Sierra Wireless DART 200 CDPD Modem User Manual

Page 189

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DART 200 CDPD Modem User’s Guide

Glossary

PN1197-00 Revision 1.0

Glossary-9

baud

A unit of signaling speed which represents the number of
discrete conditions or signaling events per send that are
transmitted or received over the link.

The frequency at which the transmission medium is
modulated.

Often used incorrectly to state data transmission speed.
By using various modulation schemes it is possible to
encode multiple bits/baud. See also, bps.

block

In CDPD, a 378 bit Reed-Solomon codeword, consisting
of 63 6-bit symbols, 47 of which are data, and 16 of
which provide block parity.

byte

An 8 bit data symbol of which there are 256 possible
combinations. Bytes are normally represented by 2
hexadecimal (0-F) digits. If the symbol can be displayed,
printed, or is used for control purposes it can also be
referred to as a character (ASCII for example). Not all
bytes are characters by this definition.

carrier

The signal you hear from your modem when it is not
transmitting information, but is still in communication
with another modem.

cell

The area surrounding a cellular tower where RF
transmissions can be received at an acceptable signal
strength. For CDPD operations the MDBS is located at
the cell site.

character

Any symbol that is text that can be displayed on the screen,
such as ASCII. Generally represents an 8-bit element of data.

See byte.

color code

A numeric identifier used to distinguish between adjacent
components of CDPD networks (MDBSs, MDISs). Used
to detect interference, or transfers between network
components.

CONNECT

With a Hayes-compatible modem, when this message
shows up on your screen, the modem is telling you it has
dialed the phone number (in Originate mode), got an
answer, received a carrier, and responded. You can now
start communications with the other computer.

data

Information exchanged between a source and
destination. This can consist of a single bit or a long
string of bits, depending on the application.

flow control

A standard for controlling the flow of data, in either
direction, between a modem and an attached device to
prevent overruns. Implementation can be by hardware
(RTS/CTS) or software (XON/XOFF) means. Sometimes
called handshaking.

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