Electronic Correlated Noise Calibration Standard for Interferometric and Polarimetric Microwave Radiometers

A new type of calibration standard is proposed which produces a pair of microwave noise signals to aid in the characterization and calibration of correlating radiometers. The proposed Correlated Noise Calibration Standard (CNCS) is able to generate pairs of broad bandwidth stochastic noise signals with a wide variety of statistical properties. The CNCS can be used with synthetic aperture interferometers to generate specific visibility functions. It can be used with fully polarimetric radiometers to generate specific 3rd and 4th Stokes parameters of brightness temperature. It can also be used with spectrometers to generate specific power spectra and autocorrelations. It is possible to combine these features and, for example, generate the pair of signals that would be measured by a fully polarimetric, spectrally resolving, synthetic aperture radiometer at a particular pair of polarizations and antenna baselines for a specified scene over a specified frequency band. The proposed CNCS will cover all the frequencies used for radiometric observations in the 1 to 40 GHz range. In specific, the Phase II project will develop the system prototypes for L and X bands. While intended for ground based characterization of radiometer systems, the technological approach is amenable to on-orbit calibration.