A Simple Yet Effective Metric for Assessing Doppler Tolerance

• Published in: IEEE transactions on radar systems 2023, Vol.1, p.12-20
• Main Authors: Quirk, Jennifer E., Chang, Rachel J., Owen, Jonathan W., Blunt, Shannon D., McCormick, Patrick M.
• Format: Article
• Language: English
• Subjects: Doppler radar; Doppler shift; Pulse compression methods; Radar signal processing; Signal analysis
• ISSN: 2832-7357; 2832-7357
• DOI: 10.1109/TRS.2023.3257020

The Doppler tolerance of a waveform refers to its behavior when subjected to fast-time Doppler shift imposed by scattering that involves nonnegligible radial velocity. The delay/Doppler ambiguity function characterizes this behavior, with notable attributes of Doppler-dependent mismatch loss (relative to zero Doppler) and possible offset in delay estimation. Previous effort has gone into establishing decision-based criteria where a binary judgement of being Doppler tolerant or not is made. Here, we consider the utility of a simple, yet effective measure of the degree of Doppler tolerance arising from a fundamental attribute of the ambiguity function that is also convenient to extract. This metric is examined in the context of a variety of different waveform classes including traditional linear/nonlinear chirps, noise-like signals, and phase codes. Extension to wideband operation is likewise considered. The purpose in doing so is to establish a consistent standard that can be readily applied, thereby permitting easy assessment across different parameterizations, as well as introducing a Doppler "quasi-tolerant" trade-space that can ultimately inform automated/cognitive waveform design in increasingly complex and dynamic radio frequency (RF) environments.