Clock Bias

Clock bias is the time offset between a GNSS satellite or receiver clock and the reference time scale (e.g., GNSS system time or UTC). Because GNSS positioning relies on precise signal travel time measurements, even nanosecond-level clock errors translate into significant range errors.

In geodesy, clock biases of both satellites and receivers are estimated as unknown parameters within the GNSS observation equations. Accurate modeling and estimation of clock bias are essential for precise positioning, time transfer, orbit determination, and reference frame realization. Satellite clock corrections are provided in broadcast ephemerides and refined in precise products generated by geodetic analysis centers.