Extron Electronics TPX 88 A User Guide - Manual (Page 23)

2-5 TPX 88 Matrix Switchers • Installation
Enhanced Skew-free A/V cable is not recommended for Ethernet/LAN
applications.
This cable is specially designed for compatibility with Extron’s Twisted Pair
products that are wired using the TIA/EIA 568 A standard.
The green, brown, and blue pairs of this cable have virtually identical lengths
and should be used to transmit the RGB signals.
The orange pair of this cable has a different length and should not be used to
transmit the RGB signals.
• You can use either wiring standard, but ensure that you use the same
standard on both ends of both cables; the cable from the transmitter and the
cable from the receiver.
• Ensure that you terminate the RJ-45 connectors for each cable properly for the
family (TP, VTT, MTP) of transmitter or receiver connected.
• On RGB video MTPs, the audio or serial data that is carried on wire pairs 3
and 6 is incompatible with the TPX 88 A. The TPX 88 A cannot switch the
audio or serial data, output the audio locally, or break the audio away.
• The TPX 88 does not switch or process wire pair 3 and 6.
°
Most TP transmitter/receiver audio (audio that is associated with the
RGBHV link) is carried on wire pair 3 and 6, so the TPX 88 cannot switch
this audio.
°
On S-video and composite video MTPs, audio is carried on wire pairs
other than pair 3 and 6, so the TPX 88 switches this audio. The TPX 88
cannot output the audio locally or break it away.
• The TPX 88 A switches and processes wire pair 3 and 6.
° The TPX 88 A switches and processes the proprietary digital audio link
that is associated with the TP transmitter/receiver family, which is
carried on wire pair 3 and 6.
Cable testing
Systems that use Extron’s skew-free UTP cable do not need to be tested for
skew.
To ensure proper cable termination, each transmission cable system that uses CAT 5
cable should be tested. Testing the cable between the RJ-45 connections at the
transmitter and TPX 88 (transmitter cable system) and between the TPX 88 and the
receiver (receiver cable system) gives the most accurate indications of cable
problems.
There are two varieties of cable runs: simple runs, in which a single cable is
terminated only at the transmitter, TPX 88, and receiver, and complex runs, which
can include patch bays and multiple terminations and lengths of cable. In either
case, the entire transmitter cabling system and receiver cabling system should be
tested.
A complete test measures cable length and tests the wire map, attenuation, NEXT,
PSNEXT, ELFEXT, PSELFEXT, return loss, ACR and PSACR. All of these tests are
critical for digital data transfer, but not for analog video. While all of these tests are
important indicators of the quality of the cable termination, the most critical testing
parameters for video transfer are wire map (T-568-A or T-568-B termination) and
pair length measurements. The largest concern is equalization of skew between
cable pairs. Cable systems of 300 feet (91 meters) or less should exhibit no
transmission problems if they pass at least CAT 5e or preferably CAT 6-D5 channel
certification testing.