Digital radiometers for earth science

Abstract

Digital microwave radiometers replace as much of the conventional analog circuitry in a radiometer as possible with an analog-to-digital converter followed by a high speed Digital Signal Processing (DSP) stage. Digital technology adds capabilities to a radiometer that would otherwise be much more difficult (and often cost prohibitive) to include. The quality of each of the performance enhancements enabled by digital radiometry (e.g. spectral resolution, RFI detectability threshold, and full Stokes polarization purity) is dependent on certain aspects of the digital technology (e.g. number of bits of digitization, digitization oversampling rate, length of transverse digital filters, number of internal bits utilized by the DSP algorithm, and core memory and logic block sizes in the DSP chip). These factors are examined and current and projected radiometer performance capabilities estimated given the current and projected state of the art in DSP technology.