VTG 300/300R • OperationVTG 300/300R • Operation
Operation, cont’d
2-17
Audio Testing Features
The VTG can output from among six different audio signal
formats. The audio level can also be selected from a range of
levels available for each audio format.
Depending on the audio signal format, the audio frequency may
be selected from a range of values.
See the Front Panel Features section in this chapter for button
descriptions.
Selecting audio signals
The following table summarizes the six audio signal formats
available through the VTG. Pressing the Signal button
repeatedly will scroll through the signals and light the green
LED indicators.
AUDIO
SIGNAL FORMAT
DESCRIPTION
Pink Noise
White Noise
Sine Wave
Random noise that has constant energy per octave.
Used in loudspeaker testing and calibration.
Random noise that has an equal energy distribution
across all frequencies between 20 Hz and 20 kHz.
Used in detecting distortion. The frequency can be set
from 20 Hz to 20 kHz (in 1/3 octave steps).
Square Wave
Polarity test
Swept Sine Wave
Used in amplitude and phase vs. frequency measurements.
The frequency can be set from 20 Hz to 5 kHz.
Proprietary waveform used in verifying the polarity of audio
wiring.
Varies the frequency of a sine wave signal continuously from
20 Hz to 20 kHz. Used to detect driver defects and
mechanical sources of distortion.
Setting the audio level
The audio level for each audio signal type is selected from a
range of values using the or Level buttons. The following
table lists the range of values.
Audio Audio Level Range Audio Level Range
Signal Format (in 2 dBu increments) (in 2 dBV increments)
Pink Noise -8 dBu to -56 dBu -10 dBV to -58 dBV
White Noise +6 dBu to -72 dBu +4 dBV to -74 dBV
Sine Wave +6 dBu to -72 dBu +4 dBV to -74 dBV
Square Wave +6 dBu to -72 dBu +4 dBV to -74 dBV
Polarity Test -18 dBu to -72 dBu -20 dBV to -74 dBV
Swept Sine Wave +6 dBu to -72 dBu +4 dBV to -74 dBV
2-16
Power
on
60-543-01
FW Ver. 1.00
EXTRON
VTG 300
Button Lock
Enabled
Button Lock
Disabled
SIGNAL
TEST
PATTERNS
Simultaneously press both buttons for
two seconds to enable button lock mode
SIGNAL
TEST
PATTERNS
Simultaneously press both buttons for
two seconds to disable button lock mode
VGA 31.5kHz
640x480 @60
3 sec.
3 sec.
3 sec.
AUDIO LEVEL
-10dBu 245mV
AUDIO FREQ.
800 Hz
Figure 2-10 — Button Lock mode
When the VTG is in Button Lock mode and powered off
and then on again, the VTG will still remain in Button
Lock mode until that mode is disabled.
To disable Button Lock mode, simultaneously press and hold the
Signal and the Test Patterns buttons for two seconds. When
Button Lock mode has been disabled, the message “Button Lock
Disabled” is displayed for 2 seconds before the VTG returns to
the default cycle.
(6 pages)
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