OSP Expert: Don McCarty

Danger Zone: Split Cable Pairs


Are you receiving repeated complaints from a customer having bandwidth circuits dropping or others on their line, yet the cable pair tests OK? It’s possible that your customer’s cable pair is split with another cable pair.  Split cable pairs cause cross-talk on longer POTS circuits, and most all of the problems on bandwidth circuits. The POTS customer hears other people but he can’t talk to them and they can’t talk to him.  Bandwidth circuits are adversely affected, especially DSL circuits. One split cable pair can and does affect the whole DSLAM. The difficult part is to first determine that the…

Wetting or Sealing Current


The following came from an interested reader, and may be an issue you’ve faced. I’d like to hear your comments!  Dear Mr. McCarty: I have been working in the area that is addressing fiber-to-the-node and fiber-to-the-home. In conversations with several of our customers, the question regarding sealing current has come up. In their application of naked DSL (just DSL no POTS voice) they are concerned with corrosion that can cause noise and circuit unbalance that can affect the data rate that they can use and the reach they can obtain. I am looking for information to see if this is…

The Changing Role of the Field Technician in the Bandwidth Business


When I started in the telephone business in 1965, the field technician’s jobs were fragmented. Technician’s responsibilities today are even more fragmented. Let’s take a trip from then until now. THAT WAS THEN On a new installation it is the responsibility of the dispatch center to program the originating equipment (OE), and to provide wiring information to the central office technician and the installer as to which OE is wired to which horizontal mainframe and to which vertical the feeder cable appears.  • The CO frame technician runs jumper wire from the horizontal main frame to the vertical main frame,…

Testing, Testing


Testing and Test Results on a Multifunction Test Set — I received the following question from a field technician in Cairo, Egypt. They have the same types of cables and the same types of service that we have here in the US, hence the same problems. One of their field technicians had questions on testing and test results on his multifunction test set. I felt this discussion might be helpful to some of you struggling with similar issues. Greetings, Sir — I would like your help when using the EXFO 635G multifunction test set. I’m really grateful for your concern…

The Challenges Inherent in Single-Pair Faults


Taking care of copper cable has never been easy. The older the cable gets, the more companies cut copper budgets, and the harder it gets to resolve cases of trouble.  Today’s field technicians typically use a variety of test equipment for fault locating in an increasingly complex and adverse environment. These tools provide tremendous advantages but only if the techs are taught how to maximize use of the equipment, and if they are given the time and other support needed from managers.  Sometimes, in spite of best efforts and good equipment, things go wrong and the job may not be…

Limited Access Install Procedures for FTTH / DSL / Bonded DSL


I was recently contacted by the GM of a small independent Telco asking me about good procedures for installation in general and also in this time of COVID-19 pandemic concerns. This is not a problem I’ve had to deal with during my active working career so I reached out to my friend, Randy Lis, the GM of Piedmont Rural Telephone Cooperative (PRTC) in Laurens, South Carolina, and asked about his processes. I have tremendous respect for Randy and PRTC. They are proactive and organized in creating and implementing best practices. Randy referred me to his Outside Plant Supervisor, Mike Foster,…

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