Provider: ingentaconnect
Database: ingentaconnect
Content: application/x-research-info-systems
TY - ABST
AU - Liang, Zhenmin
AU - Marshall, Alan G.
TI - Time-Domain (Interferogram) and Frequency-Domain (Absorption-Mode and Magnitude-Mode) Noise and Precision in Fourier Transform Spectrometry
JO - Applied Spectroscopy
PY - 1990-06-01T00:00:00///
VL - 44
IS - 5
SP - 766
EP - 775
KW - Computer applications
KW - FT-IR
KW - FT-NMR
KW - Instrumentation, FT
KW - Mass Spectroscopy
KW - Spectroscopic techniques
N2 - It is desirable to be able to predict the precision of a *repeated* measurement, based on the result of a *single* measurement and knowledge of the noise level in the original (time-domain) data. We have previously shown that precision in determination of time-domain signal
parameters (initial magnitude, frequency, and exponential damping constant for a noisy exponentially damped sinusoidal signal) from least-squares fit to a *frequency-domain* FFT spectrum is directly proportional to frequency-domain peak height-to-noise ratio and to the square root of
the number of data points per peak width, with a proportionality constant which depends on the spectral type (absorption mode, magnitude mode) and peak shape (e.g., Lorentzian, Gaussian, etc.). In this paper, we show that precision in determination of those same parameters by least-squares
fit to the *time-domain* signal itself is similarly related to time-domain initial amplitude-to-noise ratio and the square root of the number of data points per damping period. In addition, we show that although magnitude-mode spectral noise is well described by a Rayleigh distribution
in the signal-free *baseline* segments of the spectrum, noise in the vicinity of a magnitude-mode spectral *peak* is more accurately described by a normal (Gaussian) distribution. We then proceed to show that determination of spectral parameters from a time-domain data set is more
precise by a factor of √2 than estimates based on the FT absorption-mode spectrum. We further show that padding of the *N*-point time-domain data set by another *N* zeroes before FFT improves frequency-domain absorption-mode precision by the same √2 factor. Additional
zero-filling does *not* improve spectral precision. Zero-filling has no effect on precision of spectral parameters determined from time-domain data, and variable effects on parameters determined from fits to magnitude-mode spectra. The above theoretical predictions are supported by analysis
of simulated noisy data.
UR - http://www.ingentaconnect.com/content/sas/sas/1990/00000044/00000005/art00002
M3 - doi:10.1366/0003702904087145
UR - http://dx.doi.org/10.1366/0003702904087145
ER -