A scheme for resampling, filtering, and subsampling unevenly spaced laser Doppler anemometer data |
| |
| Institution: | (1) Département de Géographie, Université de Montréal, succ. Centre-Ville, CP 6128, H3C 3J7 Montréal, Québec, Canada;(2) Department of Earth Sciences, University of Leeds, LS2 9JT Leeds, UK |
| |
| Abstract: | Laser Doppler Anemometry (LDA) has proved a powerful tool for quantifying fluid turbulence and is increasingly being applied
in fields such as fluvial sedimentology and geomorphology. When operated in the burst-signal processing mode, high-frequency
velocity fluctuations are measured at irregular time internals. In many situations, there is a need to transform these data
to obtain evenly spaced velocity values but at a lower frequency. However, clear guidelines for this type of data processing
are lacking. Three steps are necessary in order to transform the original files into evenly spaced data: (1) resampling at
the average sampling rate, (2) low-pass filtering with half-power frequency adjusted to the final sampling frequency, and
(3) decimating at the desired frequency. The decision taken at each step will affect the resulting signal and may cause, if
not assessed carefully, severe problems in the signal such as aliasing errors. This paper examines each stage of data processing
and details the advantages and drawbacks of different techniques in relation to the effects on turbulence statistics (variance,
instantaneous shear stress, etc.). A standard method and specific guidelines are finally proposed.
An erratum to this article is available at . |
| |
| Keywords: | time-series analysis turbulence statistics aliasing |
| 本文献已被 SpringerLink 等数据库收录！ |
|
