Signals of Opportunity - Airborne Demonstrator (SoOP-AD): Instrument Overview, Performance During First Flights and Future Instrument Concept

The Signals of Opportunity Airborne Demonstrator (SoOp-AD) was developed as part of the NASA InstrumentIncubator Program (IIP) with the goal of maturing the use of SoOp from existing communication satellites in geostationaryorbit, operating within the heavily used P-band (under 500 MHz) spectrum for soil moisture observations. P-band offers the benefit of roughly five (5) times deeper soil penetration compared to conventional L-band methods. SoOp-AD operates in a bi-static radar configuration, and only requires reception of direct and scattered signals from the source satellite. In this paper we present an overview of the SoOp-AD instrument architecture, signal processing, internal calibration approach and preliminary results from flights over the Little Washita watershed in Oklahoma, USA. Finally, future steps towards a U-class ("cubesat") instrument concept based upon experience with the airborne demonstrator are presented.