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MDS Orbit MCR-4G Technical Manual
MDS 05-6628A01, Rev. B
Bridging:
(see
Ethernet Bridging
)
Byte:
A string of digital data usually made up of eight data bits and start, stop and parity bits.
CLI:
Command Line Interface. A method of user control where commands are entered as character strings
to set configuration and operating parameters.
CTS:
Clear to Send
Decibel (dB):
A measure computed from the ratio between two signal levels. Frequently used to express
the gain (or loss) of a system.
Data Circuit-terminating Equipment:
See
DCE
.
Data Communications Equipment:
See
DCE
.
Data Terminal Equipment:
See
DTE
.
dBi:
Decibels referenced to an “ideal” isotropic radiator in free space, frequently used to express antenna
gain.
dBm:
Decibels referenced to one milliwatt. An absolute unit used to measure signal power, as in transmitter
power output, or received signal strength.
DCE (Data Circuit-terminating Equipment)
(or Data Communications Equipment): In data communica-
tions terminology, this is the “modem” side of a computer-to-modem connection. The unit described in this
manual is hardwired as a DCE device.
DTE (Data Terminal Equipment):
A device that provides data in the form of digital signals at its output.
DTE connects to the DCE device.
ETH:
Ethernet
Fade Margin:
The greatest tolerable reduction in average received signal strength that will be anticipated
under most conditions. It provides an allowance for reduced signal strength due to multipath, slight antenna
movement or changing atmospheric losses. A fade margin of 20 to 30 dB is usually sufficient in most sys-
tems.
FPGA:
Field Programmable Gate Array
Frame:
A segment of data that adheres to a specific data protocol and contains definite start and end points.
It provides a method of synchronizing transmissions.
Hardware Flow Control:
A feature used to prevent data buffer overruns when the unit is handling
high-speed data from an RTU or PLC. When the buffer approaches overflow, the unit drops the
clear-to-send (CTS) line, which instructs the RTU or PLC to delay further transmission until CTS again
returns to the high state.
Host Computer:
The computer installed at the master unit, which controls the collection of data from one
or more remote sites.
IP:
Internet Protocol
LAN:
Local Area Network
LED:
Light Emitting Diode
mA:
Milliamperes
MAC:
Media Access Control
Poll:
A request for data issued from the host computer (or master PLC) to a Remote unit.
