ADTRAN 1287802F1, Руководство по физической установке

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Troubleshooting
61287802F1-34B 49
Revision B
7.3.2.1 Downstream Signal Level Verification
A valid optical power level delivered by the OLT must be received at the fiber jumper point in
the GPON to assure proper ONT ranging and operation. There is one optical wavelength
(1490 nm) to consider in the downstream direction that will contribute to the absolute optical
power level delivered to the ONT.
The 1490 nm wavelength is used for digital data. The individual optical power levels that
should be present at the optical fiber that is connected to the ONT are listed in Table 13 .
To verify the correct downstream optical signal levels are present:
1. Ensure all connectors are clean and dry. Refer to “Cleaning and Inspection of Compo -
nents” on page 47 for details.
2. Setup and calibrate the OPM or OLTS for wavelengths that apply to FTT transmissions
(that is 1310 nm and 1490). Verify the test equipment is capable and setup for
wavelength filtering so that you do not obtain an undesired reading of the absolute optical
power from all contributing wavelengths. Instead you are trying to measure the individual
wavelength optical power levels.
3. Connect optical fiber jumper to the test equipment as shown in Figure 20 .
Figure 20. Downstream Test Configuration
4. Verify the test equipment measurement results are within the optical signal level ranges
described in Table 13 above.
5. Do one of the following:
■ If the results are not within range, perform the necessary testing and verification
steps to validate points further up the network, towards the OLT, to locate the cause
of the optical signal level differences.
■ If the measurement results are within range, perform the steps in “Upstream Signal
Level Verification” on page 49.
7.3.2.2 Upstream Signal Level Verification
A valid optical power level delivered by the ONT must be received by the OLT on the GPON to
assure proper ONT ranging and operation. The laser output of the ONT is burst mode at 1310
nm that is controlled in the upstream direction by grants given by the OLT.
Table 13. Downstream Power Level
Optical Wavelength Minimum Power Level
1490 nm (digital) –28 dBm
OPM or OLT’s
Fiber Jumper
1490 nm