Extron electronic MTPX Plus Series manual Definitions, Skew equalization

Skew equalization

Skew exists between wire pairs when the physical length of one wire pair is different from another. 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). The signals transmitted on the shortest pair are shifted to the left if you are viewing white lines on a black background. 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. As the transmission cable length increases, the skew effect increases.

The MTPX Plus has a skew equalizer function that is available using SIS, the Windows-based control program, or built-in HTML page control. The skew function provides separate time delay circuits, on the red, green, and blue video lines on the inputs and the outputs. Each time delay circuit can be independently adjusted, from 0 to 62 nanoseconds, to properly align the red, green, and blue video signals on the displayed image. When correctly set, the red, green, or blue video signal on the shortest wire pair is delayed to properly converge the displayed video image.

UTP cable test equipment measures and reports wire pair length. The report on the various pair lengths can be used to properly equalize pair skew. If UTP cable test measurement cannot be done, pair skew can 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.

Definitions

The following terms, which apply to all Extron matrix switchers, are used throughout this manual:

Tie — An input-to-output connection

Set of ties — An input tied to two or more outputs. (An output can never be tied to more than one input.)

Configuration — One or more ties or one or more sets of ties

Current configuration — The configuration that is currently active in the switcher (also called “configuration 0”)

Global memory preset — A configuration that has been stored. Up to 32 global memory presets can be stored in memory. Preset locations are assigned to the input buttons and output buttons. When a preset is retrieved from memory, it becomes the current configuration.

All 32 global presets can be selected from the front panel for either saving or retrieving.

Room — A subset of outputs that are logically related to each other, as determined by the operator. The switchers support up to 10 rooms, each of which can consist of from 1 to 16 outputs.

Room memory preset — A configuration consisting of outputs in a single room that has been stored. When a room preset is retrieved from memory, it becomes the current configuration.

MTPX Plus Twisted Pair Matrix Switchers • Introduction 1-7