Characterization of the aquarius and juno radiometers using a programmable digital noise source

A new and improved L-Band version of a programmable digital noise source has been developed to aid in the characterization of microwave radiometers. The system consists of a commercial arbitrary waveform generator (AWG), "RF Head" frequency upconversion modulators with integral calibration reference sources, and a local oscillator. It is being used to evaluate the performance of two upcoming spaceborne microwave radiometers - the Aquarius polarimetric radiometer (a low earth orbiting ocean salinity mission) and the Juno microwave radiometer (a Jupiter orbiter for atmospheric sounding). For each of these radiometer evaluations, the programmable noise source can generate signals that: a) simulate the expected observations and test the radiometer\´s response; and b) exercise the radiometer\´s response to variations in the observations in such a way that its overall behavior can be more fully characterized.