Accuracy of real-time sky status indicator (SSI) for the characterization of a satellite communication link at microwave bands

In the framework of the incoming Alphasat communication and propagation experiment, an operative real time criterion (SSI) to discriminate among the three main atmospheric propagation statuses (clear, cloudy and rainy sky conditions) and to trigger Fading Mitigation Techniques (FMT) is proposed and analysed. Two SSI boundary threshold values were estimated: SSI_CC for demarcating between clear and cloudy conditions and SSI_CR between cloudy and rainy sky. SSI is based on brightness temperature measurements observed at 20/30 GHz by ground-based radiometer. On the two SSI thresholds, a robustness analysis was performed to account for brightness measurements accuracy as well as for improper radiometric calibration. Furthermore, an analysis of the SSI discrimination performances based on the Neyman-Pearson optimal detection is addressed.