Crestron QM-RMCRX-BA Specifications download pdf (Page 9)

Crestron QM-RMCRX-BA QuickMedia™ Receiver/Processor

standard CAT5E or CAT6 cable. Installation of any QM device is as simple as

installing one set of QM wires from output to input. Installations are flexible,

affordable, and fast.

The Crestron QuickMedia cable “CRESCAT-QM” contains one CAT5E cable

and one Cresnet

cable in siamese jackets.

CRESCAT-QM Cable

NOTE: Do not untwist the two wires in a single 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 15 ns of skew per 100 meters (328 ft.)

means that a cable will have no more than a 15 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.

Refer to Appendix B on page 65 for additional QuickMedia information.

The pin assignment is based on the EIA/TIA 568B RJ-45 Jack standard. The

following table illustrates how composite, S-video, and RGB video signals are

transmitted over the CAT5E wire.

Operations Guide – DOC. 6332 QuickMedia™ Receiver/Processor: QM-RMCRX-BA • 5

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Crestron QM-RMCRX-BA Specifications Page 9