Wohler AMP1-VS, Руководство пользователя

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© 2004 Wohler Technologies Inc. ALL rights reserved
19
AMP1-VS and AMP1-VSA User Manual P/N 821613 , Rev- B
Level Meter Rear Panel 6-Position DIP Switch Settings
Section 3: Technical Information
Line Level (Auto) Calibration, Reference Level, and Display Mode
This 6-section DIP switch sets the Line Level Calibration , Reference Level , and PPM/VU Display Mode . See below.
Line Level (Auto) Calibration:
The unit is calibrated at the factory. To recalibrate:
1) Turn on the power.
2)
Apply the desired reference level (nominal 0) signal to all channels.
3) Make sure the Reference Level DIP sections ( 2 and 3 ) are set to the nearest level of the input signal being applied for
calibration (i.e., 0, +4, +6 or +8). The user should make sure that the signal applied to all four channels is within +/- 4 dB
of the reference level selected by DIP switch sections
2
and
3
.
4)
Place DIP section
1
in the
DOWN
position.
5) Wait 10 seconds. The unit will remove the previous calibration and the new calibration will be applied.
6)
Place DIP section
1
in the
UP
position and return unit to service.
7) Only ONE auto-calibration attempt may be made for each cycling of AC power to the unit. Once the Line Level
Calibration DIP switch has been placed in the CAL position, it is necessary to cycle the power before that DIP switch will
be functional again, EVEN if a calibration attempt was unsuccessful.
If one wishes to calibrate again, turn off the power to the unit and repeat steps 1 through 6.
Reference Level:
DIP switch sections
2
and
3
determine the
Reference Level
, which adjusts the level of the input signal and the resultant level
displayed on the LED bargraphs. Factory setting is +4 dB . See DIP switch diagram below for settings.
Bargraph Display Mode:
DIP switch sections
4
and
5
determine how peak levels are displayed for the associated meters on the front panel. There are
four possible settings;
VU Only
,
VU-PPM Floating Segment
,
PPM Only
, and
PPM-PPM Floating Segment
. The
VU
Only selection has a VU floating segment when a Peak Hold value is selected using the Internal 10-Position DIP Switch
Module (see page 23 ). The factory default setting is VU-PPM Floating Segment . See diagram below for DIP settings.
Meter Calibration NOTE:
For more accurate indication of signal levels, meters are tuned to effect a “rounding” function, which occurs
BETWEEN the thresholds of any two bargraph segments. This means the level meter zero LED segment will turn on at
one-half the smallest spacing between LED segments (mid-scale resolution)
before that segment's scale indication.
Below are the offset amounts.
26-Segment Meters: The "rounding offset" is
0.5 dB
for the
Extended VU
(standard),
Digital
,
Nordic
,
BBC
, and
DIN
scales. It is
0.25 dB
for the
VU
scale.
Example:
Using the standard
Extended VU
scale, a meter calibrated for a
+4 dBu
nominal level will actually turn the zero
LED segment of the level meter on at
+3.5 dBu
(and so all segments will turn on at
0.5 dBu
before that segment’s silk-
screened scale indication).
Calibrate
Operate
+6 dB
+8 dB
1 2 3 4 5 6
Meter Calibration Reference Level Display Mode
1
2
Note: Position-6 of DIP switch is NOT used.
AMP Series Level Meter Rear Panel DIP Switch Settings
3
3 1 2 6 5 4
+4 dB
0 dB
x
x
VU - PPM
Floating Segment
2 1
PPM-PPM
Floating Segment
5 3 4 6
VU Only
PPM Only
5 4
x
See the
Level Meter Internal 10-Position DIP Switch Settings
diagram on page
20
for separately setting the
Peak Hold
and
PPM Ballistics characteristics.