Satellite TV Technology Guide For Dummies

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Satellite TV Technology Guide For Dummies

Thursday, July 9th, 2009 Subscribe To Our Feed

Television delivered by the means of communications satellite is known as Satellite TV. A satellite dish and set-top receiver box is needed on ground to receive the signal. A wide range of services and channels are offered by Satellite TV.

Satellite television begins with a transmitting antenna located at an up-link facility. Up-link satellite dishes are huge, as much as 9 to 12 meters (30 to 40 feet) in diameter. The large diameter results in more precise aiming and increased signal strength at the satellite. The dish used for up-link is aimed at a specific satellite. The up-link signals are transmitted within a specialized frequency range, so as to be received by one of the transponders tuned to that frequency spectrum onboard the satellite. The transponder resends the signals back to Earth but in a different frequency spectrum to avoid interference with the uplink signal. The retransmission typically happens in the C-band (4–8 GHz) or Ku-band (12–18 GHz) or sometimes both. The portion of the signal path from the satellite to the receiving Earth station is called the downlink.

The downlinked satellite signal becomes quite weak after traveling the long distance to Earth. A parabolic receiving dish collects the weak signal and reflects it to the dish’s focal point. A device called feedhorn is mounted on brackets at the dish’s focal point. This feedhorn is basically the flared front-end of a portion of waveguide that collects the signals at or near the focal point and conducts them to a probe connected to a low-noise block downconverter or LNB. The LNB amplifies the relatively weak signals and filters the block of frequencies in which the satellite TV signals are transmitted. The chunk of frequencies is then converted to a lower frequency spectrum 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 satellite receiver set-top box then demodulates and converts the signals to the desired form of output for television, audio, data, etc. The receiver is called an integrated receiver/decoder if the receiver includes the ability 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 TV programs to you. Equipment duplication is avoided since broadcast centers are not needed 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 television companies rate significantly higher in customer satisfaction than cable TV companies.

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