Clifford W. Kelley为其开源GPS接收机编写的文档及发表的文章，包括： 1. OpenSource GPS A Hardware Software Platform for Learning GPS.pdf 2. OpenSource Software for learning about GPS.pdf 3. OSGPS_Book.pdf（内容=4+5+6） 4. OSGPS_forward.pdf 5. OSGPS_chapter_1.pdf ~ OSGPS_chapter_6.pdf 6. OSGPS_references.pdf