Section 150-231-164
Revision 04
Page 20
TABLE 6. HLU-231 A4LB TEST PROCEDURES
Step
Action
1
The HiGain Line Unit can be looped back (NLOC in Figure 5) by sending the Addressable
Office Repeater (AOR) LPBK activation code 1111(F) 1111(F) 0001(1) 1110(E) for at least five
seconds. This causes the HLU-231 List 6D to enter its NLOC state shown in Figure 5. The
display on the HLU-231 List 6D 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 List 6D 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
shown in Figure 5. Note that all code sequences must be present for at least five seconds.
ABBREVIATIONS USED BELOW:
LU = LoopUp
LD = LoopDown
NI = Network Interface
CI = Customer Interface
ESF-DL = Extended Super Frame Data Link
ADDRESSABLE 4 (A4LB) REPEATER LOOPBACK COMMANDS
Position
Name
Code
HLU-231 LU FROM NI
NLOC
1111(F)*1111(F)0001(1)1110(E)
HLU-231 LU FROM CI
CREM
0011(3)1111(F)0001(1)1110(E)
HRU-412 LU FROM NI
NREM
1111(F)1111(F)0000(0)0010(2)
HRU-412 LU FROM CI
CLOC
0011(3)1111(F)0000(0)0010(2)
HRU-412 LU FROM NI
SMJK
11000 11000 11000 ...
HRU-412 LU FROM NI (ESF-DL)
SMJK
1111(F)1111(F)0100(4)1000(8)
HLU & HRU LD FROM NI OR CI
11100 11100 11100 ...
HLU & HRU LD FROM NI OR CI
100 100 100 ...
HLU & HRU LD FROM NI OR CI
(ESF-DL)
1111(F)1111(F)0010(2)0100(4)
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. This is the HEX number for the 4-bit
group.
3
All of the above loopbacks can also be initiated from the front panel of the HLU-231 List 6D
with the MODE and SEL push-buttons (Section B Paragraph 3.09).
