Microwave Data Systems EL805, Руководство по установке и эксплуатации

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G-2 MDS TransNET 900 I&O Guide MDS 05-2708A01, Rev. B
Extension Radio—A radio in a TransNET spread-spectrum network that
serves as a gateway between vertically adjacent sub-networks. See
Store-and-Forward.
Fade Margin—The greatest tolerable reduction in average received signal
strength that will be anticipated under most conditions. 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 systems.
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.
Frequency Hopping—The spread spectrum technique used by the MDS
TransNET 900™ transceivers, where two or more associated radios change
their operating frequencies several times per second using a set pattern. Since
the pattern appears to jump around, it is said to “hop” from one frequency to
another.
Frequency Zone—The transceivers use up to 128 discrete channels in the
902 to 928 MHz spectrums. A group of 16 channels is referred to as a zone.
The transceivers use five to eight frequency zones.
Hardware Flow Control—A transceiver feature used to prevent data buffer
overruns when handling high-speed data from the RTU or PLC. When the
buffer approaches overflow, the radio 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 station site, which
controls the collection of data from one or more remote sites.
Latency—The delay (usually expressed in milliseconds) between when data
is applied to TXD (Pin 2) at one radio, until it appears at RXD (Pin 3) at the
other radio.
MAS—Multiple Address System. A radio system where a central master
station communicates with several remote stations for the purpose of
gathering telemetry data.
Master (Station)—The one radio transceiver in a spread spectrum network
that automatically provides synchronization information to one or more
associated remote transceivers. A radio may be programmed for either master
or remote mode using software commands.
Multiple Address System (MAS)—See Point-Multipoint System.
Network Address—User-selectable number between 1 and 65000 that is
used to identify a group of transceivers that form a communications network.
The master and all remotes within a given system must have the same
network address.
Point-Multipoint System—A radio communications network or system
designed with a central control station that exchanges data with a number of
remote locations equipped with terminal equipment.