Modeling of Ocean Surface Delay Doppler Maps Measured in S-Band Signal of Opportunity Reflectometry

Signals-of-Opportunity (SoOp) remote sensing of the Earth measures the reflections of existing transmitters from Earth's surface in order to discern information on the Earth's geophysical properties. While the transmissions of Global Navigation Satellite System (GNSS) emitters have been widely used in this application, other sources are also available that can provide distinct advantages. In particular, S-band (i.e. 2.34 GHz) transmissions in the satellite-based digital audio radio service (e.g. the XM and Sirius systems) provide geostationary emissions of relatively higher power and in multiple channels of ~ 2 MHz bandwidth. The reflection of these signals for example from the ocean surface can be used to sense ocean wind speeds and other properties of the sea surface. Measurements of these reflections can be processed to produce Delay Doppler Maps (DDMs) that provide further insight into the scattering process. In this thesis, a model for ocean-reflected DDMs acquired by an airborne receiver developed by Purdue University is developed for comparison with the measurements. Particular emphasis in the comparisons is placed on scattering effects outside the specular region traditionally examined in SoOp sensing by examining portions of the DDMs at significant delay and doppler offsets with respect to the specular point. In addition, the impact of the receive antenna pattern on these portions of the DDM and on the polarization of the received signals is examined. The results show the utility of these measurements for ocean remote sensing, as well as the importance of an accurate model for ocean surface scattering for predicting the results obtained.ElectroScience LaboratoryUndergraduate Research ScholarshipNo embargoAcademic Major: Electrical and Computer Engineerin