Southwest Jiaotong University Principles of the Global Positioning System Lecture 03 YUAN LInguo EmailIgyuan@163.com Dept of Surveying Engineering, Southwest Jiaotong University Fundamental knowledg Quick Overview Kelperian 3 Laws First Law: ellipse, Sun is a focus Second law: the same area in same time Earth Third law: 1_ai Principles of the Global Positioning System 2005-3-11(21 Principles of the Global Positioning System Lecture 03 YUAN Linguo Email: lgyuan@163.com Dept. of Surveying Engineering, Southwest Jiaotong University Principles of the Global Positioning System 2005-3-11 2