Section 150-319-124
Revision 03
Page 48
TABLE 16. HLU-319 A4LB TEST PROCEDURES
Step
Action
1
The HLU-319, List 2D can be looped back (NLOC in Figure 15) by sending the Addressable Office
Repeater (AOR) LPBK activation code 1111 1111 0001 1110 (FF1E)for at least five seconds. This
causes the HLU-319, List 2D to enter its NLOC state (see Figure 15). The display on the HLU-319, List
2D alternates between NLOC (network local loop) and the margin displays. The Loopback Time-out
option (which is user settable to “None,” 20, 60, or 120 minutes) determines the duration of this
loopback, unless it is overridden by the reception of a second identical 16-bit loop-up command before
the timer expires. When this time-out override state exists, the only way to loop the HLU-319, List 2D
down is to issue one of the three loop-down commands listed in Step 2. The automatic time-out mode
is restored during subsequent loopback sessions.
2
The following list summarizes the codes required to execute all the HiGain system loopbacks (see
Figure 15). Note that all code sequences must be present for at least five seconds.
ABBREVIATIONS USED BELOW:
LU = Loop Up
LD = Loop Down
NI = Network Interface
CI = Customer Interface
ESF-DL = Extended Super Frame Data Link
ADDRESSABLE 4 (A4LB) REPEATER LOOPBACK COMMANDS
Position
Name
Code
HLU-319 LU from NI
NLOC
1111 1111 0001 1110 (FF1E)
HLU-319 LU from CI
CREM
0011 1111 0001 1110 (3F1E)
DOUBLER 1 from NI
NDU1
1111 1111 0000 0100 (FF04)
DOUBLER 1 from CI
CDU1
0011 1111 0000 0100 (3F04)
DOUBLER 2 from NI
NDU2
1111 1111 0000 0110 (FF06)
DOUBLER 2 from CI
CDU2
0011 1111 0000 0110 (3F06)
HRU-412 LU from NI
NREM
1111 1111 0000 0010 (FF02)
HRU-412 LU from CI
CLOC
0011 1111 0000 0010 (3F02)
HRU-412 LU from NI
SMJK
11000 11000 11000 ...
HRU-412 LU from NI (ESF-DL)
SMJK
1111 1111 0100 1000 (FF48)
HLU and HRU LD from NI or CI
Loop Down
11100 11100 11100 ...
HLU and HRU LD from NI or CI
Loop Down
100 100 100 ...
HLU and HRU LD from NI or CI
(ESF-DL)
Loop Down
1111 1111 0010 0100 (FF24)
Note: The left-most bit arrives first in all sequences. The detection algorithm functions reliably with a
random 10
-3
Bit Error Ratio (BER) on the facility).
3
All of the above loopbacks can also be initiated from the front panel of the HLU-319, List 2D with the
Mode and SEL push buttons (see Section C Paragraph 19.10).