Variable sensing using frequency domain
First Claim
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1. A method for monitoring an exposure of a system to a physical variable, the method comprising:
- A) periodically sensing the physical variable to produce a sequential digital data stream having a plurality of digital samples wherein the physical variable is acceleration;
B) collecting a known number of digital samples in sequence from the sequential digital data stream to form a first time domain data group;
C) applying a windowing function to the first time domain data group, the windowing function minimizing a difference between a value of a first digital sample of the first time domain data group and a value of a last digital sample of the first time domain data group;
D) converting the digital samples in the first time domain data group to respective frequency domain representations in a frequency domain after applying the windowing function to the first time domain data group; and
E) calculating the exposure of the system to the physical variable in the frequency domain using the frequency domain representations;
wherein step A) is performed using an accelerometer sensing the acceleration in at least one direction.
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Abstract
Embodiments of a method and apparatus for variable sensing using the frequency domain are taught herein. An exposure of a system to a physical variable is determined by periodically sensing the physical variable to produce a plurality of digital samples. The plurality of digital samples is converted to respective frequency domain representations. The exposure is calculated using the frequency domain representations.
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Citations
23 Claims
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1. A method for monitoring an exposure of a system to a physical variable, the method comprising:
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A) periodically sensing the physical variable to produce a sequential digital data stream having a plurality of digital samples wherein the physical variable is acceleration; B) collecting a known number of digital samples in sequence from the sequential digital data stream to form a first time domain data group; C) applying a windowing function to the first time domain data group, the windowing function minimizing a difference between a value of a first digital sample of the first time domain data group and a value of a last digital sample of the first time domain data group; D) converting the digital samples in the first time domain data group to respective frequency domain representations in a frequency domain after applying the windowing function to the first time domain data group; and E) calculating the exposure of the system to the physical variable in the frequency domain using the frequency domain representations;
wherein step A) is performed using an accelerometer sensing the acceleration in at least one direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for monitoring an exposure of a system to a physical variable, the method comprising:
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periodically sensing the physical variable to produce a plurality of digital samples using an accelerometer sensing acceleration in at least one direction wherein the physical variable is the acceleration; converting the plurality of digital samples to respective frequency domain representations; calculating the exposure of the system to the physical variable using the frequency domain representations; sequentially filling a plurality of windows with the plurality of digital signals; calculating the exposure by calculating a first exposure value using frequency domain representations corresponding to digital signals of a first one of the plurality of windows; and deciding whether to store at least one of the first exposure value and the digital signals of the first one of the plurality of windows based on the first exposure value. - View Dependent Claims (14, 15, 16, 17)
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18. An apparatus for monitoring an exposure of a system to a physical variable, the apparatus comprising:
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A) means for periodically sensing the physical variable to produce a sequential digital data stream having a plurality of digital samples; B) means for collecting a known number of digital samples in sequence from the sequential digital data stream to form a first time domain data group; C) means for applying a windowing function to the first time domain data group, the windowing function minimizing a difference between a value of a first digital sample of the first time domain data group and a value of a last digital sample of the first time domain data group; D) means for converting the digital samples in the first time domain data group to respective frequency domain representations in a frequency domain after applying the windowing function to the first time domain data group; and E) means for calculating the exposure of the system to the physical variable in the frequency domain using the frequency domain representations;
wherein the physical variable is acceleration and wherein the means for periodically sensing the physical variable comprises;an accelerometer sensing the acceleration in at least one direction; and means for converting each sensed acceleration value to a corresponding digital sample. - View Dependent Claims (19, 20, 21, 22, 23)
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Specification