HDSL4 for General Distribution Installation and Maintenance Practice
HDSL4 System Testing
61223HDSL4L2-5C
15
Figure 7. Bantam Jack Arrangements
Loopbacks
The ADTRAN HDSL4 modules respond to three different loopback activation processes. These
processes may be utilized to provide a loopback that affects either an H4TU-C or an H4TU-R
module (locally or remotely).
1. Loopbacks may be activated using the craft interface. The Loopback Options screen that
provides for the H4TU-C and H4TU-R loopbacks is described in
2. The modules respond to the industry standard for HDSL loopbacks. A detailed description
of these loopback sequences is given in
“Appendix A, Loopback, Control Codes, and
3. H4TU-R modules respond to loopbacks initiated using front panel pushbuttons.
ADTRAN HDSL4 modules contain smartloop technology. By constantly monitoring the DSX-1
for a framing pattern, ADTRAN HDSL4 modules initiate the proper loopback regardless of how
the loopback control sequence is sent (framed or unframed).
DSX-1
MON
RX
H4TU-C
DATA
PUMP
LOOP DC
POWER SOURCE
DSX-1
T
R
DSX-1
T1
R1
HDSL4
LOOP 1
HDSL4
LOOP 2
H4TU-C
HDSL4
LOOP 1
HDSL4
LOOP 2
EQ
RX
DSX-1
MON
TX
EQ
TX
RX
TX
DS1
MON
CPE
DS1
INTERFACE
H4TU-R
T
R
T1
R1
H4TU-C Bantam Jack Arrangment
H4TU-R Bantam Jack Arrangment