Noise Pulses Research Articles

Three topologies of deep neural networks for pulse height extraction

Pulse shaping is a common technique for optimizing signal-to-noise ratio (SNR) in particle detectors. Although analog or digital linear shapers are typically used for this purpose, there are nonlinear approaches, such as neural networks (NN), which have demonstrated their potential to outperform linear ones. Their nonlinear nature makes it possible to optimize the SNR of incoming pulses and extract diverse information, such as particle type and energy, with extremely short shaping time to avoid crowding. This paper shows three different NNs for shaping pulses: (a) convolutional NN (CNN); (b) recurrent NN (RNN); (c) self-attenuating NN. These NNs shape the pulses and return them unfolded avoiding stacking, and even estimate the height of the pulses when there has been saturation in the preamplifier. In this work we show the architectures of the NNs and their results using CR–RC pulses with Brownian and white noise, but they could be extrapolated to any shape and type of noise. The results obtained show that when the noise level is low and the frequency is low, all the topologies presented are a valid solution, but with white noise and high pulse arrival frequency, CNN is a better solution than the others. In the case of Brownian noise, the three topologies presented give similar results.

A guidance on measurement and evaluation methods for underwater sounds focusing on offshore windfarms

Carbon neutral is the global agenda in these years. Offshore windfarm is expected to be the major renewable energy sources. During construction and operation, intensive pulse noise and long-term continuous noise are radiated due to pile driving and windmill rotation. In 2021, we proposed a guidance on measurement and evaluation methods for underwater sounds based on discussion among a study group organized by Marine Acoustics Society of Japan. The guidance focuses on the method of underwater noise measurement and assessment of the effect of noise on aquatic animals. Long-term recording using a fixed recorder is recommended to identify the background noise level and its seasonal changes in the potential construction site. Measurement of received sound levels to three directions from the pile up to 6 km is recommended to know the asymmetric noise field due to complicated shallow water propagation. The distance at the background noise level masks radiated sound is defined as "safe distance". Noise impact assessment should be conducted in the area within this distance. This guidance is not completed yet. It should be revised according to the field tests. In addition, noise exposure criteria for each species in the ocean is required.

A Robust GPS Navigation Filter Based on Maximum Correntropy Criterion with Adaptive Kernel Bandwidth

Multiple forms of interference and noise that impact the receiver’s capacity to receive and interpret satellite signals, and consequently the preciseness of positioning and navigation, may be present during the processing of Global Positioning System (GPS) navigation. The non-Gaussian noise predominates in the signal owing to the fluctuating character of both natural and artificial electromagnetic interference, and the algorithm based on the minimum mean-square error (MMSE) criterion performs well when assuming Gaussian noise, but drops when assuming non-Gaussian noise. The maximum correntropy criteria (MCC) adaptive filtering technique efficiently reduces pulse noise and has adequate performance in heavy-tailed noise, which addresses the issue of filter performance caused by the presence of non-Gaussian or heavy-tailed unusual noise values in the localizing measurement noise. The adaptive kernel bandwidth (AKB) technique employed in this paper applies the calculated adaptive variables to generate the kernel function matrix, in which the adaptive factor can modify the size of the kernel width across a reasonably appropriate spectrum, substituting the fixed kernel width for the conventional MCC to enhance the performance. The conventional maximum correntropy criterion-based extended Kalman filter (MCCEKF) algorithm’s performance is significantly impacted by the value of the kernel width, and there are certain predetermined conditions in the selection based on experience. The MCCEKF with a fixed adaptive kernel bandwidth (MCCEKF-AKB) has several advantages due to its novel concept and computational simplicity, and gives a qualitative solution for the study of random structures for generalized noise. Additionally, it can effectively achieve the robust state estimation of outliers with anomalous values while guaranteeing the accuracy of the filtering.

To the revision of the ISO 1999:2013 standard "Acoustics. Assessment of hearing loss due to noise exposure": an excessive correction for the "impulsiveness" of noise

Introduction. In connection with the development of measuring and computer technology, new opportunities and approaches are opening up to solve the problem of measurement, hygienic assessment, normalization and prediction of hearing impairment from exposure to unstable, in particular, pulse noise.
 The study aims to analyze the applicability of a model for assessing hearing loss based on the use of an excessive correction to the exposure of impacting noise, according to the draft ISO 1999:2023 standard.
 Materials and methods. The scientists have conducted an expert and analytical comparative analysis of ISO 1999 standards, which define the basis for assessing hearing loss due to noise exposure. The experts have carried out a literary review of domestic and foreign sources on the problem of using the index of the distribution of instantaneous values of sound pressure — excess to assess constant and non-constant noise, as well as its role in the formation of hearing loss under the action of non-Gaussian pulse noise, the applicability of the prediction model of the ISO 1999 standard to various types of noise exposure.
 Results. The scientists presented the results of the analysis of: indicators for assessing the adverse effects of non-constant, including pulse noise; the relationship between the effects of non-Gaussian noise and the constant shift in the hearing thresholds of workers; statistical indicator of excess — an indirect indicator of the temporal structure of noise, a significant risk factor in combination with noise exposure in the assessment of hearing loss.
 Conclusion. Revision of the ISO 1999:2013 standard with the introduction of a new indicator of the temporal structure of noise — kurtosis, will improve the accuracy of the method of predicting hearing loss when exposed to constant, non-constant noise, including impulsive.
 Ethics. In preparing the article, the authors were guided by the ethical principles of medical research set out in the Helsinki Declaration of the World Medical Association of the last revision.
 Limitation. Features of ISO 1999 standards dedicated to the assessment of the impact of industrial noise and the assessment of noise-induced hearing impairment.

Pulsed Low-Frequency Noise Characterization on Al/ZnO/Al ReRAM to Investigate the Role of Deep-Level Oxygen Vacancy State in HRS Leakage

Pulsed Low-Frequency Noise Characterization on Al/ZnO/Al ReRAM to Investigate the Role of Deep-Level Oxygen Vacancy State in HRS Leakage

Generalizing amplitude swing modulation for versatile ultrashort pulse measurement.

In this work we broaden the amplitude modulation concept applied to the temporal characterization of ultrashort laser pulses with the amplitude swing technique. We theoretically study the effect of diverse types of relative amplitude and phase modulations. This variation of the replicas can be implemented by means of rotating zero-order waveplates to manipulate the delayed pulse replicas produced in a following multi-order waveplate, which can be more practical under certain conditions. We numerically simulate and study different scenarios under different modulations and for different noise levels and pulses. The proposed schemes are validated and compared through the experimental application to compressed and chirped pulses, confirming the applicability of the work. The simplicity, robustness and versatility of this ultrashort pulse measurement benefits the applications of ultrafast optics.

Особенности функционирования СВЧ-радиометров в условиях внешних помех.

The influence of external disturbances on the sensitivity and dynamic range of the microwave radiothermograph is considered. The results of an experimental study of the interference situation in the range up to 3 GHz are presented. The diagram of the spectral density of interference adjacent to radio astronomy windows is analyzed. The features of real observed disturbances are investigated. The classification of possible disturbances according to their characteristics is given. Algorithms for discrimination of various types of interference are considered. The sensitivity and dynamic range of the microwave radiometer are evaluated using the pulse noise suppression algorithm.

A case of occupational explosive deafness caused by non explosive strong noise

Occupational explosive hearing loss is often caused by close exposure to blasting operations or the impact waves and strong pulse noise generated by explosions of flammable and explosive chemicals, pressure vessels, etc. in the workplace. This article analyzes the diagnosis of a case of occupational explosive hearing loss caused by non explosion, in order to improve the flexible application of diagnostic standards by occupational disease diagnosis physicians.

Research and analysis on noise characteristics of low voltage power lines carrier communication

Noise is one of the most important factors affecting the reliability of low-voltage power line carrier communication. In order to fully grasp the noise characteristics, a channel analysis equipment has been designed to collect and analyze noise. The analysis results show that power line noise is mostly manifested as a combination of colored background noise and pulse noise, mainly concentrated in the frequency band below 700kHz. Compared with the low peak period of electricity consumption, the peak period has stronger time-varying noise, larger amplitude of background noise, richer components of pulse noise, and there is also jitter in the duration of periodic pulse noise.

Local model dynamics for two qubits

The density matrix model described in an earlier paper “Model Dynamics for Quantum Computing” is applied to the case of two qubits. The earlier paper provided a density matrix dynamics with unitary time-dependent gates including qubit energy splitting, entropy constraints, external bath and noise effects. The Lindblad formulation as extended by Beretta was adopted in designing this model. Visualization was provided by examining the time-evolution of the polarization vector. In this paper, the same ideas are applied to two-qubit systems, where there are now 15 time-dependent observables; namely, six polarization vectors (P→A,P→B), and nine spin-correlations (T↔). These time-dependent observables provide ready visualization of two qubit dynamics. Special emphasis is placed on the CNOT gate, which is implemented following recent outstanding developments in using silicon-based dots. By invoking a different splitting for each qubit, plus a spin–spin interaction and a carefully designed Rabi oscillation, a CNOT gate is generated. Careful analysis of the time-dependence of these aspects provides insight into CNOT dynamics. The model can be used to ascertain the sensitivity and efficacy of such a CNOT gate when subject to external environmental effects such as noise disturbances, and noise compensation, using the single-system formulation of steepest-entropy-ascent (SEA) non-equilibrium quantum thermodynamics, suitable to model controlled-gate implementations as long as the two qubits remain localized and effectively behave as a single physical four-level system. The role of careful timing in constructing an efficient CNOT gate is illustrated. The formation of Bell states and the evolution of entanglement including noise, bath and entropy considerations are examined. Extensions to the two-qubit swap, and to the three-qubit Toffoli gate dynamics are outlined. It is also shown that a simple Lindblad form can be used to introduce weak and distinct qubit noise pulses. A simple scheme for noise compensation is designed to increase purity and decrease entropy, without invocation of quantum correction methodology. It is based on using the preexisting entanglement of the environment with the quantum system and carefully designed non-Hermitian Lindblad pulses.

SiPM signal processing via multiple linear regression

This paper presents a novel approach using multiple linear regression to process transient signals from silicon photomultipliers.The method provides excellent noise suppression and pulse detection in scenarios with a high pulse count rate and superimposed pulses.Insights into its implementation and benchmark results are presented.We also show how this approach can be used to automatically detect the pulse shape from a given transient signal, providing good detection for count rates up to 90 MHz.Experimental data are used to present an application where this algorithm improves charge spectrum resolution by an order of magnitude.

Research on High Robustness Underwater Target Estimation Method Based on Variational Sparse Bayesian Inference

Pulse noise (such as glacier fracturing and offshore pile driving), commonly seen in the marine environment, seriously affects the performance of Direction-of-Arrival (DOA) estimation methods in sonar systems. To address this issue, this paper proposes a high robustness underwater target estimation method based on variational sparse Bayesian inference by studying and analyzing the sparse prior assumption characteristics of signals. This method models pulse noise to build an observation signal, completes the derivation of the conditional distribution of the observed variables and the prior distribution of the sparse signals, and combines Variational Bayes (VB) theory to approximate the posterior distribution, thereby obtaining the recovered signal of the sparse signals and reducing the impact of pulse noise on the estimation system. Our simulation results showed that the proposed method achieved higher estimation accuracy than traditional methods in both single and multiple snapshot scenarios and has practical potential.

An intelligent radar signal classification and deinterleaving method with unified residual recurrent neural network

AbstractThe accuracy of radar emitter signal sorting nowadays deteriorates due to the high flexibility and complexity of modern radar pulse streams and the density of crowded electromagnetic environment. In modern radar signal sorting based on pulse repetition interval, conventional methods usually fail to achieve acceptable accuracy and lack stable performance for two main reasons: (1) Conventional methods require a large number of pulses in the stream, which is not practical in many applications. (2) These methods are sensitive to pulse loss and random noise pulses. These two reasons are the main problem that is addressed in this paper. Our proposed model is a machine learning architecture called Unified Residual Recurrent Neural Network (URRNN). In this architecture, residual neural network and recurrent neural network are combined and modified to alleviate the forementioned shortcomings of traditional approaches and enhance the model performance in both classification and deinterleaving tasks. This aim is achieved due to the fact that URRNN extracts both spatial and temporal features, which means more information about processed stream that is exploited to enhance model performance. Three different architectural combinations of URRNN, which show high accuracy and reasonable processing time, are built and trained. The structural and functional description are provided for each architecture. Simulation demonstrates high accuracy and reliable performance of the proposed methods in different circumstances. The results are compared with the results obtained by other conventional machine learning techniques.

Self-filtering of beam fluence fluctuations at free space propagation

It is shown theoretically and experimentally that free space propagation in vacuum provides self-filtering of beam fluence fluctuations (spatial small-scale noise). The linear interference of the noise and the primary smooth beam during the propagation results in temporal filtering invoked by the noise pulse delay with respect to the primary beam pulse and in spatial filtering caused by the noise spatial walk-off from the aperture of the primary beam.

Delayed electron emission in photomultiplier tubes

The time distributions of pulses generated by noise or external light sources in the ХР2020, ХР2232В, ХР1021, FEU-85, FEU-87, FEU-93, FEU-130, and R7600U-200 photomultiplier tubes (PMTs) were investigated using an autocorrelation delayed-coincidence time spectrometer. The observed pulse time correlations were of two types: non-exponential, related to the detection of the effects of feedback ions; and exponential, caused by the interaction of secondary-emission electrons with the PMT dynodes. Detection of multi-electron events arising from the action of external radiators leads to intensification of residual-gas ionization processes in the PMT. However, no analogy is observed in the shapes of the feedback ion spectra for different types of PMT despite the identical composition of photocathodes or dynodes. This might be related to differences in PMT manufacturing processes and to possible different restructuring of molecular electron shells in the photocathode material constituents. The detection of single-electron events (noise pulses) in some of the PMTs studied was not always characterized by nanosecond-scale emissions that might be expected to result from metastable states related to properties of their photocathodes and dynodes, and on the material processing technology used in PMT manufacture. It is difficult to describe exactly the mechanisms leading to delayed electron emission. The source of such events remains open to attempts at explanation and further research.

The Effect of an Increase in the Amplitude of Pulse Noise when Propagating through Ship Cables

The Effect of an Increase in the Amplitude of Pulse Noise when Propagating through Ship Cables

Criteria for diagnosing the state of the hearing organ based on the results of the study of acoustic reflex

Introduction. This study is relevant due to the practice’s need for physiologically adequate criteria for diagnosing the state of the hearing organ of personnel exposed to the cumulative effects of high-intensity pulsed low-frequency noise. 
 The aim of the study was the theoretical and experimental substantiation of the criteria for diagnosing the state of the hearing organ according to the results of the study of the acoustic reflex.
 Materials and methods. Using the two-microphone technique of acoustic measurements, experimental studies of changes in the acoustic reflex were carried out in representatives of the experimental (subjected to cumulative effects of high-intensity pulsed low-frequency noise, n=5) and control (not subjected to such effects, n=12) groups. A total of 256 measurements were made within 6 days (191 in the control group and 65 in the experimental group) before exposure (background) and at the end of the working day. The measurement results were processed using methods of mathematical statistics: tests to determine outliers in the data set, estimates of the coefficient of variation, standard deviation, and boundaries of the 99% confidence interval of changes in the studied indicators were calculated.
 Results. Studies of the effect of high-intensity impulse noise on the organ of hearing showed that with minor changes in the threshold of the acoustic reflex, significant changes in the similarity coefficient were recorded in the experimental group, compared with the control group, which indicates its diagnostic informativeness. In the future, to establish new hygienic standards for regulation the load of high-intensity impulse noise, more extensive studies of the acoustic reflex threshold and the similarity coefficient are needed, as the most informative and sensitive methods for assessing adverse effects.
 The limitations of the study are determined by its focus on use in screening medical examinations of personnel exposed to the cumulative effects of high-intensity low-frequency impulse noise.
 Conclusion. The obtained results demonstrate the potential for studying the acoustic reflex threshold as an objective approach to early detection and prediction of negative changes in the state of the hearing organ of personnel exposed to the cumulative effect of high-intensity low-frequency impulse noise.

Novel radionuclides identification method based on Hilbert–Huang Transform and Convolutional Neural Network with gamma-ray pulse signal

Traditional radionuclide identification algorithms are based on gamma-ray spectrum analysis. A novel radionuclide identification method was proposed in this work and it was based on the combined use of the Hilbert–Huang Transform and a Convolutional Neural Network (HHT-CNN) and taken as input data gamma-ray pulses, instead of an entire gamma-ray spectrum. Firstly, HHT was used to analyze the nuclear pulse signal in frequency domain, and then the frequency in the instantaneous-frequency-edge spectrum was divided into multiple intervals, and the accumulation of amplitude in each interval was taken as the characteristic of the nuclear pulse signal. After constructing the data set with signal features, the one-dimensional Convolutional Neural Network (1D-CNN) model was established and trained to complete the nuclide recognition. In the simulated experiments, the model was tested by the nuclear pulse signals of 137Cs, 60Co, 152Eu, 133Ba, 40K, 60Co+137Cs, 60Co+152Eu and 137Cs+152Eu, which were simulated with the Geant4 toolkit and pulse signal simulator DT5800D (produced by CAEN Technologies Inc.). At the same time, the influence of pulse number and noise on the model recognition results was discussed. Finally, the model was applied to the actual experimental data to verify the model’s feasibility further. The results show that the proposed method can quickly and accurately identify radioactive nuclides. The study provides a new solution for radionuclides identification.

Adaptive Suppression Method of LiDAR Background Noise Based on Threshold Detection

Background radiation in the LiDAR detection field of view is complex and variable, and the background noise generated can easily cause false alarms in the receiver, which affects the effective detection of the system. Through the analysis of the influence of background radiation noise of LiDAR on the detection performance, an adaptive suppression method of LiDAR background noise is proposed. This method realizes the rapid suppression of background noise in the instantaneous field of view through an adaptive threshold adjustment of current steering architecture with a back-end digital-to-analog converter (DAC) correction based on the principle of constant false alarm rate (CFAR) control. Aiming at the problem of accurate noise detection and quantification in a very short time, a dynamic comparator is used to replace the traditional continuous comparator. While detecting the number of noise pulses, the measurement of the pulse duration of noise is realized, which improves the accuracy of short-time noise detection. In order to verify the actual effect of the adaptive method, experiments were carried out based on the team’s self-developed LiDAR. The experimental results show that the measured noise ratio of the adaptive mode by using this method is the lowest. Even at 12 a.m., the noise ratio of the point cloud obtained by the adaptive mode is 0.012%, compared with 0.08% obtained by the traditional mode, which proves that this method has a good ability to suppress background noise. The proportion of noise reduction of the adaptive mode is more than 80% compared with the traditional mode. It achieves noise suppression through hardware at each detection, and each adjustment can be completed within a single period of pulse detection. Therefore, it has great advantages in real-time detection compared with the back-end software noise reduction processing method, and it is suitable for the application of LiDAR in the complex background environment.

Analogy of harmonic modelocked pulses to trapped Brownian particles improves laser performance

High-repetition-rate ultrafast lasers are needed for diverse applications. Harmonic modelocking, where multiple identical, equidistant pulses circulate in the cavity, reaches beyond the practical limitations of reducing the cavity length. However, it suffers from stochastic deviations that manifest as supermodes in the radio-frequency spectrum and difficulties in maintaining the same harmonic state, often coupled with trade-offs in pulse energy, duration, or noise performance. Here, we first show that deviations in the temporal positions of the pulses contribute disproportionately more to the supermodes than deviations in their amplitudes. Then, we argue that these fluctuations are analogous to those of trapped Brownian particles. This analogy reveals that supermodes are suppressed by stronger spectral filtering, which corresponds to fluid viscosity, and higher pulse energy reduces the noise, akin to lower temperature. Guided by this intuitive picture, we construct a Yb-fibre laser incorporating strong filtering and high intracavity energies by limiting nonlinear polarisation evolution to a short section of ordinary fibre. The rest of the all-fibre cavity comprises polarisation-maintaining fibre, which additionally improves environmental robustness. We report record-high supermode suppression ratios, reaching 80 dB, excellent long-term and environmental stability, and pulse energy, duration, and noise characteristics that are similar to fundamentally modelocked lasers.