Infrasound sensor with disturbance filtering
First Claim
1. A method for filtering unwanted components from an infrasound signal, the method comprising the steps of:
- (a) sampling an infrasound signal corrupted with undesired disturbances,(b) sampling a change in fluid speed signal that is correlated with the undesired disturbances,(c) preconditioning the change in fluid speed signal using a calibration of the sensor housing,(d) filtering the preconditioned values with an adaptive filter to generate a correction term,(e) adding the correction term to the sampled, corrupt infrasound signal,(f) outputting a corrected infrasound signal,(g) feeding back the corrected infrasound signal to be used in conjunction with the past history of preconditioned values to adjust the parameters used within the adaptive filter of step (c),whereby the disturbances effects caused by changes in the fluid speed are removed from the corrupted infrasound signal to provide a filtered measure of infrasound.
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Abstract
The invention pertains to the sensing and measurement of infrasound (pressure variations with frequency content under 10 Hertz). The invention measures the infrasound pressure variations and then attenuates undesired contributions due to, but not limited to, changes in ambient fluid speed and changes in altitude of the sensing device. The undesired contributions are attenuated using an adaptive filter with the measurements of the change in ambient fluid speed and the change in altitude. This approach differs from existing applications of adaptive filtering in that the invention uses measurements of speed and displacement to improve a pressure measurement. This approach differs from existing methods for attenuating the affects of the wind on the measurement of infrasound in that it does not require the use of a large spatial averaging filter.
22 Citations
20 Claims
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1. A method for filtering unwanted components from an infrasound signal, the method comprising the steps of:
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(a) sampling an infrasound signal corrupted with undesired disturbances, (b) sampling a change in fluid speed signal that is correlated with the undesired disturbances, (c) preconditioning the change in fluid speed signal using a calibration of the sensor housing, (d) filtering the preconditioned values with an adaptive filter to generate a correction term, (e) adding the correction term to the sampled, corrupt infrasound signal, (f) outputting a corrected infrasound signal, (g) feeding back the corrected infrasound signal to be used in conjunction with the past history of preconditioned values to adjust the parameters used within the adaptive filter of step (c), whereby the disturbances effects caused by changes in the fluid speed are removed from the corrupted infrasound signal to provide a filtered measure of infrasound. - View Dependent Claims (2, 3)
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4. A method for filtering undesirable components from an infrasound signal, the method comprising the steps of:
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measuring a change in an infrasound pressure with a first sensor to generate an uncorrected infrasound signal; measuring a change in at least one of displacement and fluid velocity with a second sensor; and generating a corrected infrasound signal based on the uncorrected infrasound signal and a correction term associated with the measured infrasound pressure change, the correction term generated with an adaptive filter and based at least in part on the measured change in at least one of displacement and fluid velocity. - View Dependent Claims (5, 6, 7, 8, 9)
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10. A device for filtering undesirable components from an infrasound pressure measurement, comprising:
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a first sensor comprising an infrasound pressure measurement device; a second sensor comprising one of a fluid speed measurement device and a displacement measurement device; an adaptive filter connected to said second sensor; and a processing unit associated with said first sensor and said adaptive filter, said processing unit configured to generate a corrected infrasound signal based on a correction term determined by input from said adaptive filter and a signal from said first sensor. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification