Resolution and noise

Effect of the monochromator s slit width on noise and resolution for the ultraviolet absorption spectrum of benzene. The slit width increases from spectrum (a) to spectrum (d) with effective bandpasses of 0.25 nm, 1.0 nm, 2.0 nm, and 4.0 nm. 

In the optical, the primary standards are the Sun and Arcturus, which have digital observed spectra at very high signal-to-noise and resolution from Kurucz et al. [3] and Hinkle et al. [2]. We are redetermining the abundances of a wide variety of elements in each of these fundamental standards, then establishing astrophysical gf-values for as many optical and mid-UV lines as possible. 

Other modifications are possible to the same basic approach of seeking a filter that is optimum in the sense of least mean-square error. Backus and Gilbert (1970), for example, derive a linear filter by minimizing a sum of terms in which noise and resolution criteria are separately weighted. Frieden (1975) discusses variations of this technique. 

The closed-loop deadband is an indication of the variability in the controlled variable that results from the combined effects of actuator deadband, sensor noise, and resolution of the A/D and D/A converters. The closed-loop settling time is an indication of the combined lags of the control loop components. The closed-loop performance assessment is a means of determining whether all the major problems within a control loop have been rectified. 

Gillespie, A. B., Signal, Noise and Resolution in Nuclear Counter Amplifiers, McGraw-Hill, New York, 1953. 

Covariance spectra with 512 and 256 increments in the indirect dimension from C-labeUed microcrystaUine proteins were visually inspected with respect to their signal-to-noise and resolution enhancement [86]. The C-C correlation spectra with PARIS recoupling were recorded on the C- and N-labeUed protein Crh which is an 85 amino acid domain-swapped homodimer of catabolite repression phosphocarrier protein of approximately 21 kDa. The spectra were judged to display no difference in resolution or sensitivity. Thus direct covariance processing was... 

Some of the spectral criteria that characterize and differentiate near-IR spectrometers are wavelength accuracy and precision photometric accuracy, precision, and linearity signal-to-noise and resolution (or spectral bandwidth). Among these, the attributes... 

The resolution in an ultrasound image is, among other things, related to the duration of the ultrasound pulse, ie, the shorter the pulse the better the resolution. Imaging may not be performed when the pulse duration is longer than the time to receive an echo. The shorter the ultrasound pulse the more difficult it is to discern it from noise, and the poorer the SNR of the image. As the pulse duration is decreased, the power of the ultrasound pulse is typically increased to compensate for the poorer SNR. 

Kaye, W. and Barber, D., Noise and Digital Resolution in a Microprocessor-Controlled Spectrophotometer, Ano/. Chem. 53, 1981, 366-369. 

Figure 4. Improvement in sensitivity with the CAT. PFA and a reference peak at m/e 315. The observed improvement in signal-to-noise ratio results from the longer total scanning time and also the fact that many sweeps are made during this time. The overall improvement in signal-to-noise ratio depends on the detailed power spectrum of the noise (9). Resolution 12,000 here and for all following time averaged spectra...

However, several hours of measurement are typically needed to achieve good signal-to-noise and high resolution, especially for 2D techniques. Other 2D techniques were used for structure elucidation of carotenoids from guava and annatto seeds. ... 

So far no hypotheses are required concerning the true shape of the peak profile. Flowever, in order to avoid or reduce the difficulties related to the overlapping of the peaks, the experimental noise, the resolution of the data and the separation peak-background, the approach most frequently used fits by means of a least squared method the diffraction peaks using some suitable functions that allow the analytical Fourier transform, as, for example, Voigt or pseudo-Voigt functions (4) which are the more often used. 

Because of the limitation intrinsic to the adoption of an explicit parametrised density model, many crystallographers have been dreaming of disposing of such models altogether. The thermally-smeared charge density in the crystal can of course be obtained without an explicit density model, by Fourier summation of the (phased) structure factor amplitudes, but the resulting map is affected by the experimental noise, and by all series-termination artefacts that are intrinsic to Fourier synthesis of an incomplete, finite-resolution set of coefficients. 

Figure 35 shows the proton spectra which we obtain you can see that they are of much better quality than those we got from the on-flow experiment. The signals for acetonitrile and residual HDO have been cleanly removed using the WET sequence referred to above, and resolution and signal-noise are much better, so we can obtain coupling constants exactly. 

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