Comdial DXP Plus Series, Руководство пользователя

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8.0 Defining The T1 Terms
Bipolar
A bipolar signal is composed of alternating pulses that both represent a digital logic 1. The positive pulse is a (+)
and the negative pulse is a (-). Zero volts represents a space, or digital logic 0.
Bipolar Violation (or error)
A bipolar error is a digital logic 1 (or mark) that has the same polarity as its predecessor.
NOTE: Every time the system regenerates the signal stream, it corrects any bipolar errors; therefore, it prevents
end-to-end error checking from using bipolar errors.
B8ZS (Binary Eight Zero Substitution)
This is a technique to send an all-zero channel without violating the ones-density requirement (a single one in
each channel and no more than 15 zeros in a row). Voice transmission will not allow an all zero channel. The
system accomplishes B8ZS suppression by inserting a special bipolar error that is interpreted, not as an error, but
an all zero channel. The B8ZS feature replaces the all-zero channel two different ways. The feature replaces the
all-zero channel with the sequence 000 + - 0 - + if the preceding pulse was a +, and the feature replaces the
all-zero channel with the sequence 000 - + 0 + - if the preceding pulse was -. The + represents a positive pulse,
the - represents a negative pulse, and 0 represents no pulse. Set the B8ZS feature with switches SW1–5 and
SW1–6.
CAS (Channel Associated Signalling)
The Channel Associated Signalling is the only inbound signalling method currently supported by the DXPT1
board.
COFA (Change of Frame Alignment)
When switch SW2-6 is off, the green LED on the DXPT1 indicates whether the network source or the network
span caused the last frame synchronization. (This indication disregards the first re-sync at cold start or a system
reset —cold start and reset causes the network source to re-sync.) A COFA occurs if the network source does a
re-sync. The COFA is a diagnostic tool that identifies the source of the loss of frame synchronization.
CPE/Carrier Equipment
The DXPT1 is normally classified as Customer Premise Equipment (CPE). If you use SW2–2 to configure the
DXPT1 board to use the internal CSU while in the ESF mode, the network may require that the system be
classified as Carrier Equipment (CE). The information packet that the DXPT1 board sends to the network
contains a facility data link (FDL) maintenance message that has a bit in it that provides this identification.
CRC (Cyclic Redundancy Check)
A method of checking errors from the transmission source to the destination. For T1 operation, CRC caculates a
checksum depending on the data in a frame. The system uses CRC in ESF mode exclusively. (You must enable
CRC with DIP switch SW2-4).
Delay Dial E&M, DID Protocol Type
Once seized by a calling system, the system being called makes A=1 and B=1 until it is ready to receive digits.
When it is ready to receive digits, it makes A=0 and B=0. The system uses a delay dial protocol when wink
protocol timing is not compatible to the network.
Dial Pulse – T1
Dial pulse is a method of sending address digits (numbers) using A and B bits logic bits instead of sending DTMF
tones. Some carriers may not support dial-pulse signalling. While the method is slower when compared with
tones, it requires no DTMF receivers.
Installing The DXPT1 Line Board IMI89–193
Installing The DXPT1 Line Board – 33