I'm working on using raw measurements from a GPS receiver to compute a receiver position and I wanted to make sure the process I was using was correct. Here's what I'm currently doing: Compute satellite XYZ Get pseudorange to each satellite in range at an observation time Corrected pseudorange = pseudorange - (speed of light * SV clock bias) - (speed of light * seconds between observation and ephemeris * SV clock drift) - (40.3*TEC/f^2) - (speed of light * relativistic delay) Perform least squares using the SV positions and corrected pseudoranges Does the correction look appropriate? I'm not yet incorporating a tropospheric correction.