I love it when readers get fired up and argue with me. I’ve always said I’m not always right, and I want you to call me on it when you know a better way to do something. Russ Gundrum wrote the following response to my June article, Noise Mitigation a Problem? Hear him out but give me another chance by reading my response after Russ’ comments.

Donald:
Well, sir, you can tell that I just received my June OSP® issue that you mentioned to me last week. My teeth fell out of my mouth when you stated, “80% of your noise issues are really missed bonding and grounding problems.” I bet you are wrong! I understand that in the past several years that good bonding and grounding practices have gone by the wayside, but that is just the tip of the iceberg when it comes to AC interference.

Thank goodness there was a great article near the back of the magazine to underscore my point about AC interference. Florin Hodis with EXFO has it right in It’s Summertime! Is Your IPTV in Peak Condition? (See OSP® Magazine, June 2008, page 60) His article covered getting rid of weighty packet loss and impulse noise baggage. Here are some of his points:

He stated, “Packet loss has a major impact on IPTV quality of service (QoS) and can occur for many reasons. Some of these may include unexpected external events such as: electrical impulse noise, lightning, noise interference on DSL lines...When these unpredictable events occur, IPTV packet loss can lead to a host of problematic realities for both the service provider and end-user. We’ve all heard the tales of pixelization or blocking, freeze frame, and/or set-top box lockup. In today’s competitive market, customers have little or no tolerance for any of these real world QoS issues.”

Couldn’t have said it better myself, Florin, because I’ve been trying to say it for an awful long time now, and even my good friend Donald still doesn’t buy the message! Notice how he said “unexpected” and “unpredictable”. Well that’s what happens all the time out there in the “real” world, especially during the summertime, and it’s that damn lightning disturbing those damn power lines that causes some of these damn little issues to occur! You can spend all your time and money bonding and grounding until the cows come home, and you can still have these problems! The exception is that in today’s world, the telcos won’t have any IPTV subscribers, or any other subscribers of telecom services for that matter.

This is what you must keep in mind. If the telco has done all of the bonding and grounding work and they still have a problem, then it must be from some bad power exposure out there. There can easily be any ordinary single- or double-phase power lines, or three-phase power lines that are out of balance, and this is what you are not taking into consideration from a telco’s perspective.

Even well-balanced three-phase transmission lines get hit by lightning every now and then, and the occasional capacitor bank that cuts into the line or goes off line, or some homeowner installs a compact fluorescent lamp, a dimmer switch, or has dirty power in the house, or some plant fires up an industrial load, etc, etc.

And of course for those who have read this far, there’s a brilliant comment that everyone should be aware of: “Keep in mind that there are some distribution power related problems that can be solved only with an induction neutralizing transformer.” Oh, really now, and what might those be?

I should probably go on and mention some other good comments that Florin makes, such as his Technique#4 that “Proper bonding and grounding is an absolute must.” Gee, I wonder who he must have gotten that message from?!! But even he acknowledges that “although proper bonding and grounding does not eliminate AC interference, it does reduce impulse noise and interference from AM radio.”

I really liked the closing words of Mr. Hodis and his wisdom on Maintaining Peak Conditioning: “In order to deliver reliable IPTV service, it is extremely important to invest in the improvement of the access network infrastructure so as to minimize packet loss. Thankfully, some simple cable-plant conditioning techniques for IPTV services can eliminate a substantial number of potential subscriber complaints and consequently reduce the amount of unnecessary truck rolls.”

This is my two cents for what it’s worth! And thanks again for killing any possible deployment of INTs for IPTV services!

Sincerely,
-Russ Gundrum

Russ,
I get the point, but I do feel that field technicians must complete all bonding and grounding issues before bringing in the noise mitigation expert. Power related issues can be solved by the noise mitigation expert, but as you stated the DSL Induction Neutralizing Transformer (INT) is more than just a last resort in AC noise mitigation.

There are some definite advantages to using the DSL INT as an intricate part of any Fiber-to-the-Node (FTTN) system:

First of all, it is passive. There are no electronics or power required. It is extremely reliable and rugged. It does not require protectors. It is simple to install. It is like installing a load coil. There is no maintenance required and it is continuous operation. There is no time-delay response and no clamping the circuit to ground. The DSL INT is transparent to metallic signals and it passes DC. It is the least expensive method of solving AC induction problems, but there is more to it.

The DSL INT can eliminate potential public and technician electrical safety hazards. It instantaneously reduces over 95% of the steady-state or surge induced voltages and currents appearing at the DSLAM and DSL modem.

The DSL INT can substantially reduce VF harmonic noise (20-30dB) and impulse noise which increases signal to noise levels allowing for longer DSL circuits which will provide additional revenues.

The DSL INT can reduce repeated truck rolls and maintenance expense dollars related to troubleshooting and certifying line quality. It also reduces customer trouble reports and allows for reliable advertised high-speed transmissions which mean improved QoS. It allows the promise of cost/performance benefits of DSL technology to be realized.

By the way Russ, AT&T just got a patent on the DSL INT. Who invented it? Oh, yeah, it was you, wasn’t it?

-Donald

Signing Off
Make sure you’ve made your plans to attend OSP EXPO 2008 in Baltimore, Maryland, October 22-23. This year’s seminar lineup promises to be one of the best if not THE best yet. Stop by my booth or one of my seminar sessions (“Ask the OSP Expert”) and introduce yourself. Meanwhile, you can always email your comments to me at dmccarty@mccartyinc.com. If you are looking for onsite OSP technical training or consulting to set up processes or solve difficult trouble tickets, give me a call at 503.538.1229.