A Global Positioning System for Aquatic Surveys
Jay D. Jeffrey, David R. Edds · Fisheries · 1997
The Global Positioning System (GPS) is a superior surveying technology that quickly provides highly accurate, reproducible spatial data, even in remote reference-free areas. In this article we review fundamentals, limitations, and strengths of the technology. The GPS is a satellite-based navigation system that relies on radio signals having intrinsic error sources such as signal deflection and intentional degradation by the U.S. Department of Defense. Accuracy is measured as the spatial divergence from a known location, and precision can be expressed with the root mean square statistic. Basic or differential GPS (BGPS and DGPS, respectively) is used depending on the spatial resolution needed and time allowed for a survey. The DGPS requires more time, data processing, and personnel training but is more accurate than BGPS due to correction of signal errors. Preliminary planning and training are essential for fisheries scientists preparing to conduct aquatic surveys.