Date of Award
2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Electrical Engineering
Committee Chair
Laurie Joiner
Committee Member
Mervin C. Budge, Jr.
Committee Member
Dongsheng Wu
Committee Member
Aubrey Beal
Committee Member
Adam Panagos
Research Advisor
Laurie Joiner
Subject(s)
Analog-to-digital converters, Signal processing--Mathematics, Electronic noise, Radar
Abstract
The objective of this study was to develop an expression for signal processor signal-to-interference ratio (SIR) improvement that combines factors that have historically been treated separately into a simple closed form expression, specifically factors such as analog-to-digital converter (ADC) dynamic range, phase noise, sub-quanta signal levels, signal-to-noise ratio (SNR), gain, automatic gain control (AGC), receiver noise, and signal and clutter characteristics. The SIR expression developed in this study quantifies how much a signal processor’s performance is degraded by the inclusion of an analog-to-digital converter (ADC) with respect to an equivalent well designed all-analog design. Using this unified SIR metric, expressions for signal-to-clutter ratio improvement (ISCR) are also derived. The overall results of this study are new and unique expressions for SIR and SCR improvement that combine all the aforementioned factors. The unifying theories and expressions developed during this research, and documented herein, give simple closed form results, which give a practical approximation of observed performance, and allow for vetting of various design choices prior to costly hardware construction. The results of this analysis also prompted a study of how to design a receiver such that receiver noise would provide the ADC toggling necessary to overcome ADC dynamic range limitations and maximize the possible SIR improvement. Additionally, when measuring system performance directly, these expressions allow a means of better understanding the impact of various parameters by matching this analysis to measurement results. The application which initiated this analysis was testing of a fielded radar, where various system parameters are measured, rather than stipulated. The initial case considered is one where clutter power is assumed to control the AGC, wideband dither was provided by injecting noise from a calibrated source, and the dither noise power spectral density was white. The impact of ADC dynamic range on digital signal processor (DSP) performance is shown to be a degradation of SNR rather than a limitation of the SCR improvement or clutter attenuation capability of the DSP. A subsequent case that was considered was one in which the signal power drives the AGC. The unified SIR and SCR improvement expressions presented herein include theoretical results applicable to a broad range of radars and signal processors and can be used to aid in quantifying the effects of using an ADC in a receiver design.
Recommended Citation
German, Shawn Richard, "Signal-to-interference degradation due to ADC dynamic range for a pulsed Doppler radar digital signal processor" (2025). Dissertations. 447.
https://louis.uah.edu/uah-dissertations/447
