Instruction manual

Features
Ordinarily, bipolar violations are caused by noise hits to the signal. However,
B8ZS line coding allows the 8-bit strings to be detected at the receiving end
and converted back into the original sequence.
B8ZS line coding is preferred over ZCS because it does not cause errors in
data transmission.
B8ZS violations are passed by the ESF T1 Channel Service Unit (CSU), but not
by other CSUs. 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.
Type of Equipment (CSU)
The 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 that connects to the back of the CSU. The CSU then connects to the
modular jack on the 100D module.
There are two CSUs—an ESF T1 CSU (extended superframe) and a 551 T1 L1
CSU. The ESF T1 CSU is recommended for this system because it allows the
unit to be maintained without interrupting service and provides diagnostic and
testing capabilities, and it is the only CSU that provides B8ZS line coding. The
lower cost 551 T1 L1 CSU performs most of the functions of the ESF T1 CSU but
does not provide the B8ZS line coding required for 64-kbps data and for
maintenance features. The 551 T1 L1 CSU also does not provide diagnostic
and testing capabilities.
Line Compensation
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 Table 28.
Primary Rate Interface (PRI)
355