S-A Gets a Jump Start in Houston


Time Warner Cable is introducing a Scientific-Atlanta Inc. digital overlay system in Houston, allowing S-A set-top boxes to be used in an area typically served by Motorola Inc. equipment and accelerating the deployment of digital video recording and high-definition set-tops there.

The overlay concept — which allows an MSO to offer another vendors’ set-tops in a market typically served by one vendor’s gear because of a proprietary conditional-access system — is similar in nature to the Sony Corp.’s Passage system being field-tested by Comcast Corp. and Charter Communications Inc.

While Passage opens the field to multiple vendors beyond just S-A and Motorola, S-A’s overlay just opens the door only to its products.


Introduced with fanfare at the December 2002 Western Show, Passage is still in the field-testing mode.

But Sony now sees an opening for Passage as Comcast, Charter and others seek to rapidly convert cable systems to a more spectrum-efficient, all-digital framework, using new low-cost set-tops, preferably supplied by multiple vendors.

Sony is planning an all-digital trial in the coming months.

S-A, meanwhile, says it won’t stop with Houston.

“We have a couple of systems that are in the process of launching,” said Michael Harney, S-A president of subscriber networks, though the other systems aren’t as big as Time Warner’s Houston system. S-A is working with all cable companies, he said.

The digital overlay technology allowed Time Warner to launch S-A’s Explorer 8000 HD and HD/DVR boxes in Motorola-saturated Houston.

Harney said several thousand S-A boxes have been deployed there so far.

“S-A’s technology has accelerated our ability to launch extensive DVR and HD services to the 1.7 million homes we pass in Houston,” said Time Warner-Houston vice president of information technology Edward Crawford.

The system serves about 750,000 subscribers.

“We really do have a complete roadmap and a complete set of product offerings that in this competitive environment are really going to help a customer stay ahead,” Harney added.

S-A installed a CAO QAM (conditional access overlay quadrature amplitude modulation) device inside the Time Warner headend that encrypts part of the signal coming down the transport plant with S-A encryption for the Explorer 8000 boxes to read.


The CAO QAM grew out of the “Harmony” conditional-access project from the mid to late 1990s, Harney said.

The goal of that project was to allow operators to mix and match S-A and Motorola set-top platforms.

Although Harmony did not take off, it was not a developmental failure, said Harney.

Through Harmony, cable did agree to standard video, audio, transport, modulation and forward error correcting formats, he said. “With Harmony, there was no simulcasting of any content,” Harney said. “The only thing simulcast is the keys to the encrypted content.”

In Houston, satellite signals are received at the headend and encrypted for the Motorola system. Those signals are sent through Motorola QAM modulators to Motorola boxes in the home.

“We put the CAO QAM next to the IRT [integrated receiver transcoder],” Harney said. “We get the signal that loops through the IRT. The CAO QAM examines every packet in the MPEG transport stream in real time and determines which ones are critical. We take the Motorola packets and encrypt those with S-A system.”

S-A is encrypting only 5% of the Motorola signal — enough to defeat any piracy attempts, but small enough to avoid any extra bandwidth needs for the system.


Time Warner’s Houston system is fitting 10 to 12 standard definition signals into one QAM channel after sending the signals through a statistical multiplexer. “With the overlay, we turn up stat-mux and make a little more room to simulcast a small amount of video content,” Harney said. “No additional bandwidth is necessary to carry the S-A packets.”

The CAO QAM is a one-inch high rack unit with two sets of inputs, S-A said. Time Warner Cable has deployed a dozen or so units in Houston to handle the digital overlay and the approximate 200 video channels that are being transmitted to both S-A and Motorola boxes.

Every S-A set-top deployed in Houston has an IP modem, Harney said.

“That modem is used for conditional access and trick mode control,” he said.

S-A set-top users see the imbedded SARA programming guide, with the information streamed from an S-A server installed at the headend to each set-top in the field.

“For VOD, it runs the same client as the Motorola product,” he said. “The VOD screen icons all reside on the set-top box. The data that is used to populate the grid, the titles, the channel icons sit on the system’s Concurrent Computer Corp. VOD server.”


Although there is an element of mix and match with the digital overlay, the S-A system will only support S-A boxes.

Sony Passage aims to open cable networks completely to any set-top or even any cable-ready TV.

Greg Gudorf, Sony Electronics senior vice president, said the upcoming all-digital environment will allow a cable company to transmit all its signals in digital to the home, and provide a low-cost, all-digital set-top in current analog homes.

A number of companies, including Advanced Digital Broadcast and ATI Technologies Inc., have worked on Sony Passage specifications for such a low-cost digital set-top, Gudorf said.

When Sony launched Passage some 18 months ago, “we saw the core problem as enabling multiple conditional-access systems,” Gudorf said.

That issue remains, he said, but cable desire to migrate to an all-digital platform presents the business-level issue driving discussion around Passage.