Specifications

142 Network Design and Engineering Guide 2010-10-26
Appendix C - Glossary
Downlink Transmission of a signal from the satellite to the earth station.
Digital Video
Broadcasting_Satellite
_Second Generation (DVB
S2)
Enhanced version of the DVB S satellite broadband transmis-
sion standard with forward error correction and modulation
specifications.
Equivalent Isotropic Radi-
ated Power (EIRP)
This term describes the strength of the satellite signal in dBW
and is a result of the transponder output power and the gain of
the satellite transmit antenna.
Forward Error Correction
(FEC)
System for error control that has the sender to include redun-
dant data so errors can be detected and corrected at the re-
ceiver.
Footprint The area on the earth's surface that is covered by a satellite's
transmission beam.
Frame Unit of transmission at the data link layer. A frame may include
a header and/or a trailer, along with some number of units of
data.
Gain A measure of amplification expressed in dB.
Geostationary Earth Orbit
(GEO)
Geostationary Earth Orbit satellites orbit at 35,786 km (22,282
mi) above the equator in the same direction and speed as the
earth rotates on its axis, making them appear as fixed in the
sky.
G/T The figure of merit of an earth station or satellite transponder
expressed in dB/K. ’G’ is the antenna gain and ’T’ the system
noise temperature. The higher the G/T, the better the system.
Guard Band Transmission carriers are separated on a transponder by
spacing them several kilohertz apart. This unused space
serves to prevent the adjacent transmission carriers from inter-
fering with each other.
Home Channel (1,2) Reception channels of a SkyWAN
®
station.
Hub Central station in a star or multi-star VSAT network.
Icon Stands in the context of the SkyNMS Topology Manager appli-
cation for a graphical symbol.
Indoor Unit (IDU) VSAT network equipment typically located inside a building. It
consists of a modem and router connected to the corporate
LAN or terrestrial infrastructure. IDU or unit is the preferred
term when the physical aspects of a SkyWAN
®
modem are
treated (e.g. hardware).
Inbound In a VSAT network it is typically referred to as the transmission
from the remote station to a network hub.
Term Definition