Cox Communications upgrades system
After a long period of finger pointing among cable operators, broadcasters and the FCC, cable companies are now starting to provide high-definition television channels to their customers, often as part of a digital upgrade package.
The delivery of HDTV channels over cable is still a contentious issue and the politics and regulatory issues may go unsettled for some time to come. However, the cable companies are reacting to the demand from their customers for HD programming and are taking steps to meet the demand.
Fairfax County, Va., is one of the country's wealthiest counties and its educated populace makes it the home of many early adopters of new technologies, including HDTV. Cox Communications provides cable to much of the County and has been getting an increasing number of requests for HD.
"December 2000 was the official launch of our digital services," said David Hanzel, director of central services for Cox in Fairfax, Va. "Acceptance level has been extremely high [and has] exceeded our expectations."
Digital cable is a requirement for HDTV signals to be carried on a cable system. Although most channels on a digital cable system are standard definition, upgrading a system to digital capability paves the way for HD channels.
At the moment, the Cox system in Fairfax County carries six HD channels: HBO, Showtime, Discovery HD Theater, ESPN HD and two local broadcast channels, WJLA (ABC) and WRC (NBC). Although there are other local broadcasters with HD signals, Cox Communications has not yet finalized agreements with those stations for HD carriage.
Cox Communications plans to have its digital cable system completely built in this region by December. At that point, nearly 250,000 cable subscribers in Northern Virginia will have access to the company's digital cable service, although not all customers are expected to immediately sign up for digital.
Cox's HDTV service began in September 2002 and subscribers use a Scientific -- Atlanta 3000 series set -- top box, which connects to the customer's HD display. The boxes are sold at Best Buy stores in the region. Cox won't reveal its total number of HDTV subscribers.
TESTING THE SYSTEM
Prior to launching the service, Cox did an "alpha" and "beta" test with employees and customers in the area, testing for problems and shaking out the bugs. After getting feedback from these users, the company scheduled the launch date and the system has been trouble-free since it started.
"I've had one outage and that was due to a power failure," Hanzel said.
The Cox headend facility-or "Central System" in the company's parlance-occupies an attractive building in Fairfax, just outside the Capital Beltway. The large and tidy rack room holds about 10 rows of racks, with about 15 racks in each row.
The footprint taken up by the HD headend is surprisingly small. The four Terayon CP 7220 satellite receivers each consume 1 RU, as do the two Terayon CP 7585 8VSB off-air receivers. There is a spare off-air and satellite receiver, for a total count of 8 RU for the receive capability.
The 19.4 Mbps ASI signals are fed from the output of these receivers to a BigBand Networks' broadband multiservice router that "grooms" the signals for the Scientific-Atlanta 256QAM channel modulators. These place the HD signals onto specific channels in the Cox system. There is no interim processing or storage of these signals; as quickly as the signals come in, they go right back out again.
Each modulator ultimately carries the signals for two channels or roughly 38 Mbps of data, Hanzel said.
Between the three active modulators, a spare modulator and the BigBand groomer, the transmit end of the HD headend easily fits in a single rack, including the control computer and monitor for the groomer. In fact, the entire HD receive and transmit system for the six channels that Cox carries could fit in a single equipment rack, although Cox has it separated by receive and transmit functions.
According to Hanzel, no data is removed from the broadcasters' signal in the Cox system. He said that the full 19.4 Mbps ASI signal is fed into the modulators and out to the subscribers.
Transitioning from an analog headend and distribution plant to a system with a substantial amount of digital products was expensive. It was also a learning experience for the staff charged with maintaining the integrity of the signal and servicing customers.
"The days of adding a channel by patching it in are gone," said Ted Knarr, a Cox central systems technician.
When its digital service began, Cox field technicians received three weeks of training to understand digital cable. The HDTV service is worth the effort, Knarr said, because the pictures are spectacular.
"When they show a baseball game in HD, you can see the faces in the stands," he said.
All told, Cox spent more than $400,000 to add the HDTV service to this one headend. To upgrade the headend and distribution plant for more reliability, additional channels, digital TV and overall higher performance, a company spokesman said that Cox Communications spent $500 million in Northern Virginia alone.
Bob Kovacs is the former Technology Editor for TV Tech and editor of Government Video. He is a long-time video engineer and writer, who now works as a video producer for a government agency. In 2020, Kovacs won several awards as the editor and co-producer of the short film "Rendezvous."
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