Amplitude and Frequency Dependence of the Signal-to-Noise Ratio in LDV Measurements

2011 ◽  
Author(s):  
Patrick F. O’Malley ◽  
Joseph F. Vignola ◽  
John A. Judge
Keyword(s):  
Vibration Amplitude ◽  
Signal To Noise Ratio ◽  
Speckle Pattern ◽  
Laser Doppler Vibrometer ◽  
Signal To Noise ◽  
Velocity Response ◽  
Order Of Magnitude ◽  
Noise Ratio ◽  
Ldv Measurement ◽  
The Relationship

When making measurements using many sensors, it is expected that, within normal operating ranges, the signal-to-noise ratio is approximately linear (i.e. 20 dB/decade). This generality does not hold, however, when making measurements using a laser Doppler vibrometer (LDV). If the velocity of the target of an LDV measurement increases by an order of magnitude, changes in the speckle pattern will introduce noise into the measurand. An experiment was conducted using an LDV system to measure the velocity response of a speaker excited over several orders of magnitude in both frequency and amplitude. Results are presented showing the relationship between signal-to-noise ratio and vibration amplitude.

scholarly journals Counterfactual ghost imaging

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Jonte R. Hance ◽  
John Rarity
Keyword(s):  
Signal To Noise Ratio ◽  
Ghost Imaging ◽  
Signal To Noise ◽  
Interesting Phenomenon ◽  
Order Of Magnitude ◽  
Noise Ratio

AbstractWe give a protocol for ghost imaging in a way that is always counterfactual—while imaging an object, no light interacts with that object. This extends the idea of counterfactuality beyond communication, showing how this interesting phenomenon can be leveraged for metrology. Given, in the infinite limit, no photons ever go to the imaged object, it presents a method of imaging even the most light-sensitive of objects without damaging them. Even when not in the infinite limit, it still provides a many-fold improvement in visibility and signal-to-noise ratio over previous protocols, with over an order of magnitude reduction in absorbed intensity.

ASSESSMENT OF THE ACOUSTICS OF TEMPLE BUILDINGS AND STRUCTURES BASED ON THE PARAMETER MEASURE OF HEIGHT

2021 ◽  
Vol 97 (5) ◽  
pp. 115-121
Author(s):  
Ch.A. Ch.A. SCHIRJETSKY1
Keyword(s):  
Signal To Noise Ratio ◽  
Objective Assessment ◽  
Signal To Noise ◽  
Field Surveys ◽  
Noise Ratio ◽  
Relationship Of ◽  
Specific Sense ◽  
The Relationship ◽  
The Temple ◽  
The Church

In this paper, based on the analysis of the results of field surveys of the acoustics of canonical prayer halls of the Orthodox and Muslim confessions, a proposal for an objective assessment of the specific sense of sacredness of religious events is developed. A new parameter for assessing this feeling is presented-the so - called "height measure" of the perception of the sound of the temple, with the method of its calculation and measurement. The relationship of this parameter with the known volume criteria of echo formations is estimated, depending on the geometry of the church (first of all, on the height of the main dome) and the signal-to-noise ratio for the characteristic areas of the parishioners 'accommodation.

scholarly journals Signal-to-noise ratio in diffusion-ordered spectroscopy: how good is good enough?

2021 ◽  
Author(s):  
Jamie Guest ◽  
Peter Kiraly ◽  
Mathias Nilsson ◽  
Gareth Morris
Keyword(s):  
Experimental Data ◽  
Signal To Noise Ratio ◽  
Larmor Frequency ◽  
Time Averaging ◽  
Signal To Noise ◽  
Experimental Parameters ◽  
Noise Ratio ◽  
The Relationship ◽  
Peak Widths ◽  
And Diffusion

Abstract. Diffusion-ordered NMR spectroscopy (DOSY) constructs multidimensional spectra displaying signal strength as a function of Larmor frequency and of diffusion coefficient from experimental measurements using pulsed field gradient spin or stimulated echoes. Peak positions in the diffusion domain are determined by diffusion coefficients estimated by fitting experimental data to some variant of the Stejskal-Tanner equation, with the peak widths determined by the standard error estimated in the fitting process. The accuracy and reliability of the diffusion domain in DOSY spectra are therefore determined by the uncertainties in the experimental data, and thus in part by the signal-to-noise ratio of the experimental spectra measured. Here the Cramér-Rao lower bound, Monte Carlo methods and experimental data are used to investigate the relationship between signal-to-noise ratio, experimental parameters, and diffusion domain accuracy in 2D DOSY experiments. Experimental results confirm that sources of error other than noise put an upper limit on the improvement in diffusion domain accuracy obtainable by time averaging.

Proposal for a Laue lens with quasi-mosaic crystalline tiles

2011 ◽  
Vol 44 (6) ◽  
pp. 1255-1258 ◽  
Author(s):  
Vincenzo Guidi ◽  
Valerio Bellucci ◽  
Riccardo Camattari ◽  
Ilaria Neri
Keyword(s):  
High Resolution ◽  
Crystal Size ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Laue Lens ◽  
Crystalline Anisotropy ◽  
Order Of Magnitude ◽  
Mosaic Crystals ◽  
Noise Ratio ◽  
Very High

Quasi-mosaicity is an effect of secondary bending within a crystal driven by crystalline anisotropy. This effect can be used to fabricate a series of curved crystals for the realization of a Laue lens. It is highlighted that crystals bent by the quasi-mosaic effect allow very high resolution focusing with respect to mosaic crystals. Under the same conditions for energy passband, crystal size and flux of incident photons, a Laue lens based on quasi-mosaic crystals would increase the signal-to-noise ratio by about an order of magnitude compared to the same lens with mosaic crystals. Moreover, no mosaic defocusing occurs for quasi-mosaic crystals.

Sign in / Sign up

Export Citation Format

Share Document