scholarly journals A Versatile Analog Electronic Interface for Piezoelectric Sensors Used for Impacts Detection and Positioning in Structural Health Monitoring (SHM) Systems

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1047
Author(s):  
Lorenzo Capineri ◽  
Andrea Bulletti
Keyword(s):  
Lamb Waves ◽  
Signal To Noise Ratio ◽  
Piezoelectric Sensors ◽  
Signal Spectrum ◽  
Signal To Noise ◽  
Front End ◽  
Analog Front End ◽  
Frequency Components ◽  
Noise Ratio ◽  
The Impact

Continuous monitoring of mechanical impacts is one of the goals of modern SHM systems using a sensor network installed on a structure. For the evaluation of the impact position, there are generally applied triangulation techniques based on the estimation of the differential time of arrival (DToA). The signals generated by impacts are multimodal, dispersive Lamb waves propagating in the plate-like structure. Symmetrical S0 and antisymmetrical A0 Lamb waves are both generated by impact events with different velocities and energies. The discrimination of these two modes is an advantage for impact positioning and characterization. The faster S0 is less influenced by multiple path signal overlapping and is also less dispersive, but its amplitude is generally 40–80 dB lower than the amplitude of the A0 mode. The latter has an amplitude related to the impact energy, while S0 amplitude is related to the impact velocity and has higher frequency spectral content. For these reasons, the analog front-end (AFE) design is crucial to preserve the information of the impact event, and at the same time, the overall signal chain must be optimized. Large dynamic range ADCs with high resolution (at least 12-bit) are generally required for processing these signals to retrieve the DToA information found in the full signal spectrum, typically from 20 kHz to 500 kHz. A solution explored in this work is the design of a versatile analog front-end capable of matching the different types of piezoelectric sensors used for impact monitoring (piezoceramic, piezocomposite or piezopolymer) in a sensor node. The analog front-end interface has a programmable attenuator and three selectable configurations with different gain and bandwidth to optimize the signal-to-noise ratio and distortion of the selected Lamb wave mode. This interface is realized as a module compatible with the I/O of a 16 channels real-time electronic system for SHM previously developed by the authors. High-frequency components up to 270 kHz and lower-frequency components of the received signals are separated by different channels and generate high signal-to-noise ratio signals that can be easily treated by digital signal processing using a single central unit board with ADC and FPGA.

scholarly journals Evaluation of an Adaptive Dynamic Compensation System in Cochlear Implant Listeners

2020 ◽  
Vol 24 ◽  
pp. 233121652097034
Author(s):  
Florian Langner ◽  
Andreas Büchner ◽  
Waldo Nogueira
Keyword(s):  
Signal Processing ◽  
Cochlear Implant ◽  
Speech Intelligibility ◽  
Discrimination Task ◽  
Signal To Noise Ratio ◽  
Compensation System ◽  
Signal To Noise ◽  
Dynamic Compensation ◽  
Front End ◽  
Noise Ratio

Cochlear implant (CI) sound processing typically uses a front-end automatic gain control (AGC), reducing the acoustic dynamic range (DR) to control the output level and protect the signal processing against large amplitude changes. It can also introduce distortions into the signal and does not allow a direct mapping between acoustic input and electric output. For speech in noise, a reduction in DR can result in lower speech intelligibility due to compressed modulations of speech. This study proposes to implement a CI signal processing scheme consisting of a full acoustic DR with adaptive properties to improve the signal-to-noise ratio and overall speech intelligibility. Measurements based on the Short-Time Objective Intelligibility measure and an electrodogram analysis, as well as behavioral tests in up to 10 CI users, were used to compare performance with a single-channel, dual-loop, front-end AGC and with an adaptive back-end multiband dynamic compensation system (Voice Guard [VG]). Speech intelligibility in quiet and at a +10 dB signal-to-noise ratio was assessed with the Hochmair–Schulz–Moser sentence test. A logatome discrimination task with different consonants was performed in quiet. Speech intelligibility was significantly higher in quiet for VG than for AGC, but intelligibility was similar in noise. Participants obtained significantly better scores with VG than AGC in the logatome discrimination task. The objective measurements predicted significantly better performance estimates for VG. Overall, a dynamic compensation system can outperform a single-stage compression (AGC + linear compression) for speech perception in quiet.

scholarly journals The Geometry of Noise in Color and Spectral Image Sensors

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4487
Author(s):  
Axel Clouet ◽  
Jérôme Vaillant ◽  
David Alleysson
Keyword(s):  
Signal To Noise Ratio ◽  
Spectral Estimation ◽  
Spectral Characteristics ◽  
Color Space ◽  
Color Correction ◽  
Signal To Noise ◽  
Noise Evaluation ◽  
Noise Ratio ◽  
Correction Step ◽  
The Impact

Digital images are always affected by noise and the reduction of its impact is an active field of research. Noise due to random photon fall onto the sensor is unavoidable but could be amplified by the camera image processing such as in the color correction step. Color correction is expressed as the combination of a spectral estimation and a computation of color coordinates in a display color space. Then we use geometry to depict raw, spectral and color signals and noise. Geometry is calibrated on the physics of image acquisition and spectral characteristics of the sensor to study the impact of the sensor space metric on noise amplification. Since spectral channels are non-orthogonal, we introduce the contravariant signal to noise ratio for noise evaluation at spectral reconstruction level. Having definitions of signal to noise ratio for each steps of spectral or color reconstruction, we compare performances of different types of sensors (RGB, RGBW, RGBWir, CMY, RYB, RGBC).

Performance Analysis of Hybrid Fusion in Cognitive Radio Networks

2013 ◽  
Vol 479-480 ◽  
pp. 1027-1031
Author(s):  
Man Man Guo ◽  
Yun Xue Liu ◽  
Wen Qiang Fan
Keyword(s):  
Cognitive Radio ◽  
Cognitive Radio Networks ◽  
Signal To Noise Ratio ◽  
Radio Networks ◽  
Base Station ◽  
Good Choice ◽  
Signal To Noise ◽  
Noise Ratio ◽  
The Impact ◽  
Hybrid Fusion

Spectrum sensing is a crucial issue in cognitive radio networks for primary user detection. Cooperative sensing based on energy detection in the cognitive radio network with multiple antennas base-station is considered in this letter. To improve the sensing performance, we investigate hybrid fusion of the observed energies from the base-station and decisions (1bit, hard information) from different cognitive radio (CR) users around the base-station. Further, we present an optimized scheme where the global detection probability can be maximized according to the Neyman-Pearson criterion. Finally the impact of the change of parameters (Signal to Noise Ratio and number of CR users) in the optimized scheme is analyzed. Numerical simulations and extensive analysis confirm that hybrid fusion base on the optimized scheme is a good choice, also, Signal to Noise Ratio (SNR) and number of CR users does not have influence on the optimized scheme

scholarly journals Evaluation of Nonlinear Interference Effects in a Dispersion Managed (DM) Optical Fiber: Performance and Transmission Analysis of 16QAM Modulation using Split Step Fourier Method

2020 ◽  
Author(s):  
Reinhardt Rading
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Optical Fiber ◽  
Signal To Noise Ratio ◽  
Fourier Method ◽  
Interference Effects ◽  
Signal To Noise ◽  
Optical Links ◽  
Noise Ratio ◽  
The Impact

<div>This paper investigates the impact on the optical</div><div>signal-to-noise ratio (OSNR) of the residual per span (RDPS) in a N × 100km dispersion managed system with zero total accumulated dispersion from input to output using split step Fourier method (SSFM) -Monte Carlo simulation. </div><div><br></div><div>This paper shows that the nonlinear interference NLI does in-fact impact the performance yielding different best working power depending on the value of Nx100 km span and the type of dispersion managed link. The paper shows that dispersion uncompensated optical links are preferable to dispersion managed fibers in equalizing NLI effects in long haul optical links.</div>

scholarly journals Signal to Noise Ratio as a Cross-Platform Metric for Intraoperative Fluorescence Imaging

2020 ◽  
Vol 19 ◽  
pp. 153601212091369
Author(s):  
Asmaysinh Gharia ◽  
Efthymios P. Papageorgiou ◽  
Simeon Giverts ◽  
Catherine Park ◽  
Mekhail Anwar
Keyword(s):  
Tumor Cells ◽  
Imaging System ◽  
Signal To Noise Ratio ◽  
Size Variation ◽  
Pixel Size ◽  
Signal To Noise ◽  
Noise Sources ◽  
Noise Measurements ◽  
Noise Ratio ◽  
The Impact

Real-time molecular imaging to guide curative cancer surgeries is critical to ensure removal of all tumor cells; however, visualization of microscopic tumor foci remains challenging. Wide variation in both imager instrumentation and molecular labeling agents demands a common metric conveying the ability of a system to identify tumor cells. Microscopic disease, comprised of a small number of tumor cells, has a signal on par with the background, making the use of signal (or tumor) to background ratio inapplicable in this critical regime. Therefore, a metric that incorporates the ability to subtract out background, evaluating the signal itself relative to the sources of uncertainty, or noise is required. Here we introduce the signal to noise ratio (SNR) to characterize the ultimate sensitivity of an imaging system and optimize factors such as pixel size. Variation in the background (noise) is due to electronic sources, optical sources, and spatial sources (heterogeneity in tumor marker expression, fluorophore binding, and diffusion). Here, we investigate the impact of these noise sources and ways to limit its effect on SNR. We use empirical tumor and noise measurements to procedurally generate tumor images and run a Monte Carlo simulation of microscopic disease imaging to optimize parameters such as pixel size.

Optimal Design of High Signal to Noise Ratio Petawatt Laser Front-End Device

2014 ◽  
Vol 41 (8) ◽  
pp. 0802007 ◽  
Author(s):  
刘海辉 Liu Haihui ◽  
王韬 Wang Tao ◽  
戴亚平 Dai Yaping ◽  
李大为 Li Dawei ◽  
徐光 Xu Guang
Keyword(s):  
Optimal Design ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Signal To Noise ◽  
Front End ◽  
Noise Ratio

Application of Tonal Tracking to Ship Acoustic Signature Feature Identification

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
M. L. Seto
Keyword(s):  
Signal To Noise Ratio ◽  
Background Level ◽  
Feature Identification ◽  
Signal To Noise ◽  
Detection Range ◽  
Detection And Tracking ◽  
Acoustic Signature ◽  
Intensity Changes ◽  
Noise Ratio ◽  
The Impact

A ship’s radiated acoustic signature is known after a range measurement, but it changes from that the longer the ship is in-service. The Ship Signatures Management System (SSMS) provides an organic, real-time capability for a naval ship to monitor its own signature in order to evaluate the impact of proposed actions on its counter-detection range and sensor performance. Ship protection is enhanced through insightful and timely signature data. In particular, this paper discusses the tonal detection and tracking algorithms used to monitor on-board machinery and propeller activity. The paper specifically addresses tonals that appear or disappear as a consequence of changes in the background level, as well as that of crossed tonals. This is of significance because it impacts the SSMS’s ability to attribute cause to changes in the ship acoustic signature. In particular, it is impossible to associate tonals that are time synchronized in their frequency and intensity changes as being created by a single cause (e.g., piece of machinery) with a known tonal set. The use of tonal amplitude and the cause for the signal-to-noise ratio change, in addition to the signal-to-noise ratio, remedies the detection and tracking of tonals that appear/disappear relative to the background. The additional use of tonal width is suggested as a means to remedy the problem of crossed tonals.

scholarly journals Transmission Kikuchi diffraction: The impact of the signal-to-noise ratio

2021 ◽  
pp. 113372
Author(s):  
Tomasz Tokarski ◽  
Gert Nolze ◽  
Aimo Winkelmann ◽  
Łukasz Rychłowski ◽  
Piotr Bała ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Noise Ratio ◽  
The Impact
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