Blade Tip Timing Deflection Measurement via Phase Shift

The patent replaces conventional triggering-based ToA determination with a phase-based approach using Hilbert transform and local phase calculation. Instead of relying on amplitude thresholds or fixed voltage crossings that are sensitive to noise, the method uses the phase angle of the analytic signal derived from the proximity probe waveform. This substitution of the measurement mechanism fundamentally improves precision by providing continuous phase information that is less susceptible to noise and sampling rate limitations.

The patent changes the parameter used for ToA determination from amplitude-based metrics (maximum amplitude, fixed voltage threshold) to phase-based metrics (local phase angle). By transforming the proximity probe signal into an analytic signal and extracting the phase component, the method achieves more accurate and stable ToA measurements. The phase parameter provides continuous information that can be accurately determined even at lower sampling rates, directly addressing the measurement precision problem.

The patent changes the measurement parameter from time-domain amplitude metrics to frequency-domain phase metrics. The local phase angle can be accurately determined through spectral analysis methods that are more efficient than high-rate time-domain sampling. By working in the frequency domain and using phase information from the analytic signal, the method achieves high measurement precision without requiring proportionally high sampling rates, thus improving data acquisition efficiency.

The patent substitutes direct high-rate time-domain sampling with a phase-extraction approach using Hilbert transform and spectral analysis. This replacement allows the system to obtain accurate ToA measurements through phase angle calculation rather than requiring extremely fine time-resolution sampling. The method effectively decouples measurement precision from sampling rate requirements, improving productivity while maintaining accuracy.