![]() 1.4 The University, the Law, and Property Rights.1.3 Title IX Sexual Harassment and University Sexual Misconduct.1.2 University-Wide Conduct Regulations.1.1 University Principles of General Conduct and Regulations.A wide pulse width is generally not a problem there, since long cables are spliced several kilometers apart and resolution of close events is not a big problem.In premises cable plants, it’s common to find cable lengths of less than a few hundred meters, 1 meter patchcords and short fibers inside breakout modules on prefabricated cabling systems. The test pulse needs to have a lot of power for long cable runs, typical of outside-plant telecom or utility systems. If connections on the fiber are highly reflective-typical of many connectors-the OTDR may be overloaded again, causing an effect similar to the initial dead zone and making measurements unreliable.Most OTDRs have an option to control the power of the test pulse using pulse width. ![]() For best resolution, the OTDR test pulse should be set as narrowly as possible. Some multimode OTDRs are now usable for short length multimode premises cables but only if they are properly set up before use.The high power test pulse of the OTDR overloads the instrument’s receiver, requiring some time for recovery, making the OTDR “blind” for that period of time.Īn OTDR must always be used with a launch cable that matches the fibers being tested.Along the length of the fiber, the test pulse limits the resolution of the OTDR for finding and measuring closely spaced events, such as patchcords or broken fibers in splice closures. ![]() Most OTDRs, especially single-mode ones, are designed for long cable plants and may be inappropriate for short cables. ![]() A knowledgeable contractor should be able to educate the user on proper testing requirements.From a more technical standpoint, the first and most important consideration for OTDR use is the length of the fibers to be tested. In my experience, OTDR testing of premises cabling systems is often required by users who do not really understand when OTDR testing is appropriate or even what an OTDR is. The differences in the measurement techniques used by OTDRs and a light source and power meter means that OTDR testing may not be comparable to measured insertion loss or the actual loss the communications system will experience, especially on longer cable plants with higher loss.For this reason alone, it is recommended that insertion-loss testing be conducted even when OTDR testing is required by installation contracts. ![]()
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