RF Innovations RFI-9256, Руководство по эксплуатации

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G L O S S A R Y
©
© ©
© RF Innovations Pty Ltd, 1998 Page: 95
223889, Revision 2.2
D
Data
Any type of information, such as numbers, letters and symbols, that can be processed by a computer.
Data Bits
The actual characters being transmitted between two computers when asynchronous communications is being used. Usually 7
or 8 data bits are used. A normal byte has 8 bits. 7 data bits are used for ASCII/alphanumeric data.
Data Communications Equipme nt (DCE)
Equipment that is used to access a communications network. The DCE provides all the functions required to establish,
maintain and terminate a connection, and provides the signal conversion required for communications between the Data
Terminal Equipment (DTE) and the telephone network. With RS-232 connections, the modem is generally the DCE device
while the computer or terminal connected to a modem is generally the DTE device. See also Data Terminal Equipment.
Data Compression
An encoding technique that provides for the transmission of fewer data bits without the loss of information. The receiving
end expands the data received to its original form. For example, a ZIP file/drive, ARJ file formats, MPEG/JPEG and GIF
formats.
Data Latency
Time delay between input stream and output data.
Data Set Ready (DSR)
An RS-232 control signal used to indicate the readiness of the DCE (Usually a modem) to accept data from the DTE (usually
a terminal or computer).
Data Terminal Equipme nt (DTE)
The equipment, which provides the data source and/or receiving end of a data transmission link. The DTE may be a personal
computer, a printer, and a front-end processor to a large mainframe computer or any other device that can transmit or receive
data. With RS-232 connections the designation of DTE or DCE determines which device is responsible for generating certain
control signals. See also Data Communications Equipment.
Data Terminal Ready (DTR)
An RS-232 control signal used to indicate the readiness of the DTE for data transmission.
DB9
A port connection used in RS-232 convention with 9 pins.
DB25
A port connection used in RS-232 convention with 25 pins.
DCD
An acronym for Data Carrier Detect. See also Carrier Detect.
Dedicated Line
A communications line, which is not dialed. Also known as a leased or private line.
Decibel (dB/dBm)
Unit of measure indicating the logarithmic ratio of output signal power to input signal power. dB is relative to Watts while
dBm is scaled so that is relative to milliWatts.
Default
A value, action or setting that is automatically used by a computer system when no other explicit information has been given.
Demodulate
To recover the information being transmitted by a modulated signal. For example, a conventional radio receiver demodulates
an incoming broadcast signal to convert it into sound emitted by a speaker. See also Modulate and Modem.
Dial Tone
A call progress signal returned by a telephone-switching machine to indicate that it is ready to accept a telephone number.
ATDT (Hayes
TM
commands) supported for compatibility.
Dial-up
Establishing a temporary connection to a remote system or computer.