Fiber Distributed Data Interface (4)
Fiber optic cable
- immune to electromagnetic interference
- secure (does not emit a signal outside the cable)
- multi-mode fiber - passes several frequencies of light (a mode is a ray of light that enters the fiber at a particular angle); multi-mode uses LED as a light generating device; modal dispersion limits the bandwidth and distance (various modes of light enter fiber at different angles, and arrive at the end of the fiber at different times)
- single-mode fiber - only one mode of light propagates through the fiber; uses lasers to generate signals; modal dispersion does not exist