{{Short description|Use of distances for determining unknown coordinates of a point}}{{Distinguish|Triangulation}}right|210px|thumb|Trilateration in three-dimensional geometry right|150px|thumb|Intersection point of three pseudo-ranges '''Trilateration''' is the use of distances (or "ranges") for determining the unknown position coordinates of a point of interest.<ref>{{cite book | last=Engineers | first=A.S.C. | title=Glossary of the Mapping Sciences | publisher=American Society of Civil Engineers | year=1994 | isbn=978-0-7844-7570-6 | url=https://books.google.com/books?id=jPVxSDzVRP0C&pg=PA548 | access-date=2022-11-07 | page=548}}</ref> When more than three distances are involved, it may also be called '''multilateration''', for emphasis. The point of interest is often around Earth (geopositioning).
The distances or ranges might be ordinary Euclidean distances (slant ranges) or spherical distances (scaled central angles), as in ''true-range multilateration''; or biased distances (pseudo-ranges), as in ''pseudo-range multilateration''.
Trilateration or multilateration should not be confused with ''triangulation'', which uses angles for positioning; and ''direction finding'', which determines the line of sight direction to a target without determining the radial distance.
==Terminology== Multiple, sometimes overlapping and conflicting terms are employed for similar concepts – e.g., ''multilateration'' without modification has been used for aviation systems employing both true-ranges and pseudo-ranges.<ref name="ICAO">"Multilateration (MLAT) Concept of use", International Civil Aviation Organization, 2007</ref><ref name="Wolff">[http://www.radartutorial.eu/02.basics/rp52.en.html "Radar Basics"], Christian Wolff, undated</ref> Moreover, different fields of endeavor may employ different terms. In geometry, ''trilateration'' is defined as the process of determining absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangles. In surveying, ''trilateration'' is a specific technique.<ref>[http://www.britannica.com/EBchecked/topic/605329/trilateration Encyclopædia Britannica]</ref><ref>[http://www.diracdelta.co.uk/science/source/t/r/trilateration/source.html diracdelta] {{webarchive|url=https://web.archive.org/web/20100812144807/http://www.diracdelta.co.uk/science/source/t/r/trilateration/source.html |date=2010-08-12 }}</ref><ref>[http://www.thefreedictionary.com/trilateration free dictionary]</ref>
==True-range multilateration== {{excerpt|True-range multilateration}}
==Pseudo-range multilateration== {{excerpt|Pseudo-range multilateration}}
==See also== *Wide area multilateration
==References== {{reflist}}
Category:Geometry Category:Geopositioning