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Tests
T1 Remote Test
In the Remote Test function the local DSU transmits an in-band command to its remote DSU, di-
recting the remote to loop received signals back onto the network. The DSU sends (and accepts)
loopback activation and de-activation codes as defined by ANSI T1.403.
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 T1 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). Where the test signal originates depends on which T1 interface is being tested.
Connection at the local site can be made through the DTE interface or the front panel Line jacks.
•
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 code for five seconds,
commanding the remote unit to release the loopback.
The Remote Test function can be commanded by means of the terminal interface or by SNMP
control.
DTE
or
Test Device
DTE
Inter-
face
Figure 4-9
4-8
SC 553 DSU
TX
Driver
Framer
Analog
Receiver
T1 Remote Test, Network Interface
SpectraComm 553 Fractional T1 DSU
Installation and Operation Manual
Remote DSU
Analog
Receiver
Framer
Network
TX
Driver
T1 Tests
DTE
Inter-
face
076R155-000
Issue 7
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