Glossary of Terms and acronyms

FDMA:
Frequency Division Multiple Access. Refers to the use of multiple carriers within the same transponder where each uplink has been assigned frequency slot and bandwidth. This is usually employed in conjunction with Frequency Modulation.

Federal Communications Commission:
The US Federal Government's regulatory agency established in 1934 and responsible for regulating all forms of electronic communications including television, radio, telecommunications, mobile services and satellite communications. It is generally considered to be the world's most powerful and influential communications regulatory agency. Its decisions on satellite communications frequently impact on other countries.

Feed:
This term has at least two key meanings within the field of satellite communications. It is used to describe the transmission of video programming from a distribution centre. It is also used to describe the feed system of an antenna. The feed system may consist of a subreflector plus a feedhorn or a feedhorn only normally found at the focus of a dish antenna.

Footprint:
A map of the signal strength showing the EIRP contours of equal signal strengths as they cover the earth's surface. Different satellite transponders on the same satellite will often have different footprints of the signal strength. The accuracy of EIRP footprints or contour data can improve with the operational age of the satellite. The actual EIRP levels of the satellite, however, tends to decrease slowly as the spacecraft ages.

Forward Error Correction (FEC):
Adds unique codes to the digital signal at the source so errors can be detected and corrected at the receiver.

Frequency:
The number of times that an alternating current goes through its complete cycle in one second of time. One cycle per second is also referred to as one hertz; 1000 cycles per second, one kilohertz; 1,000,000 cycles per second, one megahertz:
and 1,000,000,000 cycles per second, one gigahertz.

Frequency Coordination:
A process to eliminate frequency interference between different satellite systems or between terrestrial microwave systems and satellites. In the U.S. this activity relies upon a computerized service utilizing an extensive database to analyse potential microwave interference problems that arise between organisations using the same microwave band. As the same C-band frequency spectrum is used by telephone networks and CATV companies when they are contemplating the installation of an earth station, they will often obtain a frequency coordination study to determine if any problems will exist.