Origins
The roots of cable TV lie in rural parts of the country, which had difficulty receiving ordinary television signals. In the 1940s and '50s, people received TV via a direct broadcast from the stations themselves to the antennas or rabbit ears in their homes. Physical obstacles such as hills or valleys could disrupt that signal, as could the curve of the Earth if the home was sufficiently far away. Viewers in rural Pennsylvania found a solution by mounting antennas to the tops of hills, then running cables down into their homes. It gave them much clearer reception and access to stations they might not otherwise receive.
Gathering the Signals
Those humble roots have since evolved to the point where cable TV has become a staple of contemporary life. Cable companies use the same notion as those folks in Pennsylvania, except on a much broader scale. The process starts with satellite signals, beamed from different television stations such as CNN and ESPN. Their broadcasts go straight up into orbit, then get beamed back down to the cable company's dish arrays. Because there are no physical obstacles, the signals come down clean. To them, the cable companies add signals from local TV stations, sent to them through cables buried in the ground. As with the satellite signals, the cables provide a very sharp signal. (Satellites aren't necessary, because local stations can run cable to the companies much more practically.)
From the Cable to Your Home
When the signals arrive, the cable company scrambles them to protect them from theft, then sends them to customers through a length of cable buried in the ground. (Most communities have extensive networks of cables, along with periodic signal boosters to ensure there's no degradation.) Because the signal travels directly through the cable into your home, there's no interference from physical obstacles and the signal is extremely clean. It also allows stations from far away to get to your home easily. (Without cable, only people in Georgia would be able to get CNN, TBS and the other Turner stations, for instance.)
The Descrambler
Once the cable reaches your home, it is run through your wall and into the cable box on top of your TV. The box acts as a descrambler, interpreting the cable signal and allowing you to view the programs clearly. It also permits shifts in frequency that allow you to change between the different available channels. (That's why you must often turn the channel with your cable box rather than your TV.)
Tags: buried ground, cable company, local stations, physical obstacles, satellite signals, their homes, with satellite