Black Box ACUVREM Appendix C Advanced Cabling Issues Skew, What is Skew?, Correcting Skew, Pins

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APPENDIX C: ADVANCED CABLING ISSUES (SKEW)

APPENDIX C: ADVANCED CABLING ISSUES (SKEW)

Appendix C: Advanced Cabling Issues (Skew)

This section discusses skew and how to minimize its effects.

What is Skew?

Each color in the RGB (Red, Green, Blue) video signal is sent down a separate pair of wires in the Interconnect cable. On many cables, the twist rates differ and this leads to each color arriving at a slightly different time and therefore spreading out on the screen.

Certain CATx cables can show noticeable skew when operating at high video resolutions over longer lengths of cable (see page 28). Skew problems are best avoided by using ‘low skew’ cable. This is CATx cable with closely matched twist rates. Please contact Technical Support for recommendations.

Correcting Skew

If a change in cable is not possible, or if you still observe color separation when using low skew cable, you could try one of the techniques described in this section:

•Optimizing pairs (to match pairs for RGB video)

•Patch cables (to minimize visible distortion)

•Extender with Skew Compensation (to delay fastest signals)

You can check the relative delays in the color signals using the test card, as described on page

29.Skew causes the color bars in the test pattern to be displayed at slightly different horizontal positions on the screen. To fully correct skew, the two color bars furthest to the left require delaying until they align with the color bar on the right (slowest).

Optimizing Pairs

This technique is a general solution for optimizing video transmission along a CATx cable. The aim is to arrange the color and data signals as shown in the following table:

Pins	Pair	Signal

7 & 8	Shortest Pair (Fastest)	Data

1 & 2	3rd Longest Pair	Blue Video
4 & 5	2nd Longest Pair	Red Video
3 & 6	Longest Pair (Slowest)	Green Video

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Contents November CAT5 KVM ExtenderACU1022A ACU1028A ACU1049A ACUVREM ACUREMSW Page User Guide Revision 2.0 November THE SERVSWITCH FAMILYWelcome to the ServSwitch Family ACU1022AACU1028A ACU1049A ACUVREMACUREMSWCautions and Notes Copyrights and TrademarksDisclaimer RADIO-FREQUENCY INTERFERENCE STATEMENTS FCC/CDC STATEMENTSFEDERAL COMMUNICATIONS COMMISSION AND CANADIAN DEPARTMENT OF COMMUNICATIONSEUROPEAN UNION COMPLIANCE STATEMENT DECLARATION OF CONFORMITYINSTRUCCIONES DE SEGURIDAD NORMAS OFICIALES MEXICANAS NOM ELECTRICAL SAFETY STATEMENTNOM STATEMENT 18. Servicio por personal calificado deberá ser provisto cuando Safety Precautions and Installation Guidelines CONTENTSTroubleshooting & FAQ Quick SetupInstallation Remote Unit Configuration & OperationAppendix B Rack Mount Options Appendix C Advanced Cabling Issues SkewAppendix F Specifications Appendix A Example ApplicationsAdjust EQ and Peak controls 1. Quick SetupQUICK SETUP Install systemOVERVIEW 2. Overview2.1 Introduction 2.2 GlossaryRemote Unit ServSwitch Brand CAT5 KVM Extender systemLocal Access KVM Switch2.3 Features Remote Units only 2.4 Product RangeKVM Extension and Remote KVM Switching kits KVM, Audio and Serial Extension kitsFamily 2.5 CompatibilityInterface Compatibility Extender CompatibilityInterconnection Cable 2.6 How to Use This GuideAdjusting Video Connection & CompatibilityOnly included in extender kits 3. Installation3.1 Package Contents INSTALLATIONEIA-568B 3.2 Interconnection Cable RequirementsSignal Colorcircuit board 3.3 Remote Unit InstallationSetting the Cable Length Jumpers Location of cable length jumpers on Remote Unit’s mainLength m Interconnect CableJumper Position Audio Device 3.4 Connecting the Remote UnitRemote Unit ACU1022A and ACU1028A kits- rear view Switching Remote Unit ACUREMSW - also supplied withACU1049A kit - rear view Audio Remote Units ACUVREM - also supplied withFocus- compensates video for smearing or over-sharpness Brightness - adjusts image brightnessRemote Unit - front view 3.5 Local Unit Installation All units Standard Local Unit - rear viewLocal Unit - front view ACU1022A and ACU1028A onlyCompatible Local Rack Hubs 3.6 Connection to Local HubsRemote Units Remote Units to extend audio, serial and KVM for up to six Simple system using ACU1006VRA Hub and ACUVREMDisplacement of 4. Remote Unit Configuration & Operation4.1 Video Configuration Overview REMOTE UNIT CONFIGURATION & OPERATIONftp//ftp.blackbox.com/connectivity/ServSwitch 4.2 Video AdjustmentsOn-line test card available at ftp//ftp.blackbox.com/connectivity/ServSwitchDIP Switch settings 4.3 Other Remote Configuration & Operation OptionsRemote Unit DIP switches on Audio/Serial/Switching SW1 DIP switchesMouse Recovery Hot Key CommandsCommand Reset Keyboard and MouseLOCAL UNIT OPERATION Power Requirements5. Local Unit Operation 5.1 OverviewChanging the Initial Hot Key 5.2 Operation of Dual Access Local UnitsHot Key Commands Local Console Commands See Appendix C Advanced Cabling Issues Skew, page 6. Troubleshooting & FAQTROUBLESHOOTING & FAQ 6.1 VideoCan the extender be used with RGB video? 6.2 Audio6.3 Serial The PC won’t boot into the correct graphics modeWhen I ‘hot-plug’ the Local Unit, the mouse no longer moves 6.4 Keyboard & MouseWhen I am typing, I get wrong or missing characters on the screen The PC comes up with ‘keyboard error’Which interconnection cable is best? 6.5 General QuestionsIs it possible to use a cable longer than 300m? Can the extender be daisy chained?APPENDIX A EXAMPLE APPLICATIONS Appendix A Example ApplicationsTakes KVM and serial signals from each CPU only two shown Touch screen network with local access to CPUs throughKVM switch KVM Switch5V PSU Information distribution system sharing a single PCACU1049A Kit ACU1049A kit with switching Remote UnitRMK19U-R2 Mounting Kit Appendix B Rack Mount OptionsAPPENDIX B RACK MOUNT OPTIONS APPENDIX C ADVANCED CABLING ISSUES SKEW Appendix C Advanced Cabling Issues SkewWhat is Skew? Correcting SkewPatch Cable Extender with Skew compensationAPPENDIX D AUDIO/SERIAL PORTS Operation & Multi-Port ConfigurationAppendix D Audio/Serial Ports Set up and OperationUsing a Microphone Audio InterfaceSet Up and Operation Version Number Format xxSyy/zz Appendix E Calling Black BoxShipping and Packaging APPENDIX E CALLING BLACK BOXVideo Input Connectors Appendix F SpecificationsAPPENDIX F SPECIFICATIONS Maximum ResolutionRemote Unit Connector Power RequirementsSignals Transferred Local Unit ConnectorACUVREM Size and Shipping WeightEnvironmental ACUREMSWPage Page Page Copyright 2009. Black Box Corporation. All rights reserved Customer Support InformationOrder toll-free in the U.S. Call 877-877-BBOX outside U.S. call Mailing address Black Box Corporation, 1000 Park Dr., Lawrence, PA