User's Manual

SPEEDLAN 9000 Series Installation and Operation User Guide
Glossary-7
Forward Error Correction (FEC)
The ability of a receiving station to correct a transmission error. The transmitter sends redundant information along with
the original bits and the receiver uses this information to find and correct errors. This can increase the throughput of a
data link operation.
Framing
Dividing data for transmission into groups of bits, and adding a header and a check sequence to form a frame.
Frequency
The number of complete cycles per second existing in a waveform. Note that frequency is measured in Hertz (Hz).
Frequency Hopping (FH)
A type of spreading technique using a PN code to change the signal’s frequency between several pre-assigned values
(hopping). Although the signal itself looks like a narrow band signal at any given point in time, it acts like a spread signal
because of the frequency hopping.
Fresnel Zone
An imaginary ellipse surrounding the direct transmission path formed by all the points from which a reflected wave would
have an increased path length of multiple of the transmitted signal’s wavelength. At least 60% of the Fresnel zone must be
unobstructed.
Full Duplex
Independent, simultaneous two-way transmission going in both directions.
Gain
The increase in signal power caused by a device such as a transmitter or antenna.
GHz
GigaHertz. Billions of Hertz.
Ground elevation
This is the approximate mean sea level (AMSL) of the terminal.
Half Duplex
A one-way directional communication line going in both directions. Only one signal can be transmitted or received at a
time