Table of Contents
Advertisement
OPERATION
3-16
Network Alarm Indication
This is a count of the number of times the CSU receives an AIS from the
network (the counter increments only when the alarm is removed). The
status line and front panel AIS indicators reflect whether the CSU is re-
ceiving an AIS.
Network Failed Signal State
A failed signal state event occurs when 10 consecutive severely ESs oc-
cur. A failed signal state ends when 10 consecutive seconds of data are
processed and no severely ESs occur. For every second a failed signal
state exists, an FS results.
Network Controlled Slips
A controlled slip event is the occurrence of a replication or deletion of one
DS1 frame by the receiving equipment. A controlled slip event occurs
when the difference in the timing between the synchronous receiving
equipment and the received signal is of such magnitude that it exhausts
the buffer capability of the equipment.
Network Bipolar Violations
A bipolar violation (BPV) event occurs when the CSU receives from the
network two or more consecutive bits that do not alternate between signal
levels as required by the network for the Alternate Mark Inversion (AMI)
line code. The status line and front panel BPV indicators reflect the cur-
rent status of BPV error events.
Network CRC Errors
A CRC error event occurs when the CRC-6 code calculated at the receiving
end does not match the CRC-6 code calculated by the transmitting end.
The CRC is a method of detecting errors in the DS1 signal, and is per-
formed on each ESF superframe. The status line CRC indicator reflects
the current status of CRC error events.
DTE Loss Of Signal
An LOS event occurs when the CSU senses an absence of equipment sig-
nal. A signal with consecutive zeros for longer than 150 milliseconds is
considered no signal. The status line TNS indicator and front panel NS
indicator reflect the current status of the equipment signal condition.
DTE Loss Of Sync
This is a count of the number of times the CSU loses synchronization with
equipment framing. The front panel TSY indicator reflects the current
status of CSU-to-equipment synchronization.
DTE Excessive Zeros
This is a count of the number of times the equipment transmits too many
consecutive zeros. The threshold for this counter is dependent on the selec-
Advertisement
Table of Contents
