The GPS Easy Suite–Matlab code for the GPS newcomer

Abstract

The Matlab computing environment has become a popular way to perform complex matrix calculations, and to produce sophisticated graphics output in a relatively easy manner. Large collections of Matlab scripts are now available for a wide variety of applications and are often used for university courses. The GPS Easy Suite is a collection of ten Matlab scripts, or M-files, which can be used by those just beginning to learn about GPS. The first few scripts perform basic GPS calculations such as converting GPS Time in year/month/day/hour/minute/second format to GPS week/seconds of week, computing the position of a satellite using a broadcast ephemeris, and computing the coordinates of a single point using pseudorange observations. The latter scripts can perform calculations such as computing baseline components using either traditional least-squares or a Kalman filter, fixing cycle slips and millisecond clock jumps, and computing ionospheric delay using carrier phase observations. I describe the purpose of each M-file and give graphical results based on real data. The Matlab code and the sample datasets are available from my website. I have also included additional text files (in pdf format) to discuss the various Time Systems and Coordinate Systems used in GPS computations, and to show the equations used for computing the position of a satellite using the ephemeris information broadcast from the satellites.