The FOTR-203 Handheld OTDR is designed to meet a wide variety of requirements for the optical fiber measurement in short and medium distance. By clicking above, I agree to Endeavor Business Media's Terms of Service and consent to receive promotional communications from Endeavor, its affiliates, and partners per its Privacy Notice. The built-in VFL can guarantee. Optical Distribution Network (ODN): Extends cables to users via passive components like backbone cables, distribution cables, fibers, junction boxes, and splitting boxes. The equipment emits a pulse of light with a specific wavelength, which is transmitted through the fibre to be measured.