How Cable TV Works – Satellite Technology – Cable TV in Spain
Many television signals are actually transmitted over radio frequencies, which travel in straight lines. So, if your TV wasn’t in the “line of sight” of the source, the signal was blocked, and your TV screen would be blank.
By putting up antennas on the high spots, and then running cables down to their homes, people living in low or non signal areas could receive the signals clearly. This idea of sending signals over cables, rather than using airwaves, was the first beginnings of what we know today as cable TV.
By the early 1990s, cable television had started to become popular, and now cable systems can deliver hundreds of channels while also providing a growing number of people with high-speed Internet access. Some cable systems even let you make telephone calls.
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.
In 1976, a new sort of cable system debuted. This system used fibre-optic cable for the trunk cables that carry signals from the CATV head-end to neighbourhoods. The head-end is where the cable system receives programming from various sources, assigns the programming to channels and retransmits it onto cables. By the late 1970s, fibre optics had progressed considerably and so were a
cost-effective means of carrying CATV signals over long distances. The great advantage of fibre-optic cable is that it does not suffer the same signal losses as coaxial cable, which eliminated the need for so many amplifiers. In the early fibre-optic cable systems, the number of amplifiers between head-end and customer was reduced from
30 or 40 down to around six. In systems implemented since 1988, the number of amplifiers has been further reduced, to the point that only one or two amplifiers are required for most customers. Decreasing the number of amplifiers made dramatic improvements in signal quality and system reliability.
Cable TV system have the advantage of being able to provide true video on demand, allow the users to select a programme to watch from a library and view it at any time they require, something that due to bandwidth and frequency restrictions, is not possible on terrestrial and satellite TV systems.