Simulation of Ambiguity Effects in Doppler Tracking of Pioneer Probes

Various models have been proposed to interpret the anomalous Pioneer Doppler data. We present in this paper a simulation tool aiming at determining signatures that could be searched in the data reduction process in order to discriminate between these different explanations. We discuss preliminary results on the seasonally modulated anomalies and compare two interpretations corresponding to a constant anomalous acceleration on one hand, to an anomalous curvature in the second sector of the gravity law on the other hand. Though the second sector interpretation could naturally induce large modulated anomalies, the adjustment of the initial conditions partly compensate these modulations and thus produces a signature resembling that of a constant acceleration. The difference between the predictions of the two interpretations is in fact close to the rms level of the residuals after the data analysis.