Editing Multipath propagation (section)

==Examples==

In analog [[fax|facsimile]] and [[television]] [[transmission (telecommunications)|transmission]], multipath causes [[jitter]] and ghosting, seen as a faded duplicate image to the right of the main image. Ghosts occur when transmissions bounce off a mountain or other large object, while also arriving at the antenna by a shorter, direct route, with the receiver picking up two signals separated by a delay.

[[File:Multipath propagation diagram en.svg|thumb|Radar multipath echoes from an actual target cause ghosts to appear.]]

In [[radar]] processing, multipath causes ghost targets to appear, deceiving the radar [[receiver (radio)|receiver]]. These ghosts are particularly bothersome since they move and behave like the normal targets (which they echo), and so the receiver has difficulty in isolating the correct target echo. These problems can be minimized by incorporating a ground map of the radar's surroundings and eliminating all echoes which appear to originate below the ground or above a certain height (altitude).

In digital radio communications (such as [[GSM]]) multipath can cause errors and affect the quality of communications. The errors are due to [[intersymbol interference]] (ISI). [[Equalization (communications)|Equalizers]] are often used to correct the ISI. Alternatively, techniques such as [[orthogonal frequency division modulation]] and [[rake receiver]]s may be used.

[[File:Gps-multipath-efect.png|thumb|left|GPS error due to multipath]]
In a [[Global Positioning System receiver]], multipath effects can cause a stationary receiver's output to indicate as if it were randomly jumping about or creeping. When the unit is moving the jumping or creeping may be hidden, but it still degrades the displayed accuracy of location and speed.