# convert GPS to XY coordinates

if i have obtain GPS coordinates as Latitude/Longitude, then i need to convert them to XY coordinates, i see this link

actually i need to get the Trilateration , in its equation i need the XY coordinates from GPS coordinates.

i need obvious and clear equation for conversion.

also how the conversion will be if i assume there is reference node !!

my application is :

i need to make Trilateration for sensor nodes and in the middle of the there is pc which get positions of nodes(depends on gps) then pc can calculate its position depend on Trilateration. So Trilateration equation use XY rather than lat/lon ?? can we use the pc as reference node to conversion.

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In order to convert from `lat/lon` to X/Y, you need to choose a Map Projection and Coordinate System based on that projection. What is your actual project? Trilateration is a means to an end, but what will you be using the points for? A word of warning about the conversion link: There is no information about the basis of conversion. This can vary significantly depending on the location of the points, and your intended use. Adding more detail will probably help you get a better answer. – Get Spatial Apr 27 '13 at 9:50
i need to make Trilateration for sensor nodes and in the middle of the there is pc which get positions of nodes(depends oon gps) then pc can calculate its position depend on Trilateration. So in Trilateration equation i need to use XY rather than lat/lon ?? can we use the pc as reference node to conversion. – Hanaa Apr 27 '13 at 11:16
QGIS (and probably all other GIS packages) does such conversions, has full details of the reference systems it uses, and a huge variety of them available for use. – johnsankey Apr 27 '13 at 17:02