RMV Operations Manual Revision Copyright illunis LLC, 2014
Page 71
4.8.1: Exposure:
ADC: Gain
4.8.2: Exposure:
ADC: Offset
The ADG gain range is from 0 to 1023 counts which represents a gain of 2 to 36dB. The pre-gain of the
CDS stage adds an additional 4dB of gain resulting in a range of 6 to 40dB. The gain curve follows a
linear-in-dB characteristic.
ADC gain can be calculated with the following equation.
Gain (dB) = 5.1 + (0.0359 * code)
Where code is the range of 0 to 1023.
The optical black clamp loop removes residual offsets in the signal chain to track low frequency varia-
tions in the CCD’s black level. During the optical black (shielded) pixel interval on each line, the ADC
output is compared with a fixed black level reference, set by the offset value. The offset value can be
programmed between 0 LSB and 255 LSB. The resulting error signal is filtered to reduce noise, and the
correction value is applied to the ADC input through a D/A converter. The optical black clamp is turned
on once per horizontal line.
