Consider the GPS for biomedical applications

One important field of research in biology is the study of the mechanisms that govern orientation and navigation of living objects in a natural environment. For this purpose, experimental techniques for localization and reconstructing a given path as a function of time are of fundamental importance. The most attractive of these techniques is certainly satellite-based. Recent developments in the Navigation System Time and Range (NAVSTAR) for the Global Positioning System (GPS) have given rise to some very interesting applications for biology and medicine. Global Positioning Systems are space-based radio positioning systems that provide 24 hour, three-dimensional position, velocity and time information to suitably equipped users anywhere on or near the surface of the earth. Here we refer to NAVSTAR GPS, operated by the U.S. Department of Defense, which is the first GPS widely available to civilian users. A system could be designed that reconstructs the path of a free ranging animal using a GPS receiver carried by the animal itself. The receiver would be operated in a continous navigation mode and record successive position data, which are then analyzed at the end of the experiment. Such an experimental technique would not suffer from the typical constraints of visual, radio, and radar techniques, where the required "electromagnetic" link between the observer and the animal limits the monitoring range and may be heavily impaired by the nature of the surrounding environment