GPS民用导航电文演变分析

摘要

主要对GPS公开的接口规范文件中民用导航电文（NAV）、（CNAV）、CNAV-2进行详细的分析与比较，总结了这3类下行导航电文的具体的电文组成、电文编排结构、电文播发方式、编码设计，并从电文参数精度提高、参数的增加、电文的改进、电文删减以及电文的编排5个方面分析了电文演变，其中重点分析了对导航电文的整体效能影响最大的电文的改进和电文编排的变化这两方面，这些变化使得GPS在播发时效、定位精度、解算效率、编排灵活性、互操作性和可扩展性上得到了提高，并且分析了这些提高表现的具体方面。%This paper analyzes detailedly navigation message NAV （Navigation）. CNAV （Civil Navigation）.CNAV-2（Civil Navigation 2） in the Interface Specification of GPS, also those navigation messages are compared. It dissertates how to design those messages from four. the content and configuration of the navigation message, the broadcasting, and code design. It discusses the improvement of navigation message from five aspects and to give emphasis to the improvement of message and the changes of data structure layout. These trans- formations improve GPS system＇s performances including broadcasting efficiency, positioning precision, compute efficiency, data structure layout flexibility, interoperability, extendibility. The paper will analyze the improvement.