ADDER X-DVIPRO-DL Panduan Pengguna - Halaman 14

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APPENDIX A - Cables for use with digital extenders

Introduction

The demands of extending high resolution DVI and HDMI digital video signals are

considerable and mean that it is not possible to use Cat5e cabling to achieve the

maximum extension distance of 50 meters. The large video bandwidth involved means

that to achieve the best possible performance from digital extenders, it is vital that the

correct cabling is chosen.

There are three important factors to consider when choosing a cable for use with digital

extenders.

IMPORTANT: Please remember that even though they use network-style

cables, the link ports of the modules are NOT Ethernet ports and must not

be connected to network switches or any other devices.

Types of cable

Twisted pair cables can have either solid or stranded conductors. Solid cables come

in bulk spools and are often referred to as infrastructure or bulk cabling. They are less

flexible than stranded cables but have less attenuation. These cables are typically run

throughout a building and terminate at the rear of a wall plate.

Solid

Stranded cabling is found in patch cables and is intended to connect the front of the wall

plate to the extender or computer using RJ45 connectors. They need to be more flexible

because the cabling gets disconnected and connected constantly.

For a digital extender application, solid conductor cables give a better performance as

these allow for a higher bandwidth and have less attenuation. Ideally a thickness of 22

AWG should be used.

Types of RJ45 connector

For each type of cable there is also an associated RJ45 connector. It is important that the

correct type of connector is used for the type of cabling.

Insulation displacement RJ45 connectors are designed to work with solid conductor cables

while insulation piercing RJ45 connectors are designed to work with stranded conductor

cables.

The teeth of the insulation displacement connectors are designed to straddle and hug

the sides of the solid center conductor of the cable.

The teeth of the insulation piercing connectors penetrate the middle of the cable and

nest in between the stranded wires. If insulation piercing connectors are used on solid

core cable then the connection will not be stable as the teeth will try to but are unable

to penetrate the solid center conductor. The teeth will then slide off the solid core and

not make a stable contact.

Types of shielding

The third and final factor in determining the cable to be used in digital extension is

shielding. The shielding protects the cable from two types of interference, internal

crosstalk and external interference. Internal crosstalk is the interference between the

Stranded

different pairs inside the cable. External interference is any interference that comes from

outside the cable. This is caused by many things; proximity to mobile phones, bundling

cables together or running them over lighting fixtures.

Internal crosstalk is most detrimental to digital extension as the signals cannot be

recovered after experiencing crosstalk. You are left with a black screen.

The most common type of shielding is Screened/Unshielded Twisted Pair (S/UTP). This has

an overall shield and will protect the signal from external interference. However it does

not provide any protection from crosstalk.

The next type of shielding is Shielded Twisted Pair (STP). This has four individual shields,

one for each data pair. This is good for protecting the signal from internal crosstalk but

does not provide an overall shield to protect against external interference.

If you combine the two types of shielding together you have Screened/Shielded Twisted Pair

(S/STP). This is also sometimes referred to as Shielded/Foil Twisted Pair (S/FTP). This has four

individual shields, one for each pair and an overall shield. S/STP is the best cable to protect

against any interference and is the cable choice to be used for digital KVM extension.

Insulation displacement

Insulation piercing