Specifications

Crestron Quick Guide to Touchpanel Connections

Doc. 4903B

Appendix A: QuickMedia Installation Notes

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.

The total accumulated skew from QM transmitter to QM receiver must not exceed 15 ns (nanoseconds).

Crestron recommends a cable with a rating of less than or equal to 15 ns over its entire length. For

example, if using a cable with a rating of 15 ns/100 meters (100 meters = 328 feet), connecting the QM-

FTCC 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

15 ns.

Further Inquiries

If you cannot locate specific information or have questions after reviewing this guide, please take

advantage of Crestron's award winning customer service team by calling the Crestron corporate

headquarters at 1-888-CRESTRON [1-888-273-7876]. For assistance in your local time zone, refer to the

Crestron website (www.crestron.com

) for a listing of Crestron worldwide offices.

You can also log onto the online help section of the Crestron website to ask questions about Crestron

products. First-time users will need to establish a user account to fully benefit from all available features.