GNSS signal processing for estimating the orbit

Method and apparatus are described for processing a set of GNSS signal data derived from signals from GNSS satellite observed by the reference station receiver, wherein the data code observations and carrier observations for each of at least two carriers over multiple epochs, comprising: obtaining an orbit start vector comprising: a time sequence of predicted positions and predicted rates for each satellite on a first interval, and the Parti Ella lead shortfalls in the predicted positions and predicted velocity with respect to initial positions initial velocities, force model parameters, and Earth orientation parameters, obtained from ionospheric-free linear combinations of the code observations and carrier observations for each satellite at multiple reference stations, and iteratively correcting the orbit start vector using at every period of ionosphere-free linear combinations will n and predicted Earth orientation parameters as soon as the ionosphere-free linear combinations of the epoch are available for obtaining updated orbit start vector values ​​comprising a time sequence of the predicted positions and predicted rates for each satellite over a subsequent interval of epochs and an estimate of Erdorientierungsparametern.