Compression at the physical interface: The A-to-I and MONTAGE programs

Progresses in physical compressive sampling under the Defense Advanced Research Agency's Analog-to-Information (A-to-I) and Multiple Optical Non-Redundant Aperture Generalized Sensors (MONTAGE) programs are more about finding aggressive forms of generalized sampling under which measurements consist of transformation, projections or encodings of the signal onto discrete digital data. The two projects differ in that the former seeks to revolutionize very high temporal bandwidth analog to digital signal conversion whereas the latter aims to revolutionize very high spatial bandwidth analog to digital signal conversion. Nevertheless, MONTAGE focuses on data conversion approaches while both have realized new opportunities and established various important bounds on the sampling required as a function of prior and ancillary information.