Data Translation DT3155, User Manual

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Chapter 2
8
Video Input Channels
The DT3155 supports monochrome video input from one of four
software-selectable video channels (0 to 3). The channel is
software-selectable.
By default, channel 0 is selected.
Chrominance Notch Filter
If the video signal has chrominance information on it, as is the case
with the NTSC/RS-330 and PAL video formats, you can use software
to apply an AC chrominance notch filter to remove the chrominance
information. The chrominance notch filter for 60 Hz is set to
3.58 MHz, while the chrominance filter for 50 Hz is set to 4.43 MHz.
By default, no filter is selected.
Black and White Levels
Black level is defined by DT-Open Layers as the voltage below which
all other voltages are digitized to black. Conversely, white level is
defined as the voltage above which all other voltages are digitized to
white. For ease of use, both of these voltages are measured at the
camera's output.
The DT3155 supports a minimum black level of
+
1.275 mV and a
maximum black level of 306 mV, in increments of 1.195 mV. By
default, the black level is
+
53.855 mV for 60 Hz and 1.275 mV for
50 Hz.
The DT3155 supports a minimum white level of 351
.1
mV and a
maximum white level of 1.009 V, in 255 steps of 2.58 mV. By default,
the white level is 714.8 mV for 60 Hz and 700 mV for 50 Hz.