SCTE Sustaining (corporate) Member since 1984 Title: President, Arcom Broadband background: In 1995, Tresness was named president of Arcom, which produces test equipment used to locate problems in cable plants. In 2001, he formed Arcom Digital, the technology arm of Arcom, where he also serves as president. He has been in cable industry since 1983 and holds both a BSEE and an MBA. Common path distortion (CPD) is a fact of life in cable plants, isn’t it? Are some operators in a sort of denial on this problem? I don’t think anyone is in denial that CPD is a problem. People in the field know how difficult, frustrating and time consuming CPD can be to track down-and how it can affect voice, data and video. When CPD is viewed using traditional test equipment, the type of CPD they are used to seeing is what we call high-level CPD. At that point, it is most likely already adversely affecting the network. Some question how often this happens and whether it is worth investing to address this issue. In our system, we have the ability to look well below the system noise floor-typically around -80dB. This adds a whole new dimension to being able to see what is going on in the plant. The operator now has the ability to see problems early and fix them before they are network-affecting. We call this "predictive maintenance," which, prior to the invention of this, was not even a possibility. What do you mean by being able to get to "root causes" of network problems? In the many systems that we have installed, one of the things that we have found is that frequently a CPD source is also the cause of some other problem like noise or ingress. Intuitively this makes sense. CPD occurs when there is some deficiency in a connection point within the network. Frequently, this deficiency is caused by moisture getting into the connector or device and then oxidizing. If moisture can get in, obviously other problems like noise can be present. We’ve also found that the level of CPD does not necessarily correspond to the severity of the problem. There have been cases where the source location of low-level CPD was caused by water or a surface contact issue, such as a missing seizure screw, creating major system impairment. The deficient connection was the root cause of the problem. Could you explain how you use CPD against itself, i.e., as a way to track CPD? CPD is a nonlinear distortion. When there is a source of CPD, as signals propagate through the source, beats and intermodulation products are generated. Low-level CPD sources generate little beats; high-level CPD sources generate big beats. By knowing where to look for these intermodulation products, and by having information about when in time the source signal was transmitted, we are able to calculate the time distance to the source. We can then use this information and compare it to a database containing all the devices in the network, in order to tell the operator exactly which device is having a problem. Your new platform requires less dedicated spectrum? How so? The simple answer is that the system uses both analog and digital channels themselves as the radar probing signals. We look at these signals at the headend and calculate what the spectral components of any CPD occurring in the field would look like. We then compare this to signals coming back in the return … We then use correlation processing to find at which point the two signals are statistically the same. As operators become more digital and less analog, does this affect your ability to find problems? That doesn’t affect how our CPD Hunter operates, as the number and type of channels is not a factor; it still pinpoints CPD, regardless. The same can’t be said for traditional CPD troubleshooting techniques. The recurring 6 MHz (NTSC) pattern that can be viewed on a spectrum analyzer when high-level CPD is present only exists because of multiples of analog carriers. Without these analog carriers, CPD will become indistinguishable from noise-that doesn’t mean it’s not there, it just appears in a different form. How key is automation to network monitoring and maintenance? We have built a great deal of automation into our system-our goal being to make it as easy to use as possible, while providing useful information. This automation allows easy viewing of which nodes are currently having problems and provides a predictive element in telling which nodes are most likely to have problem at some point in the future. We then take this one step further by integrating electronic maps of the network into our system. This uniquely allows the operation to not only know when they have a problem, but also where in the network the problem is.