Hdsl System Testing | ADTRAN 3060 guide

Status Mode

After selecting the LTU from the SCU, the display enters Status mode. It alternately displays loop margin for each HDSL loop, any active alarm condition, and general status conditions.

The HDSL loop margin is displayed for each loop that is active with the messages “1=xx” and “2=xx” where

xxis the HDSL loop margin for that loop. The loop margin is held on the display for 2 seconds. The loop margin will not be displayed if that loop is in start-up or LOS condition.

E1 Core Frame Mapping

The function of E1 core frame mapping is to assign 2048 kbps framed E1 data to a 2304 kbps core frame filled with 2048 kbps data. This converts a 32-byte E1 frame into a 36-byte core frame (a ratio of 1:1.125). The extra four bytes are filled with TSO, TS16, or AIS data. Once the 36-byte core frame data block reaches the HDSL loops, the data is split between the two HDSL loop pairs.

4. HDSL SYSTEM TESTING

The ADTRAN HDSL system provides extensive ability to monitor the status and performance of the G.703 signals and HDSL loop signals. Detailed performance monitoring is provided by the V.24 Control Port on the ADTRAN System Controller Unit (SCU). These features are valuable in troubleshooting and isolating any system level problems that may occur at installation or during operation of the HDSL system.

LTU G.703 Bantam Jack

The LTU provides two dual Bantam jacks on the front panel. These jacks provide a metallic splitting and test access of the G.703 interface for connecting test equipment to transmit and receive signals with the LTU. See Figure 3.

HDSL Loopbacks

The E1 LTU offers five diagnostic loopbacks for use in verifying proper data path operation. These loopbacks are activated via the V.24 craft interface.

These loopbacks disrupt normal data transmission. Make sure that you receive prior authorization to place an HDSL circuit out of service prior to activating any loopback. These loopbacks remain active until cleared or by expiration of the loopback timeout period. See Figure 4.

T1
G.703
R1
G.703		LTU
MON		LTU
RX
EQ		HDSL	HDSL
EQ		HDSL	LOOP 1
RX		LOOP 1
	LTU	LOOP DC
	DATA	LOOP DC
	DATA	POWER SOURCE
	PUMP	POWER SOURCE
	PUMP
EQ		HDSL	HDSL
TX		LOOP 2	HDSL
			LOOP 2
G.703
MON
TX
T
G.703
R

Figure 3. LTU Span Powering Diagram

NTU Local Loopback

The NTU HDSL transceivers are looped back at a point immediately before the HDSL termination. This loopback enables a complete checkout of the NTU data path. The NTU Local Loopback is activated via the V.24 craft interface.

NTU Remote Loopback

The NTU HDSL transceivers are looped back at a point immediately before the G.703 termination. This loopback enables a complete checkout of the NTU data path, the HDSL link, and the LTU data path. The NTU Remote Loopback is activated via the V.24 craft interface.

LTU Local Loopback

The LTU HDSL transceivers are looped back at a point immediately before the HDSL termination. This loopback enables a complete checkout of the LTU data path. The LTU Local Loopback is activated via the V.24 craft interface.

LTU Remote Loopback

The LTU HDSL transceivers are looped back at a point immediately before the G.703 termination. This loopback enables a complete checkout of the NTU data path, the HDSL link, and the LTU data path. The LTU Remote Loopback is activated via the V.24 craft interface.

Section 61182007L1-5, Issue 1

61182007L1-5A