68
SoundExpression
trellis coding.
A method of modulation
which targets specific modulation points.
Signals falling outside of these points are
treated as line noise, thus ensuring greater
noise immunity over a given line. QAM
(Quadrature Amplitude Modulation)
functions similarly, but has a broader
tolerance and results in lesser noise immunity
than trellis coding.
X
XON/XOFF
. XON and XOFF are the names of
two different flow control characters. See also
flow control.
Acknowledgments
The Complete Modem Reference. Gilbert Held.
John Wiley & Sons, Inc.
Upgrading and Repairing PCs. (Second
Edition). Que Corporation.
©1995. All rights reserved. No reproduction
of this document in any form is allowed
without permission in writing from the
vendor. The vendor is not liable for any
damage resulting from technical or editorial
errors or omissions contained in this
document. The information in this manual is
subject to change without notice. Revisions to
the product(s) in this manual may occur at
any time without notice.
Trademarks
All references to computer systems, software,
and peripherals use trademarks owned by
their respective manufacturers.
Publication Date
: August, 1995
Printed in the U.S.A.
SESRSALL.PM5
zero) command enables numeric responses.
The Q1 command disables their use entirely.
Example: “OK” (word), or 0 (numeric)
indicates that the modem successfully
executed a command.
retrain
. An adjustment process performed
when one of the modems detects signal
distortion or line noise which threaten data
integrity.
RTS/CTS
. Request to Send/Clear to Send.
RTS and CTS are two control signal lines
between the modem (DCE) and terminal
(DTE) which allow the terminal to control the
flow of information. See also flow control.
S
sleep inactivity timer
. Determines the length
of time the modem operates in normal mode
with no activity before entering low-power
“sleep” mode.
split-speed direction
. Determines which
direction (transmit or receive) has the 75bps
channel and which has the 1200bps channel.
standard AT-command
. The basic AT
command set, originated by Hayes
Microcomputer Products, Inc.
synchronous communication
s. A method of
transmission in which data bits are sent
continuously at the same rate under the
control of a fixed frequency clock signal.
T
touch-tone dialing
. Push-button tone dialing
as used on contemporary phone sets. The dial
modifier ATDT sets the modem to “tone”
mode. Tone dialing is faster and more reliable
than older-style pulse dialing.
