GRASS VALLEY 8920ADC -, Instruction Manual

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14 8920ADC Instruction Manual
Configuration
Output Level Adjustment
To correctly adjust the 8920ADC for your digital application, determine
your maximum operating level and set the Coarse Level gain jumpers on
the module circuit board as described below. This is the level above which
digital clipping occurs.
Example Maximum Operating Level Setting
A setting of +24 dBu is a common maximum level. Using +24 dBu as the
maximum level, refer to
Table 4 to select the lowest input level range that
includes the maximum level of +24 dBu. Select the Coarse Level Setting pin
4 to 5 jumper setting (refer to
Figure 5 on page 18 ) because it is the highest
level supported by that range and requires the least amount of gain to bring
+24 dBu up to 0.0 dBFS level. This will give the best signal-to-noise ratio
that the system can deliver.
Setting Maximum Operating Level
Once you have determined the proper coarse level jumper setting, perform
the following steps:
1.
Set the Function Rotary Switch (SW1) on the front of the module circuit
board to the position marked 0 as shown at left.
2.
Remove the module from the frame and set jumpers on JP5 and JP6 to
the jumper setting that you determine using
Table 4 .
3.
Return the module to the frame.
Using Level Gain Toggle Switches
Note The toggle switches change input levels by increments of approximately
0.1 dB when held momentarily. Holding the switch up or down for about 1
second activates a continuous change mode that ramps the change rate from
about 0.1 dB per second to 0.6 dB per second. The yellow CONF LED will
flash slow (0.1 dB rate) or fast (0.6 dB rate) to indicate the change rate.
Table 4. Jumper Coarse Level Settings for 0.0 dBFS Output
Input Level JP5/JP6 Jumper Position
12 to 16 dBu Pins 1 and 2
16 to 19 dBu Pins 2 and 3
19 to 25 dBu Pins 4 and 5
25 to 28 dBu Pins 5 and 6
012
34
5
67
89AB
C
D
EF
Default
Position