1. Basic Knowledge of GPS In 1973, DOd organized a Joint P Office (JPO) located at the U.S. Air Force Systems Command's Space The s Second Lecture Division, Los Angeles Air Force Base(AFB)to what?

Outline Review u Examined basics of GPS signal structure and how gnal is tracked a Looked at methods used to acquire satellites and start g Today we look at

Perigee and Apogee: The point of closest approach of the satellite with respect to the earth's center of mass is called perigee and the most distant position is the apogee. Nodes: The intersection between the equatorial and the nit sphere is termed the nodes, where the ascending node defines the northward

1.1 Physical Fundamentals This attenuation is usually expressed in decibels (dB). By definition, an attenuation of n dB means signal propagation from the that the original field strength is decreased by ite to the user by means of factor of 10-0In electromagnetic waves. Such waves Physical quantities

1. Errors related to GPs Satellites 2. Errors related to GPS signal propagation in atmosphere 3. Error related to gPs receivers Gv Principles of the Global Positioning System

GPS定位的基本观测量是观测站(用户接收天线)至 GPS卫星(信号发射天线)的距离(或称信号传播路 径),它是通过测定卫星信号在该路径上的传播时间 (时间延迟)或测定卫星载波信号相位在该路径上的 变化周数(相位延迟)来导出的

1卫星在空间绕地球运行时,除了受地球重力场的引 力作用外,还受到太阳、月亮和其它天体的引力影 响,以及太阳光压、大气阻力和地球潮汐力等因素 影响 口若假设地球引力场的影响为1,其它引力场的影响均小于 105

1定位方法分类 按参考点的不同位置划分为 绝对定位(单点定位):在地球协议坐标系中,确定观测站相对地 球质心的位置

一.天球坐标系空间固定的坐标系,该坐标系与地球自转无关,对描述卫星的运行位置和状态极其方便。 二.地球坐标系 与地球体相固联的坐标系统,该系统对表达地面观测站的位置和处理GPS观测数据尤为方坐标系统是由坐标原点位置、坐标轴指向和尺度所定义的

1.1 Terminology Definitions 3. Point Positioning ys. Relative positioning The coordinates of a single point are determined when 1. Code Range vs, Carrier Phase Code measurements(meter level) Carrier phase measurements(millimeter range). Single point positioning