Multitech CommPlete MT5634HD8, Руководство пользователя, Страница: 79 / 99

Glossary
CommPlete Communications Server 73
Asynchronous Transmission : The
transmission of data in which each character is
a self-contained unit with its own start and stop
bits. This is a common method of transmission
between a computer and a modem. One
character at a time, encoded into a series of
electrical pulses, is transmitted or received.
This is the oldest method of data transfer.
When it is used with error correcting software
and data compression algorithms, along with
the increase it maximum attainable speeds, it
continues to be a viable alternative to
synchronous transmission.
ATM (Asynchronous Transfer Mode) : A high
speed switching technique suitable for MAN’s
(Metropolitan Area Network) and broadband
ISDN transmission.
Auto Answer : A modem feature which enables
the modem to “off-hook” when it detects an
incoming call.
Auto Dial : Some modems provide this feature
for asynchronous dialing. This feature is a pre-
defined macro that allows the user to enter the
location of a phone number (i.e. N0 through N9)
and have the modem go off-hook, dial and
establish the connection. With the auto dial
feature, an asynchronous terminal can establish
a dialing directory without running a
communication software package.
AUTOEXEC.BAT (AUTOmatic EXECute
BATch)
: A DOS batch file that executes when
the computer is started. This file contains the
basic start-up commands that help configure
the system.
Automatic Dialer : A device which is
programmed to place a call to a predetermined
number any time it is taken “off-hook”.
B
Background : An activity that takes place in
the PC while you are running another
application. In other words, the active user
interface does not correspond to the
‘background’ task. In Windows™, the area
behind the active window. Compare with
foreground.
Backup : Additional resources or duplicate
copies of data on different storage media for
emergency purposes.
Band : The range of frequencies between two
defined endpoints.
Bandwidth : The transmission capacity of a
computer channel, communications line or bus. It
is expressed in cycles per second (hertz), the
bandwidth being the difference between the
lowest and highest frequencies transmitted.
The bandwidth of a phone line is about 3000Hz
with QAM, you get up to 14,400 bps. Bandwidth
is often stated in bits or bytes per second.
Baseband signal : An unmodulated signal
which is transmitted at its original frequency
and may be digital or analog.
Baud : Rate, the signaling rate of a line, the
switching speed, or the number of transitions
(voltage or frequency changes) that are made
per second. Transmission speeds are often
expressed in baud, though bits per second is
more accurate. The speed at which your
computer talks to your modem.
BCC (Block Check Character) : An error
control method used in character-oriented or
byte-synchronous protocols. Two 8-bit BCC’s are
used to create the CRC (Cyclic Redundancy
Check) field of a synchronous data packet.
Bell 103 : The U.S. modulation standard for
300 bps full-duplex transmission over dial-up
lines.
Bell 201 : The U.S. modulation standard for
2400 bps half-duplex transmission over dial-up
lines or full-duplex transmission over 4-wire
lines. Primarily used in synchronous modems.
Bell 202 : The U.S. modulation standard for
0-1200 bps, half-duplex transmission over 2-
wise, or full-duplex transmission over 4-wire
leased lines.
Bell 208 : The U.S. modulation standard for
4800 bps, half-duplex transmission over dial-
up lines, or full-duplex transmission over 4-wire
lines. Primarily used in synchronous modems.
Bell 212A : The U.S. modulation standard for
1200 bps full-duplex transmission over dial-up
lines.
Binary : A numbering system based on two
digits, 1 and 0, which is conductive to the two-
state digital electronics used within computers.
All input to a computer is encoded as a binary
value. Binary also refers to a file format that