Correcting Distortions in Measurements of Atmospheric Pressure Fluctuations |
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Authors: | Tihomir S Hristov |
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Institution: | (1) Department of Mechanical Engineering, Johns Hopkins University, 3400 N. Charles Str., Baltimore, MD 21218, USA |
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Abstract: | Although recognized as important, measurements of turbulent atmospheric pressure are considered difficult and are conducted
infrequently. Here we discuss the essential elements in the design of an instrument for measuring turbulent fluctuations of
atmospheric pressure. Our analysis of the instrument’s dynamics is focused on the signal distortions resulting from a pneumatic
filter, a necessary element in the instrument’s design. Such distortions substantially affect the observed spectral scaling
of the pressure field as well as other quantities of physical interest, such as pressure-velocity 〈p, v〉 and pressure-wave 〈p, η〉 covariances. We propose a computationally efficient discrete-time signal processing method for complete compensation of
pneumatic filter distortions and review the criteria for selecting the instrument parameters (sampling frequency and time
constant), so that digital filter distortions, precision degradation, clipping, and over-damping, are simultaneously avoided.
This correction method must be an inherent part of the instrument’s design. |
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Keywords: | Discrete-time signal filtering Pneumatic filter Pressure measurements Turbulence measurements |
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