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LTPH-UM-1109-01, Issue 1 Testing
H2TU-C-231 List 2 January 9, 2002 51
A3LB and A4LB Test Procedures
The H2TU-C-231 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-C-231 to enter the NLOC state. The
Loopback Time-Out setting (see “Setting the Loopback Time-Out Option” on page 46) 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-C-231 down is to issue one
of the three loopdown commands listed in Table 18. The automatic time-out mode is restored during subsequent
loopback sessions.
Table 18 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.
The Armed mode has an automatic time-out of 120 minutes, but this timer is reset to 120 for any
of the following events:
• Loopback terminates (manually or time-out)
• Query
• Alternate query
• Far End activate
• Another ARM command
This timer is inhibited while any of the valid command codes are being sent. Once the codes
are removed, the timer restarts at 120.
Table 18. Addressable Repeater Loopback Commands (A3LB and A4LB)
Name Binary Code
(a)
(Hexadecimal Equivalent)
(a) The leftmost bit arrives first in all sequences. The detection algorithm functions reliably with a random 10
-3
BER on the
facility. The entire arming and loopback sequence can also be initiated at the remote H2TU-R location.
Description
NLOC 1111-1111-0001-1110 (FF1E) H2TU-C-231 loopup from NI
CREM 0011-1111-0001-1110 (3F1E) H2TU-C-231 loopup from CI
NREM 1111-1111-0000-0010 (FF02) H2TU-R loopup from NI
CLOC 0011-1111-0000-0010 (3F02) H2TU-R loopup from CI
SMJK 11000-11000-11000 ... H2TU-R loopup from NI
SMJK 100000 100000 100000 ... H2TU-R loopup from NI
(b)
(b) Not supported by A4LB.
SMJK 1111-1111-0100-1000 (FF48) H2TU-R loopup from NI (ESF-DL)
Loopdown 11100-11100-11100 ... H2TU-C and H2TU-R loopdown from NI OR CI
Loopdown 100-100-100 ... H2TU-C and H2TU-R loopdown from NI OR CI
Loopdown 1111-1111-0010-0100 (FF24) H2TU-C and H2TU-R loopdown from NI OR CI (ESF-DL)