NEC ELECTRA ELITE IPK II, Руководство по аппаратному обеспечению системы, Страница: 638 / 642

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A - 2 Glossary of Abbreviations
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Document Revision 3 Electra Elite IPK II
CRC Cyclic Redundancy Check
CRC is a common method to establish that the data is correctly received
in data communications. This process checks the integrity of a data
block. A CRC character is generated at the transmission end. Its value
depends on the hexadecimal value of the number of ones in the data
block. The transmitting device calculates the value and appends it to
the data block. The receiving end makes a similar calculation and
compares its results with the added character. If there is a difference,
the recipient requests retransmission.
DN Directory Number
Unique number (telephone number) assigned to each telephone or data
terminal.
ISDN Integrated Services Digital Network
An international plan to migrate the public switched network to the
universal implementation of standard digital technology.
LBO-Line Build
Out A combination of induction, capacitance, and resistance is added to a
cable pair to increase its electrical length by a desired level of
impedance and loss characteristics.
Local Loop
Back An internal process where data goes through the entire chip during
Transmit and Receive cycles.
Line Loop Back Allows the user to check Transmission Line Continuity.
LSA Line Synchronization Alarm Detection
An FT1 trunk looses frame synchronization. Frame synchronization
occurs when a given digital channel (time slot) at the receiving end is
aligned with the corresponding channel (time slot) of the transmitting
end as it occurs in the received signal. Usually extra bits (frame
synchronization bits) are inserted at regular intervals to indicate the
beginning of a frame and for use in frame synchronization.
LCR Least Cost Routing
A feature that automatically chooses the lowest cost telephone line to
the destination.
OOF Out-of-Frame Condition
During FT1 transmission, an Out-of-Frame error occurs when two or
more of four consecutive framing bits are in error. When this condition
exists for more than 2.5 seconds a Red alarm is sent by the OOF
detecting unit. Equipment that receives this Red alarm responds with a
Yellow alarm.
OPX Off-Premise Extension
A telephone that is located in a different office or building from the main
phone system. The OPX is connected by a dedicated telephone line.
This extension has all abilities of the telephone system.
Abbreviations Definition