CeBit 2008Cat5 cable is a good choice for long distance transmission of PC VGA video within a building. Many buildings are already wired with structured Cat5 cable for the computer network and Cat5 or Cat6 UTP cable is cost effective and manufactured to an industry standard. It is also very easy to install compared with high quality SVGA cable.
Extenders that use Catx UTP cable as the transmission medium can be referred to as Cat5 extenders, VGA extenders or Video extenders. KVM extenders refer to extenders that transmit Keyboard, Video and Mouse data over Catx UTP cable.
CatX extenders are now widely available and work by converting the analogue RGB signal to differential analogue signals for transmission over 3 of the twisted pairs within the cable. The fourth pair in the cable is used for transmission of power or audio and sometimes also for serial data transmission.
CatX extenders include the CatX Mini VP. This transmitter/receiver pair can be powered entirely by the VGA source output, a unique extender product.
CatX extenders work very well in most applications for distances from 1 meter to 300 meters (depending on the model) and at resolutions up to 2048 x 1536. CatX extenders also include receiver that can be daisy chained together using Cat5 to an overall distance of up to 2000m.
Electrical noise can also result in degradation of the extended picture and grounding differences between the transmitter and receiver may result in a flickering image or moving bars on the screen. The same cabling standards apply as if an Ethernet network was being installed.
Another common problem associated with the extension of VGA video using Cat5 UTP cable is skew, or colour shift. This effect can be found in any Cat5 UTP cable as well as Cat5e and Cat6 while some Cat5e and Cat6 cables do not show any real effects of skew at all.
The effect of skew can be seen as a coloured shadow around objects on a video screen. It occurs when the pairs of wire within the cable are twisted at slightly different rates to reduce crosstalk between pairs. Because of these differences between wire pairs, video signals for different colours travel different distances before they reach the remote receiver. When one colour signal arrives behind the others because the wire is longer, you get a red, green, or blue shadow around the objects on your video screen. You are more likely to experience skew on longer cable runs (greater than 50 meters).
There are low skew Cat5 cables available on the market specifically for use with video extension products. CatX Skew62 is a standalone skew correction device that will correct skew on existing cable runs where any brand of extender has already been installed.
Long distance CatX receivers have skew correction built in to them and these are the best devices to choose where you think you may experience video problems due to skew.
Another factor to consider when choosing any extender is whether the extender is dual access. If you need a keyboard, monitor and mouse near your computer as well as at a distance, or, if you need to connect your computers into a local KVM switch as well as grant remote access to a single remote user, you will need a dual access KVM extender. The CatX KVM Universal transmitter fulfills all these requirements.
CatX Data extenders will also transmit serial data for the remote connection of touch screens, serial printers, modems and other serial devices.
Other useful features, offered by the CatX range, includes rack mount and wall mount options and the CatX Mini range with a zero footprint where space is at a premium.