7E Communications
   

Glossary Terms Beginning F

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Fade margin
The difference between the calculated or actual performance of a link and the threshold of operation; see Threshold margin.
FDMA
Frequency division multiple access: refers to the use of multiple carriers within the same transponder where each uplink has been assigned a frequency slot and bandwidth, usually employed in conjunction with frequency modulation.
FEC
Forward error correction: data correction signal added at the uplink to enhance concealment of errors that occur on the passage of the signal via the satellite to the downlink.
Feed
Generic term for the feedhorn, or the feedhorn and the antenna; a generic term for a transmission.
Feeder link
Backbone Earth-satellite links in contribution and distribution networks.
Feedhorn
In SNG, the assembly on the end of the arm extending out from the antenna from which signals are transmitted into the focus of the antenna.
Fibre-optic
Transmission process using mono-frequency sources of light modulated with a signal or group of signals transmitted through a glass fibre.
Field
Partial scan of a frame; there are two fields in a single TV frame.
Figure of merit
G/T: a measure of the performance of a downlink station expressed in units of dB/K, depending on the receive antenna and low noise amplifier combination G (in dBi), and the amount of receiving system noise T expressed as a temperature in kelvin (K). The higher the G/T number, the better the system.
Firewire
IEEE 1394: data transfer standard for consumer and semi-professional audio-visual devices.
Flange power
The output power of the HPA delivered to the output port for delivery to the uplink antenna.
Flight-case
Electronics transit case built for ruggedness, typically made from aluminium alloy or polypropylene, with internal shockproofing, to withstand the rigours of shipping by air.
Flux-gate compass
Electronic compass.
Flyaway
Transportable earth station used for SNG which can be broken down and transported in cases to location.
FM
Frequency modulation.
Footprint
Arrangement of satellite coverage beams to cover a particular area; a map of the signal strength of a satellite transponder showing the EIRP contours of equal signal strengths as they cover the Earth's surface.
Forward error correction
FEC: inner convolutional coding that adds unique codes to the digital signal at the source so errors can be detected and corrected at the destination.
fps
Frames per second.
Frame
A single TV picture is referred to as a 'frame' and there are two 'fields' in every frame.
Frequency
The number of times that an electromagnetic wave goes through a complete cycle in one second. One cycle per second is referred to as 1 Hertz (Hz) and is the basic measurement of frequency.
Frequency band
Specific span of electromagnetic spectrum.
Frequency co-ordination
Process to analyse and eliminate frequency interference between different satellite systems or between terrestrial microwave systems and satellites.
Frequency modulation
Process whereby a carrier signal is shifted up and down in frequency ('deviates') from its 'at rest' (centre) frequency in direct relationship to the amplitude of the baseband signal.
FSS
Fixed-Satellite Service: ITU designation.