The Dish

A satellite dish is one type of antenna receiving the specific broadcast source. The standard dish normally is in parabolic shaped or half bowl surface and there is a feed horn located in the centre. When receive the radio signal from Satellite, it is refected at the curved dish to the feed horn. The feed horn is able to decrypt and decompress the signal and send to the home receiver box.

When the signal is transmitted, the transmitter works in the opposite way of the receiver. The controller will send the beam through the horn, and the dish focuses the signal into a relatively narrow beam. The beam finally is sent back to the Satellite.

Although we know radiowave signal are not transmitted in absolute line of sight, however if there is obstable such as mountain or trees, the signals will be distorted. So the dish installation is important to make sure we receives a clear signal.

Some of the systems allow the dish to pick up signals from two or more satellites at the same time. The standard dish with a single horn is able to pick up the signals from the satallites which are close enough together. This may degraded the quality due to the dish isn't aimed directly at one or more satellites while receiving signals. Some new dish design two or more horns to pick up different satellite signals. As the satellites are positioned differently, the beam hit the curved dish at different angles so that the beam hits each of the horns respectively.

Feed horn is also called low noise blockdown converter, or LNB. The LNB 's function is to amplify the radio signal which is bouncing off the dish and filters out the noise. The noise is the unwanted signal which is coupled during far tramission from Satellite. To amplify the radio signal, the ratio of noise become smaller and yet the LNB passes the amplified, filtered signal to the satellite receiver inside the viewer's house.

The Receiver

Satellite TV radio sginal eventually goes to the receiver . The receiver executes 4 major functions:

• It decrypts the encrypted signal. The receiver needs the authorized decoder chip to get back the original signal of programming package. The provider can communicate with the chip to adjust the decoding programs. The provider may occasionally test every receiver to check for illegal de-scramblers, as an electronic counter measure (ECM) against illegal users.
• It converts the digital MPEG-2 signal into an analog video signal to display in standard television. In the United States, receivers convert the digital signal to the analog NTSC format. More advanced dish and receiver setups is capable to output HDTV signals.
• It only takes one individual channels from many programming channels. When we change the channel on the receiver, it just display that channel to your TV. Some of the receiver can tape a channel and watch another but some cannot. But you can't watch two different programs by using the same receiver. If you want to watch two different channels, you need to have two receiver hook up with the conventional cable.
• It can schdedule for the pay-per-view programs and you can check the billing information through satellite tv.

Receivers have other function. Most receivers have parental lock-out options, its purpose is to avoid children from easily accessing the non educated channels. They can present the scheduled programming information in the onscreen programming guide and some have built-in digital video recorders (DVRs), which ease to pause, rewind and fast forward such as the home computer.