Fig. 1
From: Orbital bistatic radar observations of asteroid Vesta by the Dawn mission
Typical progression of received radar signal over the course of an occultation. The frequency spectra show power received in the same circular (SC) and opposite circular (OC) polarization a before/after occultation, b during entry into occultation, c during occultation, and d during exit from occultation of orbit 355. All surface echoes during occultation entry are Doppler-shifted to lower frequencies than the direct signal, while all surface echoes during occultation exit exhibit Doppler shifts to higher frequencies than the direct signal
