GRASS VALLEY XIP-3901, User Manual

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Configuring the XIP - 3901 - UC / -DC / -FS Applications with iControl
Clean Switch Regions and Examples
To determine the limits of a clean switch region, you must know the input’s line length in
μs. The first region is delimited by +½ line and ½ line of the reference. For example, with an
HD (1080i59) signal, the line length is 29.65 μs and so the first region lies between 14.83 μs
and 14.83 μs. Other regions can be found by adding or removing a multiple of line length to
the two boundaries.
Example:
For an HD (1080i59) input signal, we have these clean switch regions:
• 1 line and 14.83 μs to 0 line and 14.83 μs;
• 0 line and 14.83 μs to 0 line and 14.83 μs;
• 0 line and 14.83 μs to 1 line and 14.83 μs; etc.
Practical examples:
Example 1:
We have two HD (1080i59) sources, one that indicates an offset of 10 μs with
respect to the reference (A) and the other an offset of 20 μs (B). We know that a clean switch
region limit is present at ½ line, which corresponds to 14.83 μs. We can now determine that
this switch will not be clean, because the two sources are on opposite sides of the limit and
are therefore not in the same clean switch region.
Figure 7-17:
Clean Switch Regions Example 1
Example 2: We have two HD (1080i59) sources, one that indicates an offset of 30 μs with
respect to the reference (A) and the other an offset of 20 μs (B). We know that a clean switch
region limit is present at +½ line and another one at ½ line plus one line. These correspond
to 14.83 μs and 44.48 μs. We can now determine that this switch will be clean, because the
two sources are inside the same clean switch region.
-10μs
-14.83 μs
-20μs