ISE Magazine, August 2019

AU G U S T 2 0 1 9 WWW ISEMAG COM 4 3 FIBER TESTING In this 3rd installment on the OTDR we discuss the importance of proper instrument setup how it impacts your test results quality and the resulting data Better Configuration for Your Testing Scenario Better Results As noted in earlier articles the OTDR is a powerful testing tool especially when used by a properly trained technician A critical part of getting the most from this valuable tool is a direct result of properly setting up and configuring the OTDR for each specific test situation The majority of OTDR test technicians either work for large communications service providers or test contractors Our company specializes in advanced infrastructure testing and provides fiber characterization certification training or CFCE http www fiberinsight com cfce html When I cover best practices for ensuring proper test setups and consistent inspection and cleaning I often get pushback from technicians about the time required for this type of preparation The reality today is that many technicians are under significant pressure from management to focus on completing the job quickly often leading to tests being performed without best practices being followed But there is a reason the concepts discussed in this article series are considered best practices and skipping them can compromise the very advantages offered by using the comprehensive multi tool OTDRs available on the market today My response to that pushback is simple Spending the time and financial resources to utilize an OTDR and then not following proper procedures is a waste of critical time and money What is the point of expending the budget and effort to obtain the tool if you do not intend to use it properly We begin this discussion by looking back to the visibility scenario introduced in Part 1 of this series June 2019 issue Example Mid Span Multiple Closely Spaced Events A technician shooting between 2 data centers submits traces showing links that appear fine at the time but engineers reviewing the trace data later see the mid span where trouble is suspected with 1 wide reflection and 1dB loss Engineers are aware of a patch through with about 150m of fiber in between patches but they are unable to view the 2 patch interfaces individually In this example illustrated in Figure 1 the trace might appear normal at first look or to the untrained eye But to a skilled OTDR user and based on the trace view and OTDR settings a shorter pulse width could potentially separate and measure each of the mid span panels This problem could have been avoided if proper OTDR settings had been pre configured to allow for the visibility needed in this scenario In this article we discuss how to prevent these situations by using OTDR settings to get the most accurate test results even as situations change We also look at ways its efficiency can be improved allowing settings to be loaded faster and more consistently while still meeting company time limitations Understanding OTDR Settings The OTDR is a complex device with a myriad of settings which can seem overwhelming at first look It helps to break the settings down into categories well discuss each category Category 1 Initial Pre Test Setup Shot Category 2 Test Acquisition Settings Category 3 Launch and Receive Fiber Lengths Category 4 Display and Analysis Settings Category 5 File Naming and Storage By Tim Yount and Carla Yount Tim Yount@ Fiberinsight com @ y_ tyount404 @ fiberinsight Welcome to Part 3 of a 4 part series on getting the most out of your OTDR In Part 1 ISE magazine June 2019 Are You Getting the Most Out of Yours https www isemag com 2019 06 fiber optic otdr tips techniques we summarized the capabilities of the OTDR and discussed recent enhancements In Part 2 ISE magazine July 2019 3 Key Questions You Must Answer About Link Connectivity https www isemag com 2019 07 fiberoptic otdr tips techniques 2 we explored connectivity and how important it was to obtain valid and accurate test results and we provided some guidelines about best practices