GPS Satellite Position Prediction System Development

Development of a GPS Satellite Position Prediction System Based on MATLAB

GPS satellite orbit prediction is one of the core technologies in satellite navigation, using mathematical models to forecast satellite positions in space at future time points. This article demonstrates how to build a GPS satellite position prediction system with animation capabilities using MATLAB.

Core Algorithm Architecture: Orbital Parameter Processing: The system first parses satellite ephemeris data, including Keplerian orbital parameters and time correction parameters. Key parameters consist of semi-major axis, eccentricity, inclination angle, and other orbital elements. MATLAB implementation typically involves reading navigation message files using textscan or fread functions.

Position Calculation Model: - Calculation of satellite position in the orbital plane using Kepler's orbital equations, implemented through iterative solutions of Kepler's equation with newtonRaphson or fzero functions - Coordinate transformation to Earth-Centered Inertial (ECI) frame using rotation matrices - Conversion to Earth-Centered Earth-Fixed (ECEF) coordinates considering Earth's rotation via transformation functions - Final conversion to latitude, longitude and altitude representations using ecef2lla or similar coordinate transformation functions

Error Compensation Mechanism: - Relativistic effect corrections applied through mathematical compensation terms - Clock error compensation using polynomial correction algorithms - Optional atmospheric delay correction models (ionospheric/tropospheric)

User Interface Design Key Points: - Data input panel: Allows users to import ephemeris files or manually input orbital parameters using uigetfile and uicontrol components - Time control module: Sets prediction start time and duration through datetime objects and sliders - Visualization area: 3D Earth model displaying satellite trajectories using sphere and surface plotting functions - Animation controls: Play/pause/speed adjustment features implemented with timer objects and callback functions - Result output: Displays current satellite coordinates and orbital parameters in real-time text boxes

Animation Implementation Key Technologies: - Utilization of MATLAB's hgtransform for 3D spatial transformations and object positioning - Frame rate control through timer objects with precise timing intervals - Trajectory plotting using plot3 function and instantaneous position marking with scatter3 - Enhanced visual effects by overlaying Earth textures with image mapping techniques

System Expansion Directions: - Multi-satellite cooperative display with color-coded trajectory plotting - Signal coverage analysis through visibility cone calculations - Ground station visibility analysis incorporating elevation mask angles - Validation with real ephemeris data import and accuracy assessment

The MATLAB implementation leverages its powerful matrix computation capabilities and visualization tools, enabling faster prototype development compared to traditional C++ implementations. It is particularly suitable for educational demonstrations and algorithm validation scenarios. The animation interface provides intuitive observation of spatial characteristics and temporal evolution patterns of satellite orbits through dynamic visualization.