User's Manual

Appendix I: Optical test Procedures
Optical Back-reflection Testing
MA 2000 Installation and Configuration Guide 74
6. Connect the laser to port I1 of the coupler as shown in Figure 7-5.
Figure 7-5. Test Procedure Connections
7. Connect the Power Meter to port I2 of the coupler as shown in Figure 7-5.
8. Wrap the O2 pigtail around a pencil of diameter 7 to 8 mm as illustrated.
9. The power meter readings should be < –58 dBm; otherwise, clean connector O1 and
measure again.
10. Connect the cable under test to connector O1.
11. Record Power Meter Reading as Backreflection, BRcut, of the cable under test. The power is
measured in dBm units. This is the same value as the backreflection.
For example, if the power meter shows –58 dBm, the backreflection is –58 dB. The
maximum backreflection from the SC/APC connectors should be < –57 dB.
Long cables will have a higher BR since the cable itself reflects a small amount of light. This
small amount can grow to a considerable amount over a long length of fiber. To factor out this
cable backreflection, perform a mandrel wrap on the cable adjacent to the connector under test
and perform all measurements with the mandrel wrap.