f/D Ratio

The ratio of an antenna's focal length to diameter. It describes antenna "depth".

F-connector

A standard RF connector used to link coax cables with electronic devices.

Faraday Rotation

When peak sunspot activity highly charges the Earth's ionosphere, the vectors of linearly-polarized satellite signals can be rotated or "twisted" through interaction with the Earth's atmosphere.

FCC

The Federal Communications Commission, the regulatory board which sets standards for communications within the United States.

FDM

Frequency Division Multiplex

FDMA

Frequency Division Multiple Access

FEC

Forward Error Correction. Coding technique used in digital transmission.

Feeder, Feed Line

Co-axial cable transmission line connecting outdoor and indoor units.

Feedhorn

A satellite TV receiving antenna component that collects the signal reflected from the main surface reflector and channels this signal into the low-noise amplifier (LNA).

FET

Field-Effect Transister. Semiconductor device used in LNAS, LNBS, and LNCS. See also GaAs.

Fiber-optic cable

Wires made of glass fiber used to transmit video, audio, voice or data providing vastly wider bandwidth than standard coaxial cable.

Field

One half of a complete TV picture or frame, composed of 262.5 scanning lines. There are 60 fields per second for black/white TV and 59.94 fields per second for colour TV in NTSC transmission. In the PAL broadcast system there are 50 fields per second.

FM

Frequency modulation. A modulation method whereby the baseband signal varies the frequency of the carrier wave. Also referring to audio service broadcast over 88 MHz-108 MHz.

Figure 8 Cable

An aerial cable configuration in which the conductors and the steel strand which supports the cable are integrally jacketed. A cross section of the finished cable approximates the figure "eight".

Filter

A device used to reject all but a specified range of frequencies. A bandpass filter allows only those signals within a given band to be communicated. A rejection filter, the mirror image of bandpass filter, eliminates those signals within a specified band but passes all other frequencies.

Flame Resistance

The ability of a material not to propagate flame once the heat source is removed.

Flex Life

The measurement of the ability of a conductor or cable to withstand repeated bending.

FMFB

Frequency Modulation Feedback, a technique for deviation reduction and threshold extension.

Focal Length

The distance from the reflective surface of a parabola to the point at which incoming satellite signals are focused, the local point.

Footprint

The portion of the earth's surface covered by the signal from a communications satellite.

Forward Error Correction

FEC is a technique for improving the accuracy of data transmission. Excess bits are included in the outgoing data stream so that error correction algorithms can be applied upon reception.

FR-1

A flammability rating established by Underwriters Laboratories for wires and cables that pass a specially designed vertical flame test. This designation has been replaced by VW-1.

Frame

One complete TV picture, composed of two fields and a total of 525 and 625 scanning lines in NTSC and PAL systems, respectively.

Frequency reuse

A technique which maximizes the capacity of a telecommunications satellite through the use of spatially-isolated beam antennas andlor the use of dual polarities.

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 a Hertz, 1,000 cycles per second a kilohertz, 1,000,000 cycles per second a megahertz, and 1,000,000,000 cycles per second a gigahertz.

Front Porch

The portion of the horizontal blanking pulse that precedes the horizontal sync pulse.

FSK

Frequency shift keying.

FSS

Fixed-Satellite Service.