For example, new services generally don’t get beyond a few market trials if they require cable providers to 1) summarily clean off several 6 MHz channels, 2) find a big chunk of room in the headend, 3) overhaul field training, 4) overburden customer service representatives, or 5) support a new billing system.
Saying that something “doesn’t scale” is a death kiss to the company that makes that something. It means that for any or all of the reasons listed above, a service provider doesn’t trust it enough to roll it out to lots of customers.
Usage: “Yes, dear supplier, your robust platform for the broadband space sounds perfectly magical. But is it scalable?”
Either way, the intent is to protect premium content, like Cinemax, HBO, Showtime or Starz!, from unauthorized receipt. Only those people who order and pay for those services get a descrambler to decode the encrypted services.
Analog television signals were scrambled by any of several methods, including: Jumbling the audio or baseband carrier; suppressing the TV sync signal; using phase modulation; and inverting the video picture. Sync suppression is generally acknowledged as the most common analog TV scrambling technique, and dates back to the mid-1970s.
As cable providers moved toward “all digital,” or, at least, less analog, a first step was to move all premium channels to the digital shelf space, and start replacing those analog descrambler boxes with digital versions.
Usage: “Interdiction is another example of analog scrambling techniques. People liked it because they could continue using the remote that came with their TV.”
Using MPEG-2 compression to squeeze a digitized TV signal conserves a quarter to a third of the bandwidth it needed when it was analog. Put another way, where analog TV takes up a 6 MHz slot of bandwidth (including “guard band”), SDTV takes up but 1.5 MHz. This is why multiple SDTV signals can be crammed into the space of one analog TV signal.
In the early days of cable digital TV, estimates went as high as a 24:1, using statistical multiplexing. Currently (2005), the rule of thumb is ten to 12 digital TV signals per 6 MHz, denoted as 10:1 or 12:1 compression.
Also called “switched digital broadcast (SDB)” and just plain “switched video.”
The idea of switching video isn’t new. The first forays of telephone companies into video distribution, in the mid-’90s, included switching. (After all, it is called the public switched telephone network.) The effort attracted professional skepticism from cable engineers, who thought switching was too expensive for prime time. “Gold plated,” they called it.
That tune changed in 2004-2005. Switched video techniques regained the attention of cable technologists, because it looked like a useful way to “manufacture” additional digital bandwidth. How much bandwidth? Efficiency gains for switched video are measured as a ratio: The number of available switched broadcast channels to the number of channels being viewed. A 2:1 ratio, for instance, says that of 160 digital channels, 80 aren’t being watched. Or, put another way, 160 channels can fit into the space of 80 channels.
Switched video plays nicely with digital simulcast — once all channels are available in a digital format, they, too, can be switched. Switched video doesn’t play nicely with digital video devices that aren’t configured for two-way communications — such as the uni-directional TVs and HDTVs that grew out of the plug-and-play agreement.
As this dictionary was being written (2005), three fairly extensive tests of switched broadcast technologies were underway at three cable companies: Cablevision, Cox, and Time Warner Cable. Early results showed strongly for bandwidth conservation, but technologists were concerned about complexity and operational impacts.
The latest prefix for security, as of this writing (2005), is “downloadable” — meaning, protection methods that can be electronically transmitted to a device, and refreshed as needed.
The consumer electronics sector prefers to see the word “no” in front of the term “selectable output controls.” Nobody wants to be the guy who sells something — like an expensive HDTV — that suddenly doesn’t work as anticipated.
This could happen, the CE industry argued in the mid-2000s, if studios or copyright holders injected a “cripple code” into their choice titles. The code would alert a cable or satellite set-top box to disable certain digital outputs. No bits, no picture.
The notion of “selectable outputs” entered the industrial lexicon in December of 2002, when the cable and consumer electronics industries filed a 78-page “memorandum of understanding” to the FCC, which became known as “the plug and play agreement.” In it, cable agreed to not engage in selectable output controls.
It was a conditional agreement: They agreed to leave digital outputs alone, so long as the satellite side agreed to do the same. Why? To avoid this potential scenario: A copyright holder gives a major video competitor an earlier release on a popular title, on the condition that selectable output controls are enabled to protect copying.
Put to use, semiconductor materials are manipulated into things like diodes, transistors, and integrated circuits. Semiconductor chips, then, are essentially a really huge combination of transistors and diodes, arranged in specific ways to make a signal do specific things.
Usage: “That area over there is our on-demand server farm.”
The early chapters of subscription VOD (SVOD) inadvertently landed the “session” squarely on the “uh-oh” list. In one early SVOD trial, consumers were offered free access to a plump list of premium, episodic TV shows. (This was before DVRs.)
One thing became immediately (and dismayingly) clear to the network engineers involved: People watch SVOD much, much differently than they watch “traditional” VOD (movies). They sample, bail out, try a different title, sample again. They rewind more, pause more — in short, people create way more sessions with SVOD, than they do when watching movies on demand.
The session snafu story goes like this: In the summer of 2001, 26,000 HBO customers in Time Warner Cable’s Charlotte, N.C. system were given the ability to watch episodes of “The Sopranos” and “Sex in the City” on demand, with trick modes, for free. (It was, after all, a trial.) Within two hours, some 3,000 people were intrigued enough to check it out — an 11.5% response rate.
Things started to go wrong pretty quickly: Way more people had shown up for the party than anticipated. The first to respond was the equipment that sets up sessions and streams. It had a panic attack. The headend controller, suddenly busier than it had ever been in its life, stressed out, and started speaking in tongues. The server, hearing mostly babble from the controller, fell asleep.
Since then, “sessions” and “session management” have become as much of a focal point as “thick v. thin,” when planning for digital set-tops stacked with two-way applications.
The need for session-based encryption became evident after digital TV manufacturers were required, by law, to include digital tuners in their larger sets. Most opted to also include a CableCARD slot, which, in turn, requires QAM (Quadrature Amplitude Modulation) circuitry. Prior to that moment, the only devices containing QAM tuners were issued from the protected domain of the cable provider.
The placement of QAM devices in digital TVs and HDTVs meant that it was theoretically and technically possible for one house, with a digital TV set, to tune the VOD stream of a digital cable neighbor. This was a troubling possibility. What if the VOD stream was, say, an adult title, and the neighbor was, say, just off the school bus?
As a direct result, session-based encryption emerged. Its function is to scramble an on-demand session, sometime after it leaves the server, but before it enters the house. In some cases, the scrambling happens inside the edge QAM; other systems “bulk-encrypt” or “pre-encrypt” stored content, before it reaches the QAMs.
The “why do it” list:
1) Operators didn’t want to be left in the dust of consumer perception for not being “all digital.”
2) By making all channels available in a digital format, customers with digital and HDTVs get a consistent viewing experience, from one channel to the next.
3) New simulcast customers, who perhaps were previously analog-only, no-box-required customers, suddenly get access to on-demand and interactive offers.
4) Once all channels are available digital, work can begin on reclaiming analog spectrum and moving toward a truly “all digital” network.
Charter Communications started the simulcast trend in Long Beach, Calif., in 2003, when it shifted 96 analog channels into its digital tier. Since then, Comcast, Time Warner, and Adelphia developed fast-track simulcast plans. If those plans play out as described, two thirds of cable customers in the U.S. will be set up to get all channels in a digital format by the end of 2006.
Because the installed base of analog TVs and VCRs can’t interpret an incoming digital signal without a converter, work continues to develop a low-cost adapter, variously called “the $35 box,” “the $50 box,” “the $99 box,” “the box that isnt a box,” and “the dongle.” Until such a device is ubiquitously deployed on all analog TVs and VCRs, a “flash cut” to all digital/no analog is unlikely: Nobody wants to be the guy who kills the TV signal feeding the extra bedroom, kitchen, or any other additional outlets in a house.
The nuts and bolts of SIP are significantly different than the nuts and bolts of the VoIP technology first fielded by cable providers, known as “NCS,” or “Network-based signaling.” In essence, SIP assumes a “dumb” broadband network. It asks nothing of broadband, really, except for a ride. Instead, SIP anchors its smarts in the end points.
SIP isn’t something consumers see. What they do see, in SIP-based offers, is an adapter box, usually tied to a low-cost voice service. The phone plugs into the box, the box plugs into the cable or DSL modem.
Because broadband doesn’t heed normal geographies, a big selling feature is the ability to call, say, your niece, who is interning abroad, using your local area code.
Another big feature of SIP-based offers is the notion of “presence” (see definition), which is one of those terms that doesn’t work well in spoken conversations. (Network provider: “We have presence.” Consumer: “Give them to me!”) Presence tracks where a person is, using what devices (cell phone, instant messaging client, office phone, home phone). It lets people control how “available” they are for conversations. Maybe you want your spouse to reach you on all possible numbers. Or, maybe you set yourself in “do not disturb” mode on all devices. Sometimes people call this “find me/follow me” (or don’t.)
The existence of SIP-based services gave rise to another new term, which began circulating in early 2005: “Over the top.” As in, SIP services ride “over the top” of ordinary broadband connections. Generally, if one guy is providing the broadband bandwidth for a second guy, who’s offering “over the top” services of a competitive nature, the first guy is the unhappiest.
That said, cable providers are outfitting their technical specifications to accommodate SIP techniques, and especially presence services, into their plans.
Note that cable television engineers generally reserve signal-to-noise ratio for discussions about baseband signals (digital bits before theyre modulated), and use carrier-to-noise ratio (“CNR” or “C/N”) to describe RF signals. In digital systems, SNR is characterized as energy-per-bit divided by noise-per-Hertz.
Like so many other things of the digital world, a soft switch is a server. In the language of the PacketCable 1.0 voice specification, for instance, “soft switch” is synonymous with “call management server.” Its role is to replicate, in software, the features noted in the front pages of the phone book: Placing and receiving calls; handling call waiting, call forwarding, caller ID.
Usage: The backbone is an OC-48 SONET ring.
Spread spectrum is sometimes called “frequency hopping,” because the packets containing the intended message jump around to various frequencies within the spectral range. The technique was initially used by the Dept. of Defense to transmit coded information so that enemy forces couldn’t intercept it. It is also the main component of CDMA (Code Division Multiple Access) systems, such as those used by PCS phone providers, like Sprint.
Historically, spread spectrum is credited to the actress Hedy Lamarr, who patented it in 1942. As the story goes, she was romantically involved with a ranking military official in Europe, and endured the tedium of being treated as a bubblehead long enough to collect the facts she needed to develop what she called her “secret communication system.”
Maybe you know someone who can magically stuff two more suitcases into the crowded overhead bin on the airplane, or the truck of the car? Statmuxing is like that.
Generally, statistical multiplexing, in cable television systems, works by organizing the data rates of digital TV signals to be transmitted, depending on the amount of change, from frame to frame, of those various digital video channels.
Engineers sometimes shorten the pronunciation of “statistical multiplexing” to “statmux.”
The whole point of digital compression is to remove frame-to-frame redundancy, thereby freeing up more space. But, different channels may have different amounts of redundancy: Consider an airing of “I, Robot,” compared to something with slower action, such as a “talking head” news program.
Plus, the network that;s airing “I, Robot” may subsequently air something more sedate — “My Dinner with Andre,” for example. Meaning, the peak data rate even within a channel can vary greatly. Statistical multiplexing is the stuff that looks at the whole slate of programs to be sent out in a compressed, digital format, finds the blank spots, and uses the bandwidth of the blank spots for those channels that are peaking.
Another analogy: Driving a rush-hour highway. Aggressive drivers seek open spots, amid lanes of cars moving at different speeds, dodging in and out to keep moving toward the destination. A freeway statmux would magically calculate which cars are moving at what rate, and organize everything so that there weren’t any blank spots. Slow moving traffic really would stay to the right, and faster moving cars to the left.
The term “streaming media” seems to have originated in the Internet community, and particularly from the likes of Real Networks, as a way to categorize and describe the process of listening to or watching audio and video files to a PC, over the Internet.
This in and of itself wasn’t new; what was new was the ability to do it without having to download the entire file to the PC for later play — thus the “streaming” part of the descriptor. The process usually requires a downloaded “player,” which can be used multiple times to decode and present audio or video files encountered on a particular Web site.
The player does all the heavy lifting for A/V files, taking the incoming data flow and translating it into sound and pictures that are played on the PC.
Spectrally speaking, the visual information sits at one place within the 6 MHz channel (1.25 MHz up from the lower edge of the 6 MHz chunk), the color at another place (3.58 MHz above the visual carrier), and the audio at yet another place (4.5 MHz above the visual carrier). All together, the visual, audio and color make whats called a “composite video” signal — the whole thing.
Individually, those three characteristics have a constant and predictable spectral relationship to each other. The visual carrier calls the shots; it’s the constant. The audio and color information sits on subcarriers, which always reside at the same precise distance from the video carrier.
Subcarriers are sometimes used to convey information, other than color or audio, that goes with the video. In the old days of commercial insertion, for example, the subcarrier audio feed carried cue tones, which, in turn, triggered video tape machines to play out the advertisements.
Because it connotes an additional monthly subscription fee — ranging from $3.95-$9.94 — content providers for SVOD tend to be the premium channels: HBO, Showtime, Starz!, etc.
Consumers generally “find” SVOD content through a link on the electronic program guide. Stored titles can be retrieved to view “anytime,” with fast forward, rewind, and pause functionality.
But as high bandwidth connections become more pervasive, and electronic gadgets like digital camcorders, digital still cameras and Web cams become more mainstream, the whole genre of user-generated digital content will push the need for symmetrical connections.
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