Pulse Width Measurement via Frequency Domain Analysis
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Solution Overview
Problem
Existing methods for measuring pulse width in tire-mounted monitoring devices face challenges in noisy conditions, requiring heavy filtering that distorts the signal and complicates reference point selection, and are not generalizable across varying pulse shapes and rates.
Innovation Solution
A method and apparatus that utilize a frequency analyzer to produce a frequency representation of the pulse, determining a minimum value in this representation to estimate pulse width, which inherently acts as an effective noise filter without pre-filtering, preserving the original pulse shape and allowing for real-time adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy filtering is applied to reduce noise in poor signal-to-noise ratio conditions, then noise reduction is improved, but the shape of the signal is distorted and pulse width measurement accuracy deteriorates
Solution Approach 1:
The patent transforms the signal from the time domain to the frequency domain using Fast Fourier Transform (FFT). By analyzing the frequency spectrum and identifying the dominant frequency component, the system can determine pulse width without applying time-domain filtering. This dimensional transformation allows noise reduction while preserving signal shape, as the frequency domain analysis inherently filters out broadband noise while maintaining the characteristic frequency of the pulse signal.
2Adaptability or versatility
If the pulse width measurement method is adapted to different pulse shapes and rates, then measurement versatility is improved, but system complexity increases due to real-time filter adjustment requirements
Solution Approach 1:
The patent employs a universal frequency-domain analysis approach that works for various pulse shapes and rates without requiring separate processing paths. The FFT-based method extracts the dominant frequency from the frequency spectrum, which can be inverted to obtain pulse width for any pulse type. This single universal algorithm replaces multiple specialized filters that would be needed for different pulse characteristics, thereby reducing system complexity while maintaining high versatility.
Data Source
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AI summary
A tyre monitoring apparatus comprising a monitor installed on a tyre and a pulse width measuring apparatus for measuring the width of pulses produced by the monitor. The pulse width measuring apparatus comprises a frequency analyzer for producing a frequency representation of the pulse, a signal processor for determining a minimum value of the frequency representation, and a pulse width estimator that inverts the minimum value to produce a measurement for the pulse width. The tyre monitoring apparatus uses the pulse width measurement as an indication of characteristics of the tyre.