Polarization Mode Dispersion: Concepts and Measurement: The performance of high-speed, digital fiber optic communications systems depends upon how reliably the receiver is able to distinguish closely spaced bits of information. Dispersive effects — physical mechanisms that broaden transmitted pulses — degrade this process.
OTDRs: Finding the Weak Spots in Fiber Links: The optical time-domain reflectometer (OTDR) is used to characterize a fiber optic span. It performs single-ended tests and can calculate fiber attenuation and uniformity and splice and connector losses. It can also locate breaks and determine fiber length. Its ability to locate and measure reflectance and loss makes it the troubleshooting and fault locating equipment of choice. New generation OTDRs include advanced functions such as macrobend location, active-fiber testing and automatic trace acquisition.