Modern bandwidth requirements in active tracking

Derek J. Burrell

doi:10.1117/12.3027950

7 October 2024 Modern bandwidth requirements in active tracking

Derek J. Burrell

Proceedings Volume 13149, Unconventional Imaging, Sensing, and Adaptive Optics 2024; 131490L (2024) https://doi.org/10.1117/12.3027950
Event: Optical Engineering + Applications, 2024, San Diego, California, United States

Abstract

For several decades, the Tyler frequency has provided the tracking community with a reliable estimate of the bandwidth required to track an object through turbulence consistently. Specifically, it determines a 3-dB bandwidth at which the expected one-axis/one-sigma residual G or Z tilt equals the diffraction angle of a given system. That analysis, however, arrives at tractable solutions by operating in continuous rather than discrete time. Furthermore, it assumes only a first-order lowpass filter as the dynamic controller model. This paper extends Tyler’s original treatment to address each of these potential limitations by analyzing digital rather than analog controllers and generalizing beyond a single-pole transfer function for higher-order control. It further identifies an additional bandwidth constraint from image-plane speckle noise associated with coherent illumination. At its most severe, speckle can reduce precision to the point of becoming stringent than turbulence as a limiting factor in tracking performance. Reducing the sample rate can then allow for speckle averaging, which in turn leads to improvements in track precision and ultimately buys back performance. This trade space poses an optimization problem, with proposed solutions in the form of modified bandwidth requirements that depend upon system diffraction angle, object angular velocity and speckle contrast ratio. Validation from wave-optics simulations and computer-aided control system design informs the analytical tools developed here and demonstrates their applicability to modern challenges in active tracking.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Derek J. Burrell "Modern bandwidth requirements in active tracking", Proc. SPIE 13149, Unconventional Imaging, Sensing, and Adaptive Optics 2024, 131490L (7 October 2024); https://doi.org/10.1117/12.3027950

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