User guide

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Skew compensation adjustments (AV201R only)
The twisted pair cabling used to
link the AV modules consists of four
pairs of wires per cable. Three of
these pairs are used to convey the
red, green and blue video signals.
Due to slight differences in twist
rate between the wire pairs, the
red, green and blue video signals
may not arrive at precisely the
same time. This effect is visible as
separate colour shadows on high
contrast images and is particularly
apparent when using higher screen
resolutions over long distances and
also when using certain types of
category 5e cables.
Skew compensation adjustments are made using two rotary dials, the first
affects the relationship between the green and blue colour signals (SKEW
GB) while the second (SKEW RG)
operates similarly on the red and
green signals. Each dial delays one
of its stated colours in relation
to the other. By using both dials
it is possible to correctly align all
three colours. The effects of skew
are easiest to view and adjust
when distinct red, green and blue
elements, in close proximity, are
present within the screen image.
An appropriate test pattern is
suppliedontheAVCD-ROMor
alternatively you can create your own test pattern as discussed opposite.
NOTE: Both video outputs are equally affected by your skew adjustments.
SKEW
GB
SKEW
RG
BRIGHT
SHARP
ADDERLINK
SKEW RG dial
SKEW GB dial
To create a skew test pattern
1 Run any image creation/editing application, such as the Paint program
supplied with Windows.
2 Using the image application create three
stacked horizontal rectangles (one red, one
green and one blue) that fill the width of
the screen.
3 Draw a vertical black line down across
the coloured bars and then repeat this
vertical line at intervals along the width
of the coloured bars. These lines create
breaks across the colours and give you
more opportunities to view the horizontal
position of each colour relative to the others.
To display the supplied skew test pattern
1 InsertthesuppliedAdderCD-ROMintothe
CD player of the computer.
2 Within Windows, use the My Computer
option (usually available as a desktop icon
or within the Start menu) to view the
contentsoftheCD-ROM.Double-clickthe
SkewTest entry to display the standard test
pattern.Ifnecessary,selecttheFull screen
option from the File menu to maximise the
application window so that the image fills
the screen.
The screen will show a series of fine red,
green and blue crosses which should all
be in line, vertically and horizontally- skew
affects the horizontal placement of the
colours.
1 2345678
8
6
5
2
8
6
5
2
Data signal
Red
video signal
Green
video signal
Blue
video signal
7
3
4
1
7
3
4
1