.[.A satellite vehicle compensation system (100) predicts the motion of two satellite vehicles and enhances the predictions with real-time updates of one or both of the vehicles. Using feedback loops (132, 134), the differences between the prediction and the actual motions are looped back to improve the accuracy of the motion predictor..]. .Iadd.A communications system includes a first communications node and a second communications node. A transmission frequency and/or a receiving frequency is compensated based on a predicted relative motion between the first and second communications nodes. The predicted relative motion is based on a first signal that is representative of a predicted motion of the first communications node and a second signal that is representative of a predicted motion of the second communications node. Real-time information may be used to minimize an error between predicted and measured motions of the first and/or second communications node..Iaddend.