FOURTH QUARTER 2009 1531-636X/09/$26.00©2009 IEEE IEEE CIRCUITS AND SYSTEMS MAGAZINE 43 Feature Digital Object Identifier 10.1109/MCAS.2009.934706 Implementation of a Complete GPS Receiver Using Simulink Gihan Hamza, Abdelhaliem Zekry, and Ibrahim Motawie Abstract During the past few years a lot of efforts have been exerted to make the inner working of the GPS receiver visible, clear and easy to learn and modify either on the level of software or hardware. This article adds a step on the route toward the implementation of a more visible, clearer, and easier to learn and modify a single frequency GPS receiver using the C/A code on the L1 carrier. Simulink was used in the implementation of such receiver, thereby introducing a new look for the SDR technology that can be ac- complished via a graphical user inter- face environment. I. Introduction D uring the past decade a lot of efforts have been exerted not only to open the inner working of the GPS receiver but also to facilitate the education of the design and implementation of such system. The Software-Defined Radio technique was used as a tool in the imple- mentation. From the efforts that were exerted in this field are: The open source GPS project that was initiated in 1995 and leaded by ■ Clifford Killy and Douglas Baker (with collaboration with others) [1]. This project had an educational aims to help any GPS enthusiast to learn deeply the internal working of the GPS receiver. They developed both a commercial hardware and software that constitute a complete GPS receiver. The hardware was introduced by developing two chip- sets called GP1010 and GP1020. The GP1010 was used as a front-end and performs the acquisition phase; while The GP1020 was the track- ing and navigation data extraction chip that has 6 correlators chan- nels [2][3]. The software of this project was a C program written in Borland C. This program contained a library of the GPS functions such as the satellite location by using the almanac, the ephemeris, comput- ing the navigation solution and decoding the navigation message. Dick Benson, a consulting application engineer at Mathworks: de- ■ veloped an incomplete single channel GPS receiver using Simulink. He implemented acquisition, partial tracking, and no pseudorange in SIMULINK [4]. The efforts of Kai Bore and Dennis Akos (with collaboration with ■ others) fruited a book titled “A Software-Defined GPS and GALILEO © COMSTOCK Feature