Also known as multipath interference (MPI). Signal attenuation and distortion due to multipath propagation.Wireless radio or optical signals bounce off of physical obstructions they encounter between a transmitter and a receiver.Those signal elements that travel the most direct routes not only arrive soonest, but also suffer less absorption and diffusion attenuate the least and, therefore, are the strongest. Those that travel the least direct routes arrive last and are weakest. In broadcast television and poorly installed cable television, ghosting is the result of multipath fading. In broadcast television and poorly installed cable television, MPI specter, or ghosting, is the result of multipath fading. Signals that travel different paths but arrive at approximately the same time can cancel each other.All of these factors contribute to multipath fading. See also attenuation, diffusion, distortion, ghosting, MPI specter, multipath absorption, and propagation.