ADC HiGain H2TU-C-202 User Manual page 27

LTPH-UM-1208-01
HDSL2 BER Threshold (HBER) Option. The HBER option permits the monitoring of loop integrity and
reporting of alarms when excessive errors are detected. The PM primitive used for this purpose is the CRC
checksum performed on the HDSL2 frame for both directions of transmission. It is, therefore, called a block error
rate rather than the bit error rate associated with the DS1 interface. The CRC errors and counts are displayed on
the Monitor screen for both the H2TU-C and H2TU-R. The HBER option allows an alarm to be generated if the
total number of CRCs at either the H2TU-C or H2TU-R exceeds the selected BER threshold during the last
1-minute interval.
•
HBER option = 1E-6. Alarm is generated if CRC > 93
•
HBER option = 1E-7. Alarm is generated if CRC > 9
Once initiated, the HBER count clears when the CRC count drops below the selected threshold. Selecting NONE
inhibits this alarm.
RAI to RAI-CI toward NET (RACI) Option. The H2TU-C in conjunction with the H2TU-R supports the
RAI-CI function.
The RAI-CI signal is a RAI signal which contains a signature indicating that an LOF or AIS failure has occurred
in the customer installation (CI) at the H2TU-R unit and that the defect or failure which caused the origination of
that RAI is not found in the signal from the network. Therefore, RAI-CI is transmitted toward the network when
the following two conditions are simultaneously true at the point from which RAI-CI originated (at the H2TU-R,
toward the network):
•
Condition 1—RAI is received from the CI.
•
Condition 2—No LOF, LOS, or AIS failure is detected in the signal received from the network.
Sending RAI-CI terminates within 500 µs when either of the following occurs:
•
Cessation of RAI from the CI.
•
Declaration of LOF, LOS, or AIS in the signal from the network.
To prevent the transmission of RAI-CI during the failure-clearing interval of a network failure, the transition from
RAI to RAI-CI is delayed for 20 seconds following the detection of conditions 1 and 2 above. Since RAI-CI meets
the definition of RAI, it may be detected and used exactly as RAI. The longer period of time required for detection
of RAI-CI does not affect its use for functions which require RAI.
The RAI-CI pattern is a function of the payload frame format as follows:
• ESF—The RAI-CI signal is a repetitive pattern in the Frame Bit for Data Link (FDL) with a period of 1.08
seconds. RAI-CI is formed by sequentially interleaving 0.99 (+/- 2 ms) seconds of the normal message
00000000 11111111 (right-to-left) with 90 milliseconds (+/- 2 ms) of the message 00111110 11111111
(right-to-left) to flag the signal as RAI-CI.
•
SF—The SF-RAI-CI signal is transmitted inband by setting each of the 24 channel time lots to 1000 1011
(left-to-right). In addition to the criteria specified above, the generation of SF-RAI-CI has to be held off for
1 second to examine the DS0s for a framed, all-zeros pattern. If present, the generation of SF-RAI-CI is
suspended for the duration of the all-zeros pattern.
Since the RAI to RAI-CI conversion modifies the payload, an RACI option is available to inhibit
the RAI to RAI-CI conversion for those applications that cannot tolerate payload modifications.
H2TU-C-202 List 7G June 6, 2003
Provisioning
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