The Vidéotron Challenge

Vidéotron ltée is a pioneer in the Canadian cable industry and a classic example of the winds of change that swept the business world in the last two decades. A subsidiary of Le Groupe Vidéotron ltée, Vidéotron was founded as a modest cable company in a suburb of Montréal over 30 years ago, and is today the second-largest cable television company in Canada and the largest in Québec. The company offers a variety of services, including cable television, pay-TV and digital television, and provides dial-up and high-speed cable modem Internet access. By early 1999, Vidéotron had over 1.5 million basic service subscribers.

The Vidéotron Challenge

Anyone familiar with the industry is aware that today's cable companies have now progressed far beyond the simple delivery of cable television to customers. The problem was arguably not as big in previous times when cable companies used their lines for one-way television signal transmission. The arrival of cable modems, more than anything, promoted wide scale return path usage. Return path data transmission, however, is particularly vulnerable to outside electrical interference, or ingress. Customer down-time, no longer a minor annoyance, had become a critical problem that was no longer acceptable in an increasingly competitive environment. A way had to be found to isolate network problems without shutting down entire nodes.

According to Yves Picard, Vice President Engineering and New Technologies Development for Vidéotron, "the only way we could do anything was (to) disconnect each distribution line to see what the effect will be at the headend... it doesn't make any sense to maintain the plant like that... when you have ingress, you need to find exactly which branch is defective and try to isolate it."

The traditional method of identifying and locating ingress starts at the headend. Checking each node for ingress involves connecting an analyzer to one test point at a time - a process that can take hours, depending on the number of nodes and travel time. Typically, the source of the ingress is located by a process of elimination. Starting at the node, return pads are removed from each feeder leg of the node - interrupting the return path - until the ingress disappears. Then, it is narrowed to a distribution area. Traveling downstream from the node, the technician will then go to the next active device (line amplifier) and repeat the process. The process can be repeated two, three or more times before the ingress is isolated to a single distribution leg. Each distribution leg can have up to four actives and 30 or more passive devices (multitaps, couplers, splitters), which translates into a minimum of two hours at the headend to confirm a problem exists plus four hours or more in the field isolating the ingress. This, quite literally, involves the climbing of poles, the opening of manholes, etc.

The Solution: Electroline's CLEARPath» CPM module

Electroline had attracted industry attention through the use of its RF distance addressable systems switch technology for relatively limited customer applications (apartment buildings, etc.). Vidéotron, which had run a pilot project using return path applications, approached Electroline in 1996 to determine whether the same technology could be used for network line management.

The result was the launch of the CLEARPath CPM module. The CPM's detection capability allows an offending segment to be isolated from the rest of the network, keeping the return path clear and the network operational until the damage is repaired.

The CLEARPath Solution

Field installation of CLEARPath CPM switches resulted in major operational savings, reducing the fault locating time from hours or even days down to minutes, without any disruption of paying services. Vidéotron's technicians can, from one location, perform extensive testing of the return path. The system is also scaleable, meaning that additional CPM switches can be added as needed, driving the ingress localization process further into the distribution plant.

The second key benefit is that existing paying customers experience no disruption with this process. Trouble-free customers are happy customers, the bread and butter of any business. By early 1999, Vidéotron had installed over 10,600 CLEARPath CPM switches in its Montréal-area network, with at least 1,500 more planned for the near future.

How CLEARPath works

To locate the source of ingress using the CPM CLEARPath switching modules, a 6 dB pad is selectively switched in on the return path. These switches are non-disruptive and will not affect high-speed data services. In locations where ingress is severe, where services are not yet deployed or undergoing modernization, it is possible to momentarily shut down (terminate) the 5-42 MHz band. Field switching is controlled by Electroline's Cable Ingress Management (CIM) software, and results are displayed on a spectrum analyzer for interpretation. If the screen displays a reduction in ingress by 6 dB or if the ingress disappears (depending on the option selected), the offending network segment has been identified, and it is then a matter of switching the CLEARPath CPM devices deeper into the network in order to establish the precise origin of the ingress. Once the ingress source is located within the segment or area, technicians are dispatched to the site.