I built this tracking device in college ... I dug it out of the basement and added information about it onto my projects blog. You may find my blog interesting. Feel free to browse all the projects on my blog and provide feedback and questions.
http://home.comcast.net/~panofish/WEBLOG/2...vice/index.html
http://home.comcast.net/~panofish/WEBLOG/2...vice/index.html