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ArcLight Hub User’s Guide
xviii 1081006 Rev. 001
DAL
Desired access level Level of access required by a user.
dB
Decibel A measure of the ratio between two
quantities (power and intensity).
DHCP
Dynamic host config. protocol A set of rules used by a communications
device (such as a computer, router or
networking adapter) to allow the device to
request and obtain an Internet address
from a server which has a list of addresses
available for assignment.
DLL Delay locked loop A digital circuit similar to a phase-locked
loop (PLL), with the main difference being
the absence of an internal oscillator.
DMS
Degrees, minutes, seconds Position and time measurements.
DNS
Domain name system Stores and associates many types of
information with domain names, but most
importantly, it translates domain names
(computer hostnames) to IP addresses.
DSS Digital satellite system The assumed acronym expansion of the
DSS digital satellite television
transmission system used by DirecTV.
Eb/No
Energy per bit per noise A parameter used in signal power spectral
density processing and telecommunications
similar to signal-to-noise ratio (SNR). It
defines the SNR per bit and is an
important measure to evaluate and
compare different digital communication
systems.
EIRP Equivalent
isotropically Effective isotropic radiated
radiated power power is the amount of
power that would have to
be emitted by an isotropic antenna to
produce the peak power density observed
in the direction of maximum antenna
gain.
Ethernet Switches
Cisco rack-mounted servers Switches that run Cisco IOS software.
FEC Forward error correction A system of error control for data
transmission, whereby the sender adds
redundant data to its messages, which
allows the receiver to detect and correct
errors (within some bound) without the
need to ask the sender for additional data.
FLR
Forward link receiver The link from a fixed base station to a
mobile user.