How They Work: “How Cable TV Works”

As we move towards the launch of the “Digital TV” transmissions worldwide, it is important to have a rejoinder at the various TV modes that have been in use for nearly half a century or so. Some of the African states have just began enjoying Terrestrial Television a decade or two ago and others may have not yet began enjoying it even though the y have the capabilities to do so. Never has the power of Television been as strong as it is now; we get to know what is happening in one part of the globe just as it is happening, thanks to the advancement in Satellite technology! In the early days to telecasting, there were all sorts of bottlenecks but that is gradually disappearing, thanks to the “Global Village” concept! In the olden days, countries like the USA were relying on Cable TV in disseminating their programming. The earliest cable systems were, in effect, strategically placed antennas with very long cables connecting them to subscribers’ television sets. Because the signal from the antenna became weaker as it travelled through the length of cable, cable providers had to insert amplifiers at regular intervals to boost the strength of the signal and make it acceptable for viewing. According to Bill Wall, technical director for subscriber networks at Scientific-Atlanta, a leading maker of equipment for cable television systems, limitations in these amplifiers were a significant issue for cable system designers in the next three decades. “In a cable system, the signal could go through as many as 50 (or more) signal amplifiers before reaching your house, on every 300 metres or so, there would be an amplifier, and you would get noise and distortion. Plus, if one of the amplifiers failed, you lost the picture. Cable got a reputation for not having the best quality picture and for not being reliable.” In the late 1970s, cable television found a solution to the amplifier problem. By then, they had also developed technology that allowed them to add more programming to cable service. In the early 1950s, the cable systems began experimenting with ways to use microwave transmitting and receiving towers to capture the signals from distant stations. In some cases, this made television available to people who lived outside the range of standard broadcasts. In other cases, especially in the north eastern United States, it meant that cable customers could have access to several broadcast stations over the same network. For the first time, cable was used to enrich television viewing, not just make ordinary viewing possible. This started a trend that would begin to blossom fully in the 1970s. The introduction of CATV (community antenna television) stations and the spread of cable systems ultimately led manufacturers to add a switch to most new television sets. People could set their televisions to tune to channels based on the Federal Communications Commission (FCC) frequency allocation plan, or they could set them for the plan used by most cable systems. The two plans differed in important ways. eddie@afrowebs.com