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ServSwitch Wizard VGA/USB
724-746-5500 | blackbox.com
Page 24
What is skew and why is compensation needed?
The twisted pair cabling supported by the ServSwitch Wizard VGA-USB modules consists of four pairs of wires per cable,
three of which are used to convey red, green and blue video signals to the remote video monitor. Due to the slight difference
in twist rate between these three pairs, the red, green and blue video signals may not arrive at precisely the correct times.
This is visible as separate color shadows on high contrast screen images. This effect is particularly apparent when using higher
screen resolutions and some types of category 5e cables.
The video compensation system within the remote module allows you to delay or advance the timing of any of the color
signals so that they all arrive at the monitor at the correct times.
Take a close look at a locally connected display. From left to right, groups of pixels are usually arranged in the order: R / G
/ B and the signals must arrive in the correct order to obtain the optimum screen image. The skewtest.exe pattern (on the
supplied CD-ROM) in particular helps to highlight the pixel layout by showing very narrow horizontal and vertical lines.
Test images while compensating
For best results while adjusting video compensation, arrange a combination of elements
on the remote display. We suggest the following:
• Roughlyhalfofthescreentodisplaystandardoperatingsystemcoloriconsonamid-
green wallpaper.
• Aquarterscreenoftheskewtest.exepattern(availableonthesuppliedCD-ROM).
• Aquarterscreenofstandardblacktextonawhitebackground.
Note: You need to set all of the above BEFORE entering video compensation mode
because the USB keyboard will be isolated from the computer.
3.4 Video compensation
The ServSwitch Wizard VGA-USB modules include a video compensation system that allows you to get the best results from your
remote video display(s). Using this special mode you can configure:
• Cable type - Select the type of link cable used.
• Cable length - Enter the length of the link cable.
• Video gain - Alter the signal gain for the image.
• Color skew - Adjust the timing of each color to fine tune the image.
• Expert mode - Please contact Black Box technical support for details.
The
skewtest.exe
test pattern
showing its RGB
crosses. In this case,
the green signal can be
seen out of line with the
other two colors.