Notch Filter Zero Phase Shift Vibratory Flow Meter
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Solution Overview
Problem
Conventional notch filters in vibratory flow meters induce phase shifts in the resonant component, causing frequency drift and complicating the drive algorithm or circuit, which is not ideal for maintaining accurate measurements.
Innovation Solution
A notch filter is configured to pass the resonant component with zero phase shift by centering its passband at the resonant frequency of the sensor assembly, minimizing phase shift over a range of frequencies and using fixed-point precision to reduce computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional notch filters are used to filter out non-resonant components, then the test tone components are effectively removed from the feedback loop, but the resonant component experiences phase shift and frequency drift
Solution Approach 1:
The patent changes the parameters of the notch filter by introducing a variable phase shift that is dynamically adjusted based on the resonant frequency of the sensor assembly. This allows the filter to maintain its noise rejection capability while compensating for phase shifts in the resonant component, thereby resolving the contradiction between filtering effectiveness and frequency accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where the actual resonant frequency is continuously monitored and used to adjust the phase shift parameter of the notch filter. This closed-loop control ensures that the filter adapts to frequency drift while maintaining effective attenuation of non-resonant components, thus preserving both filtering effectiveness and measurement precision.
2Reliability
If the notch filter is designed to attenuate non-resonant components, then test tone filtering is achieved, but the drive algorithm complexity increases due to phase compensation requirements
Solution Approach 1:
The patent simplifies the drive algorithm by dynamically adjusting the phase shift parameter of the notch filter to automatically compensate for resonant frequency variations. This parameter adaptation eliminates the need for complex phase compensation calculations in the drive algorithm, thereby maintaining effective signal filtering while reducing algorithmic complexity.
3Measurement precision
If the notch filter passband is centered at the resonant frequency, then phase shift is minimized, but the filter may not effectively attenuate non-resonant components at different frequencies
Solution Approach 1:
The patent makes the notch filter dynamic by allowing its center frequency and phase shift parameters to be adjusted in real-time based on the detected resonant frequency of the sensor assembly. This dynamic adaptation ensures that the passband remains centered at the resonant frequency for minimal phase shift, while the stopband effectively attenuates non-resonant components at different frequencies, thus resolving the contradiction between phase shift minimization and noise rejection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures accurate and stable measurement by eliminating phase shifts in the resonant component, simplifying the drive algorithm, and reducing computational complexity while maintaining efficient signal processing.
Implementation Method 1
the notch filter is configured to receive a sensor signal from the sensor assembly, the sensor signal being comprised of a first component at a resonant frequency of the sensor assembly and a second component at a non-resonant frequency and pass the first component and substantially attenuate the second component with the notch filter
Implementation Method 2
the first component is passed with substantially zero phase shift, wherein the notch filter is adjusted such that the first component is passed by centering a passband of the notch filter at the resonant frequency of the sensor assembly
Data Source
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AI summary
A meter electronics (20) having a notch filter (26) configured to filter a sensor signal from a sensor assembly (10) in a vibratory meter (5) is provided. The meter electronics (20) includes the notch filter (26) communicatively coupled to the sensor assembly (10). The meter electronics (20) is configured to receive the sensor signal from the sensor assembly (10), the sensor signal being comprised of a first component at a resonant frequency of the sensor assembly (10) and a second component at a non-resonant frequency and pass the first component and substantially attenuate the second component with the notch filter, wherein the first component is passed with substantially zero phase shift.