Transitioning From Analog To Digital Broadcast Transmission Part I
Television’s original developers and regulators did their best to give us a simple and easy-to-use home entertainment device, given the technology at hand then. The ability to send moving pictures through the air in real time was one miracle; making their reception easy enough for the average family was another. Regularly scheduled telecasts began in the United States in 1939 just 3 years after they’d already begun in Britain. The first stations in Canada didn’t launched until 1952, although many Canadians were already receiving broadcasts from northern U.S. stations. In the days before digital broadcast technology, there were analog broadcasts of varying types that were incompatible from country to country.
The National Television System Committee (NTSC), made up of corporate and governmental representatives, devised the transmission standards for North American TV. They included 525 horizontal lines (including 480 devoted to the picture), at 60 interlaced fields or half-frames (for 30 total frames) of black-and-white pictures per second, transmitted on 6 MHz channels, with frequency-modulated (FM) audio. In the early 1950s, a second NTSC was formed to add color information to the signals. The committee chose RCA’s “compatible” color scheme, which enabled existing black-and-white TV sets to receive monochrome versions of color transmissions. This coloring was done by adding a color signal (chrominance) to the existing brightness signal (luminance), which added color without enhancing the signal. By the mid-1980s, the NTSC phased in stereo sound and closed captioning subtitles for the hearing impaired, which were the last major additions to NTSC analog TV. For more than 4 decades, all video innovations including videotape, camcorders, cable, VCRs, and other video equipment sold in the United States and Canada would be made to these NTSC specifications. The NTSC color standard has long been derided by videophiles as “never the same color” becuase of the relatively fuzzy picture and the wandering color hues, but NTSC will soon become part of history.
When European countries decided to switch to color in the 1960s, they chose to go with newer and more advanced broadcasts standards — either PAL (phase alternating line), developed in Germany, or SÉCAM (séquentiel couleur avec mémoire, or sequential color with memory), developed in France. Both of these standards offered more lines with better color than NTSC, but were not only incompatible with the NTSC system but also within their own countries’ black and white telecasts. Even with the different standards, European viewers enjoyed sharper pictures with higher resolution and more stable colors than those in North America. As well, for several years, Europe’s broadcasters would simulcast the same shows on separate color and black and white channels, before they finally shut off the black-and-white channels. The British Broadcasting Corporation launched color channels in 1967 and didn’t scrap the last black and white channels until in 1985.
Now, the United States and Canada are going through a similar transition from analog to digital television technology advancements that include the ever important color-stabilization, among other things. Digital television transition is a game changer for the way we watch TV in the near future.
Filed Under: Education