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Digital Convergence

  1. Atoms into Bits
  2. The Negroponte Switch
  3. Analogue to Digital: Technical Notes
  4. The Example of Photography
  5. Split Screen
  6. High Definition Television (HDTV) or Smart-TVs?
  7. Broadcast, Cable or Twisted-Pair (Telephone) Delivery?
  8. Bandwidth Comparison
  9. Links

Atoms into Bits

Scrambled TV, (c) M. Soules

Possibly more than any other term in the digital age, convergence conveys both the promises and hazards of using 1's and 0's to communicate. At it's most basic, convergence refers to the ways that various analogue media can be translated into digital bytes and manipulated by a computer. A webpage is a good example of this "new media": the whole thing can be assembled on a desktop computer which combines text, image, sound, video, animation, and other digital effects . In the early 1990s, however, an emphasis was placed on the convergence of the computer and television. A decade later, the convergence equation is more complicated: television, computers, cellphones, the internet, and their delivery systems--cable, wireless, telephony, satellite, broadcast--are scrambling the vision of the future.

Bringing separate analogue media together is possible because each has been translated to the digital form and can thus be combined and manipulated in a digital processor, the computer. We now have digital telephones and televisions replacing the older analogue versions, CDs and DVDs competing with audiotape and LPs, film and video. Print books can now be circulated as digital files, downloaded over phone lines or cable, and arrive as electronic books--again, all a series of 1's and 0's. It is this kind of convergence that is causing such a ferment of technological prediction.

As noted above, convergence often refers to the coming together of telephone, cable, and broadcast technologies, where telcos and the cable giants vie for carrier and content rights that have traditionally been separated by telecommunications regulators like the FCC (Federal Communications Commission in the US) and the CRTC (Canadian Radio-Television Telecommunications Commission). However, the phenomenal growth of multimedia and networked computers in the mid-1990ís forced many commentators to revise the terms of the equation. While deregulation is still an important concern, the availability of bandwidth for networked computers, and the development of affordable full motion video technology and cable modems re-defined the terms of the changing convergence equation. The networking of computers on the internet is, probably more than anything, defining convergence in the early years of the 21st. C.

The Negroponte Switch

In "Products and Services for Computer Networks" (Scientific American: The Computer in the 21st Century, 1995, 102-109) , Nicholas Negroponte discusses how telephone and television delivery systems will "trade places":

Broadcast spectrum is scarce, whereas fiber, like computing power, is something we can just keep making more of. Those facts mean that the channels for distributing different types of information...will trade places. Most information we receive through the ether today--television for example--will come through the ground by cable tomorrow. Conversely, most of what we now receive through the ground--such as telephone service--will come through the airwaves. Two rules of thumb define how information should be distributed. First, use the broadcast spectrum to communicate with things that move: cars, boats, airplanes, wrist telecommunication terminals, dog collars, scuba tanks and the like. Second, deliver information to the desktop or living room by fiber. (104)

Negroponte suggests that the FCC should "put the television networks and independent stations on notice that their spectrum will slowly be withdrawn and encourage the cable operators and telephone companies to begin collaborating immediately."

Analogue to Digital: Technical Notes

When we call something an analogue medium, we are referring to the fact that there is a continuous physical relationship between the original message and its reproduction. Speech and writing are represented by print in a book; musical sounds are represented by grooves in an LP or magnetized iron particles on an audio tape; light bouncing off an object is focused by a camera lens to change the colours of chemicals on film. There is often a one-to-one correspondance between the signal and its translation into a physical medium, or reproduction. (Analogue and analogous both derive from the Greek ana-logos meaning "proportion" or "ratio." The most general sense of analogous is thus "corresponding in some particular," making it synonymous with "similar, alike, comparable.")

In the lingo of computing, this definition has been extended and made more particular. Analogue is

the term applied to any device, usually electronic, that represents values by a continuously variable physical property, such as voltage in a electronic circuit...[A]nalog means both variation and proportion. An analog device can represent an infinite number of values within the range the device can handle. In contrast, digital representation maps values onto discrete numbers, limiting the possible range of values to the resolution of the digital device. (Microsoft Computer Dictionary, 19)

Essentially, analogue means "continuously variable" when referring to computers.

Sampling

An analogue-to-digital converter (ADC) translates analogue signals to digital signals. While the analogue signal is continuously variable within a range of values, a digital signal consists of discrete numeric values represented by binary patterns of 0's and 1's. An A-D converter periodically measures (samples) the analogue signal and converts each measurement to the corresponding digital value. The higher the sample rate, the greater the fidelity of the digital output. An A-D converter, for example, can be used to convert sound represented as an analogue electronic signal--a sine wave--to a series of digital samples that can be stored in memory, on hard disk, or on a compact disk. It is this conversion that has revolutionized the way information is recorded, stored, transmitted, and integrated. While analog signals are continuous--like waves--digital signals are discrete--like numbers. The discrete (and unambiguous) quality of digital signals means that when digitally encoded audio or video information is amplified, copied or otherwise processed, the output is identical to the input. As noted above, the quality of the digital signal is dependent on the number of samples taken at the input stage.

"Analogue signals are application specific; digital signals are generic" (Ellis 229). Ellis illustrates this important principle by asserting that the analogue information generated by the wavy grooves of the LP "can't be altered or enhanced in any way. It can only be played back, with a greater or lesser degree of fidelity, just as it was recorded in the vinyl. Digital signals on the other hand, are not dependent for their existence on a particular physical medium....Most importantly, they can be reprocessed and enhanced indefinitely with the aid of computers." The CD player and the digital processor of the computer "speak the same language of binary digits and handle information in exactly the same logical way" (229).This characteristic of digital media is essential for the application of compression algorithms in image and music files.

Digit comes from the Latin digitus --finger or toe--two handy measuring devices associated with the Arabic numerals 1 to 9 and 0. Digital is virtually synonymous with binary when referring to computers, which process information coded as combinations of binary digits (bits). One bit can represent at most two values; 2 bits, four values; 8 bits, 256 values etc. Values that fall between two numbers are represented as either the higher or lower of the two. (Microsoft Dictionary120) Binary digital computers are based on two states, logical ON and OFF, represented by two voltage levels, arrangements of which are used to represent all types of information--numbers, letters, graphics symbols, and program instructions. Digital recording converts information to "strings of 1's and 0's that can be physically represented on a storage medium. In a computer, a magnetic disk drive converts electric impulses representing 1's and 0's to magnetic flux changes in which magnetic particles on a disk are oriented in one of two possible directions. Taken together, the alignment of all the particles on the disk represent digitally recorded information" (121). In a digital signal, information is represented by "discreet states"--for example, high voltages and low voltages--rather than by continuously variable levels in a continuous stream, as in an analogue signal.

Digital Idioms

In his book Digital Mantras, Steven Holtzman considers how the digitization of image and sound will stimulate artists and musicians not just to make familiar effects in a new way, but to create new effects which are idiomatic to the computer. Just as computer interfaces use familiar analogies such as the desktop, trash bin, file folder and notepad to make computers less threatening, so do many programs use analogies to make the digital operation seem familiar to the user: the digital paintbrush or spraycan, and color palettes in visual programs; frequency modulation in audio programs--terminology that borrows from existing paradigms. Faced with the new digital technology, the human mind tends to resort to analogies to describe the new information-processing environment.

Holtzman asks the difficult question, "What means of expression are idiomatic to computers?" He then goes on to suggest that, in terms of music, the musician consider the ways that the computer creates a sound:

Perhaps the idiomatic sounds of a computer can be found in representing sound the way a computer creates sounds: in terms of machine instructions. Not Fourier synthesis, not frequency modulation synthesis, but store, retrieve, add, subtract, multiply, divide, and logical shift. (243)

In the shift from analog to digital signal processing, Holtzman is suggesting, old paradigms are expressed as analogies to promote familiarity and acceptance of the new technology; these analogies also tend to limit the ways in which we are able to use the new digital technologies creatively.

McLuhan called this the "rearview mirror syndrome," a situation extensively documented by media analysts: early mechanical printing made copies of manuscripts; early photographs mimicked painting; radio stations broadcast concerts and revues; early television presented plays and radio-style news reports; the internet adopts old business models or forms of entertainment like streaming video (aka television).

We are now faced with the rapid integration of digital technologies into our lives, and the choices can be baffling. Do we trade in an excellent analogue camera for a digital camera that loads images directly into our desktop computer? Do we subscribe to the digital or analogue cellphone plan? Should we hang on to our collection of vinyl? 8-track tapes? cassettes? How do we compose music using a piece of software and a keyboard designed for typing? Does the convenience of email give us more time, or more responsibility? The answers to these and thousands of similar questions have become part of our everyday news and social interaction. As Nicholas Negroponte pointed out in his 1995 Being Digital, our world is fast exchanging the trade in atoms for the trade in bits: "The change from atoms to bits is irrevocable and unstoppable," he claims (4). Many of us may feel exactly as Negroponte does--that our present is being determined by technology. However, there are many aspects of human life not so easily converted from the analogue to the digital, and making that distinction is important to our ability to negotiate the changes brought by convergence.

The Example of Photography

Segment of Diesel Ad with Churchill and FDR at Yalta, 1945

From its origins, the technology of photography has been based on the effect of continuously varying light on chemicals, whether those chemicals are found on a metal, glass, or celluloid medium. Photography has claimed to provide images so closely analogous to reality that it has been used to record the facts of life: news, commercial products, the moments of a life, landscapes, technical illustrations and so on. Of course, there are some who have also made the case that the composition, framing, and selection process of photography ideally suits it for promotional and propagandistic purposes, made all the more powerful for the apparent documentary qualities of the light-impinging-on-chemical technology. The advent of digital photography and image manipulation in the 1980's provided commentators an ideal opportunity to reassess the "objective" nature of the medium.

Digital photography differs from conventional photography in that a digital camera does not use a silver-halide based film to capture an image. A digital camera exposes the light reflecting off an image to a CCD (charge-coupled device) element that is covered with thousands of semi-conductors overlaid with green, red, and blue filters. Photons of light excite each element of the CCD, which converts photons to electrical information that is then transformed to digital data and stored in a solid-state memory or hard disk. After the image has been captured, some digital camera systems require that a camera be connected to a computer by a cable and the image downloaded to the computer using software supplied with the camera. A photograph can also be digitized by a scanner that converts lines and shading to combinations of 0's and 1's by sensing different intensities of light and dark. Once in a digitized form, the image may be altered--in a program like Photoshop--in an increasing range of eye-opening, reality-shaping ways. While a digital photo may look like its analogue counterpart, it is really a different object--it's a map of information.

Split Screen

Written in 1992 by David Ellis, Split Screen: Home Entertainment and New Technologies attempted to provide background on digital convergence to help readers understand where they might be headed in terms of home entertainment. Ellis provides some historical context for our current situation:

The 200--500 channel universe is coming not from the creative ferment of the production community, but through the development by engineers of "digital video compression": a process which takes redundancy out of a video signal and compresses it into a narrower bandwidth. This allows broadcasters to distribute many more video signals without a corresponding increase in the number of channels. This will result in the splitting of the electronic pathway into the TV, from cable, satellites, wireless providers, and the telcos. The TV screen is splitting in functional terms as well: no longer will the TV be used for the sole purpose of watching programs.

Ellis predicted that "smart" TV sets would act more and more like computers because they would either have computers embedded in them, or would be linked to computers. He envisioned that TV sets would also act as all-purpose monitors of household security and mechanical functions, and communicate with outside agencies such as banks and stores.

From our perspective now, we can see that his vision of convergence has not necessarily come to pass: we would not monitor household systems with our television, but with a desktop or laptop computer. Instead, television has fragmented into the digital delivery of additional specialty and pay-per-view channels while computer monitors have dominated the intelligent functions: from online gaming to shopping online. High definition television (HDTV) and large flat screens have yet to deliver smarter TV, just much improved image and sound--the home theatre.

High Definition Television (HDTV) or Smart-TVs?

While HDTV has been under development for over a decade, it will probably be another 10 to 15 years before it finds wide consumer acceptance. Improvement in picture quality and a change in aspect ratio--the ratio of screen width to height--from 4:3 to 16:9--are main features of HDTV. The new aspect ratio brings the television format more in line with film. One of the factors influencing the acceptance of HDTV is that the new broadcast standard must be compatible with the old NTSC--National Television Systems Committee--standard (525 horizontal lines, 30 frames/second, adopted by the FCC in 1941). For example, old black and white sets are still able to receive colour broadcasts, just as mono sets can receive stereo broadcasts. Also HDTV requires 5 times the bandwidth of NTSC--from 6 MHz to 30 MHz in some systems--putting it into competition with other bandwidth users like cellular phones. In the U.S., many broadcasters were given access to the additional spectrum in exchange for their promise to introduce digital broadcasting and HDTV. However, they have been slow to implement HDTV because it promises little in return in terms of revenue, while the extra equipment and broadcasting costs are considerable. For more information, check the HDTV Newsletter or Public TV and the transition to digital broadcasting.

Broadcast, Cable or Twisted-Pair (Telephone) Delivery?

The on-going debate over the expansion of service delivery to homes is shaped by at least two observable conditions:

  1. Rights holders and distributors of movies, sports events and other program material are using new video technologies to move the box office into the home--accelerating the changeover from free TV to pay-TV.
  2. The regulatory framework is outmoded: for example, compression technologies are challenging the historic rationale for governments to regulate bandwidth scarcity.

Traditional differences between television and telephone technologies include:

  1. Technical: TV is a broadband technology using point-to-multipoint public communication. Telephones use a narrowband technology and operate through switchable networks to enable point-to-point private communication.
  2. Functional: TV is a video medium that developed historically as a passive, in-home entertainment device. Telephony developed historically to carry interactive voice, then data traffic, and has always been as important for business transactions as for residential applications.
  3. Economic: Conventional television is a free "public good," supported by advertising and distributed over the air to the public without discrimination. Until recent deregulation, telephony was always considered a natural monopoly and telephone services are financed by subscriber fees and toll charges.

Technically, TV has moved closer to telephony with the spread of cable and the introduction of addressable descramblers. Important differences remain in terms of bandwidth and interactivity: the transmission of high bandwidth video or TV signals by cable does not lend itself easily to the two-way, switched interactivity of a telephone network. However, combining cable's high bandwidth network with the "switchability" of the telephone network in one line into the consumer's home has been fiercely resisted by both cable and telephone interests. Especially in Canada, we are seeing not convergence so much as a crossing of traditional boundaries as the two industries go after each other's turf.

One of the longstanding traditional obstacles to convergence is the principle of the separation of content and carriage required of common carriers. For example, under its enabling legislation, the Bell Canada Act, Bell is explicitly forbidden not only from holding a broadcast license but also from in any way controlling the contents or influencing the "meaning or purpose of messages transmitted" through its facilities. On the other hand, cable companies in Canada are allowed by the Broadcasting Act to originate programming. Rogers Communications, for example, owns controlling interests in broadcast companies. There is thus a "regulatory lag" based on traditional distinctions which is complicating the convergence of cable and telephony.

In the meantime, wireless delivery--cellphones, satellite, and standards like bluetooth--promise to redefine the more traditional convergence debates. We'll soon be using portable cellular devices to access the internet, debit our charge cards, and dictate to our computers from a distanc--and, of course, to call home. Satellite and Geophysical Positioning Systems (GPS) will turn both vehicles and people into mobile computing devices. As Steve Mann continues to show, wearable computing will allow us to take the show on the road.

Stay tuned! The debate over the convergence of media--illustrated by the short review above--has been active since at least the early 1990's. When we look at our newspapers, listen to the news, or visit our nearest computer store, we see that the debate is still being fiercely waged in the marketplace. And it seems that bandwidth is a key component of the convergence equation.

Bandwidth Comparison

A CD-ROM holds approximately 680 MB of data. The table below shows how long it would take to transmit this data at varying speeds. 

Type
Speed
Approx. Transmit Time
(680 MB)
 
Standard Modem
56 Kbps 
27 hours 
 
ISDN - 2 channel
128 Kbps 
12 hours 
 
Cable Modem
300 kbps-1.5 Mbps 
6 to 1 hrs. 
Broadband
DSL
128 kbps to 1.5 Mbps
12 to 1 hrs.
Broadband
T1.5
1.5 Mbps 
59 mins. 
 
T3(DS3)
44.736 Mbps 
2 mins. 
 
OC-3
155 .52 Mbps 
35 secs. 
 
OC-12
622.08 Mbps 
9 secs. 
 

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