Karsky, Dick . 2004. Comparing Four Methods of Correcting GPS Data: DGPS, WAAS, L-BAND, and Postprocessing. 0471 2307. Missoula, MT: U.S. Department of Agriculture, Forest Service, Missoula Technology and Development Center. 6 p.
Describes four methods used to correct global positioning system (GPS) data and compares their relative accuracies. The correction methods include three that operate in real time—differential GPS (DGPS), the wide area augmentation system (WAAS), and satellite service providers transmitting corrections on L-band frequencies—and one that requires correcting the GPS data after it has been collected (postprocessing). The best methods, from the most to the least accurate, are: postprocessing GPS data, using DGPS beacons to correct GPS data in real time, using satellite service providers transmitting corrections over L-band frequencies to correct GPS data in real time, and using the wide area augmentation system to correct GPS data in real time.
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