Extron electronic IN1130, IN1124, IN1128 user manual Receiver Cabling, Equalizing pair skew

Installation and Operation, cont’d

The Microtest OMNI SCANNER 2 performs comprehensive certification testing to the proposed CAT 6 standards. Other manufacturers also make testing equipment. The tests include advanced diagnostics for troubleshooting the cause and location of many cable and termination problems. For simple installation testing, the Microtest MICRO SCANNER PRO tests wire map and cable length, including individual cable pair length.

Equalizing pair skew

The manufacturing process for network (CAT 5) UTP cable leads to a condition called pair skew. For best results, pair skew needs to be equalized when using the CAT 5 cable in A/V

Extron skew compensation coax cables are available in lengths of 2 through 20 feet, see Appendix A for part numbers.

Extron IN1128

TP Transmitter/DA

8

7

6

5

Computer

CAT 5 UTP Cable

applications. The design of Extron’s skew-free A/V UTP cable minimizes pair skew to the point that equalization is not required.

Skew exists between pairs when the physical length of one wire pair is different from another. As the transmission cable length increases, the amount of skew increases. Skew affects the displayed image when the differential length between wire pairs exceeds 2 feet, causing the timing of the red, green, and blue video signals to appear out of alignment (horizontal registration errors). A white vertical line on a black field can appear as individual red, green, and blue lines that are close together; the signal transmitted on the shortest wire pair leads the other colors and appears to the left on the display.

Extron IN1130

TP Receivers

Pair	RGB video
1, 2	Red
3, 6	Green
4, 5	Blue

IF cable measurement indicates that the pair with wires 1 and 2 is four feet shorter than the other signals...

... THEN insert a 15HD-to-BNC extension cable and a four-foot skew compensation cable to equalize UTP skew for red video.

Projector

UTP cable test equipment measures and reports wire pair length. The report on the various pair lengths can be used in equalizing pair skew. The nominal velocity of propagation (NVP — the speed at which the signal travels on the transmission line, measured as a percentage of the speed of light) of TP cable is very close to that of conventional coaxial cable. The similarity in NVP means that:

• by using an Extron IN9045-L6 15HD male-to-5 BNC male,

6’cable, to adapt the output on a 15-pin HD connector to

Figure 2-8 — Pair skew equalization

Receiver Cabling

The IN1130 (figure 2-6) outputs two identical sets of RGB video and mono audio. This receiver can also receive component video, S-video, or composite video and output them on the R, G, and B signal lines.

7Output 1 and 2 — Connect the desired video output devices to

BNC connectors,

• and then adding an additional length of coax equal to the

5 1

the rear panel output 15-pin HD connectors.

Outputing component video, S-video, or composite

length of pair skew, placed on the receiver’s output,

you can equalize the effects of pair skew (figure 2-8).

If UTP cable test measurement cannot be done, pair skew can

15 11

video on the 15-pin HD connectors requires an Extron IN9045-L6 15HD male-to-5 BNC male, 6’cable.

still be equalized by viewing a test pattern with a critical eye. Examine the test pattern for loss of horizontal registration and, through a process of trial and error, equalize any pair skew with coax extensions on the red, green, and/or blue outputs.

8Audio output 1 and 2 — Connect the mono PC audio output on these 3.5 mm jacks to local powered speakers.

2-8 IN1124/28/30 Transmission System • Installation and Operation IN1124/28/30 Transmission System • Installation and Operation 2-9