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Cable - ready TVs

Sat, 07/31/1999 - 8:00pm
Jeffrey Krauss, Digital Cable Dreamer and President of Telecommunications and Technology Policy
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By Jeffrey Krauss, Digital cable dreamer and President of Telecommunications and Technology Policy

Although most of the cable TV and digital TV receiver interconnection and interface issues have been resolved, there is still work to be done, and at least one dispute. The issues are seen most clearly within the context of defining the "digital cable-ready TV set." The consumer electronics manufacturers view cable-ready TVs as those that connect to the drop cable with an F-connector. But connecting to a cable set-top is another story.

Their dream vs. my dream

The TV set makers dream of a world where the broadcast signal is defined by a fixed standard and "innovation" means making the TV set produce better pictures at lower cost. That's pretty much the way analog television was. They dream of a world where there are no set-top boxes, and all of the cable TV circuitry is built into their TV sets. The biggest problem with this dream is that the digital television specification is very flexible, and new services will be developed that use the broadcast or cable signal as a platform, but require some new hardware elements.

My dream is that set-top boxes will be needed to support these new services, because consumers can't be expected to junk their $2,000 digital TV sets just to play some new multimedia game or use some new interactive service.

The cable and consumer electronics industries have agreed on the interface between the digital set-top and the digital TV, namely, the IEEE 1394 "FireWire" specification with the AV/C command language. But most TV makers don't want to put that connector into their TV sets. Some want to use only the antenna terminals as an interface, and want to require the set-top box to remodulate its output onto channel 3. Some want to use wideband analog components video signals as the interface. Never mind that the cable industry supports the 1394 interface. And never mind that the motion picture industry has given its blessing to a copy protection technology that works on the 1394 interface, but has not accepted any copy protection techniques for the remod interface or the component interface.

Delivery of the first digital cable set-top boxes with a 1394 interface connector has been promised for later this year. No promises have been made for the first "set-top-ready" digital TV set; we'll have to watch and wait.

But there are a bunch of issues that are either agreed on, or much closer to resolution. For example, cable-ready TVs will comply with the standards for digital video (ATSC A/53 and A/65), the cable TV channel plan (EIA-542) and the RF performance standard (EIA-23). These TVs will be able to demodulate 64-QAM and 256-QAM signals, as well as 8-VSB and 16-VSB. They will be able to decode the additional video formats defined for cable in SCTE DVS 033, which go beyond the video formats defined for broadcast TV. However, a dispute remains over still pictures. In the broadcast TV standard, still pictures (refreshed say every 30 seconds) are prohibited because it is considered user-unfriendly to tune into a channel and have to wait up to 30 seconds to have the picture displayed. But cable wants to use still pictures in connection with audio services and other services!

There is agreement that cable-ready TVs will contain a security interface connector, known as the Point of Deployment (POD) module interface. This module will make it possible to receive the out-of-band channel with its entitlement messages, and to decrypt premium programming without needing a set-top box. The out-of-band channel will also carry emergency alert messages, and channel map information so that the TV tunes to the proper cable channel. Digital TVs may also make use of the POD interface, but without a POD module inserted. This is because only non-encrypted (in-the-clear) channels can be viewed without a POD module, but viewers should still be able to receive emergency alert messages. The cable industry has agreed that emergency alert messages will be inserted at the cable headend into the in-band data stream in these non-encrypted channels. Of course, over-the-air broadcast channels will already contain their own emergency alerts.

In addition to inserting emergency alert messages into non-encrypted channels, there may also be a need for cable operators to insert some additional data, related to the broadcast PSIP data defined in ATSC A/65, so that TV tuners will know how to navigate and what channels to tune to when the viewer changes channels. Anyway, it remains to be seen just how many other "in-the-clear" digital channels a cable system will carry. There is at least some feeling in the industry that all of the "enhanced basic" cable program services will be encrypted in digital cable systems.

So when will these cable-ready TVs be available? The first-generation 1998 digital TVs did not tune cable frequencies, did not demodulate QAM signals and did not connect with digital cable boxes. The broadcast industry views these TV set deficiencies as the biggest barriers to the success of digital television broadcasting. The second-generation 1999 digital TVs will be on the market in time for Christmas, and we'll all be watching to see what features they contain

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