Advances in Video QoE Control Facilitate SPs’ Efficiency Goals

Steve Liu, VP, video network monitoring, Tektronix

Steve Liu, VP, video network monitoring, Tektronix

December 11, 2012 – Tektronix has taken ground-breaking steps toward strengthening video service providers’ ability to meet rigorous quality standards through use of better tools at interfaces with transport backbones and at the edges of the network.
To overcome limited monitoring capabilities at points where video is handed off to regional headends Tektronix has introduced monitors capable of comprehensively identifying and diagnosing quality impediments on programming feeds operating at up to 3 gigabits per second. At the same time, the company has issued a new edge device, the SentryEdge II, which detects RF modulation and transport stream errors across multiple QAM channels simultaneously, allowing technicians to quickly identify potential problems before they impact subscribers’ quality of experience.

“Both of these products are industry firsts,” says Steve Liu, vice president of video network monitoring at Tektronix. “QoE (quality of experience) monitoring at 3 Gbps is three times the previous bitrate capacity for monitoring devices, and our SentryEdge II is the first RF quality monitoring device capable of remotely monitoring up to eight channels concurrently.”

The need for QoE monitoring at up to 3 Gbps stems from the growing use of 10 Gbps fiber transport to deliver video to headends, where the handoff at any point might include 500 to 1,000 live video programs, including those earmarked for use with switched digital video systems. Before the addition of 10 gigabit interfaces to the firm’s Sentry and Sentry Verify product lines, the only products suitable for 10 gig networks offered very basic monitoring capabilities, such as registering packet loss, Liu notes.

“You need to look at more than packet loss to understand quality problems,” he says. “We provide the means to do both QoS and QoE at 3 Gbps.”

The firm’s Sentry platform incorporates advanced QoE monitoring capabilities while Sentry Verify handles QoS monitoring, he explains. By having the capacity to perform comprehensive monitoring of baseband signals before they enter transcoders operators can identify source problems that could impact the viewing experience while avoiding “chasing false alarms” resulting from alerts about inconsequential packet losses, he says.

The new Sentry Edge II is meant to solve another challenge for operators, which is to more efficiently perform RF monitoring of QAM channel output at the network edges, including hubs and local headends, With the choice of four- or eight-tuner models, operators can speed the process of monitoring channels across up to 1 GHz of spectrum, Liu says.

“Exceptional RF analysis across all channels gives operators a proactive way to diagnose RF issues before customers complain,” he says. The rack-mounted server system provides Web interfaces for remote monitoring 24 x 7 and generates email notices if performance is subpar, which, as Liu notes, is a vast improvement over the traditional mode of performing QAM signal spot checks on RF analyzers. If operators want to maintain steady monitoring of their most important premium channels, they can “park some of the tuners on those channels and perform round robin monitoring on the rest,” he says.

Sentry Edge II performs high-quality MER (modulation error ratio) measurements up to 41dB as compared to most traditional analyzers, which only register MER variations at 30 dB or below, Liu adds. This is good enough for assessing whether there’s a problem at the user end but not for assessing whether degradations at the QAM output are likely to diminish performance at the set-top. “You need to know if the signal is degrading to 36 or 38 dB if you want to be proactive,” he says.

The new monitoring system allows engineers to quickly isolate problem sources by generating metrics on other variables as well, including RF lock indication (including LED on rear panel); input signal level; carrier-to-noise; carrier offset, pre-forward error correction bit error rate and others. “In-home monitoring is important, but you need information from the source in order to correlate issues and understand what’s going on in the network,” Liu says. “The ability to make sense of all the data is quite challenging.”