Five Essential Functions for Geodetic Coordinate Conversion and Satellite Navigation Calculations

Analysis of Geodetic Coordinate to WGS84 Coordinate Conversion and Related Calculation Functions

This article introduces a suite of practical functions for geodetic surveying and satellite navigation, comprising five core functional modules:

Geodetic Coordinate to WGS84 Coordinate Conversion Implements precise transformations between different coordinate systems, considering Earth ellipsoid parameters. Supports mutual conversion between latitude/longitude/height coordinates and Earth-Centered Earth-Fixed (ECEF) Cartesian coordinates. The conversion process strictly follows international geodetic standards, ensuring spatial data consistency in GIS systems and satellite positioning. Implementation typically involves using transformation matrices and ellipsoidal parameters (semi-major axis, flattening) to calculate precise coordinate offsets.

Satellite Position Calculation Computes satellite spatial positions at any given time based on ephemeris parameters, accounting for temporal variations in Keplerian orbital elements. Supports orbit prediction for navigation satellite systems like GPS/BeiDou, providing accurate satellite position data for positioning solutions. The algorithm processes broadcast ephemeris data to calculate satellite coordinates using Kepler's equation and perturbation corrections.

Ionospheric Delay Correction Utilizes classical models like Klobuchar to calculate signal propagation delays based on ionospheric parameters and user location. This module effectively reduces ionospheric effects on satellite signals, significantly improving positioning accuracy for single-frequency receivers. The implementation involves modeling ionospheric electron content and applying time-dependent correction coefficients from navigation messages.

Tropospheric Delay Correction Estimates radio signal propagation delays through the troposphere using Saastamoinen or Hopfield models, considering influences from atmospheric pressure, temperature, humidity and other meteorological parameters. Suitable for accuracy correction under various climatic conditions. The code typically implements zenith delay calculation with mapping functions to convert to slant delays.

Integrated Positioning Calculation Combines the above fundamental modules to achieve complete processing from raw observations to final coordinates, including error correction and coordinate conversion key steps. This functional module can be directly applied to satellite navigation receiver software development. The implementation involves sequential processing of observational data through atmospheric correction models, satellite position computation, and least-squares adjustment for position solution.

These functions collectively form a core algorithm set for satellite positioning, with significant application value in professional fields such as surveying, navigation, and seismic monitoring. Developers can independently call individual functions based on specific requirements or combine them to build complete positioning solution workflows.