Installation guide

FlipTop Touchpanel Computer Center Crestron QM-FTCC-TPS4
CresCAT-QM Cable
NOTE: Do not untwist the two wires in a single twisted pair for more than
1/3-1/2" (0.84 – 1.27 cm) when making a connection. The twists are critical to
canceling out interference between the wires.
The QuickMedia transport mechanism performs delay compensation on each video
input to compensate for signal skew, and frequency/bandwidth compensation for
cable length. Signal skew occurs when part of the signal is delayed with respect to
other signal components. The amount of skew largely depends on the length and
design of the wire. Because CAT5 consists of twisted pairs that are twisted together
in the cable, unequal wire lengths are created.
The maximum aggregate cable length from QM transmitter to QM receiver is limited
by the loss of bandwidth over long distances and the amount of available skew
compensation. A cable rated at 22 ns (nanoseconds) of skew per 100 meters (328 ft.)
means that a cable will have no more than a 22 ns difference between the fastest and
slowest RGB signals over 100 meters of cable.
To determine the allowable maximum length of installed cable, the installer must
first perform a calculation based on the skew rating of the cable. The use of low-
resolution signals may allow increased cable length but must be tested with the
sources to be used. To ensure sufficient bandwidth to support signal resolutions up to
1600 x 1200, the maximum aggregate cable length should not exceed 328 feet.
Skew compensation is primarily relevant to RGB sources; however, any/all video or
VGA signals may experience a loss of quality over very long lengths of cable. This
phenomenon is due to the added resistance and capacitance of longer cable lengths,
and is not particular to either Crestron and/or QuickMedia systems.
The total accumulated skew from QM transmitter to QM receiver must not exceed 22
ns. Crestron recommends a cable with a rating of less than or equal to 22 ns over its
entire length. For example, if using a cable with a rating of 22 ns/100 meters (100
meters = 328 feet), connecting the QM-FTCC-TPS4 transmitter with 150 feet of
cable to a QM-MD7x2 switcher, and then using another 150 feet to connect the QM-
RMCRX-BA receiver, the accumulated skew over the entire 300 feet should not
exceed 22 ns.
4 • FlipTop Touchpanel Computer Center: QM-FTCC-TPS4 Operations & Installation Guide - DOC. 6393