Observation and simulation of direct and reflected GPS signals in Radio Occultation Experiments



GPS/MET radio occultation observations are analyzed with the radio holographic method. Using the Multiple Signal Classification algorithm power spectra of 2038 radio holograms observed between 2 February and 16 February 1997 are calculated. In about 28% of the analyzed L1-band spectra secondary frequency components are found at power levels of about 10–20 dB below the main component. These secondary components are interpreted as signatures of GPS signals reflected at Earth's surface. Results from geometrical ray tracing simulations support our interpretation.