User's Manual

Cross-
Polarization
Discrimination
This specifies the signal isolation achieved when the receiving
element of an antenna is perpendicular to the radiating element.
This is important when co-locating Access Points.
11.4 D
dB
Decibel. A relative measure used to specify power gains and
losses. The difference between power P1 and power P2 expressed
in dB is: 10log
10(P1/ P2)
DB-9
A D-shaped connector to the serial port on EI ON equipment, with
nine pins. Used to connect the IDU and PC.
dBd
dBd is antenna gain referenced over a half-wave dipole. This is an
antenna with a doughnut-shaped radiation pattern. Gain of a
Standard Dipole = 2.14 dBi.
dBi
dBi is antenna gain referenced to an isotropic radiator. This is a
theoretical antenna that radiates equally in all directions, like the
sun. EI ON references antenna gain in dBi. The conversion factor is
0 dBd = 2.14 dBi
dBm
A power measurement with respect to one milliwatt. This is an
absolute measure of power rather than a relative measure such as
a gain or a loss.
Default Gateway
IP Address
This is the address of the gateway from the wireless network to
the wired one. All packets bound for a destination on the wireless
network must go here first. All packets meant for the next network
must leave from here.
Diffraction
Diffraction occurs when a radio signal bounces off a solid object.
The level of diffraction could lead to connectivity problems if the
remaining signal level is too low. Two types of diffraction are
shadowing and multipath.
Dipole
An antenna fed from the center. Antenna gains are often
measured in relation to a standard dipole.
Downtilt
Some antennas have a downtilt or an uptilt. The tilt further focuses
the signal either downward or upward with respect to the horizon.
A tilt may be either electrically built into the antenna or achieved
mechanically with the mounting gear. A downtilt or uptilt may be
required when there is a significant deviation between the
elevation of the remote sites and the base site.
Dynamic Time
Allocation
(DTA)
A process for determining how active a CPE is. A poll allows a unit
a brief time to respond before considering that remote an idle one.
LibraPlus 5860 User Guide Appendix B: Def initions: D Page 81 of 95