Kramer Electronics VP-200xl - Manual (Page 10)

KRAMER ELECTRONICS LTD. 9
Computer based graphics is used in video production, in presentation
applications, for education purposes and more. It is frequently necessary to
distribute PC graphics from one source to one or more acceptors. Figure 2
describes a typical VGA/XGA distribution where one source is distributed to
different acceptors inputs.
Perform the following steps:
1) Connect VGA/XGA source to the input of the distributor.
2) Connect XGA/VGA acceptor/s to the output/s of the distributor.
3) Operate the distributor, source and acceptors.
6.2 Handling signal losses
High-resolution VGA/XGA signals are very sensitive to cable length and quality.
Long and/or low quality cables tend to degrade the signal quality, resulting in
image “smear” and fine-detail loss, as well as signal level attenuation.
The VP-200xl allows the user to handle and correct those problems, using the
built-in amplifiers in the machine. Using very high quality cables of 1-2 meter
length will not require and adjustment, even when the signals involved are
UXGA signals (1600x1200 resolution). Standard cables will allow at that length
resolutions of 640x480 and sometimes 800x600. If longer standard cables are
used, even at those low resolutions, cable compensation is needed.
Even with the best available compound cables (several thin cables in one sleeve)
at SXGA resolution (1280x1024) or UXGA resolution, over five meters there will
be apparent signal depreciation. In low quality cables, those high-resolution
signals will be affected at distances even shorter than one meter.
The VP-200xl has two user adjustable controls, which should be used as
following:
1. If you see a signal detail loss (resulting in image “smear” and blurring on the
screen) turn carefully the EQ. control knob clockwise, until the lost details
will reappear and original resolution will be resumed. This control gradually
compensates for the losses incurred within the cable due to its design or
length. Bear in mind though that beyond a certain distance, dictated by the
cable stray-capacitance (cable measure of quality) losses cannot be
completely recovered. In this case, it is advised that a lower graphics
resolution should be chosen or the cable should be replaced with a better one.
2. If the whole signal is being attenuated, the image on the screen will become
darker. In this case, turn carefully clockwise the LEVEL control knob.
Overdoing this control will result in image “burnout” and might damage the
signal receiver, therefore, adjusting this control should be done very
carefully. Between the EQ. control (that should be adjusted first) and the
LEVEL control, much of the lost signals maybe restored.