General DataComm SpectraComm 800 T3, Руководство по установке и эксплуатации

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Diagnostics Diagnostics Overview
076R160-000 SpectraComm 800 T3 Data Service Unit 4-3
Issue 4 Installation and Operation Manual
Local Loopback with Self Test
The Local Loopback Test with Self-Test checks the internal circuits of the local DSU, isolated from
both the DTE and the network. The test procedure involves two functions:
• Local Loopback Test causes the DSU loops transmit data back as receive data.
• Self-Test causes the DSU to enable its internal Test Pattern Generator to provide the
signal for the Local Test loop and enable its Test Pattern Checker to verify the signal. The
DSU is isolated from its DTE while the Test Pattern Generator and Checker are enabled.
The TM indicator is On during the test. The TM indicator remains On as long as the test pattern is
received without errors. TM indicator blinks off when an error is detected.
Figure 4-2 Local Test with Self Test
SC800 T3 DSU
Tx DRIVER
ANALOG
RECEIVER
T
3
N
E
T
W
O
R
K
F
R
A
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DTE
INTERFACE
TEST
PATTERN
GENERATOR
TEST
PATTERN
CHECKER