Solutions Corner

Technical advice for our products

As part of our consultant relations program, the Clarity customer service organization posts answers to the most common questions on this site. Watch this page for new information every couple months. If you need further information, please contact us any time.

Q:		How do you choose the right cable to use with Clarity's new Long Distance Courier (LDC)?
A:		One factor includes a difference in category cable and Ethernet connections.

As noted in the recent LDC product announcement, Clarity is now offering two long-distance RGBHV signal courier solutions that use CAT 5 cables for distances of up to 450 feet or up to 1500 feet. The basic concept is that a transmitter is placed close to the "VGA" source. That transmitter converts the signal to a protocol that will run over a category cable to a receiver, where the signal is converted back to the original "VGA" form and feeds the display. "VGA" can mean signal resolutions from 640 x 480 VGA through 1600 x 1200 UXGA @ 60 Hz. However, for the best results, care should be taken when choosing the specific category cable to run in your application.

Relative to the technology and cable, there are a few things that may not be intuitively obvious:

1. The protocol for display signal transport over category cable is entirely different than packet protocol for Ethernet networks.
2. The best cable for ethernet may not be the best for display signals.
3. All category cable is not created equal.

It's easy to get in trouble here because it's increasingly common that CAT 6 is specified for an entire facility, but many CAT 6 cables can be difficult to get the best display signal performance. The difficulty is rooted in display signal skew that is different on each of the RGB channels, and is due to incremental differences in twisted pair lengths within the category cable. Skew is rarely an issue for TCP/IP applications, as Ethernet runs are limited to 328 feet, whereas these LDC applications can run up to 1500 feet.

While a device exists to compensate for reasonable amounts of display signal skew, it represents additional installation cost. For this reason, we recommend specifying a skew-free cable to be used in conjunction with our LDC products, such as the cost-effective Belden PVC (YM-48375) and Plenum-rated (YR-48585) products. Other skew-free products we have tested are listed in the Product Bulletin.

If you have questions about the design, application or use of Clarity products in your system, please contact us at 503-570-0700.

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Planar Systems, Inc.
Control Room and Digital Signage Business Unit
1195 NW Compton Way
Beaverton, OR 97006-6959

Technical Support
Phone: (503) 748-5799
Toll-free: 1 (866) PLANAR1
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