Data Translation DT3155, User Manual

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Principles of Operation
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Video Area
The total video area is a complete set of horizontal and vertical input
lines from which you extract the active video area and the frame
within the active video area. The total video area includes all parts of
the signal, including nonvisual portions such as horizontal and
vertical blanking information. (Blanking information is the data not
included in the active video area; it contains sync and other
information.)
The total video area is as wide as the total pixels per line (the entire
area between two consecutive horizontal sync signals) and as tall as
the total lines per field (the entire area between two consecutive
vertical sync signals).
You can calculate the total pixels per line as follows:
You can calculate the total lines per field as follows:
Active Video Area
The active video area floats in the total video area. The active video
area is defined as that part of the incoming signal that contains valid
video data (not blanking or sync information). Therefore, the active
video area consists of the visible portion of those lines containing
visible pixel data. Its top is set by the first active line, its left side is set
by the first active pixel, it is as wide as the active pixel count, and it is
as tall as the active line count.
For more information about the horizontal and vertical signals that
comprise the total video area and the parameters you can set to
specify the active video area, refer to the following sections.
Total pixels per line
pixel clock frequency (MHz)
horizontal frequency (kHz)
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Total lines per field
horizontal frequency (kHz)
vertical frequency (Hz)
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