中文摘要：

目前，越来越多的低轨卫星上都搭载了用于精密定轨的星载GPS接收机，星载GPS已成为低轨卫星精密定轨的主要手段之一．星载GPS精密定轨精度依赖于GPS星历及钟差精度．基于SHORDE—Ⅲ非差动力学定轨功能，以2005年8月1日至8月7日一周的GRACE卫星实测数据为例，采用事后精密轨道（igs）、快速轨道（igr）和超快速轨道（igu）三种GPS星历在同等条件下定轨，估计GPS星历精度对低轨卫星定轨精度的影响，实际计算结果表明igs和igr两类GPS星历定轨精度相当，约为9．5cm，igu星历定轨精度略低于igs和igr星历，约为10．5cm：高频GPS卫星钟差数据对定轨精度会产生1-6cm影响．

英文摘要：

Today more and more Low Earth orbiting satellites （LEOs） of new scientific missions are equipped with a GPS receiver for precise orbit determination （POD）, on-board GPS has become one of the main POD approaches. However, the on-board GPS POD accuracy obviously relies on the accuracy of GPS orbit and clock products. Based on the zero-difference dynamic POD approach of SHORDE-III program, this paper shows the influence of GPS orbit and clock on the POD accuracy of LEO using real GRACE data and three types of IGS orbit products between 1 Aug. and 7 Aug. The results indicate that IGS final precise orbit product （igs） and rapid orbit product （igr） have the equal POD accuracy which is about 9.5cm, the POD accuracy using ultra-rapid orbit product （igu） is about 10.5cm which is a little worse than igs and igr; High-rate GPS clock products have an impact of about 1-6 cm on the POD accuracy of LEO.