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Global Positioning System: Difference between revisions
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*'''Surveying''' — Survey-Grade GPS receivers can be used to position [[survey marker]]s, buildings, and [[road construction]]. These units use the signal from both the L1 and L2 GPS frequencies. Even though the L2 code data are [[encrypted]], the signal's [[carrier wave]] enables correction of some [[ionospheric]] errors. These dual-frequency GPS receivers typically cost US$10,000 or more, but can have positioning errors on the order of one centimeter or less when used in carrier phase [[differential GPS]] mode. | *'''Surveying''' — Survey-Grade GPS receivers can be used to position [[survey marker]]s, buildings, and [[road construction]]. These units use the signal from both the L1 and L2 GPS frequencies. Even though the L2 code data are [[encrypted]], the signal's [[carrier wave]] enables correction of some [[ionospheric]] errors. These dual-frequency GPS receivers typically cost US$10,000 or more, but can have positioning errors on the order of one centimeter or less when used in carrier phase [[differential GPS]] mode. | ||
*''' | *'''Mapping and [[geographic information system]]s (GIS)''' — Most mapping grade GPS receivers use the carrier wave data from only the L1 frequency, but have a precise [[crystal oscillator]] which reduces errors related to receiver clock [[jitter]]. This allows positioning errors on the order of one meter or less in real-time, with a differential GPS signal received using a separate radio receiver. By storing the carrier phase measurements and differentially [[post-processing]] the data, positioning errors on the order of 10 centimeters are possible with these receivers. | ||
*'''Geophysics and geology''' — High precision measurements of [[crust (geology)|crustal]] strain can be made with differential GPS by finding the relative displacement between GPS sensors. Multiple stations situated around an actively deforming area (such as a [[volcano]] or [[fault zone]]) can be used to find strain and ground movement. These measurements can then be used to interpret the cause of the deformation, such as a dike or sill beneath the surface of an active volcano. | *'''Geophysics and geology''' — High precision measurements of [[crust (geology)|crustal]] strain can be made with differential GPS by finding the relative displacement between GPS sensors. Multiple stations situated around an actively deforming area (such as a [[volcano]] or [[fault zone]]) can be used to find strain and ground movement. These measurements can then be used to interpret the cause of the deformation, such as a dike or sill beneath the surface of an active volcano. | ||