MERLIN LEGEND Communications System Release 5.0
Feature Reference
555-650-110
Issue 1
June 1997
Features
Page 455
Primary Rate Interface (PRI) and T1
negative then positive, pulse. If two positive or two negative pulses are received in
succession, a bipolar violation occurs. Bipolar violations are normally caused by
noise hits to the signal; however B,8ZS uses a specific binary sequence with
bipolar violations as a code for an all-zero channel octet.
B8ZS line coding is preferred over ZCS because it provides no possibility of
corrupting data transmissions.
B8ZS violations are passed by the ACCULINK™ 3150 and 3160/3164, and
ESF T1 channel service units (CSUs) but not by other CSUs.
Channel Service Unit
3
0
The channel service unit (CSU) is the interface between the 100D module and the
DS1 facility provided by the telephone company. This facility contains 24 channels
on one 4-pair wire.
The CSU is a hardware component needed when two endpoints are located in
different buildings or when the distance between the two endpoints makes office
or line repeaters necessary. The CSU is located on the customer’s premises and
is used to connect the system to DS1 network facilities. The CSU has the
following functions:
■
It terminates an outside DS1 facility on the 100D module.
■
It ensures that the signals entering the public network comply with the
requirements of the DS1 facility as specified by the FCC.
■
It includes maintenance, diagnostic, and testing capabilities.
There are several channel service units: ACCULINK 3150 and 3160/3164 ESF T1
CSUs, ESF T1 CSU (no longer available but still supported), and 551 T1 L1 CSU
(no longer available but still supported). The ACCULINK 3150 or 3160/3164
CSUs are recommended for this system because they allow maintenance without
interrupting service and provide diagnostic and testing capabilities as well as
B8ZS line coding. They can be programmed remotely or on-site, using menus.
The lower-cost 551 T1 L1 CSU does not provide the B8ZS line coding required for
64-kbps data (clear channel signaling support) and for maintenance features, nor
does it provide diagnostic and testing capabilities for the DS1 facility.
Line Compensation
3
0
Line compensation adjusts for the amount of cable loss, in decibels (dBs), based
on the length of cable between the 100D module and the CSU or other far-end
connection point. The factory setting is a value of 1, which allows a maximum loss
of 0.6 dB. The possible settings are shown in
.
