Satellite TV

Satellite TV

This form of television is delivered by way of orbiting communications satellites located approximately 37,000 km above the earth's surface. The first satellite TV signal was transmitted from Europe to the Telstar satellite, hovering over North America in 1962. The first domestic North American satellite to carry television was Canada's Anik 1, which was launched in 1973.

Satellite TV (like other communications relayed by satellite) starts with a transmitting satellite antenna located at an uplink facility. Uplink satellite dishes are directed toward the satellite that its signals will be sent to and measures as much as 9 to 12 meters (30 to 40 feet) in diameter.

The larger the satellite dish, the more accurate positioning and improved signal reception it offers. The satellite TV signals is transmitted to devices located on-board the satellite,  called transponders, which in turn retransmit the satellite signal back towards the Earth at a altered frequency.

Because the satellite signal weakens after traveling through space, it is collected by a parabolic receiving dish, which then reflects the weak signal to the dish's focal point (eye) and is received, then down-converted to a lower frequency band and amplified by a device called a low-noise block down converter, or LNB.

Different forms of satellite antenna, which does not use a directed parabolic dish and can be used on a mobile platform such as a vehicle (car satellite system), was recently announced by the University of Waterloo.

The satellite TV signal, now being amplified, travels to a satellite TV receiver box through a coaxial cable (RG-6 or RG-10), instead of the standard "RG-59" and is converted by a local oscillator to the L-band range of frequencies. Special on-board electronics in the receiver box help tune the signal and then converts it to a frequency that a standard television can use.