HAMILTON and LONDON Ont. – The winner of the 2009 Cartt.ca Society of Cable Telecommunications Engineers Ontario Chapter Cable-Tec Expo editorial internship is Dan Chelchowski of Rogers Cable.
Cartt.ca, the Canadian cable, radio, television and telecom industry’s leading news source, each year offers one member of the Ontario Chapter of the SCTE the chance to attend the annual Cable-Tec Expo, the premier cable telecommunications technical trade show.
It is being held this week in Denver, Colo.
This is an annual opportunity aimed at those technicians or young engineers whose company might not normally send them to this conference. We began in 2007 when Cogeco Cable VOD engineer JR Graterol covered the show in Orlando for Cartt.ca. In 2008, Clearcable’s Christian Isla won the honour.
As members will recall, we ran an essay contest earlier this year and the winning author, Chelchowski, a network maintenance technician based in London, won the trip to the Expo which includes flight, three nights accommodation, food, and a media pass to the conference, courtesy of Cartt.ca.
His essay on our topic: “switched digital versus other bandwidth saving opportunities, " was judged best of the bunch by a three-person panel of SCTE Ontario board of directors Bruce Marshall of Mountain Cable, Boris Eventov of Cogeco and Cartt.ca editor and publisher Greg O’Brien. It is published below.
Of course, there is a catch to the win. Dan will be working hard while in the Mile High City – covering the show as a freelance journalist, reporting on what he sees in the sessions and hears from suppliers he’ll meet in by-lined articles that will appear on Cartt.ca in the coming days.
The press pass gets him on the trade show floor and into any conference sessions and will provide Cartt.ca readers with a viewpoint from someone with a technical focus.
This is an opportunity worth several thousand dollars to Chelchowski (pictured) and Rogers London – and one we hope many SCTE Ontario members will take advantage of in 2010, when Cartt.ca offers the same opportunity to chapter members.
Thanks to all those who entered essays this year and watch your in box for 2010!
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Switched Digital vs. Other Options
By Dan Chelchowski
As technology advances to meet customer demand for bandwidth and reliability, so does the need for a more efficient cable plant.
In the past when bandwidth reached limitations, cable MSOs spent a lot of time and money rebuilding the plant to increase the frequency spectrum. Now the cost of upgrading to 1 GHz capacity is greater than the benefits, so engineers across the globe are working on ways to increase capacity utilizing cable plants already in operation.
Switched Digital Video (SDV) is currently the leading choice to use existing bandwidth more efficiently.
Studies show that around 80% of television viewers are watching the top five channels at any given time, yet digital set-tops receive all of the channels all of the time. SDV creates the ability to stream channels on demand to unique set-tops. Therefore, transmission of all the channels is no longer required, and bandwidth usually reserved for “low-viewership” channels can now be used for much more.
The average 256-QAM carries 10 to 12 standard definition channels and a QAM utilizing SDV is only limited by the number of tuned set-tops and the number of streams available. This drastically increases the amount of channels that can be transmitted within that same 6 MHz bandwidth. The obstacle is managing which channels get switched to maintain a picture perfect experience for our customers.
There are other ways to increase bandwidth capacity, and one of them is also in use today.
Optical fibre node segmentation is a popular way to expand network capacity. It utilizes wavelength division multiplexing (WDM) to potentially quadruple up and downstream bandwidth. Multiple optical carriers are multiplexed on a single optical fibre using different wavelengths of light. Segmentation is driven by traffic congestion in the transmission of narrowcast data. Every time a node is “split”, the number of modems travelling together in an optical carrier is reduced by about half. This is great for reducing packet loss and increasing reliability, but it cannot be used to increase the number of possible channels available to customers.
Digital compression can increase the channel capacity of QAMs, and there are two new forms that could if implemented: Improving 256-QAM to 1024-QAM, and MPEG-4 video encoding. 256-QAM allows for 256 different signal combinations, so increasing to 1024-QAM would increase the amount of bits-per-symbol by a factor of four. Essentially, this quadruples the amount of data carried by each QAM and would greatly increase the number of channels.
However, a higher-order QAM is more susceptible to noise and other distortions, resulting in a higher bit error rate. This reduces the reliability of the services making it a less attractive approach to increasing capacity.
MPEG-4 is a standard that defines compression of digital audio and video. It’s widely used outside cable plants today in video communications, but is still developing as a standard for A/V compression in a digital QAM environment. Currently, MPEG-2 is the encoder of choice, again, because of its reliability.
Customers demand more and more every day from their cable provider: More HD channels, faster internet speeds, and more choice. SDV is essentially and “on demand” service that allows customers to choose one channel to watch whenever they want.
While this is not a new experience for our customers, those channels they choose would not otherwise be available without the power of SDV.
