OSP Expert: Don McCarty

Returning to Earth


By Vernon May Don and I have brought another of our disagreements to conclusion. He has always insisted that the power lines impact broadband service. My position has been that the pure harmonics of 60 Hz have so little power at the DSL frequency range that they have no impact. When compared to the background noise levels from pair-to-pair crosstalk within the binder groups, it’s next to nothing. In this case, we were both right — kind of. As we discussed what Don saw in the field and what I saw in the field, some factors previously not considered came…

Updates on “5 Questions About Fiber Optic Bonding, Grounding, and Locating”


From the September 2016 OSP Expert Column Our September 2016 OSP Expert column on fiber optic cable bonding and grounding, co-written by Vernon May and me (mostly Vernon’s work), caused quite a stir. The responses to the 5 questions have ranged from “finally, somebody asked these questions” to “you guys are going to get somebody killed”. (You can read this column again at http://www.isemag.com/2016/09/5-questions-about-fiber-optic-bonding-grounding-and-locating/.) Given the responses, Vernon offered to address this topic again. Here are his thoughts. September 2016 Column Summary Don and I received a question from a reader early in 2016. His position was that he completely…

Answers to the questions posed in last month’s column


Last month Vernon May and I decided to pose a few good questions on the use of the copper infrastructure to provide quality service to your customers. If you missed that column, take a look back before reading the answers below. How well did you do? COPPER INFRASTRUCTURE QUESTIONS QUESTION 1. When testing the cable pair, the digital multi-meter shows a 150 k ohm Ring ground. Using the resistance bridge feature set to 24-gauge on the technician’s multi-functional test set shows a distance to the fault of 700 feet. The cable map shows 300 feet of 24-gauge cable to a…

Challenge your team to test their knowledge of the copper infrastructure


Together, Vernon May (a DSL trainer) and I think this last column of 2016 is a good opportunity to test your knowledge of the copper infrastructure. If you’ve read our columns regularly this year, you should have a leg up on acing this test. If you’ve taken our copper cable infrastructure and/or DSL training, you better get all the answers right! (Answers will be in the January 2017 column, and available online then, too, at www.isemag.com.) The first group of questions addresses the health of the copper infrastructure. Before installation of any service the cable pair should be tested to…

The Job of the Field Technician in the Copper Infrastructure


The cable pair in the copper infrastructure carries AC signals at different amplitudes in different phases at different frequencies without interference or disturbance from AC signals from other circuits on other cable pairs in the same binder group. At least this is how it is designed to work. When it doesn’t perform as it should, and the customer complains of a service interruption on any circuit, it is the job of the field technician to determine if there is a problem with the cable pair, a problem with the circuit riding on that cable pair, or if it is a…

Series Resistance


Its Effect on Bandwidth Circuits on the Copper Infrastructure In my July 2016 column, “What Is a Good DSL Circuit?”, Vernon May mentioned 66 blocks and DSL.* Later, in a McCarty newsletter, Vernon responded to a reader question concerning 66 blocks in outside plant. In this month’s column, we will again look at the issue of 66 blocks, and the effect of series resistance on copper circuits in general. When we look at any connection of copper conductors, that connection must be 0 ohms at any frequency. Any series resistance, even as low as 5 ohms in series on paired…

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