The Telecommunications Industry Association (TIA), an information and communications technology standards organization, has released TSB-4979, “Practical Considerations for Implementation of Encircled Flux (EF) Launch Conditions in the Field.”
According to the organization, TSB-4979 “outlines precise specifications that define the launch condition of test sources into multimode fiber that have been standardized and are mandatory for testing optical attenuation of installed multimode cabling per TIA-568.”
Two possible implementation methods to help field test equipment meet standard encircled flux launch conditions are described in the document.
“The first method can be used with any light source—overfilling or underfilling—from any test supplier. [This is] considered a ‘universal controller,’” the TIA explained. “The second method is a light source and launch cord combination (the launch cord could include a controlling device), perhaps from a specific test supplier, that together meet the EF requirements. [This is] considered a ‘matched controller.’” The advantages and disadvantages of each implementation method are also covered, and uncertainty of measurements and ‘best practices’ advice is provided.
