How Satellite TV Works – Satellite Technology – Satellite TV in Spain

Satellite TV is the television system wherein communication satellites orbiting the Earth bring about the transmission of television signals. It is a wireless system that facilitates the relay of TV programs by means of satellite communication. In many countries around the world, satellite television services are used for providing the consumers with more number of TV channels and a wider range of services.

The satellites that aid the transmission of television signals have elliptical or geostationary orbits. The television satellites are all in geosynchronous orbit, meaning that they stay in one place in the sky relative to the Earth. Each satellite is launched into space at about 7,000 mph (11,000 kph), reaching approximately 22,200 miles (35,700 km) above the Earth. At this speed and altitude, the
satellite will revolve around the planet once every 24 hours — the same period of time it takes the Earth to make one full rotation. In other words, the satellite keeps pace with our moving planet exactly. This way, you only have to direct the dish at the satellite once, and from then on it picks up the signal without adjustment, at least when everything works right.

The satellite houses transponders, which receive signals from the antenna. The uplinked signals are tuned to a frequency range that corresponds to that of the transponders. The transponders retransmit the signals back to Earth. Before they are retransmitted, the signals undergo a process of translation wherein they are transmitted at a different frequency band in order to avoid interference with the uplink signal.

The signals that are transmitted by the transponders on a satellite are received by the parabolic dish. On account of travelling a substantially large distance, the signal received by the dish is weak. The signal is reflected towards the feedhorn, a device mounted at the focal point of the dish. The function of a feedhorn is to collect the received signal and conduct it towards the low-noise block downconverter (LNB).

The LNB amplifies the signal and converts it to a frequency that is suitable for transmission over a cable, precisely to the L-band range. The LNB transmits the signal over the intra-facility link (IFL) to the satellite receiver. IFL refers to the coaxial cable that connects the indoor and outdoor satellite equipments. Owing to
the LNB, the handling of L-band signals becomes easy. Also, low-cost cables can be used to connect the television receiver with the TV dish and the LNB. The satellite receiver sends the signals to the television set and it is ready to come alive!

Sometime the satellite TV provider encrypts the signals to keep people from accessing it for free. Encryption scrambles the digital data in such a way that it can only be decrypted (converted back into usable data) if the receiver has the correct decryption algorithm and security keys, usually in the form of a viewing card and monthly payment / subscription.