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Harmonic Gateway Backs VOD, HD Deployments

Harmonic Inc. will introduce a new narrowcast-services gateway (NSG) designed for Scientific-Atlanta Inc.-based cable systems, as well as a high-definition gateway box meant to improve the efficiency of video-on-demand and high-definition television rollouts.

The NSG 8200 allows MSOs to use existing, proprietary encryption-based conditional-access systems to transport video streams through their plant more efficiently, via Gigabit Ethernet technology.

"One of the key challenges for MSOs is to upgrade their networks incrementally as they deliver interactive services such as VOD," said Harmonic Convergent Systems Division president Yaron Simle. "The NSG 8200 brings to proprietary networks some of the advantages available to open systems, including scalability, flexibility and incremental expansion."

Harmonic's predecessor NSG model, the 8100, is designed to work with Motorola systems. With an MSO Motorola VOD rollout, the 8100 supports eight QAM (quadrature amplitude modulation) channels in a single-rack unit. It also processes, filters and multicasts streams from video servers.

Because content is encrypted within the S-A box, Harmonic devised a new NSG for S-A systems. Under that scenario, VOD content is delivered from the server in an application-specific interface (ASI) format. It then goes to the NSG 8200, which converts it into S-A's QAM system and then ships it to the set-top box.

"We bring the S-A system into the future," Simler said.

Harmonic said it has deployed more than 1,000 NSG 8100 gateways across a number of major MSOs, although Cablevision Systems Corp. is its only announced customer.


Each NSG 8100 has eight QAMs, Simler said. Typically, a server that spits out 240 video streams requires three NSG gateways. Since the NSG 8200 doesn't include QAM modulation, the price is lower than the 8100, about $80 per stream, Simler said.

Operators favor using Gigabit Ethernet transport for VOD rollouts based on a confluence of factors, Simler said. For one thing, digital penetration continues to grow. And the prospect of subscription VOD and free on-demand content raises the prospect of tremendous increases in session setup and teardown, as well as system-wide VOD traffic.

Adding more servers to handle this traffic isn't the answer, according to Simler.

Using Gigabit Ethernet technology, operators can transport VOD streams among centralized and distributed server architectures, reducing future capital costs and making the network more efficient.

A single Gigabit Ethernet stream carries approximately 240 MPEG-2 channels, according to Simler. "And with GigE, you can put servers away from the QAM," he said.

Separately, Harmonic is introducing an HDTV conversion box for cable operators. At present, MSO's HDTV might have four or five boxes at the headend to convert off-air HD signals into digital cable signals, Simler said.

Harmonic's BNG 6000 broadcast-network gateway series, priced at about $10,000, supports four HDTV feeds via ASI inputs and combines them into two outputs.

There are nine principal national HDTV feeds — two each from HBO and Showtime, as well as feeds from ABC, CBS, NBC, Fox and PBS. The BNG 6000 outputs are either DVB-ASI, to feed premium channels downstream to scramblers, or 256 QAM RF outputs to send over-the-air signals to the plant.