Television transmitted by the means of communications satellite is known as Satellite TV. On ground, the signal is received by a satellite dish and set-top receiver box. A large number of services and channels are catered for by Satellite TV.
Satellite television begins with a transmitting antenna located at an uplink facility. Uplink satellite dishes are very large, as much as 9 to 12 meters (30 to 40 feet) in diameter. More precise aiming and improved signal strength at the satellite are the main benefits of such large dishes. The dish used for uplink is pointed towards a specific satellite. To ensure that uplink signals are received by one of the transponders tuned to a specialized frequency spectrum onboard the satellite, the up-link signals are transmitted within the same frequency spectrum. The transponder retransmits the signals back to Earth but in a different frequency range to avoid interference with the uplink signal. The resending typically happens in the C-band (4–8 GHz) or Ku-band (12–18 GHz) or sometimes both. The leg of the signal path from the satellite to the receiving Earth station is called the downlink.
After traveling the long distance to Earth, the downlinked satellite signal becomes quite weak. The signal is collected by a parabolic receiving dish, which reflects the weak signal to the dish’s focal point. Affixed on brackets at the dish’s focal point is a device called a feedhorn. The signals at or near the focal point are collected by this feedhorn which is basically the flared front-end of a portion of waveguide and then sends them to a pickup connected to a low-noise block downconverter or LNB. The block of frequencies in which the satellite TV signals are transmitted is filtered and boosted by the LNB. The chunk of frequencies is then converted to a lower frequency range in the L-band spectrum by the LNB. Direct broadcast satellite dishes are fitted with an LNBF which integrates the feedhorn with the LNB.
The signals are then demodulated and transformed to the desired form of output for TV, audio, data, etc by the satellite receiver set-top box. The receiver is called an integrated receiver/decoder if the receiver includes the capability to unscramble or decrypt. The cable connecting the receiver to the LNBF or LNB must be of the low loss type RG-6, quad shield RG-6 or RG-11, etc. It cannot be standard RG-59.
The main benefit of satellite television is that providers (like Dish Network or DirecTv) don’t have to lay miles upon miles of cable to deliver television programs to you. Equipment duplication is avoided since broadcast centers are not required in every city. This saves you money because satellite television is less expensive to maintain and up-grade, no re-laying of cable to up-grade services is needed. If the primary uplink center has a problem, the secondary uplink center automatically takes over broadcasting. That’s why satellite television has a less than 1% outage rate. Satellite TV companies rate significantly higher in customer satisfaction than cable TV companies.