Figure 3. Htu-R Mon Diagram; Figure 4. Hdsl Loopbacks - ADTRAN T200 Installation And Maintenance Manual

DS1 MON Bantam Jacks
The jack labeled "MON" provides a non-intrusive
access point for monitoring the transmit and receive
signals at the DS1 interface point.
In general, the monitoring jacks provide a
non-intrusive tap onto a signal line that permits the
connection of test equipment to monitor the
characteristics of that signal. For example, the DS1
MON jack on the HTU-R could be used to connect
to a bit error rate tester to monitor for
synchronization, test patterns, etc. Figure 3 is an
illustration of specific jack detail.
HTU-R

Figure 3. HTU-R MON Diagram

Note: For the MON jacks, the Tx and Rx
indications relate to the direction of the
signal to/from the HTU-R, respectively.
HTU-R Network Loopbacks
The HTU-R responds to multiple loopback
activation processes. The loopback position is a
logic loopback located within the HTU-R internal
HDSL transceiver. See Figure 4.
First, manual loopback activation may be
accomplished using the control port of the HTU-C.
Refer to the ADTRAN HTU-C Installation and
Maintenance practice (P/N 61246001LX-5) or other
HTU-C practices for more information.
61246026L6-5B
T
R
Tx
CUST
MON
Rx
T1
R1
Section 61246026L6-5, Issue 2
HTU-C Network-Side Loopback
LOCAL
DSX-1
LOOP
HTU-C
HTU-R Customer-Side Loopback
X
LOCAL
AIS
HTU-C
HTU-R Network-Side Loopback and/or
HTU-R NIU Loopback
LOCAL
DSX-1
LOOP
HTU-C
HTU-C Customer-Side Loopback
X
LOCAL
AIS
HTU-C
HTU-R Bilateral Loopback
LOCAL
LOOP
HTU-C
HRE Network-Side Loopback
DSX-1
HTU-C
HRE#2 Network-Side Loopback
DSX-1
HTU-C HRE #1
X = Signal Inactive
D = Data Sent

Figure 4. HDSL Loopbacks

Second, the HTU-R will respond to the industry
defacto HDSL loopback codes as designated in the
ANSI document T1E1.4/92. A synopsis of the
method described by ANSI is presented in
Appendix A.
Third, the HTU-C will respond to manual loopback
activation by pressing the LOC LBK button on the
faceplate. This will activate a bilateral loopback at
the HTU-R.
AIS
DS1
X
HTU-R
DS1
LOOP
HTU-R
AIS
DS1
X
HTU-R
DS1
LOOP
HTU-R
DS1
HTU-R
AIS
X
DS1
X
HRE HTU-R
AIS
X
X
HRE #2 HTU-R
DS1
5