Characterization and behavioral modeling of frequency-selective limiters for improved in-band interference suppression

Committee: 

Dr. Kenney, Advisor      

Dr. Ansari, Chair

Dr. Causey

Dr. Yang

Abstract:

The objective of the proposed research is to develop advanced digital signal-processing techniques for a frequency-selective limiter (FSL) to mitigate in-band distortion inherent to its operation. These innovations will improve its spectral selectivity as an automatically tuned notch filter and cancel intermodulation distortion (IMD) to increase spectral efficiencies when using FSLs to mitigate interference or extend receiver dynamic range in dense spectral environments. The methodology of this proposal leverages mature algorithms developed for power amplifiers, including state-of-the-art models, as well as predistortion and interference-cancellation techniques, to develop an FSL model that is sufficiently accurate to implement model-based post-distortion signal processing. This model includes (for the first time in FSLs) spectral asymmetries in IMD, and a key model refinement relates these asymmetries to the relative-phase relationship of IMD components and transient behavior in FSLs. These enhancements significantly increase the fidelity between modeled and measured data, compared to existing FSL models, thereby enabling (for the first time) post-distortion signal processing to make FSLs more attractive for use in dense spectral environments.