ADC 150-2450-55, Technical Practice

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LTPH-TP-1047-01, Issue 1 Loopback Operation
H2TU-R-402 List 5E March 12, 2001 33
A3LB and A4LB Test Procedures
The H2TU-C can be looped back by sending the Addressable Office Repeater (AOR) LPBK activation code
1111-1111-0001-1110 (FF1E) for at least 5 seconds. This causes the H2TU-R to enter the NLOC state. The
H2TU-C Loopback Time-Out (LBTO) setting determines the duration of this loopback unless it is overridden by
the reception of a second identical 16-bit loopup command before the timer expires. When this time-out override
state exists, the only way to loop the H2TU-R down is to issue one of the three loopdown commands listed in
Table 13 . The automatic time-out mode is restored during subsequent loopback sessions.
Table 13 summarizes the codes required to execute Addressable 3 (A3LB) and Addressable 4 (A4LB) repeater
loopback commands. All code sequences must be present for at least 5 seconds.
SmartJack Test Procedure
The HiGain H2TU-R supports the standard SmartJack loopback which can emulate a Network Interface Device
(NID) for the purpose of loopback testing of the HiGain HDSL2 circuit. SMJK and NREM loopbacks perform the
same functions, but their initiation differs. SMJK indicates that the loopback was initiated by any of the three
SmartJack loopup commands listed in
Table 14 . NREM, on the other hand, is initiated by the 3-in-7 inband
command or by a command issued from the maintenance terminal.
The SmartJack loopback option, LPBK, enables or disables the ability of the H2TU-R to emulate the family of
SmartJack loopback commands listed in
Table 14 .
Table 13. Addressable Repeater Loopback Commands (A3LB and A4LB)
Name Description Binary Code
(a)
(Hexadecimal Equivalent)
(a) The leftmost bit arrives first in all sequences. The detection algorithm functions reliably with a random 10
-3
Bit Error Ratio (BER)
on the facility.
NLOC H2TU-R loopup from NI 1111-1111-0001-1110 (FF1E)
CREM H2TU-R loopup from CI 0011-1111-0001-1110 (3F1E)
NREM H2TU-R loopup from NI 1111-1111-0000-0010 (FF02)
CLOC H2TU-R loopup from CI 0011-1111-0000-0010 (3F02)
Table 14. SmartJack Loopup and Loopdown Commands
Inband 2-in-5
Loopup Code Inband 3-in-5
Loopdown Code
(a)
(a) These universal loopdown codes can release any and all existing loopup states regardless of loopback direction or method
of initiation. The codes are permanently enabled and independent of all loopback option settings, including the LPBK option.
Out-of-Band ESF FDL
Loopup Codes Out-of-Band ESF FDL
Loopdown Codes
(a)
Inband 1-in-6
Loopup Code Inband 1-in-3
Loopdown Code
(a)
11000 11100 1111-1111-0100- 1000 1111-1111-0100-1000 100000 100
SMJK loopbacks can only be activated by inband commands.