Transient Noise Research Articles

All-Digital Adaptive Clocking to Tolerate Transient Supply Noise in a Low-Voltage Operation

This paper presents an all-digital technique to modulate the system clock and local clocks in response to global and local voltage noise to prevent timing errors during low-voltage operation. The critical path replica circuits are utilized to change the clock period within a clock cycle in response to transient supply noise. Measurement in 130-nm CMOS demonstrates reliable operation of a test pipeline over a wide dc (1.3-0.74 V) voltage range. At 0.81 V, the pipeline operates without timing errors at 7.2% higher frequency even under a 189-mV transient voltage droop.

Autonomous Oscillation Control Loop Design for Amplitude Controlled, Frequency Read-Out-Type Resonant Sensors

This paper suggests an autonomous oscillation control loop for frequency read-out-type resonant sensors that produces outputs of variable frequency depending on the input of an external physical quantity. The design goal of the oscillation loop is simultaneously to stabilize the resonance characteristics of the sensor and to automatically track the resonant frequency in order to guarantee highly reliable sensor performance. To this end, the concept of automatic gain control (AGC) is applied so that the loop is designed to maintain the oscillation amplitude as one control objective. The second control objective is to achieve resonance condition tracking even when external influences such as disturbance and noise exist. For the verification of the proposed control loop design, an example resonant sensor system is modeled, and a control loop and controller that accompany the system are also designed. Finally, the proposed loop performance was demonstrated via simulations which consider practical noise elements. The theoretical results were further verified via sensor's transient responses and noise analysis.

Simulation chain for acoustic ultra-high energy neutrino detectors

Acoustic neutrino detection is a promising approach for large-scale ultra-high energy neutrino detectors in water. In this paper, a Monte Carlo simulation chain for acoustic neutrino detection devices in water is presented. It is designed within the SeaTray/IceTray software framework. Its modular architecture is highly flexible and makes it easy to adapt to different environmental conditions, detector geometries, and hardware. The simulation chain covers the generation of the acoustic pulse produced by a neutrino interaction and the propagation to the sensors within the detector. In this phase of the development, ambient and transient noise models for the Mediterranean Sea and simulations of the data acquisition hardware, similar to the one used in ANTARES/AMADEUS, are implemented. A pre-selection scheme for neutrino-like signals based on matched filtering is employed, as it can be used for on-line filtering. To simulate the whole processing chain for experimental data, signal classification and acoustic source reconstruction algorithms are integrated. In this contribution, an overview of the design and capabilities of the simulation chain will be given, and some applications and preliminary studies will be presented.

Transient noise spectra in resonant tunneling setups: Exactly solvable models

We investigate the transient evolution of finite-frequency current noise after the abrupt switching on of the tunneling coupling in two paradigmatic, exactly solvable models of mesoscopic physics: the resonant level model and the Majorana resonant level model, which emerges as an effective model for a Kondo quantum dot at the Toulouse point. We find a parameter window in which the transient noise can become negative, a property it shares with the transient current. However, in contrast to the transient current, which approaches the steady state exponentially fast, we observe an algebraic decay in time of the transient noise for a system at zero temperature. This behavior is dominant for characteristic parameter regimes in both models. At finite temperature the decay is altered from an algebraic to an exponential one with a damping constant proportional to temperature.

Using single transients on the performance analysis of electrochemical noise amplifiers

The acquisition of electrochemical noise is always connected with the question of appropriate measuring devices. The noise measurement system shall allow to process the apparent fluctuations in an electrochemical cell in the low millivolt or microampere range and to record them without any changes. The measurement amplifier is an essential part of the measurement system, but its behavior in the chain of signal processing is difficult to define by a corrosion expert. The present article shows possibilities for the determination of the performance of a noise measurement amplifier. A dummy cell model is often used to get a realistic approach to the sources of electrochemical noise. This article introduces a model describing the generation of single transients from the basic electrochemical corrosion reactions. The model determines fluctuations in the potential which can be measured as voltage fluctuations on a real dummy cell circuit. With the help of a special arbitrary signal generator, artificial noise transients based on this description are applied to a commercial noise measurement system. The acquired signals are compared with the original signals from the signal source and the influences of the noise amplifier on the signals are discussed.

Closed-Form Expressions for the Maximum Transient Noise Voltage Caused by an IC Switching Current on a Power Distribution Network

Closed-form expressions for transient power distribution network (PDN) noise caused by an IC switching current are derived for a PDN structure comprised of traces with decoupling capacitors. Criteria for identifying a dominant decoupling capacitor for an impulse switching current are also proposed. The derived PDN noise expressions are validated with measurements of currents at both local and bulk capacitors, the PDN impedance, and the total voltage noise in an operating consumer device.

A Novel Adaptive Distance Protection Scheme Based on Variable Data Window

The trip speed of traditional step mode distance protection with inverse time characteristics is quite slow when a short circuit fault occurs at the end of the protected line. To deal with this problem, a novel measured impedance convergence based inverse time distance protection is proposed in this paper. In this method, the convergence of measured impedance can dynamically reflect the level and attenuation degree of post-fault transient noise, and the method can adaptively decide the data window length of protective algorithm according to the result of real-time measured impedance convergence. More specifically, the faster the measured impedance convergence is, the shorter data window length of protective algorithm and the faster trip speed will be. Furthermore, a comprehensive adaptive variable data window distance protection scheme is established by using aforementioned two methods synthetically, which can overcome flaws of single method and efficiently improve trip speed of zone 1 of distance protection. Finally, the feasibility and effectiveness of the proposed scheme is proved with the simulation results. Ill. 8, bibl. 10, tabl. 4 (in English; abstracts in English and Lithuanian).DOI: http://dx.doi.org/10.5755/j01.eee.123.7.2365

Evaluation of a Transient Noise Reduction Strategy for Hearing Aids

Transient noise can be disruptive for people wearing hearing aids. Ideally, the transient noise should be detected and controlled by the signal processor without disrupting speech and other intended input signals. A technology for detecting and controlling transient noises in hearing aids was evaluated in this study. The purpose of this study was to evaluate the effectiveness of a transient noise reduction strategy on various transient noises and to determine whether the strategy has a negative impact on sound quality of intended speech inputs. This was a quasi-experimental study. The study involved 24 hearing aid users. Each participant was asked to rate the parameters of speech clarity, transient noise loudness, and overall impression for speech stimuli under the algorithm-on and algorithm-off conditions. During the evaluation, three types of stimuli were used: transient noises, speech, and background noises. The transient noises included "knife on a ceramic board," "mug on a tabletop," "office door slamming," "car door slamming," and "pen tapping on countertop." The speech sentences used for the test were presented by a male speaker in Mandarin. The background noises included "party noise" and "traffic noise." All of these sounds were combined into five listening situations: (1) speech only, (2) transient noise only, (3) speech and transient noise, (4) background noise and transient noise, and (5) speech and background noise and transient noise. There was no significant difference on the ratings of speech clarity between the algorithm-on and algorithm-off (t-test, p = 0.103). Further analysis revealed that speech clarity was significant better at 70 dB SLP than 55 dB SPL (p < 0.001). For transient noise loudness: under the algorithm-off condition, the percentages of subjects rating the transient noise to be somewhat soft, appropriate, somewhat loud, and too loud were 0.2, 47.1, 29.6, and 23.1%, respectively. The corresponding percentages under the algorithm-on were 3.0, 72.6, 22.9, and 1.4%, respectively. A significant difference on the ratings of the transient noise loudness was found between the algorithm-on and algorithm-off (t-test, p < 0.001). For overall impression for speech stimuli: under the algorithm-off condition, the percentage of subjects rating the algorithm to be not helpful at all, somewhat helpful, helpful, and very helpful for speech stimuli were 36.5, 20.8, 33.9, and 8.9%, respectively. Under the algorithm-on condition, the corresponding percentages were 35.0, 19.3, 30.7, and 15.0%, respectively. Statistical analysis revealed there was a significant difference on the ratings of overall impression on speech stimuli. The ratings under the algorithm-on condition were significantly more helpful for speech understanding than the ratings under algorithm-off (t-test, p < 0.001). The transient noise reduction strategy appropriately controlled the loudness for most of the transient noises and did not affect the sound quality, which could be beneficial to hearing aid wearers.

Scheduling of Accuracy-Constrained Real-Time Systems in Dynamic Environments

Many real-time embedded systems are sensitive to both the accuracy and timeliness of job results. In this letter, two sources of inaccuracy are considered for such systems: 1) input data noise (IDN) due to the environmental transient noises, and 2) age of data (AD) related to the time of capturing data, which may depend on the length of time between capturing and using the input data. Thus, in the presence of one or more jobs in the system, some tradeoffs are needed among capturing data with an appropriate IDN when the environment is less noisy, reducing AD, and respecting the timeliness of jobs. Our emphasis in the current study is to model firm real-time jobs having some thresholds for the inaccuracy and handle the aforementioned tradeoff by the system scheduler. An online accuracy-aware real-time scheduler is also proposed and evaluated.

Low-frequency ambient noise characteristics and budget in the South China Sea basin

A sound record measured by a moored hydrophone in the South China Sea basin was analyzed. Sampled at a rate of 1.6 kHz and with a duty cycle of approximately 1-min-on and 14-min-off, the measured time series captures the spectral characteristics and variability of the ambient noise in the less-than-800-Hz band over an annual cycle. Using a combination of automated and manual screening methods, the dominant regular and transient noise sources were identified and categorized, which include shipping, wind waves, seismic air-gun surveys, shots/explosives and sonar. Intermittent self noise (squeaking sounds) that prevailed at times during the passage of the very large-amplitude internal waves was also identified. In addition to the noise budget, the variability in the daily and monthly means and variances of the measured noise spectrum and band levels were examined. In order to gain insights into the predictability of the ambient noise field in this marginal sea, the interpretation of the data was facilitated with temperature records measured with moored instruments, wind and precipitation time series from the US Naval Operational Global Atmospheric Prediction System (NOGAPS), and vessel motion simulation based on historical shipping density and lane structure. [Research sponsored by the Office of Naval Research.]

Classroom acoustics 2012: Recent developments, current issues, and field reports

This introductory paper provides an overview of the papers in this session. It showcases important findings of the UK’s Essex Study by David Canning &amp; Adrian James (2012) which confirms large listening benefits for reducing reverberation times (RT) to 0.4 sec or less. The Essex study also found a marked drop in LA90 for occupied classrooms when RT was halved. This introductory paper also briefly reviews the Acoustical Society of America’s initial actions leading to development of the influential ANSI standards on classroom acoustics (S12.60 - 2010/Parts1 and 2), and subsequent outreach actions, including publication of Classroom Acoustics booklets. (Two new booklets, one aimed at Educators and the other aimed at Architects, are being prepared for publication.) Also reviewed is the ongoing struggle to incorporate meaningful noise and reverberation time criteria into design guidelines for the California Collaborative for High Performance Schools, Los Angeles Unified School District, and LEED for Schools. Finally, it shows that noise transients occurring during classroom noise measurements can make quiet classrooms seem misleadingly noisy.

New approach to time domain classification of broadband noise in gravitational wave data

Transient broadband noise in gravitational wave (GW) detectors---also known as noise triggers (referred to as triggers for brevity)---can often be a deterrant to the efficiency with which astrophysical search pipelines detect sources. It is important to understand their instrumental or environmental origin so that they could be eliminated or accounted for in the data. Since the number of triggers is large, data mining approaches such as clustering and classification are useful tools for this task. Classification of triggers based on a handful of discrete properties has been done in the past. A rich information content is available in the waveform or ``shape'' of the triggers that has had a rather restricted exploration so far. This paper presents a new way to classify triggers deriving information from both trigger waveforms as well as their discrete physical properties, using a sequential combination of the longest common subsequence (LCSS) and LCSS coupled with Fast Time Series Evaluation (FTSE) for waveform classification, and the multidimensional hierarchical classification (MHC) analysis for the grouping based on physical properties. A generalized $k$-means algorithm is used with the LCSS (and $\mathrm{LCSS}+\mathrm{FTSE}$) for clustering the triggers using a validity measure to determine the correct number of clusters in absence of any prior knowledge. The results have been demonstrated by simulations and by application to a segment of real LIGO data from the sixth science run.

Quantifying the computational efficacy of nanocomputing channels

Information-theoretic computational efficacy measures are introduced and applied to the analysis of interacting effects of noise and structural randomness in nanocomputing channels. Two complementary measures–the computational fidelity and representational faithfulness–are shown together to quantify the efficacy with which a particular noisy computing channel implements a specified logical transformation. The statistics of these two measures, evaluated for an ensemble of nanocomputing channels with random sample-to-sample structural variations, allows quantitative characterization of the interacting effects of transient noise and structural randomness in the channel ensemble. Application of these efficacy measures is illustrated for artificial nanocomputing channels–noisy quantum-dot cellular automata arrays with random defects–although they can be used to quantify the computational efficacy of a wide variety of artificial or natural nanoscale networks with computational capabilities.

Transient vibration and sound radiation of a stiffened plate

The transient vibration and sound radiation (TVSR) of a stiffened plate was investigated using the time-domain finite element method and time-domain boundary element method. A four-noded stiffened-plate element was adopted in this method; this allowed the plate to have arbitrary elastic boundary conditions and the stiffeners with any shape to be located at arbitrary positions inside the plate. The in-plane deformation of the plate was taken into account. The transient vibration predicted by the present approach showed a good agreement with earlier published results. The proposed method was subsequently applied to a parametric study that examined the effects of the stiffeners on the TVSR of a window, which is a typical plate structure. The results showed that the stiffeners (or their locations) notably influenced the window’s TVSR responses, thereby demonstrating the possibility of using appropriate stiffeners to improve the transient vibration and noise isolation performance of a practical window.

A Semiempirical Noise Modeling Method for Helicopter Maneuvering Flight Operations

A new model for Blade-Vortex Interaction noise generation during maneuvering flight is developed in this paper. Acoustic and performance data from both flight and wind tunnels are used to derive a non-dimensional and analytical performance/acoustic model that describes BVI noise in steady flight. The model is extended to transient maneuvering flight (pure pitch and roll transients) by using quasisteady assumptions throughout the prescribed maneuvers. Ground noise measurements, taken during maneuvering flight of a Bell 206B helicopter, show that many of the noise radiation details are captured. The result is a computationally efficient Blade-Vortex Interaction noise model with sufficient accuracy to account for transient maneuvering flight. The code can be run in real time to predict transient maneuver noise and is suitable for use in an acoustic mission-planning tool.

A Method to Determine the Existence of Genuine Interharmonics

Interharmonic components can often be seen from the discrete Fourier transform (DFT) results of measured voltage or current waveforms. These components may be caused by various factors, such as transient waveform distortions or noises. They are not necessarily related to the real interharmonics. This letter presents a simple method to verify the existence of a genuine interharmonic component contained in the DFT results. The method can also reveal the characteristics of the component. The method has been demonstrated on various field measurement data that contain genuine and false interharmonic components.

The characterization of Virgo data and its impact on gravitational-wave searches

Between 2007 and 2010 Virgo collected data in coincidence with the LIGO and GEO gravitational-wave (GW) detectors. These data have been searched for GWs emitted by cataclysmic phenomena in the universe, by non-axisymmetric rotating neutron stars or from a stochastic background in the frequency band of the detectors. The sensitivity of GW searches is limited by noise produced by the detector or its environment. It is therefore crucial to characterize the various noise sources in a GW detector. This paper reviews the Virgo detector noise sources, noise propagation, and conversion mechanisms which were identified in the three first Virgo observing runs. In many cases, these investigations allowed us to mitigate noise sources in the detector, or to selectively flag noise events and discard them from the data. We present examples from the joint LIGO-GEO-Virgo GW searches to show how well noise transients and narrow spectral lines have been identified and excluded from the Virgo data. We also discuss how detector characterization can improve the astrophysical reach of GW searches.

Analysis of Common-Mode Noise for Weakly Coupled Differential Serpentine Delay Microstrip Line in High-Speed Digital Circuits

This study investigates the mechanisms of generation of the transient transmission common-mode noise in a differential serpentine delay line under weak coupling condition. The generation mechanism and the frequency of common-mode noise are investigated with reference to the time-domain transmission waveform and the differential-to-common mode conversion mixed-mode S-parameters using the circuit solver HSPICE and 3-D full-wave simulator HFSS, respectively. The generation mechanisms of common-mode noise include length mismatch between vertical-turn-coupled traces, the length effect of parallel-coupled traces, and the crosstalk noise effect. Moreover, a graphical method based on wave tracing is presented to illustrate the cancellation mechanism of near-end common-mode noise for the symmetrical differential serpentine delay line. Some practical, commonly used layout routings of the differential serpentine delay line are investigated. Some important design guidelines are provided to help design differential serpentine delay line with low common-mode noise. A comparison between simulated and measured results validates the equivalent circuit model and analytical approach.

Data quality studies of enhanced interferometric gravitational wave detectors

Data quality assessment plays an essential role in the quest to detect gravitational wave signals in data from the LIGO and Virgo interferometric gravitational wave detectors. Interferometer data contain a high rate of noise transients from the environment, the detector hardware and the detector control systems. These transients severely limit the statistical significance of gravitational wave candidates of short duration and/or poorly modeled waveforms. This paper describes the data quality studies that have been performed in recent LIGO and Virgo observing runs to mitigate the impact of transient detector artifacts on the gravitational wave searches.

Scaling behaviors of transient noise current in organic field-effect transistors

Top-contact and bottom-gate organic field-effect transistors (OFETs) based on poly(3-hexylthiophene), P3HT polymer has been fabricated with thermal treatment condition. Transient noise currents of the OFETs are measured at various source–drain voltages ranging from 0V to −60V with respect to a fixed gate voltage of −60V. The results from conventional power spectral density method are compared with the more robust Detrended Fluctuation Analysis. The latter has been proven to be reliable for fractal signals particularly in the presence of nonstationary effects. Interesting transitions between multiscaling and monoscaling behaviors are observed in the power spectral density as well as the Detrended Fluctuation Analysis plots for different applied source–drain voltage Vds. Uncorrelated white noise characteristics are observed for noise current measured at low Vds, meanwhile 1/f noise-like scaling behaviors are observed at intermediate Vds. At higher Vds, the noise characteristics appeared to be close to Brownian-like power-law behavior. The scaling characteristics of the transient noise current can be related to the charge carrier dynamics. It is also found that large numbers of trap centers are induced when the device is stressed at high applied Vds. The existence of these trap centers would disperse charge carriers, leading to 1/f type noise that could diminish the presence of Brownian noise in a very short time.