Boca SoundExpression 14.4VSP, Руководство пользователя

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H
half-duplex . Signal flow in both directions, but only one way at a time with each modem
alternating between send and receive.
Hayes-compatible . Hayes Microcomputer Products, Inc. developed the AT command set which
has become a de facto industry standard. Hayes commands are always initiated with an AT
(attention code) prefix.
hook flash . The dial modifier “!” causes the modem to go on-hook (hang-up) for one-half
second. Also controlled by the ATH command.
L
LAPM . Link Access Protocol Modem. A V.42 ARQ type of error correction protocol where
LAPM may be activated with or without V.42bis data compression.
leased line . Also referred to as a private line. A leased line is obtained from a communications
company (carrier) to provide a transmission medium between two points. The line consists of a
permanent dedicated circuit between two points, or to set of previously arranged points. The
cost of the line is usually based on the distance between locations. This is in contrast to switched
or dial-up lines, which can be connected to any point on the network.
line modulation . The means by which a carrier is varied to represent a signal carrying
information. In a modem, the user ’s digital data is used to modulate the modem’s transmitter ’s
carrier or carrier to allow the digital signal to be carried over analog facilities.
long space disconnect . Determines whether or not modem disconnects when it receives a
continuous break from a remote modem. Controlled by the ATY command.
loopback tests . There are four types of loopback tests which are as follows: (1) the local digital
loopback tests the operation of the DTE, including whether or not data is leaving the terminal or
computer port; (2) the local analog loopback tests the digital and analog circuits of the modem;
(3) the remote digital loopback checks the operating condition of the line and remote modem; (4)
the remote analog loopback tests the line to the remote modem.
M
MNP . Microcom Networking Protocol. A series of data communications protocols developed by
Microcom for full-duplex, error-free communications.
Glossary of Modem Communication Terms