HDD Notch Filter Calibration via Phase Comparison
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Solution Overview
Problem
Existing notch filters for hard disk drives (HDDs) face challenges in accurately calibrating the notch frequency to account for resonance frequencies generated by shock sensors, leading to false signals and requiring incremental adjustments that are time-consuming and lack precise frequency tolerance.
Innovation Solution
A digital selectable notch filter with a calibration logic system that uses phase comparisons and binary searching to converge on the correct notch frequency, employing a D flip flop to determine phase delays or advancements, allowing for precise filtering of resonance frequencies without the need for absolute frequency tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If incremental adjustments are used to calibrate the notch filter frequency, then the notch filter can be adjusted to account for resonance frequencies, but the calibration process becomes time-consuming and lacks precise frequency tolerance
Solution Approach 1:
The system uses a D flip-flop to capture the phase relationship between the shock sensor signal and the notch filter output signal. This phase information is fed back to a calibration logic that automatically adjusts the notch filter frequency setting. The feedback mechanism eliminates the need for time-consuming incremental adjustments by directly indicating whether the notch frequency needs to be increased or decreased based on the captured phase state.
Solution Approach 2:
The calibration system is self-adjusting through the automatic calibration logic that uses the phase information from the D flip-flop to modify the notch filter frequency. The system performs its own calibration without requiring external incremental adjustments, thereby reducing calibration time while maintaining precise frequency alignment with the shock sensor's resonance frequency.
2Measurement precision
If the notch filter frequency is set with absolute frequency tolerance, then precise filtering can be achieved, but the system becomes complex and requires multiple incremental changes to determine the correct frequency
Solution Approach 1:
The D flip-flop acts as an intermediary element that captures and stores the phase relationship between the shock sensor signal and the notch filter output. This single binary state (0 or 1) from the flip-flop provides sufficient information for the calibration logic to determine the direction of frequency adjustment needed, simplifying the calibration process while maintaining precise frequency setting capability.
Solution Approach 2:
The calibration logic changes the notch filter frequency parameter based on the phase state captured by the D flip-flop. By using phase information as the basis for parameter adjustment, the system achieves precise frequency alignment without requiring complex calibration procedures or absolute frequency tolerance specifications, thereby reducing system complexity.
3Measurement precision
If the resonance frequency is determined using electrical impulse stimulation, then the resonance frequency can be identified, but the notch filter still requires multiple incremental changes and absolute frequency tolerance to achieve accurate filtering
Solution Approach 1:
After the resonance frequency is identified through electrical impulse stimulation, the system uses a D flip-flop to capture the phase relationship between the shock sensor signal and the notch filter output. This phase feedback is fed to calibration logic that automatically adjusts the notch filter frequency setting, eliminating the need for multiple incremental changes and reducing the time required to achieve accurate filtering while maintaining precise resonance frequency identification.
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
The solution effectively filters out resonance frequencies, improving signal accuracy and reducing calibration time by using phase differences to adjust the notch filter frequency, ensuring precise alignment with the shock sensor's resonance frequency.
Implementation Method 1
uses phase comparisons and binary searching to converge on the correct notch frequency, employing a D flip flop to determine phase delays or advancements
Implementation Method 2
A digital selectable notch filter with a selectable notch frequency... effectively filters out resonance frequencies
Implementation Method 3
a shock sensor of the hard disk drive, coupled to the selectable notch filter, the shock sensor having at least one resonance frequency
Data Source
AI summary
An apparatus for use with a hard disk drive, comprising: a selectable notch filter with a selectable notch frequency; a shock sensor of the hard disk drive, coupled to the selectable notch filter, the shock sensor having at least one resonance frequency; a flip flop coupled to an output of the notch filter and an output of the shock sensor; a calibration logic coupled to an output of the flip flop, wherein an output of the calibration logic is coupled to a selection input of the selectable notch filter.