Grass Valley 8901 - Manual (Page 27)

8901/8902/8906 Instruction Manual 27
Functional Description
Functional Description
Refer to the block diagram in Figure 14 for the following functional
description.
Note Feature functionality depends on the module type. Refer to Table 1 on page 7
for a feature comparison between module types.
Input Amplifier
The 8900 Analog Video DA module buffers the incoming video before it is
fed to the equalizer section. The common mode rejection ratio (CMRR) is
set at the factory by balancing the input bias between the differential
inputs. The AC/DC restorer and clamp circuit correction voltage is fed
back to the buffer for the final stage of DC restoration.
Figure 14. 8900 DA Functional Block Diagram
Equalizing Amplifier
The equalizing amplifier is formed by two video op-amp circuits working
in parallel. Equalization is accomplished by balancing between the two
amplifier’s values with a front edge EQ adjustment. On-board jumpers
must be set to select the cable length EQ range from either 0–500 ft. or
500–1000 ft.
DC Restore/
Clamp (8906)
Factory
calibrated
CMRR
DC Restore/Clamp
correction voltage
EQ
Adjust
White
Clip
Adjust
Gain
Adjust
Microcontroller
(8906)
Remote control/monitoring
Input
Buffer
Equalizer (8902 and 8906)
Output
Drivers
Analog
Outputs
8271_09
8906