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Maintenance
5.2 Fault Isolation
The modem has been designed so that a competent technician can isolate fault conditions
without removing the modem from its location. The fault monitoring capability of the
modem is designed to aid the operator in determining the cause of a failure.
System faults are reported in the Faults menu, and stored faults are reported in the
StFaults menu.
Refer to Figure 5-4 for an illustration of the modem fault tree.
Refer to Section 3.2.1.3.1 for further information on each fault.
MOD FAULTS
IF SYNTHESIZER
DATA CLOCK SYN
I CHANNEL
Q CHANNEL
AGC
MODULE
DEMOD FAULTS
CARRIER DETECT
IF SYNTHESIZER
I CHANNEL
Q CHANNEL
DESCRAMBLER
BER THRESHOLD
MODULE
5–8
T
T
T
R
R
C
C
T
R
X
X
X
X
X
X
X
O
O
M
M
I
F
F
F
F
A
A
A
A
A
L
L
F
A
E
E
U
U
U
U
Q
Q
A
A
O
L
L
L
L
R
R
T
T
T
M
M
U
T
F
F
T
A
A
P
L
R
L
R
U
U
L
L
E
E
E
U
E
L
L
E
E
T
D
L
D
L
T
T
D
D
A
A
Y
O
Y
L
R
F
E
E
F
D
L
A
INTERFACE FAULTS
Y
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
COMMON EQUIPMENT FAULTS
1
1
1
1
1
1
1
1
1
1
1
1
1
Figure 5-4. Fault Tree
TX CLK ACTIVITY
TX INTF
BUFFER UNDERFLOW
BUFFER
RX INTF FLTS
BUFFER CLK ACT
BATTERY/CLOCK
-12V POWER SUPPLY
+12V POWER SUPPLY
+5V SUPPLY
CONTROLLER
INTERFACE MODULE
SDM-100A Satellite Modem
T
T
T
R
R
C
C
T
X
X
X
X
X
O
O
X
M
M
F
I
F
F
F
A
F
A
A
A
A
E
E
L
U
U
U
U
Q
Q
A
L
O
L
L
L
R
U
T
T
T
T
F
F
M
T
A
A
P
L
R
L
R
U
U
L
U
E
E
E
E
L
L
E
T
D
L
D
L
T
T
D
A
A
O
Y
Y
L
R
F
E
E
F
D
L
A
Y
1
1
1
1
1
1
1
1
1
1
1
1
Rev. 0
R
X
A
L
A
R
M
L
E
D
1
1
1
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