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UBC Theses and Dissertations
Apodization of absorption and magnitude mode fourier transform spectra and the effects on SNR and resolution Lee, Judy Pihsien
Abstract
The problem of sidelobes surrounding a peak in a Fourier transform spectrum is alleviated by apodization. This is performed by multiplying the time-domain function by a window function. A systematic study of the effects of window functions on damped time-domain signals is made by examining the resulting lineshapes at specific dynamic ranges for both the absorption and magnitude modes. A symmetrical window is shown to be effective for the magnitude mode, and half of the symmetrical shape is better for the absorption mode. Selection of a recommended window is based on the required dynamic range. For an increasing dynamic range, the Noest-Kort and Norton-Beer F3, Filler E0.20, and Kaiser-Bessel are efficient for the absorption mode; and the Hamming, 3-term Blackman-Harris and Kaiser-Bessel work for the magnitude mode. Sidelobes are often eliminated at the expense of SNR and/or resolution, therefore these factors are also examined. All of the recommended windows show sufficient SNRs except for the Noest-Kort. The apodized absorption spectra are well resolved, with a 10% valley as the criterion for resolution. The magnitude spectra do not display a simple pattern, and also show a phase dependence; however these are explained by the absorption and dispersion components. These findings lend themselves to various applications.
Item Metadata
Title |
Apodization of absorption and magnitude mode fourier transform spectra and the effects on SNR and resolution
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1986
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Description |
The problem of sidelobes surrounding a peak in a Fourier transform spectrum is alleviated by apodization. This is performed by multiplying the time-domain function by a window function. A systematic study of the effects of window functions on damped time-domain signals is made by examining the resulting lineshapes at specific dynamic ranges for both the absorption and magnitude modes. A symmetrical window is shown to be effective for the magnitude mode, and half of the symmetrical shape is better for the absorption mode. Selection of a recommended window is based on the required dynamic range. For an increasing dynamic range, the Noest-Kort and Norton-Beer F3, Filler E0.20, and Kaiser-Bessel are efficient for the absorption mode; and the Hamming, 3-term Blackman-Harris and Kaiser-Bessel work for the magnitude mode. Sidelobes are often eliminated at the expense of SNR and/or resolution, therefore these factors are also examined. All of the recommended windows show sufficient SNRs except for the Noest-Kort. The apodized absorption spectra are well resolved, with a 10% valley as the criterion for resolution. The magnitude spectra do not display a simple pattern, and also show a phase dependence; however these are explained by the absorption and dispersion components. These findings lend themselves to various applications.
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Genre | |
Type | |
Language |
eng
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Date Available |
2010-06-21
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0060529
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.