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Glossary of Terms

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Antenna System Gain: A figure, normally expressed in dB, representing the power increase resulting from the use of a gain-type antenna. System Losses (from the feed line and coaxial connectors, for example) are subtracted from this figure to calculate the total antenna system gain.

Bit: The smallest unit of digital data, often represented by a one or a zero. Eight bits (plus start, stop, and parity bits) usually comprise a byte.
Bits-per-second: See BPS.
BPS: Bits-per-second. A measure of the information transfer rate of digital data across a communication channel.
Byte: A string of digital data usually made up off eight bits and start, stop and parity bits.

Decibel (dB): A measure of 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
DCE Data Circuit-terminating Equipment (or Data Communications Equipment). In data communications terminology, this is the "modem" side of a computer-to-modem connection. By default, MDS 9810/24810 transceivers are set as DCE devices.
Digital Signal Processing: See DSP
DSP: Digital Signal Processing. In the MDS 9810/24810 transceivers, the DSL circuitry is responsible for the most critical real-time tasks; primarily modulation, demodulation, and servicing of the data port.
DTE: Data Terminal Equipment. A device that provides data in the form of digital signals at its output. Connects to the DCE device.
DTMF Diagnostics: This is a form of remote diagnostics used in older MDS radios suck as the MDS 2310 and 4310. Tomes communicate diagnostics information between radios in a network. It disables SCADA data flow during diagnostic pooling.

Equalization: The process of reducing the effects of amplitude, frequency or phase distortion with compensating networks.

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 multi path, 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 Zone: The spread spectrum technique used by the MDS 9810/24810 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.

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.

A mode of remote diagnostics that queries and commands radios in a network which has an impact on the delivery of the system payload data. This mode of diagnostics is much faster than the Non-Intrusive Diagnostics mode. It is the opposite of Non-Intrusive Diagnostics.
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.
MCU: Microcontroller Units. This is the processor responsible for controlling system start-up, synthesizer loading, hop timing, and key-up control.
Microcontroller Unit: See MCU
Mode: This refers to the programmed function of an MDS spread spectrum radio - master or remote. (See also Remote Station and Master Station.)
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.
Network-Wide Diagnostics: An advanced method of controlling and interrogation MDS radios in a radio network.
Non-Intrusive Diagnostics: This is a mode of network-wide diagnostics that queries and commands radio in a network without halting system payload data. Diagnostic data is collected non-intrusively over a period of time by being interspersed with SCADA system data. It is the opposite of Intrusive Diagnostics.

Passive Messaging: See Non-Intrusive Diagnostics.
Payload Data: This is the application's user communication data which is sent over the radio network. It is radio data that is primary purpose of the radio communications.
Point-Multipoint Systems: A radio communications network or system designed with a central control station that exchanged data with a number of remote locations equipped with terminal equipment.
Poll: A request for data issued from the host computer (or master PLC) to a remote radio.
Polling Remote: In point-to-multipoint point radio networks, the polling remote is the radio that connects the SCADA host and makes direct radio contact the repeater.
PLC: Programmable Logic Controller. A dedicated microprocessor configured for a specific application with discrete inputs and outputs. It can serve as a host or as a RTU.

Radio Network: The complete set of radios through which a single polling scheme can operate. The radio network defines the scope of units that can be addressed through a single Remote Diagnostics connection.
Remote Radio: A radio in a spread spectrum network that communicates with an associated master station. A radio may be programmed for either master or remote mode using software commands.
Radio Sub-Network: A set of radios that communicate using the same frequency plan (either fixed frequency or frequency hopping). The radio network is composed of one or more radio sub-networks.
Remote (Station): A radio in a spread spectrum network that communicates with an associated master station. A radio may be programmed for either Master or Remote mode using software commands.
Remote Diagnostics: A diagnostics system that allows the interrogation and configuration of a radio at a distance site.
Remote Terminal Unit: See RTU
RTU: Remote Terminal Unit. A data collection device installed at a remote radio site.

SCADA: Supervisory Control And Data Acquisition. An overall term for the functions commonly provided though an MAS radio system.
Standing Wave Ratio: See SWR.
SWR: Standing Wave Ratio. A parameter related to the ratio between forward transmitter power and the reflected power from the antenna system. As a general guideline, reflected power should not exceed 10% of the forward power.

Unit Address: A value used to identify a specific radio in a Radio Network. The unit address can range from 0 to 65000, and can be changed to a five-digit number ranging from 10000 to 65000 using the UNIT command at the radio command line. Radios ship from the factory with a unit address consisting of the last four digits of the radio's serial number.

Zone: See Frequency Zone.

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