Direct time-of-arrival difference signal estimation for blade tip timing measurement from an information non-increase perspective

Blade Tip Timing (BTT) measurements typically rely on converted physical quantities (e.g., displacement) rather than the Time of Arrival (TOA) signals. This approach often introduces uncertainties associated with secondary observations. This study proposes a novel BTT signal processing paradigm based on information theory. It articulates the information non-increase principle and provide quantitative proof, followed by introducing an information volume metric to guide the design of sampling structures. Simulations and experiments validate the correctness of the information non-increase principle, and a systematic analysis of the proposed information volume metric is conducted. Experimental results demonstrate that even TOA difference signals contain richer and cleaner blade vibration information compared to converted displacement signals. The information non-increase principle is expected to offer a new direction for guiding BTT measurements from the perspective of information transmission.