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l
If
Config State
is
failed
, it indicates that the ONT configuration recovery fails. A possible
cause of this failure is that the ONT is bound to an incorrect ONT profile. To resolve this
problem, run relevant commands to issue a correct ONT profile, or reset the ONT.
l
If
Match State
is
match
, it indicates that the configured capacity set of the ONT is the same
as the actual ONT capabilities. If
Match State
is
mismatch
, it indicates that the configured
capacity set of the ONT is different from the actual ONT capabilities, which will cause
registration failure. In this case, add a new ONT service profile.
Step 4
Check the statistics of the ONT.
l
In the GIU mode, run the
display port statistics
command to query the traffic statistics of
the upstream port of the ONT. Specifically, check whether receive and transmit traffic exists.
l
In the GPON mode, run the
display statistics ont
command to query the performance
statistics of the ONT PON port.
l
In the GPON mode, run the
display statistics ont-eth
command to query the performance
statistics of the ONT.
Step 5
Check the data configuration of the ONT.
l
Run the
display dba-profile
command to check the DBA profile bound to the ONT.
l
Run the
display service-port
command to check whether the traffic stream configuration is
correct.
l
Run the
display vlan
command to check whether the upstream port of the ONT is added to
a VLAN.
Step 6
Check the status of the upper-layer device. Specifically, check whether the OLT is in the normal
state.
----End
6.2 Tools Used for Troubleshooting
This topic describes the tools required for troubleshooting: digital multimeter and optical power
meter.
6.2.1 Digital Multimeter
This topic describes the functions and usage instructions of the digital multimeter.
6.2.2 Optical Power Meter
This topic describes the appearance, functions, and usage instructions of the optical power meter.
6.2.1 Digital Multimeter
This topic describes the functions and usage instructions of the digital multimeter.
The digital multimeter is a simple and practical test meter frequently used in the electrotechnical
and electronic industries. It is inexpensive, convenient to carry and easy to use, and has a
complete set of functions.
Basically, the digital multimeter is used to measure the resistance, DC voltage, AC voltage,
current and capacitance, and test diodes and triodes.
To use the digital multimeter, do as follows:
EchoLife HG8240/HG8245/HG8247 GPON Terminal
Service Manual
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1.
Turn on the power supply. (If a digital multimeter without a dedicated power switch is used,
skip this step.)
2.
Select the items to be tested.
3.
Choose a proper measurement range.
4.
Perform the measurement correctly.
5.
(Optional) Press the button for keeping the current measurement value unchanged.
6.
Read the measurement value.
6.2.2 Optical Power Meter
This topic describes the appearance, functions, and usage instructions of the optical power meter.
The optical power meter is a necessary test meter for testing an optical fiber communication
system. It is mainly used to measure the optical power of various wavelengths at multiple
measurement points of an optical link. Optical power indicates the energy of the light at a
measurement point of an optical link and is an important index of the optical fiber network.
When the optical power is smaller than a specified value, the optical receive end will fail to
detect optical signals. In other words, the optical receive end cannot receive the signals sent from
the transmit end. Hence, it is important to use the optical power meter correctly.
The following considers EXFO's PPM-350B optical power meter as an example to describe how
to use an optical power meter. (Other dedicated optical power meters for PON are used in a
similar way.)
The PPM-350B optical power meter can measure the optical power of various wavelengths,
including 1310 nm, 1490 nm, and 1550 nm in the GPON network.
Figure 6-2
shows the
appearance of the PPM-350B optical power meter.
Figure 6-2
Appearance of the PPM-350B optical power meter
6 Troubleshooting
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As shown in
Figure 6-2
, the PPM-350B optical power meter is different from common optical
power meters. Specifically, the PPM-350B has a downstream input optical port and an upstream
input optical port and can display the optical power of three wavelengths: 1310 nm, 1490 nm,
and 1550 nm.
Figure 6-3
shows the common measurement points.
Figure 6-3
Measurement points of the optical power in the GPON network
Maintenance engineers should also know related optical specifications on the ONT side, such
as the maximum output optical power of the 1310 nm wavelength, minimum input optical power
of the 1490 nm wavelength, and receiver sensitivity of the 1490 nm or 1550 nm wavelength.
Table 6-2
lists the optical specifications on the ONT side.
Table 6-2
Optical specifications of optical ports on GPON ONTs
Parameter
Type
Wavelength
(nm)
Unit
Min.
Max.
Upstream data
1310
dBm
+0.5
+5
Downstream
data
1490
dBm
-28
-8
Downstream
CATV
1550
dBm
-8
+2
To use an optical power meter, do as follows:
1.
Connect optical fibers to optical ports correctly in upstream and downstream directions.
2.
Turn on the power supply.
3.
Choose the measurement unit (dB or dBm).
4.
Perform the measurement.
Figure 6-4
shows the measurement interface of the optical power meter.
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Figure 6-4
Measurement interface of the optical power meter
Optical channel loss is the total insertion loss caused by optical fibers, optical splitters, optical
fiber connectors, and fiber connection points.
Table 6-3
shows the estimation of optical channel
loss in the engineering design.
Table 6-3
Optical loss parameters in engineering
Item
Average Loss (dB)
Connection
point
Connector
0.3
Mechanical
splicing
0.2
Fusion splicing
0.1
Optical splitter
1:64
19.7
1:32
16.5
1:16
13.5
1:8
10.5
1:4
7.2
1:2
3.2
Optical fiber (G.
652)
1310 nm (1 km)
0.35
1490 nm (1 km)
0.25
Optical channel loss = L x a + n1 x b + n2 x c + n3 x d + e + f (dB)
6 Troubleshooting
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NOTE
l
a indicates the average loss of an optical fiber per kilometer (unit: dB/km). L indicates the total length
of the optical fiber (unit: km). The loss of patch cords and pigtail fibers used in engineering can be
ignored because they are usually very short.
l
b indicates the loss of a fusion splicing point (unit: dB) and n1 indicates the number of fusion splicing
points.
l
c indicates the loss of a mechanical splicing point (unit: dB) and n2 indicates the number of mechanical
splicing points.
l
d indicates the loss of a connector (unit: dB) and n3 indicates the number of connectors.
l
e indicates the loss of an optical splitter (unit: dB). Only 1-level optical splitting is considered here. In
the case of 2-level optical splitting, the loss of two optical splitters must be considered.
l
f indicates the engineering margin, and generally its value is 3 dB.
6.3 Fault Locating According to the LED Status
This topic describes how to locate a fault according to the status of the LEDs on the ONT.
6.3.1 POWER LED Off
This topic describes how to locate the fault when the POWER LED does not illuminate.
6.3.2 PON LED Off
This topic describes how to locate the fault when the PON LED does not illuminate.
6.3.3 LOS LED Blinking
This topic describes how to locate the fault when the LOS LED blinks.
6.3.4 LAN LED Off
This topic describes how to locate the fault when the LAN LED does not illuminate.
6.3.5 TEL LED Off
This topic describes how to locate the fault when the TEL LED does not illuminate.
6.3.6 USB LED Off
This topic describes how to locate the fault when the USB LED does not illuminate.
6.3.7 WLAN LED Off
This topic describes how to locate the fault when the WLAN LED does not illuminate.
6.3.8 WPS LED Off
This topic describes how to locate the fault when the WPS LED does not illuminate.
6.3.9 CATV LED Off
This topic describes how to locate the fault when the CATV LED does not illuminate.
6.3.1 POWER LED Off
This topic describes how to locate the fault when the POWER LED does not illuminate.
Procedure
Step 1
Check whether the power adapter matches the device.
Step 2
Check whether the power cables are properly connected.
Step 3
Check whether the POWER button is pressed for power-on.
EchoLife HG8240/HG8245/HG8247 GPON Terminal
Service Manual
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