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Loopback Operation
These selections determine 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-231 down is to issue one of the three loopdown commands listed in Step 2. The automatic
time-out mode is restored during subsequent loopback sessions.
Table 15
summarizes the codes required to execute Addressable 3 and 4 (A3LB and A4LB) repeater loopback
commands. All code sequences must be present for at least 5 seconds. The abbreviations used in
follows:
•
LU = LoopUp
•
LD = LoopDown
•
NI = Network Interface
•
CI = Customer Interface
•
ESF-DL = Extended Super Frame Data Link
Information specific to HiGain doublers is shown in bold in
Table 15. Addressable 3 and 4 (A3LB and A4LB) Repeater Loopback Commands
Position
HLU-231 LU FROM NI
HLU-231 LU from CI
HDU DOUBLER 1 FROM NI
HDU DOUBLER 1 FROM CI
HDU DOUBLER 2 FROM NI
HDU DOUBLER 2 FROM CI
HRU LU FROM NI
HRU LU FROM CI
HRU LU FROM NI
HRU LU FROM NI (ESF-DL)
HLU and HRU LD FROM NI OR CI
HLU and HRU LD FROM NI OR CI
HLU and HRU LD FROM NI OR CI (ESF-DL)
a The left-most bit arrives first in all sequences. The detection algorithm functions reliably with a random
-3
10
Bit Error Ratio (BER) on the facility. The entire arming and loopback sequence can be initiated at the
remote HRU location.
b This is the HEX number for the 4-bit group.
44
Name
Code
NLOC
1111(F)
CREM
0011(3)1111(F)0001(1)1110(E)
NDU1
1111(F)1111(F)0000(0)1000(4)
CDU1
0011(3)1111(F)0000(0)0100(4)
NDU2
1111(F)1111(F)0000(0)0110(6)
CDU2
0011(3)1111(F)0000(0)0110(6)
NREM
1111(F)1111(F)0000(0)0010(2)
CLOC
0011(3)1111(F)0000(0)0010(2)
SMJK
11000 11000 11000 ...
SMJK
1111(F)1111(F)0100(4)1000(8)
Loopdown
11100 11100 11100 ...
Loopdown
100 100 100 ...
Loopdown
1111(F)1111(F)0010(2)0100(4)
September 22, 1998
150-231-165-01, Revision 01
Table 15
Table
15.
a
b
1111(F)0001(1)1110(E)
HLU-231 List 6E
are as
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