Cable Still Soft on ATSC Signal Carriage


In March, both Charter Communications and Comcast Cable announced that they would make HDTV programming available to a number of major-market digital cable subscribers by the second half of this year. But not much has happened since.

Now that the cable industry as a whole has responded to FCC Chairman Michael Powell's call for voluntary HDTV carriage by the cablers, broadcasters are concerned that it's the same old rhetoric without substance. They say that cable operators are allocating a limited amount of bandwidth for HDTV movies supplied by HBO and Showtime, but very few are passing through true 1080-line HDTV signals from local broadcast stations.

Cable operators said they have invested $60 billion - $1,000 per cable subscriber - to upgrade their infrastructure to provide HDTV and other broadband services.

Broadcasters are speculating that the latest announcement is simply noise for the FCC's benefit to keep the digital must-carry wolves at bay. Powell's April 4 letter, calling on the consumer electronics, broadcaster, and cable industries to "voluntarily" break the logjam that has plagued the rollout, may have spurred some activity, they said, but incompatibility issues and a lack of complete carriage continue to exist.


After spending millions of dollars to get digital signals on the air, broadcasters are frustrated by the lack of digital carriage in the market and the fact that after a cable headend converts an ATSC HD signal to 256 Quadrature Amplitude Modulation (QAM), the signal is not being displayed in full 1080i or 720p video resolution. Cable executives themselves admit that some information sent by broadcasters along with the video and audio, such as Program and System Information Protocol (PSIP) and other data designed to correct for transmission errors, is cut out to conserve bandwidth. Yet, they insist that quality is not compromised.

Converting ATSC signals to 256 QAM is "much more efficient for us," said Mark Hess, Comcast vice president of digital television services. "The signals going out over the air include lots of information - like forward-error correction - that is not necessary within a cable system. By being efficient in how we handle the signals, we can squeeze two HDTV channels into a single 6 MHz slot."

In the analog environment, MPEG-2-compressed NTSC signals are converted to QAM for digital distribution throughout the cable system, then are re-encoded and displayed as analog on a consumer's TV set. In digital, the signal stays digital from the satellite, through the headend and on to the home.

But leaving out PSIP data can result in problematic channel surfing for consumers, said Pat Holland, vice president of Engineering for KOMO-TV and KOMO-DT in Seattle. At present, the local cable operator (AT&T, soon to be Comcast) does not carry KOMO-DT's digital signal.

"I think it's become clear that cable is not interested in carrying DTV in its native [ATSC] format, which is unfortunate," he said. "There are a number of problems with carrying the digital signals in QAM. They've got more spectrum than all of us [broadcasters] put together on their cable systems, so it's not a spectrum issue. It's my understanding that they're interested in parsing out the payload of DTV signals when it benefits cable operators most."

Holland said he and many of his fellow broadcast engineers wonder: If they go to the trouble of sending program guide information within the digital signal to HD receivers, are cable operators going to transpose this information, or will they prefer that their customers use the cable company's own existing EPG? The answer appears obvious.

"How will consumers feel when their HDTV set can't tune to the [broadcast] channel they want because the local cable operator isn't sending the correct PSIP information?" he asked.

Going into their annual convention last month, the top ten U.S. MSOs, led by the National Cable & Telecommunications Association (NCTA), sent a letter to Chairman Powell stating that the cablers had agreed to help get broadcasters' digital signals into consumers' homes. Those cable systems in the top 100 markets with more than 25,000 subscribers and "activated bandwidth" of at least 750 MHz will carry the signals of up to five commercial or public TV stations or cable networks that provide HDTV programming during at least 50 percent of their primetime schedule or a substantial portion of their broadcast week.

In March, St. Louis-based Charter, which serves about seven million analog subscribers (and two million digital) in 40 states, said that it would make HD programming available to digital cable customers by the third quarter of this year. Comcast, soon to be the nation's largest MSO (if its merger with AT&T Broadband is approved) with over 21 million subscribers (five million digital), said that it too would offer HD programming to its digital subscribers in major markets served by the company by the end of 2002, and will begin deploying the service in the Washington, D.C., area this summer.

Comcast was one of the first cable companies to offer HDTV to customers, deploying it on systems in Philadelphia late last year. Hess said that the digital signals of the local ABC and NBC Philadelphia affiliate stations are being carried, with various primetime shows in HDTV and with the rest of the programs (except for "The Tonight Show" on NBC) in standard-definition digital.

WPVI-DT (ABC) Engineering Director James Gilbert acknowledged being carried, but the station has experienced a few technical difficulties resulting in its cable channel sometimes going black. "We aren't sure whether it's our problem or the cable company's, but it only shows up on their system, " he said.


Conserving bandwidth on its systems, digital HD ATSC signals carried by Comcast are converted to 256 QAM and displayed on a consumer's TV set with an extra "sidecar" device that plugs into a digital set-top box. Hess said that when the HD service was announced in Philadelphia last year, there was a waiting list of more than 1,000 people to get the HD signal decoder. Comcast claims about 3,000 digital subs are using the HD set-top box currently.

Eventually the technology will be integrated into an advanced digital set-top box manufactured by either Motorola or Scientific-Atlanta, depending upon geographic location. Also, as stated in NCTA President Robert Sachs' letter to Powell, cable operators will begin to place orders for integrated HD set-top boxes with digital connectors and provide these boxes to customers who request them. A spokesman for Scientific-Atlanta said that it has shipped 38,000 of their Explorer 3100HD digital interactive set-tops, designed to handle HDTV and interactive services, to several different operators since May 2001.

Comcast's HDTV service in the Washington, D.C., region will include the HD signal of public broadcaster WETA-HD and Comcast's SportsNet all-sports HD channel. In fact, Comcast SportsNet will offer more than 200 HDTV sporting events starting in 2003, about half in the Philadelphia market and half in the Baltimore/Washington, D.C., markets. HDTV coverage will include the Philadelphia Phillies, Flyers and 76ers as well as the Baltimore Orioles and Washington Wizards and Capitals.

To watch these HD shows, customers with high-definition televisions need a separate HDTV set-top box or sidecar device, to be either sold (approximately $399) or rented ($9.95 per month) by the cable operators. Consumers must also subscribe to some type of digital tier service. Of concern to many is that the boxes, if bought outright, would not work in a different part of the country on a different cable system.

Time Warner Cable, with 12 million subs, also provides the HD feeds of HBO and Showtime. As with agreements it has made with PBS stations in Columbus, S.C., Raleigh, N.C., Milwaukee, Wis., and Allentown, Pa., Time Warner has allocated five channels on its digital tier to accommodate local CBS affiliate WRAL-DT's multi-casting strategy, including one for true HDTV. This came in handy during "March Madness" (the NCAA basketball tournament), when the cable operator carried several different games simultaneously.

"When you look at it, we're helping them roll out digital cable," said John Harris, director of special projects and programming for WRAL-DT. "We're providing the programming that they can use to sell against DBS."

Looking at the entire U.S. landscape, the cable industry appears willing to comply with Chairman Powell's desire to move the DTV transition forward, but the National Association of Broadcasters recognizes that behind the broad announcements of HDTV carriage, there are technical issues yet to be resolved.

"We look forward to the day when cable operators carry all digital broadcast signals in their entirety," said NAB President and CEO Eddie Fritts. Cable TV is a business that has always put profits ahead of signal quality, the organization contends.