This is your virtual hands-on lab for testing insertion loss. You will use the tools and instruments above to simulate testing with actual instruments.With each step you will choose the appropriate equipment and set them up for the next step in the process. Along the way, you will be asked questions about the process and the test results.
We'll start by reviewing the tools and instruments we need for the lab.
Test Instruments And Components
Test Light Source: portable, stable source using a LED for multimode or laser for singlemode fiber at the proper wavelengths.
Optical Power Meter: A fiber optic light meter calibrated in the proper wavelengths for multimode and singlemode fiber.
Connector Inspection Microscope: To examine the condition of the connectors being used in the test - both on reference cables and the cable plant being tested. The microscope may be a handheld optical microscope or a video microscope like the display shown here.
Reference Cables: Matching the fiber type (multimode or singlemode) with connectors compatible with the test instruments and the connectors on the cable plant to be tested.
Connector Mating Adapters: To allow connecting reference cables to each other and the cable plant being tested.
Connector Cleaner Kit: Wet/dry cleaner for connectors.
Singlemode or Multimode?
Insertion loss is tested basically the same way with singlemode or multimode cable plants. The biggest difference is in the test source - a LED for multimode fiber at 850nm and 1300nm or laser at 1310nm and 1550 nm for singlemode fiber and of course the meter is calibrated for the corresponding wavelengths. Multimode cabling is primarily used in premises applications like LANs or security, and the links are short with relatively low loss. Singlemode links can be low loss in premises or metro applications or quite high for long haul. In any case, you need to know what loss to expect when you test, so we will cover loss budgets later in this exercise.
Ready? Let's start with some review of insertion loss testing.