 Audio & MIDI Interface User Manual

Page 90

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C U E M I X F X

90

In

Min/Max

mode,

Min

and

Max

set the smallest

and largest displayed amplitude.

Waveform Recognition

The Waveform Recognition option searches
through new audio data looking for a waveform
which most resembles that which was previously
displayed. The region where this takes place is a
small window around the line marking time equals
zero, denoted by the extra vertical graph lines
surrounding it. There are two kinds of waveform
recognition available: Type I and Type II.

Figure 10-36: Waveform Recognition menu

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 10-37) 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 10-37: Trigger settings

Criteria

The criteria check boxes (Figure 10-37) determine
the conditions that the trigger is looking for and
where it will look for them.

The

Left

check box causes the condition to be

looked for in the left channel of the signal; likewise,
the

Right

check box 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

check boxes determine the slope

of the event. When the

Pos

check box is enabled,

the trigger will look for an event where amplitude is
increasing; likewise, enabling the

Neg

check box

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).

Trigger indicator

Trigger menu

Criteria check boxes

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