Changing channels

Digital video

Every time an analogue video signal is transmitted, amplified, recorded or edited, the resulting picture gets a little worse. Communication experts have long known that by converting the complex analogue wave into simple digital pulses the signal can be regenerated many times without this deterioration. In recent years digital technology has been applied to television. Among the most common applications have been in broadcast production, long distance transmission of network feeds, and a variety of consumer formats. Digital formats tend to provide a crisper picture, stereo or multi-channel sound, and a wider selection of program materials and supplementary information. All depend on compression software that reduces the amount of data that must be transmitted and stored.

In 1997, Canada’s two direct-to-home satellite services began beaming digital signals to subscribers. They were followed by cable operators, who offered digital as an enhancement of their regular analogue services. In both cases, operators offered a wider selection of specialty channels as well as “pay-per-view” movies. At around the same time Canadians began to purchase DVD (digital versatile disc) players that played back programming stored digitally on a shiny plastic disc resembling an audio compact disc. Also in the late 1990s, manufacturers began to sell digital camcorders that offered the additional advantage of editing on a personal computer. The Museum has examples of a DVD player (20000006) and the “set top boxes” required to decode digital satellite and cable signals for a conventional television (20000014, 20000016).

DVD players like this JVC model (20000006) play back digitally recorded video signals, ca 2000. (CSTM/Peter Lindell)

Scientific Atlantic “set top box” (20000016) decodes digital cable television signals, 2000. (CSTM/Peter Lindell)

The future

The video field is currently experiencing a great deal of technical change. New digital technologies like high definition television (HDTV), flat panel displays, home theatre, and video on demand have recently been introduced to consumers. The adoption of digital format opens up numerous possibilities for treating video signals like any other form of data. Video signals are routinely combined on radio and fibre optic communication channels with other forms of information. Broadcasters and home video buffs perform editing at computer work stations. Users of DVD players access additional information on the program they are watching by pressing a button on their remote control. Subscribers to digital television services can browse program guides or order up movies just as readily. With the proper decoder and keyboard, they can convert their television into a terminal for accessing the Internet. Conversely, a personal computer user with a high speed Internet connection can view and even record high definition video signals. At this time it is not clear how this technology will evolve or how widely it will be adopted. While digital systems present certain opportunities that are eagerly anticipated and adopted by technophiles, most Canadians can be expected to make a more measured assessment of their needs and their financial means. As the picture becomes clearer, the television collection of the Canada Science and Technology Museum will evolve to reflect it.