  SARComm is a novel wireless communication system that enables passive
satellite backscatter connectivity using existing spaceborne synthetic aperture
radar (SAR) signals. We demonstrate that SAR signals from the European Space
Agency's Sentinel-1 satellite, used to image Earth's terrain, can be leveraged
to enable low-power ground-to-satellite communication. This paper presents the
first cooperative, on-the-ground target that modulates SAR backscatter to send
information bits and analyzes how to extract them from publicly available
Sentinel-1 datasets. To demonstrate the system, we evaluate the effectiveness
of modulating the radar cross section of corner reflectors both mechanically
and electronically to encode data bits, develop a deployment algorithm to
optimize corner reflector placement, and present a SAR processing pipeline to
enable communication.
