GLOSSARY

Physical Units & Definitions | Satellite Terminology | Devices / Hardware | Signal Processing

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bit	A unit of information representing the physical state of a system having one of two values, such as on or off.
bit/s	Number of bits of information transferred or transmitted every second.
bps	Alternative expression for bit/s.
kbit/s	Information transfer rate, equal to 1,000 bit/s.
Mbit/s	Information transfer rate, equal to 1,000,000 bit/s.
byte	A sequence of bits processed as one unit of information. A byte is a digital "word" normally consisting of eight bits.
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dBi	The relative gain of an antenna with respect to an equivalent isotropic antenna, expressed on the decibel logarithmic scale.
dBW	The power of a signal in watts, expressed on the decibel logarithmic scale.
dBW/m2	Power of a radio wave incident on a surface area of one square metre, measured in watts and expressed on the decibel logarithmic scale
dBK	The equivalent noise temperature of a device in kelvin, expressed on the decibel logarithmic scale.
dB/K	Units used to express the Figure of Merit or G/T of an earth station, with the dimensions of 1/kelvin, expressed on the decibel logarithmic scale.
decibel (dB)	A unit for comparing two currents, voltages or power levels based on a logarithmic scale. It is used particularly for expressing the difference between very large and very small values (expression: R = 10*log10(r), where r is the linear ratio and R is the ratio in dB).
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frequency	The number of times that an electrical or electromagnetic signal repeats itself in a specified time. It is usually expressed in cycles per second, or hertz (Hz). Satellite transmission frequencies are usually expressed in gigahertz (GHz).
frequency band	A range of frequencies used for transmission or reception of radio waves (e.g. 10.7 GHz to 12.75 GHz).
frequency spectrum	A particular distribution of electromagnetic radiation with frequency, which is characteristic of the source of the emission. In satellite communication systems, the spectrum of a transmitted signal depends upon the modulation scheme employed. The term "frequency spectrum" is also used more generally to refer to a continuous range of frequencies.
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gigahertz (GHz)	Unit of frequency equal to 1,000,000,000 Hz.
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hertz (Hz)	SI unit of frequency, equivalent to one cycle per second. The frequency of a periodic phenomenon that has a periodic time of one second.
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kelvin (K)	Basic SI unit of thermodynamic temperature.
kilohertz (kHz)	Unit of frequency equal to 1,000 Hz.
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megahertz (MHz)	Unit of frequency equal to 1,000,000 Hz.
Msymbol/s	Unit of data transmission rate for a radio link, equal to 1,000,000 symbol/s. Can be directly related to the bandwidth required to establish the transmission link (e.g. 33 MHz for a transmission rate of 27.5 Msymbol/s).
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symbol	A unique signal state of a modulation scheme used on a transmission link, which conveys one or more information bits to the receiver.
symbol/s	The number of symbols transmitted every second.
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UTC	Coordinated Universal Time. A time-scale which forms the basis of a coordinated dissemination of standard frequencies and time signals throughout the world.
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watt (W)	SI unit of power, equal to 1 joule/second.
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