Signal-to-Noise Ratio Comparison for Dispersive and Non-Dispersive Flame Atomic Fluorescence Measurements

1975 ◽  
Vol 29 (1) ◽  
pp. 52-57 ◽  
Author(s):  
V. I. Muscat ◽  
T. J. Vickers ◽  
J W. E. Rippetoe ◽  
E. R. Johnson
Keyword(s):  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Atomic Fluorescence ◽  
High Background ◽  
Fluorescence Measurements ◽  
Solar Blind ◽  
Dispersive System ◽  
Measurement Signal ◽  
Background Emission ◽  
Noise Ratio

Signal-to-noise ratios achievable with dispersive and nondispersive atomic fluorescence systems are compared. In this comparison particular attention has been devoted to considerations affecting optimization of the dispersive system with low and high background flames. Relative signal and noise values are reported for Hg and Fe atomic fluorescence with dispersive, solar-blind nondispersive, and filter nondispersive systems with C2H2-air, separated C2H2-air, H2-air, and H2-O2-Ar flames. It is concluded that, when due consideration is given to optimization of the dispersive system for atomic fluorescence measurements, use of a nondispersive system will not generally provide an improvement in the measurement signal-to-noise ratio and may result in a decreased signal-to-noise ratio with an atomizer of even moderate background emission, such as the separated C2H2-air flame.

A Test to Measure Subjective and Objective Speech Intelligibility

2002 ◽  
Vol 13 (01) ◽  
pp. 038-049 ◽  
Author(s):  
Gabrielle H. Saunders ◽  
Kathleen M. Cienkowski
Keyword(s):  
Speech Intelligibility ◽  
Signal To Noise Ratio ◽  
Hearing Aid ◽  
Clinical Tool ◽  
Signal To Noise ◽  
Speech Reception ◽  
Measurement Signal ◽  
Perceptual Performance ◽  
Noise Ratio ◽  
Performance Discrepancy

Measurement of hearing aid outcome is particularly difficult because there are numerous dimensions to consider (e.g., performance, satisfaction, benefit). Often there are discrepancies between scores in these dimensions. It is difficult to reconcile these discrepancies because the materials and formats used to measure each dimension are so very different. We report data obtained with an outcome measure that examines both objective and subjective dimensions with the same test format and materials and gives results in the same unit of measurement (signal-to-noise ratio). Two variables are measured: a “performance” speech reception threshold and a “perceptual” speech reception threshold. The signal-to-noise ratio difference between these is computed to determine the perceptual-performance discrepancy (PPDIS). The results showed that, on average, 48 percent of the variance in subjective ratings of a hearing aid could be explained by a combination of the performance speech reception threshold and the PPDIS. These findings suggest that the measure is potentially a valuable clinical tool.

Rocket Experiment by Electronic Camera for Studying the Metallic Discontinuities in the Ultraviolet Spectrum of ‘A’ Stars

1971 ◽  
Vol 41 ◽  
pp. 361-362
Author(s):  
M. Combes
Keyword(s):  
Spectral Resolution ◽  
High Efficiency ◽  
Signal To Noise Ratio ◽  
Absolute Calibration ◽  
List Type ◽  
Signal To Noise ◽  
Concave Mirror ◽  
Rocket Experiment ◽  
Solar Blind ◽  
Noise Ratio

1.Ultraviolet spectra (1400–1800 Å) of Ap, Am and normal A stars are needed by F. Praderie, R. Bonnet and R. Cayrel.The spectral resolution has to be nearly 1 Å. Accurate relative photometry (5%) and absolute calibration (30–50%) are required.A rocket experiment, proposed to ESRO by M. Combes and P. Felenbok is planned for launch in 1972.2.As neutral silicon and magnesium are very efficient ultra-violet absorbents, A stars ultraviolet fluxes are very faint (Praderie, 1968).Then a very luminous optical set-up and a high efficiency receiver have to be used. A 30 cm in diameter concave objective grating is associated with a Lallemand electronic camera. The grating (2000 //mm; //l) is holographically made (Labeyrie, 1969). The electronic camera is electrostatically focussed. A semi-transparent solar-blind CsL photocathode is used (Carruthers, 1966).3.A little mirror, placed against the grating and forming a direct view of the sky, permits to establish an absolute wavelength scale.During the fly, before and after stellar observations, a little concave mirror mounted into the opening side-door is used to form on the photocathode a spectrum of a Deuterium calibrated lamp. Two photomultipliers, one on each side of the electronic camera, control the lamp stability.The complete mounting is calibrated in the laboratory using a thermopile as reference, before the launch and after the recovery of the waterproof payload.4.The chosen stars are the brightest Ap and Am stars: α Dra (Ap; mv = 3.64; equivalent type A 0) and α2 Lib (Am; mv = 2.75; equivalent type A3-A7).It seems to be possible to obtain spectra (1400-1800 Å) of the Ap star with a spectral resolution of 1 Å and a signal to noise ratio better than 40. But at a pinch one may accept a resolution of 2 Å and a signal to noise ratio of 15 for the shortest range of the Ap star spectrum.

scholarly journals Transport Mechanism of Enhanced Performance in an Amorphous/Monoclinic Mixed-Phase Ga2O3 Solar-Blind Deep Ultraviolet Photodetector

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1111
Author(s):  
Haowen Liu ◽  
Honglin Li ◽  
Shuren Zhou ◽  
Hong Zhang ◽  
Shiqiang Fan ◽  
...  
Keyword(s):  
Corona Discharge ◽  
Transport Mechanism ◽  
Signal To Noise Ratio ◽  
Band Alignment ◽  
Mixed Phase ◽  
Signal To Noise ◽  
Solar Blind ◽  
Comprehensive Performance ◽  
Deep Ultraviolet ◽  
Noise Ratio

Recently, as an emerging material, ultrawide bandgap Ga2O3 has been investigated extensively in solar-blind deep-ultraviolet (DUV) photodetectors (PDs). High sensitivity and signal-to-noise ratio of PDs are essential for the detection of solar-blind DUV signals; however, such factors are often not mutually compatible. In the present study, an amorphous/monoclinic homogeneous mixed-phase structure was demonstrated to be significantly beneficial in enhancing the comprehensive performance of Ga2O3 solar-blind DUV PDs, especially with respect to sensitivity and the signal-to-noise ratio. Further experimental and theoretical findings provide insights on the transport mechanism of enhanced performance in the mixed-phase Ga2O3 solar-blind DUV PD. For effectively separating the photogenerated carriers, a type-II band alignment between amorphous and crystalline Ga2O3 can be exploited. Furthermore, the change of the barrier height of the mixed-phase interface also has a significant impact on the transport properties of the mixed-phase Ga2O3 PD. Additionally, the potential applications of mixed-phase Ga2O3 PD in high-voltage corona discharge were explored, and clear and stable corona discharge signals were obtained. The results of the present study may promote understanding of DUV photoelectronic devices with various mixed-phase Ga2O3 materials and provide an efficient approach for promoting comprehensive performance in future solar-blind detection applications.

scholarly journals Extracting low signal-to-noise ratio events with the Hough transform from sparse array data

Geophysics ◽  
2018 ◽  
Vol 83 (3) ◽  
pp. WC43-WC51 ◽  
Author(s):  
Gil Averbuch ◽  
Jelle D. Assink ◽  
Pieter S. M. Smets ◽  
Läslo G. Evers
Keyword(s):  
False Alarm ◽  
False Alarm Rate ◽  
Hough Transform ◽  
Signal To Noise Ratio ◽  
Automatic Detection ◽  
Image Processing Technique ◽  
Beam Forming ◽  
Signal To Noise ◽  
High Background ◽  
Noise Ratio

Low-frequency acoustic, i.e., infrasound, waves are measured by sparse arrays of microbarometers. Recorded data are processed by automatic detection algorithms based on array-processing techniques such as time-domain beam forming and [Formula: see text] analysis. These algorithms use a signal-to-noise ratio (S/N) value as a detection criterion. In the case of high background noise or in the presence of multiple coinciding signals, the event’s S/N decreases and can be missed by automatic processing. In seismology, detecting low-S/N events with geophone arrays is a well-known problem. Whether it is in global earthquake monitoring or reservoir microseismic activity characterization, detecting low-S/N events is needed to better understand the sources or the medium of propagation. We use an image-processing technique as a postprocessing step in the automatic detection of low S/N events. In particular, we consider the use of the Hough transform (HT) technique to detect straight lines in beam-forming results, i.e., a back azimuth (BA) time series. The presence of such lines, due to similar BA values, can be indicative of a low-S/N event. A statistical framework is developed for the HT parameterization, which includes defining a threshold value for detection as well as evaluating the false alarm rate. The method is tested on synthetic data and five years of recorded infrasound from glaciers. It is shown that the automatic detection capability is increased by detecting low-S/N events while keeping a low false-alarm rate.

Fault detection of wheel in wheel/rail system using kurtosis beamforming method

2019 ◽  
Vol 19 (2) ◽  
pp. 495-509 ◽  
Author(s):  
Long Chen ◽  
Yat Sze Choy ◽  
Tian Gang Wang ◽  
Yan Kei Chiang
Keyword(s):  
Fault Detection ◽  
Background Noise ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
High Background ◽  
Detection Systems ◽  
Rail System ◽  
Diagnosis Method ◽  
Noise Ratio ◽  
Rolling Noise

Fault detection systems are typically applied in the railway industry to examine the structural health status of the wheel/rail system. We herein propose a time-domain kurtosis beamforming technique using an array of microphones for the fault identification and localisation of the wheel/rail system under an environment with high background noise. As an acoustics-based noncontact diagnosis method, this technique overcomes the challenge of the contact between the sensors and examined structures, and it is more applicable for impulsive signals of broadband nature, such as impact noise generated from faults on the wheel surface. Moreover, the application of kurtosis enables the identification and localisation at low signal-to-noise ratio. Under such circumstance, the impulsive signals generated by faults were totally merged in rolling noise and background noise. Meanwhile, different types of faults on the wheels could be identified and localised by observing the kurtosis value on the beamforming sound map. The effectiveness of the proposed method to diagnose the type of wheel fault with low signal-to-noise ratio and moving source has been validated experimentally. This method may provide a useful tool for the routine maintenance of trains.

Triggering Conditions for GRACE Ranging Measurement Signal-to-Noise Ratio Dips

2017 ◽  
Vol 54 (1) ◽  
pp. 327-330 ◽  
Author(s):  
Nate Harvey ◽  
Charles E. Dunn ◽  
Gerhard L. Kruizinga ◽  
Lawrence E. Young
Keyword(s):  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Measurement Signal ◽  
Triggering Conditions ◽  
Noise Ratio

scholarly journals Ceilometer lidar comparison: backscatter coefficient retrieval and signal-to-noise ratio determination

2010 ◽  
Vol 3 (6) ◽  
pp. 1763-1770 ◽  
Author(s):  
B. Heese ◽  
H. Flentje ◽  
D. Althausen ◽  
A. Ansmann ◽  
S. Frey
Keyword(s):  
Signal To Noise Ratio ◽  
Backscatter Coefficient ◽  
Signal To Noise ◽  
Night Time ◽  
High Background ◽  
Comparison Results ◽  
High Background Noise ◽  
Ratio Determination ◽  
Noise Ratio ◽  
New Generation

Abstract. The potential of a new generation of ceilometer instruments for aerosol monitoring has been studied in the Ceilometer Lidar Comparison (CLIC) study. The used ceilometer was developed by Jenoptik, Germany, and is designed to find both thin cirrus clouds at tropopause level and aerosol layers at close ranges during day and night-time. The comparison study was performed to determine up to which altitude the ceilometers are capable to deliver particle backscatter coefficient profiles. For this, the derived ceilometer profiles are compared to simultaneously measured lidar profiles at the same wavelength. The lidar used for the comparison was the multi-wavelengths Raman lidar PollyXT. To demonstrate the capabilities and limits of ceilometers for the derivation of particle backscatter coefficient profiles from their measurements two examples of the comparison results are shown. Two cases, a daytime case with high background noise and a less noisy night-time case, are chosen. In both cases the ceilometer profiles compare well with the lidar profiles in atmospheric structures like aerosol layers or the boundary layer top height. However, the determination of the correct magnitude of the particle backscatter coefficient needs a calibration of the ceilometer data with an independent measurement of the aerosol optical depth by a sun photometer. To characterizes the ceilometers signal performance with increasing altitude a comprehensive signal-to-noise ratio study was performed. During daytime the signal-to-noise ratio is higher than 1 up to 4–5 km depending on the aerosol content. In our night-time case the SNR is higher than 1 even up to 8.5 km, so that also aerosol layers in the upper troposphere had been detected by the ceilometer.

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