Satellite -vs- Cable TV
Now let’s talk quality. As we said earlier, cable gets it’s channels the same way DBS does, with a slight difference. Cable used to be like DBS. Each cable system had dozens of large satellite dishes in the back yard to get their programming from the channel providers. Then they had to convert those signals to new frequencies for their converter boxes.
But that has changed since digital TV became the new standard. These days, there is a center office somewhere in your region that receives the services from the digital satellite like DBS does. For example… My region of PA has a central office located between Lebanon and Reading. This office recieves all of the channels (such as CNN, USA, ESPN, C-SPAN, HBO…etc) from the digital satellite in very high definition. Then they insert all of these channels onto a fiber optic system that runs throughout the region.
Some local stations put their station programming on the fiber optic for re-transmission on other regional cable systems. All of the local cable systems pull these channels from the fiber optic in very high resolution and little to no compression to maintain the original quality. Then they redirect the bit-streams of those channels onto their cable line as a digital bit-stream with codes for their own systems.
These codes identify the channels and route them to the proper channel numbers on your converter box. Many areas now use fiber optic cables on the poles, then convert the optical signal to a wire signal through a device called a node mounted on a pole near your home. The conversion from optical to wire is a direct conversion with little to no loss of quality. At most, the loss is less than 4%.
Cable TV uses the same frequencies that they used before. They are all VHF and UHF frequencies, some of which are used for over the air channels. Each channel is the same bandwidth as a TV station uses. (6MHz). Over the air stations, can fit 1 HD channel and 2 or 3 more SD channels on to their one single channel. Cable does not send signals through the air.
They send signals directly to you on a closed circuit fiber optic, and coaxial cable. This allows cable companies to use a little compression to fit up to 2 HD channels, and 3 SD channels on the same single 6MHz channel. Or they can put 3 HD channels on one single channel. Or they can put up to 10 SD channels on one single channel. So the 175 channels that cable companies have to use, can carry up to 1,000 channels.
The digital compression rate is low enough to retain 96% of the original quality. Once the signal leaves the cable head unit, it only goes through 1 conversion in the digital converter box in your home.
I said we would touch base on FiOS. FiOS boasts that they are better than cable and can offer a lot more. Well…….they are lying. FiOS works pretty much the same as Cable TV does. They run fiber optic on the poles, just like cable. But the difference is, FiOS runs fiber optic cable all the way into your home. Where as Cable TV runs copper wire from the pole into your home. But the secret to this is, there is no difference in quality or bandwidth between Cable and FiOS. The major difference is, Cable is available damn near everywhere. FiOS is very limited in it’s coverage areas.
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