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Diagnostics
Remote Lineloop and Remote Payload Loop Tests
In the Remote Test function, the local DSU transmits an in-band command to its remote DSU,
directing the remote to loop received signals back onto the network. The remote loopback provides
a path through the DSU, the network, and the remote DSU for an externally generated test signal.
Remote Test checks the local DSU, a portion of the remote unit, and the T3 line. During Remote
Loop:
•
The DSU transmits the in-band loop-up command to its remote DSU.
•
In response to the command, the remote unit performs a digital loopback and loops the
receive signal back to its transmit path.
•
The DTE interface of the local DSU remains active.
•
A test signal has to be generated and checked externally either by a DTE or by a bit error
rate tester (BERT). Connection at the local site can be made through the DTE interface.
•
The device supplying the test signal is responsible for error detection and reporting.
•
The loopback remains in effect until the DSU transmits a loop down command to the
remote unit to release the loopback.
Note
Remote loopbacks are for C-Bit Framing only.
DTE
Figure 4-6
DTE
Figure 4-7
4-6
MASTER SC800 T3 DSU
Tx DRIVER
F
R
DTE
A
INTERFACE
M
E
R
ANALOG
RECEIVER
Remote Line Loopback Test
MASTER SC800 T3 DSU
Tx DRIVER
F
DTE
R
A
INTERFACE
M
E
R
ANALOG
RECEIVER
Remote Payload Loopback Test
SpectraComm 800 T3 Data Service Unit
Installation and Operation Manual
Diagnostics Overview
REMOTE SC800 T3 DSU
T
3
ANALOG
RECEIVER
F
N
R
E
A
T
M
W
E
R
O
R
Tx DRIVER
K
REMOTE SC800 T3 DSU
T
3
ANALOG
RECEIVER
F
N
R
E
A
T
M
W
E
R
O
R
Tx DRIVER
K
DTE
INTERFACE
DTE
INTERFACE
076R160-000
Issue 4
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