Tests
Channel Tests
076R155-000
SpectraComm 553 Fractional T1 DSU
4-17
Issue 7
Installation and Operation Manual
Channel Digital Loop
A Channel Digital Loop commands the DSU to loop all the DS0s assigned to carry channel data
back to the remote. The remote site is responsible for test pattern generation and checking.
A Channel Digital Loop can be initiated from the terminal interface or by SNMP control.
Figure 4-18
Channel Digital Loop
Channel LL with Self Test
Channel Local Loop (LL) with Self Test commands the DSU to turn on its channel-level test pat-
tern generator and checker and to loop data back at the channel interface. Local Loopback with Self
Test checks the channel interface circuitry isolated from both the DTE and the rest of the DSU.
During this test the DSU clamps the channel data it transmits to the T1 link to marks.
Local Loop with Self Test can be commanded by means of the terminal interface or by SNMP
control.
Figure 4-19
Channel Local Loop with Self Test
SC 553 DSU
DTE
Inter-
face
Framer
TX
Driver
Analog
Receiver
Network
SC 553 DSU
TPG
TPC
Framer
TX
Driver
Analog
Receiver
DTE
Inter-
face
