| Buying a TV is no longer just a case of choosing the set you want, installing it and connecting it to the antenna; with the advent of new technologies, the options are much wider than this, and in some ways more confusing. So for a simple guide to some of the TV systems that are available - look no further! |
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Satellite TV Satellite TV is a way of transmitting TV signals via a satellite. The signal is received to the broadcasting center in a high resolution high quality form. At the broadcasting center, it is compressed using an MPEG standard, encrypted so that it can only be read by customers who have paid to receive it, and the resulting signal is beamed to a satellite in geosynchronous orbit - that is an orbit that allows it to be in a constant position relative to the earth.
The signal is picked up by the customer's satellite dish - aligned to the satellite by line of sight - passed to the customer's receiver, decrypted, decoded to give a full picture, and then passed to the TV to be enjoyed by the customer. This allows almost anyone to receive TV, as there are enough satellites for almost everyone in the country to be in line-of sight of a satellite.
Cable TV Cable TV is a great way of receiving TV if you live in a city, where it is possible to lay down fiber-optic cable in most districts. This works in a similar fashion as satellite TV, except that rather than beam the signal up to a satellite, it is transmitted via a fiber-optic cable laid underground. Compression and encoding is applied in the same way, and the customer has a receiver that decodes and decompresses the signal.
However, there are limits to both the length of the cable that can be used, and the number of users, as the signal is split for every branch of cable, and therefore degrades unacceptably if there are too many users or the cable is too long.
Digital TV The technical bits of digital TV are really about the format in which the picture and sound of a TV program are broadcast - instead of being sent in an analog format, they are sent in digital "code."
In order to be able to receive this format, you, the customer, have to have a digital TV which can "decode" the digital format. There are some real advantages to users with digital TV. It allows lots of new technology to be used, including flat screen TV, high-definition TV (HDTV) which gives a far better quality picture, multicasting, where two or more programs can be broadcast over the same signal bandwidth, and Dolby surround sound.
Antenna TV This is traditional line-of-sight TV where an antenna picks up a signal broadcast using terrestrial transmission stations. The problem is - because of the curvature of the earth, and because signals cannot pass through something as dense as the earth - transmission and booster stations have to be quite ubiquitous to transmit to most locations.
There are many areas where the TV signal cannot be received by the antenna, particularly in rural areas where the economics of transmission stations simply do not make sense. This transmission can be either an analog or a digital signal, and if it is an analog signal there is usually no need of a receiver beyond the antenna to decode and decrypt the signal.