A single receiver in a dense forest does not get enough information to determine its location using the GPS system, which requires a lock on four different satellites. Obstructions in the forest (trees to most people) typically prevent receivers from communicating with more than one or two satellites at any single time.
A student team took more than 1400 measurements to help characterize the EM propagation and GPS performance in forests.
A Wireless@VT effort, headed by Michael Buehrer, an associate ECE professor, is developing outdoor sensor network technology that enables receivers to share GPS information and determine their own location. Nodes will share their limited GPS information to calculate a known coordinate for at least one node in the network. By range-finding between themselves, the nodes will know each other's relative location and be able to precisely compute the latitude and longitude for each node.
In an effort to characterize the EM propagation and GPS performance in forest environments, a team of graduate and undergraduate students measured 93 different locations in four different forest environments. More than 1400 measurements were recorded in light brush and light, medium, and dense forest situations.
The undergraduates were funded under the National Science Foundation (NSF) Research Experience for Undergraduates (REU) program. Undergraduate students involved were Alyse Bowers, Kyle Forrester, Chris Hutchens, Jason McKillican, and Brian Sarbin. Their work was presented in a paper at the 2008 IEEE Wireless Communications and Networking Conference.
The team was led by postdoctoral research faculty member Chris Anderson and a graduate student team of Haris Volos, Bradley Fellow Chris Headley, and Tao Jia. Anderson is now an assistant professor of ECE at the United States Naval Academy.