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Tests
T1 Local Test with Self-Test
Local 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 Test — the DSU loops transmit data back as receive data.
•
Self-Test — the DSU enables its internal Test Pattern Generator to provide the signal for the
Local Test loop and enables its Test Pattern Checker to verify the signal. The DSU is
configurable to use a variety of test patterns when the test is commanded from the terminal
interface or an SNMP controller. The DSU is isolated from its DTE while the Test Pattern
Generator and Checker are enabled.
The T1 and TM indicators are On during the test. The Test Mode (TM) indicator remains On as long
as the test pattern is received without errors and blinks when an error is detected.
The Local Test with Self-Test function can be commanded by means of the terminal interface, by
SNMP control, or by means of front panel switches. Self-Test commanded by front panel switch-
es always uses a QRS pattern.
Note
Tests cannot be performed by means of front panel switches when the front panel has been inhibited by
an SNMP controller or by the terminal interface. Front panel enabled is the default condition.
ON
INS
I
L
N
I
N
O
E
U
T
RSP
SD
RD
EQ
BPV AIS
OOF NS
TM ALM
T1
CH
RL
TX
M
O
RX
N
553
Figure 4-11
4-10
TPG
DTE
Inter-
face
TPC
TPG = Test Pattern Generator
TPC = Test Pattern Checker
2. TM indicator On during test. Blinks to indicate a detected
error. Lit steadily while pattern is received correctly.
1. To start the test from the front panel, press T1 momentary
action switch and hold for 2 seconds.
T1 indicator is lit during the test.
Self Test run by front panel switch always uses QRS.
Press switch again to end the test.
T1 Local Test with Self-Test, Network Interface
SpectraComm 553 Fractional T1 DSU
Installation and Operation Manual
SC 553 DSU
TX
Driver
Framer
Analog
Receiver
T1 Tests
Network
076R155-000
Issue 7
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