ADTRAN 1287722G1, Руководство по установке и обслуживанию

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Troubleshooting
61287722G1-5B 39
Signal Level Verification
The following sections detail signal level verification if problems are encountered when
service activation of an installed SBU ONT is performed. Both Downstream signal Level
Verification on page 40 and “Upstream Signal Level Verification” on page 40 are discussed.
Downstream Signal Level Verification
A valid optical power level delivered by the OLT must be received at the drop cable point to
assure proper SBU 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 SBU ONT.
The 1490 nm wavelength is used for digital data. The individual optical power level that
should be present at the optical fiber that is connected to the SBU ONT are listed in Table 11 .
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 38 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 drop cable to the test equipment as shown in Figure 19 on page 39.
Figure 19. Downstream Test Configuration
4. Verify the test equipment measurement results are within the optical signal level ranges
described in Table 11 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.
Table 11. Downstream Power Level
Optical Wavelength Minimum Power Level
1490 nm (digital) –28 dBm
1490 nm
Drop cable
OPM
OLTS
or