Standard cable service, both analog and digital, works on a “broadcast” model, in which every available channel is sent to every subscriber all of the time, regardless of what is actually being watched. Sending more channels than you’re actually watching just takes up more of the capacity on the cable pipe – capacity that could be used for other important purposes.

As this article succinctly puts it:

One of the primary benefits of SDV is that it frees up bandwidth because it only delivers the channel a customer is viewing.

In previous posts – like this one on net neutrality or this one on consumption-based billing – we’ve referred to the competing demands on network bandwidth. Your local cable system has a finite amount of capacity over which to provide all of the voice, video, and data services that its consumers demand.  A tool like SDV is one method of clearing up bandwidth for other services, allowing your cable provider to offer faster broadband speeds, more HD and niche programming, and other new services.

That’s why the FCC has endorsed cable’s use of SDV (For example, see this FCC Order regarding deployment of SDV by Cox and Time Warner Cable.).  Other multichannel video providers use SDV, including AT&T’s U-verse service, which is 100% switched digital.

Two-Way Services Need Interactivity

Some people want to receive digital cable service with devices other than a cable-provided set-top box, such as a TiVo DVR.  For purposes of authentication, a CableCARD needs to be used as part of that connection. You can read this blog post to get the background on CableCARDs, but the salient detail here is that the  2002 agreement between the cable and consumer electronics industries that led to CableCARDs only covered devices that receive one-way cable services, such as the channels that are continually “broadcast” on the cable pipe without anyone actually requesting them.

These one-way devices are known by the long – yet descriptive – name “Unidirectional Digital Cable Ready Products.”  UDCPs were never designed or intended to be able to receive Video-on-Demand, electronic program guides, and other two-way services that require interaction between a set-top box and the cable operator’s plant – and the FCC required UDCP manufacturers to expressly warn consumers of those limitations.

Based on the description above, you might easily surmise that SDV requires interactivity.  A channel request goes up the line to your cable provider, and then the requested content is sent back.

Even though UDCP devices were never intended to receive content delivered over a two-way platform, the cable industry and TiVo worked together to develop a solution for consumers who were using TiVo UDCP devices on systems where some channels were delivered using SDV.  That solution is called a “Tuning Adapter,” because it is a device that connects to a consumer’s TiVo box and provides the two-way functionality to request (or “tune” to) SDV content.  A TiVo press release (NCTA and TiVo Announce Switched Digital Solution for HD DVRs) and this 2007 news story (TiVo, NCTA Team Up on Switched Digital) outline the joint development.

In April, the FCC launched two proceedings about video devices, one of which asked questions about whether Tuning Adapters are working.  Although TiVo’s website asserted that the Tuning Adapter “works well” for accessing SDV content (TiVo’s website declared “there are no known issues with Tuning Adapters and Premiere/XL, TiVo HD/XL, and Series3 HD DVRs”), TiVo is now proposing that the FCC mandate a completely different solution. Or as Todd Spangler put it in Multichannel News, TiVo wants to replace “the Tuning Adapter that cable developed in conjunction with TiVo.”

My next post will look into just that issue.

Here is some of the coverage:

• Charlotte Observer
• Light Reading’s Cable Digital News
• Elon University’s The Pendulum

One takeaway from the event was that there seemed to be very high awareness of the transition, but there also continues to be some confusion between the digital transition involving over-the-air broadcast stations and the digital transition that cable operators have been conducting for a few years.

For example, here’s a recent post from the Cultured State blog: The 2009 Digital TV Transition: Flirting With Disaster. The author insists that “the cable television industry isn’t telling the whole truth on what’s about to happen to your cable service.” The false charge is leveled that you won’t be able to continue to receive your cable signal unless you have a set-top box or a Digital Cable Ready TV. Proof is offered in the form of a July article from MSNBC’s Bob Sullivan.

As it so happens, I’ve already addressed Sullivan’s piece:

Bob Sullivan, senior writer for MSNBC.com’s Technology section, posted an article today entitled “The ‘Other’ Digital TV Conversion Might Cost You,” which purportedly attempts to clear up some confusion about the coming Digital Television transition. In fact, it simply sows more confusion. Sullivan has tried to establish (falsely) a direct relationship between the upcoming “DTV Transition” and efforts by cable operators to expand their video offerings and enhance other services.

Read the whole thing for the full explanation, but suffice to say that cable needs to manage its bandwidth, which is why we see things like switched digital video or channels being moved from analog tiers to digital. This has been going on for some time and has nothing to do with the Digital TV Transition of next February.

A sinister portrait is painted of the cable industry’s intentions regarding set-top boxes. I will simply refer you to comments I made to the TV Barn blog:

“If you switched to DirecTV or Dish, you have to have a new box. If you switch to Verizon FiOS or AT&T’s U-verse, you have to have a new box. It baffles me to no end why there are four companies competing with cable and nobody has ever complained that you have to have a set-top box for them.”

Michael Marcus at the Spectrum Talk blog also has concerns: 6 Months to Go and Some DTV Confusion Continues. He tries to wade through a variety of website, but concludes, “…if you have your analog TV set connected directly to the cable system and select channels directly with your TV set tuner, you might be in trouble in the near future.”

What he’s referring to is that cable operators have offered to carry local broadcast signals on analog tiers for three years, unless the cable system goes all-digital. This does not seem to be sufficient for him:

Note that the FCC requirement only deals with local over-the-air signals (e.g. signals from NAB and MSTV members), not C-SPAN, CNN, The Food Network, etc. So the quote from the DTV Transition Coalition above (actually linked through the NCTA site) that says “TV sets that currently receive programming through cable or satellite are not likely to be affected by the transition to digital.” is at best a half truth. So is the FCC quote, “Analog TVs will continue to work with cable, satellite, VCRs, DVD players, camcorders, video games consoles and other devices for many years”. But if your idea of TV is limited to what the 15% of American homes without cable or satellite actually see, then the information is correct.

Once again, we’ve got apples and oranges. The Transition is about over-the-air broadcast stations. If cable channels have to be moved from analog to digital, that is a completely separate issue.