ISE Magazine, August 2019

I S E I C T S O L U T I O N S E D U C AT I O N 8 Dont give up on the tough cases of power influence and circuit noise My colleague Russ Gundrum and I helped Sam a fiercely dedicated manager solve a problem that several technicians were unable to resolve and they gave up The customer had so much noise on her line that she was unable to hear or talk without a cell phone she was left without a connection to the outside world When the problem was resolved she actually cried Neither Russ nor I collected a dime and yet we agreed this was the best compensation weve received in our decades of solving trouble cases We were honored to meet this manager who was dedicated to delivering a great customer experience The Challenge The unbearable noise on this customers line could have been resolved quickly if the power company and telco had teams identified who would collaborate across boundaries Ive rarely seen this happen however that doesnt mean you cant help the customer There are solutions and steps you can take to find a path to success when you have noise caused by power influence PI The Process On May 8 I forwarded an email to Russ from Sam an OSP Manager who explained some things about a customers line such as the total loop length was 35973 feet The PI was almost at 90 dBrnC and this was with a 12 pair induction neutralizing transformer INT installed It had been over 100 dBrnC before the INT was placed But even with well balanced pairs you would still have an unacceptable level of circuit noise Russ talked to Sam the next day and said it sounded like they didnt have a good exciter pair for the INT as it should be dropping much more of the PI Plus it might not be at the right location to cause the best noise reduction Russ also suggested that a voltage to ground measurement should be made on the pair on both sides of the INT and then read the voltage drop across the INT on that pair If the INT is properly excited you should read approximately the sum of those 2 voltages If you dont then the INT isnt working properly You should make sure the exciter pair goes to a good ground at both ends of the circuit and that there are no grounds on any other pairs close to the INT as this will affect its performance Russ also pointed out the fact that since the significant frequency levels of the PI were at the higher end of the voice band 3 or more exciter pairs might be needed to get enough excitation current through the INT to do its job Turns out that wouldnt be a problem to do since she was the only one working circuit in the cable After trying more exciter pairs and moving the INT towards the node the PI was reduced to 80 dBrnC and the noise was also reduced 20 dB However since the induced voltage was COPPER EXPERT dmccarty@ mccartyinc com For more information email or visit www mccartyinc com Don McCarty is the Copper Expert columnist for ISE magazine discussing the issues around provisioning testing and maintaining copper for all services from POTs to IPTV Don is also President of and the Lead Trainer for McCarty Products a technical training and products company training field technicians cable maintenance installation repair and Central Office technicians and managers SNIX placed at customers NID