Noise Measurement Techniques Research Articles

"Projekt TyreRoadNoise" -- Data-based study of effects on controlled and real drive noise emission

Road traffic noise affects the quality of life of many citizens. In particular, the noise emitted by electric vehicles is mainly caused by tyre-road contact. There are many conflicts of interest between the performance characteristics of tyres and road surfaces. Therefore, more accurate prediction models are needed to exploit the potential for reducing tyre-road noise emissions during development. To this end, the TyreRoadNoise project team is developing a physics- and data-based tyre-road noise prediction model over a three-year period. A multi-manufacturer fleet of vehicles will collect extensive data on tyre-road noise emissions and their influencing parameters using simple measurement methods. AI methods will be used to estimate relevant parameters and correlations, which will be validated by measurements in controlled environments. The model should make it possible to extrapolate emissions on other routes from appropriate measurements on a specific road and to derive mitigation measures. Data and models will be made publicly available for future use. This article identifies the research needs, gives a brief overview of the project and describes the tyre-road noise measurement techniques used. Interested parties are invited to discuss and participate in the project.

Simplified Laser Frequency Noise Measurement Using the Delayed Self-Heterodyne Method

Here, we report on a simplified laser frequency noise measurement technique employing an acousto-optic modulator, a delay line, and a real-time oscilloscope. The technique is a slight modification of the typical delayed heterodyne method. Instead of using a swept frequency spectrum to analyze the laser emission spectrum, the waveform captured on a real-time oscilloscope is used to directly calculate the laser frequency noise. The oscilloscope bandwidth and sampling requirements can be kept modest by choosing a modulator driven at a few hundred megahertz, making this technique attractive for a large number of laboratories. We show the frequency noise measurements of two different lasers with linewidths at 2.7 kHz and 2 MHz. We took the opportunity to investigate the noise floor of the frequency noise measurement system, and we found that the noise floor of the frequency noise measurement depends on the power level of the laser that is being characterized, with the kilohertz linewidths laser requiring more power to reduce the noise floor to acceptable levels.

Stochastic Electrochemical Measurement of a Biofouling Layer on Gold.

Adsorption of a biofouling layer on the surface of biosensors decreases the electrochemical activity and hence shortens the service life of biosensors, particularly implantable and wearable biosensors. Real-time quantification of the loss of activity is important for in situ assessment of performance while presenting an opportunity to compensate for the loss of activity and recalibrate the sensor to extend the service life. Here, we introduce an electrochemical noise measurement technique as a tool for the quantification of the formation of a biofouling layer on the surface of gold. The technique uniquely affords thermodynamic and kinetic information without applying an external bias (potential and/or current), hence allowing the system to be appraised in its innate state. The technique relies on the analysis of non-faradaic current and potential fluctuations that are intrinsically generated by the interaction of charged species at the electrode surface, i.e., gold. An analytical model is extended to explain the significance of parameters drawn from statistical analysis of the noise signal. This concept is then examined in buffered media in the presence of albumin, a common protein in the blood and a known source of a fouling layer in biological systems. Results indicate that the statistical analysis of the noise signal can quantify the loss of electrochemical activity, which is also corroborated by impedance spectroscopy as a complementary technique.

Noise-assisted transport mechanism analysis and synaptic characteristics in ZrOX/HfAlOX-based memristor for neuromorphic systems

In this work, we compare the resistive switching characteristics between Ti/ZrOX/TiN and Ti/ZrOX/HfAlOX/TiN. The bilayer structure of the ZrOX-based device enables power consumption reduction owing to a lower forming voltage and compliance current. Moreover, the on/off ratio of the Ti/ZrOX/HfAlOX/TiN device (>102) is higher than that of the Ti/ZrOX/TiN device (>10). We use the 1/f noise measurement technique to clarify the transport mechanism of the Ti/ZrOX/HfAlOX/TiN device; consequently, ohmic conduction and Schottky emission are confirmed in the low- and high-resistance states, respectively. In addition, the multilevel cell, potentiation, and depression characteristics of the Ti/ZrOX/HfOX/TiN device are considered to assess its suitability as a neuromorphic device. Accordingly, a modified National Institute of Standards and Technology database simulation is conducted using Python to test the pattern recognition accuracy.

Environmental Noise Measurement Technique and Evaluation of Contribution of a Large Industrial Enterprise to Noise Pollution in the Neighboring Residential Area

Introduction: Strong influence of noise on the urban population is one of the problems of a large city. The main sources of noise include road transport, industrial enterprises, and construction sites. A combined exposure to various sources of noise impedes assessment of their effects on the population. Distinguishing one noise source from another is a difficult measurement task. Objective: To measure noise levels close to a large industrial enterprise given busy traffic nearby, and determine contributions of the industry and road transport to the noise situation in the neighboring residential area. Materials and methods: In summer 2022, noise levels were measured in the vicinity of a large industrial enterprise located in the city of Perm in the daytime and at night at seven and eight sites, respectively, using a sound and vibration meter of the “Assistant” series with an additional “Monitoring” mode. The subsequent processing of chronograms in the “Monitoring” software enabled us to distinguish the noise generated by the industry from that of road traffic using the “Cut” function that removes interferences. Processing of the results using the “energy subtraction” technique allowed quantification of contributions of various sources to the local noise pollution. Results: In this study, noise was measured in a residential area adjacent to an industrial enterprise and the obtained results are provided. Noise levels from the enterprise were determined using a specialized software. The calculated contributions to the noise environment in the residential area vary between 0.035 and 0.603. The conclusion is made about a possible effect produced by noise from the analyzed industrial enterprise on people living on this territory. Conclusion: The effect of industrial noise on people living close to industrial premises is significant only at nighttime.

Self-Heating of Annealed Ti/Al/Ni/Au Contacts to Two-Dimensional Electron Gas in AlGaN/GaN Heterostructures

In this work, we investigated the self-heating effects of annealed Ti/Al/Ni/Au ohmic contacts and two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures under strong electric field by using the short pulse current–voltage and microwave noise measurement techniques. The experimental results demonstrated that the self-heating phenomena in ohmic contacts with the increase of current may dominate over the electrical performances of 2DEG channel. Moreover, the excess noise temperature of contact resistance was found to be more than four times higher than that of 2DEG channel at the same high current density values. The results reveal the importance of self-heating of the ohmic contacts on the device performance under short-duration (only 100 ns) and low-duty-cycle (only 10−5) pulse regime.

Track width measurement in heat-assisted magnetic recording systems using the cross-track DC noise method

This paper uses a cross-track DC noise measurement technique to determine the written track width in heat-assisted magnetic recording (HAMR). The method is approached as a simple, no-extra-hardware-required technique on a spin-stand to determine the written track width as well as the DC noise amplitude at the center track in a HAMR system. The track width data show the expected trends with changing laser operating current () and write current (), and they are strongly correlated with track density capabilities and physical near-field transducer (NFT) peg width. The written track width is essentially defined by the which increases as increases. The method is useful for comparing the magnetic responses of different writer pole or NFT peg geometries, as well as media design comparison to provide insight into the head/component necessary to improve HAMR system performance, which is useful HAMR recording parameters for head/media designers and test engineers.

Timing jitter characterization of free-running dual-comb laser with sub-attosecond resolution using optical heterodyne detection.

Pulse trains emitted from dual-comb systems are designed to have low relative timing jitter, making them useful for many optical measurement techniques such as optical ranging and spectroscopy. However, the characterization of low-jitter dual-comb systems is challenging because it requires measurement techniques with high sensitivity. Motivated by this challenge, we developed a technique based on an optical heterodyne detection approach for measuring the relative timing jitter of two pulse trains. The method is suitable for dual-comb systems with essentially any repetition rate difference. Furthermore, the proposed approach allows for continuous and precise tracking of the sampling rate. To demonstrate the technique, we perform a detailed characterization of a single-mode-diode pumped Yb:CaF2 dual-comb laser from a free-running polarization-multiplexed cavity. This new laser produces 115-fs pulses at 160 MHz repetition rate, with 130 mW of average power in each comb. The detection noise floor for the relative timing jitter between the two pulse trains reaches 8.0 × 10-7 fs2/Hz (∼ 896 zs/Hz), and the relative root mean square (rms) timing jitter is 13 fs when integrating from 100Hz to 1MHz. This performance indicates that the demonstrated laser is highly compatible with practical dual-comb spectroscopy, ranging, and sampling applications. Furthermore, our results show that the relative timing noise measurement technique can characterize dual-comb systems operating in free-running mode or with finite repetition rate differences while providing a sub-attosecond resolution, which was not feasible with any other approach before.

All-fiber transient phase noise characterization of polarization maintaining Yb-doped fiber amplifiers

We demonstrated an all-fiber phase noise measurement technique to detect transient phase variation of polarization maintaining Yb-doped fiber amplifier based on active phase locking of an optical heterodyne detection system. The root mean square, power spectral density, and drift velocity in the phase noise were analyzed for both core-pumped single clad fiber amplifier and clad-pumped double-clad fiber amplifier. The phase noise was further analyzed in terms of the seed laser power, amplifier output power, and fiber optic component configurations. The phase drift velocity measurements at various amplifier output powers indicated the optical phase were closely related to the temperature variations.

Understanding the thermal degradation mechanism of perovskite solar cells via dielectric and noise measurements

Long term stability is a major obstacle to the success of perovskite solar cell (PSC) photovoltaic technology. PSC performance deteriorates significantly in the presence of humidity, oxygen and exposure to UV light and heat. Here the change in charge transport properties of PSC with temperature and the associated significant drop in device performance at high temperature have been investigated. The latter is shown to be primarily due to an increase in charge carrier recombination, which impacts the open-circuit voltage. To understand the pathway of temperature-induced degradation, low-frequency 1/f noise characteristics, and the capacitance-frequency, as well as capacitance-voltage characteristics have been investigated under various conditions. The results show that at high operating temperature accumulation of ions and charge carriers at the interface increase the surface recombination. Aging experiments at different temperatures show high stability of PSCs up to temperature <70 °C, but a drastic, irreversible degradation occurs at higher temperature (≥80 °C). Low-frequency 1/f noise study revealed that the magnitude of normalized noise in degraded perovskite solar cells is four orders of magnitude higher than the pristine device. This study shows the power of low-frequency noise measurement technique as a highly sensitive non-invasive tool to study the degradation mechanism of PSCs.

Oxide Edge Trap Density Extraction in Silicon Nanowire MOSFET From Tunnel Current Noise Measurement in Gated Diode Like Arrangement

Edge traps in the gate oxide of silicon nanowire MOSFETs have been extracted from tunnel current noise measurement in a gated diode like arrangement. We have found that, low frequency noise in tunnel current results from collective response of the edge traps available within the gate oxide surrounding band-to-band generation (BTBG) region of silicon nanowire, and when the BTBG region is accessed by favorable terminal biases. From detail modeling of the phenomenon, we derived a closed form expression of the tunneling current noise power spectral density (PSD) employing which oxide edge trap density in nanowire MOSFET had been extracted through its fit with the experimental noise PSD data. We furthermore validated our model for different BTBG biases, and contrasted our result with the bulk oxide trap density in identical MOSFET, while the latter was separately estimated from the gate current noise PSD measurement. Mismatch between the oxide bulk trap and edge trap concentrations has been found, whereby actual edge trap density remains otherwise hidden from the widely employed gate current noise measurement technique. It is because, the present scheme improves the resolution of the extracted oxide edge trap concentration in surrounded gate MOSFET owing to constricted tunnel current flow near the corner of the gate which imposes selectivity on the oxide edge traps

Vibration analysis in the process of operation of installations and machines from the oil industry

Vibrations are alternative movements made by the mechanical system in relation to the reference state, being caused by disruptive forces (excitations) whose sizes, directions or points of application vary over time. From the multitude of parameters that, by measuring, give an image of the operating state, the vibrations and noise produced by machines and machines have attracted the attention of researchers, designers, builders and specialists in operation in recent years. Also the vibration and noise offer a high sensitivity to the analysis, but also individuality to the concrete situations, only apparently repeated. The development of vibration and noise measurement techniques, as well as the development of signal processing techniques, have allowed important improvements in the control, monitoring and diagnostic systems. The vibration diagnostics of the state of operation of facilities, installations and machinery in the oil industry is based on the fact that in the energy transfer process, oriented towards the realization of a given function, different components, located on the route of the transfer, can be excited mechanically, and thus the vibration. Monitoring the operation of the installations and machines in operation by the specific parameters of the operating process, by vibration, temperature etc., is recognized as an important way to increase the reliability, operating efficiency, reduce production and operating costs. For use or installation of monitoring systems is to check normality operation, to detect deviations potential „problems” and to provide information, decision support and interventions to disconnect or shutdown and for diagnosis. The accumulation, classification, analysis of these results, gathered in diagnostic databases, with the help of advanced processing techniques, are capable of ensuring, first of all, the objectivity of the diagnosis.

Highly-Sensitive Phase and Frequency Noise Measurement Technique Using Bayesian Filtering

Spectral purity of laser sources is typically investigated using phase or frequency noise measurements, which require extraction of the optical phase. This is a challenging task if the signal-to-noise-ratio (SNR) of the spectral line or the linewidth-to-noise-ratio (LNR) are not sufficiently high. In this letter, we present a statistically optimal method for optical phase noise measurement that relies on coherent detection and Bayesian filtering. The proposed method offers a record sensitivity, as the optical phase is measured at a signal power of -75 dBm (SNR of -11 dB in 1.1 GHz receiver bandwidth). Practically, this means that the phase noise measurements are, up to a high-degree, not limited by the measurement noise floor. This allows measurements down to -200 dB rad 2 /Hz and up to 10 GHz, which is useful when measuring the Schawlow-Townes (quantum noise limited) laser linewidth. Finally, the estimated optical phase is highly accurate allowing for quantum limited signal demodulation. The method thus holds the potential to become a reference measurement tool.

Electrochemical noise of Li-ion battery: measurement with load-interrupt technique

The electrochemical noise of a commercially produced Li-ion battery was measured during discharge by means of a constant value resistor using two approaches: continuous discharge and discharge with interruptions. Power spectral density and standard deviation calculation techniques were applied to analyse the electrochemical noise behaviour for different states of charge values. It was shown that electrochemical noise does not disappear immediately following load removal. Noise decreases in amplitude for several hours, reaching the thermal noise level afterwards. Unfortunately, it is not likely that the described electrochemical noise measurement and analysis method can be used for practical state-of-charge estimation of the batteries of investigated type due to the majority of changes in electrochemical noise behaviour taking place at the very end of the discharge process regardless of discharge technique. Nevertheless, the novel load-interrupt realisation of electrochemical noise measurement provided some new interesting insights into the electrochemical noise-generating processes in rechargeable batteries. It was shown that the electrochemical noise measurement technique can be used as a means of detecting over-discharge for Li-ion batteries. The same load-interrupted measurement result was also obtained in continuous discharge mode.

Измерение шумов волоконно-оптических источников излучения

Noise measurement technique of fiber-optical radiation sources was developed. The experimental device for carrying out the specified measurements was done. The analysis of noise sources in spontaneous emission amplifiers showed that the main source is phase noise of spontaneous radiation. When optical radiation is detected in the photodetector, additional noise appears in the output electrical signal. In it, additional noise of the photodetector is added to the noise of radiation source: shot noise arising from the conversion of optical signal into electrical and thermal noise of the converter elements. Spectrum analyzer is used to separate phase noise of spontaneous emission and noise of photodetector. The measurements record two noise spectra, one – the total noise of spontaneous emission amplifier and photodetector, the other – the noise spectrum of one photodetector. As a result of mathematical processing phase noise of radiation source is allocated. The spontaneous emission amplifier works as a part of fiber-optical gyroscope. The integrated optical phase modulator circuit and synchronous detector operating at frequency of 100 kHz are used to reduce noise. Therefore in these researches noise analysis is performed in the narrow spectral range near the specified frequency. Thus, the relative optical noise levels in of 1 Hz bandwidth for several spontaneous emission amplifiers were measured. They were on the order −130 dB in compared to the intensity of effective signal. Then relative levels of optical noise from sources with different emission bands were investigated. It has been established that with increase in emission bandwidth, the relative magnitude of optical noise decreases. The results obtained qualitatively coincide with results of theoretical calculations. This conforms the correctness of developed methodology for measuring the relative optical noise level of quantum generators.

Environmental noise levels in hospital settings: A rapid review of measurement techniques and implementation in hospital settings.

Background:Hospitals provide treatment to improve patient health and well-being but the characteristics of the care environment receive little attention. Excessive noise at night has a negative impact on in-patient health through disturbed sleep. To address this hospital staff must measure night-time environmental noise levels. Therefore, an understanding of environmental noise measurement techniques is required. In this review, we aim to 1) provide a technical overview of factors to consider when measuring environmental noise in hospital settings; 2) conduct a rapid review on the equipment and approaches used to objectively measured noise in hospitals and identify methodological limitations.Design:A rapid review of original research articles, from three databases, published since 2008. Studies were included if noise levels were objectively measured in a hospital setting where patients were receiving treatment.Results:1429 articles were identified with 76 included in the review. There was significant variability in the approaches used to measure environmental noise in hospitals. Only 14.5% of studies contained sufficient information to support replication of the measurement process. Most studies measured noise levels using a sound level meter positioned closed to a patient’s bed area in an intensive care unit.Conclusion:Unwanted environmental noise in hospital setting impacts negatively on patient and staff health and well-being. However, this literature review found that the approaches used to objectively measure noise level in hospital settings have been inconsistent and poorly reported. Recommendations on best-practice methods to measure noise levels in hospital environments are provided.

Influence of lift off on Barkhausen noise parameters of construction steel

Abstract The magnetic Barkhausen noise (MBN) measurement technique is a popular magnetic method used for non destructive detection of microstructural changes in ferromagnetic materials. The MBN parameters depend on the gap between the excitation yoke and measured object. To suppress the negative influence of lift off, we tried to find a parameter of the MBN, which could be independent of lift off changing in a practical range. The lift off effect was analysed experimentally on construction steel samples with various levels of carbon content. We found that the amplitude distribution is a promising parameter of MBN in this regard. Measurement results showed that the slope of amplitude distribution was roughly independent of lift off.

An Investigation into the Reverse Transformation Mechanisms in the Heat Treatment of Austenitic Stainless Steel

Abstract Cold working of austenitic stainless steel results in the formation of α′-martensite (ferromagnetic) within the host material (paramagnetic). The role of α′-martensite and carbide precipitation in the reverse transformation mechanism during the heat treatment of AISI 304 is presented. A magnetic Barkhausen noise (MBN) measurement technique was employed to characterize the transformation mechanisms. MBN was found to be an effective tool for studying the transformation mechanisms of austenite to α′-martensite during material deformation as MBN and the ferromagnetic phase showed a good correlation. AISI 304 specimens plastically strained to 51 % were subjected to annealing heat treatment (from 100°C to 1,100°C) for 30 minutes. The α′-martensite to austenite reversion mechanisms were found to have a significant effect on residual stress and materials magnetic properties, thus limiting MBN effectiveness in studying the reverse transformation process. Residual stresses go from tensile to compressive between 500°C and 600°C as a result of the transformation mechanisms, as the austenitic phase is larger than α′-martensite and therefore compresses the remaining α′-martensite. It is suggested that ϵ-martensite has a significant role in the dislocation structural mechanisms in the heat treatment of AISI 304.

Characterization of a CMOS 135-GHz Low Noise Amplifier with Two Different Noise Measurement Methods

A D-band low-noise amplifier (LNA) has been developed based on a 65-nm CMOS technology, which showed a measured peak gain of 16.1 dB at 134.5 GHz. The noise property of the fabricated amplifier was characterized with two different noise measurement techniques: the cryogenic Y-factor method and the N-times power method. The two methods showed a minimum value of the noise figure of 10.7 dB and 14.7 dB, respectively.

Wideband Noise Measurement Technique in Duplex Systems for RF Interference

A wideband noise measurement technique with improved isolation is demonstrated for a practical mobile phone. The liquid crystal display (LCD) baseband noise modulated with a transmitted radio frequency (RF) signal interferes with the received RF signal, resulting in an RF desensitization problem. A wideband and simple measurement setup based on a 180° hybrid coupler is proposed and demonstrated to characterize the modulation and its coupling behaviors in duplex systems. This setup overcomes the frequency limitation of a duplexer-based measurement setting. In addition, signal-to-noise ratio improvement in the proposed measurement technique is quantitatively analyzed.