Time-domain Noise Research Articles

Comparison of time domain noise source localization techniques: Application to impulsive noise of nail guns

Microphone array techniques are an efficient tool to detect acoustic source positions. The standard technique is the delay and sum beamforming. In the time domain, the generalized cross correlation of the microphone signals is used to compute the Spatial Likelihood Functions (SLF) of all microphone pairs and the noise source map is provided by the arithmetic mean of these functions. To improve the former noise source map, which means narrowing the main lobe and removing side and spurious lobes, several techniques have been developed in the past. In this work, the performances of three of these techniques (in terms of source position detection, amplitude estimation and computation time) are compared in the case of both synthetic and real data: (1) energetic and geometric criteria are applied in order to remove the SLF with useless information, (2) the arithmetic mean is replaced by the generalized mean and (3) linear inverse problem is solved with sparsity constraint. In the case of real data, the source to be located and quantified is an impulsive noise radiated by nail guns which is recorded by a spiral arm microphone array.

Areawide dynamic traffic noise simulation in urban built-up area using beam tracing approach

Modeling areawide traffic noise in both space and time domain is a tedious work, especially in urban built-up area. A smart, accurate and rapid method was developed specifically for fixed grid sources and receivers(S-R), which consisted of the precomputed S-R attenuations in off-line, dynamic traffic noise simulation in real time and a database to connect two parts together. In off-line part, beam tracing approach was used to simulate sound propagation among buildings, taking multiple reflections and diffractions into consideration. Firstly, the spatial subdivision was used to subdivide 2D space into a series of order triangles, and then beam tracing algorithm recursively traced beams through these triangles, which was represented by beam tree data structure. In real-time part, the dynamic simulation of traffic provides time-variant input of traffic flow parameters to vehicle emission model, which was then assigned to the nearest source. After deducing S-R attenuations from database, dynamic immissions at grid receivers are obtained by summing up sources inside their circular viewport. Therefore, the outputs (Ln, Leq and LNP) were available to assess the noise pollution levels on a spatial and temporal scale. A part of Zhujiang New Town in Guangzhou was chosen as a validation area, measurement results were in general good agreement with simulations.

Method Using Simultaneously Measured Cylinder Pressure to Separate Contribution of Combustion Noise from Vehicle Interior Noise in Time Domain

Method Using Simultaneously Measured Cylinder Pressure to Separate Contribution of Combustion Noise from Vehicle Interior Noise in Time Domain

Low control-power wavelength conversion on a silicon chip.

We demonstrate controlled wavelength conversion on a silicon chip based on four-wave mixing Bragg scattering (FWM-BS). A total conversion efficiency of 5% is achieved with strongly unbalanced pumps and a controlling peak power of 55 mW, while the efficiency is over 15% when using less asymmetric pumps. The numerical simulation agrees with the experimental results. Both time domain and spectral domain noise measurements show as low as 2 dB signal-to-noise ratio (SNR) penalty because of the strong pump noise, two-photon absorption, and free-carrier absorption in silicon. We discuss how the scheme can be used to implement an all-optically controlled high-speed switch.

Frequency-Domain Optimization of Digital Switching Noise Based on Clock Scheduling

The simultaneous switching activity in digital circuits challenges the design of mixed-signal SoCs. Rather than focusing on time-domain noise voltage minimization, this work optimizes switching noise in the frequency domain. A two-tier solution based on the on-chip clock scheduling is proposed. First, to cope with the switching noise at the fundamental clock frequency, which usually dominates in terms of noise power, a two-phase clocking scheme is employed for system timing. Second, on-chip clock latencies are manipulated to target harmonic peaks in specific frequency bands for the spectral noise optimization. An automated design flow, which allows for noise optimization in user-defined application-specific frequency bands, is developed. The effectiveness of our design solution is validated by measurements of substrate noise and conductive EMI (electromagnetic interference) noise on a test chip, which consists of four wireless sensor node baseband processors each addressing a distinct clock-tree-synthesis strategy. Compared to the reference synchronous design, the proposed clock scheduling solution substantially reduces noise in the target GSM-850 band, i.e., by 11.1 dB on the substrate noise and 12.9 dB on the EMI noise, along with dramatic noise peak drops measured at the 50-MHz clock frequency.

Full-Chip Power Supply Noise Time-Domain Numerical Modeling and Analysis for Single and Stacked ICs

In this paper, a distributed circuit model for on-die power distribution network in single and 3-D ICs is developed, and a set of difference equations are derived based on the circuit model and numerically solved using the finite-difference method. Both IR-drop and simultaneous switching noise, two components of power supply noise (PSN), are iteratively solved in time domain, thereby enabling a transient analysis of PSN. Under the assumptions that on-die power/ground pads, power density, and decoupling capacitors are uniformly distributed, PSN within a unit cell is accurately simulated with <1% error compared with HSPICE simulation. By reducing modeling grid fineness, the numerical modeling approach is applied to a full chip that has multiple blocks with nonuniform power/ground pads, power density, and decoupling capacitance density. Based on full-chip modeling, the PSN distribution of a two-die stack is simulated, and the impact of increasing decoupling capacitance and power/ground pads is investigated.

MOSFET gate induced time domain noise simulation accuracy benchmarking

Analysis of MOSFET gate induced transient noise simulation accuracy was performed and the limitation on accurately estimating MOSFET noise performance in the high frequency wireless communications region was identified, validating transient noise simulation against AC noise. The gate noise source is the only one that increases with frequency and this behaviour cannot be simulated accurately using SPECTRE/RF. To enable the design community to accurately simulate gate induced noise in nonlinear circuits, a simple and practical methodology to overcome this limitation is provided, using a highpass filtering-based white noise source approach.

Common-Mode Noise Suppression of Differential Serpentine Delay Line Using Timing-Offset Differential Signal

In this paper, in order to reduce the common-mode noise, a differential serpentine delay line using the timing-offset differential signal is proposed. The time-domain transmission common-mode noise is greatly reduced from 0.0266 to 0.0126 V, and the time-domain reflection differential-mode noise is maintained the same as compared with the differential serpentine delay line using the zero timing-offset differential signal. Besides, the differential-to-common mode conversion is reduced; the differential-to-differential and differential-to-common mode reflections are kept small. Furthermore, the differential-to-differential mode transmission is maintained the same and the eye diagram is improved. In order to verify the simulation results, scaled up circuits are fabricated and measured where the measurement results are in good agreement with the simulation results.

Optimal CCD readout by digital correlated double sampling

Digital correlated double sampling (DCDS), a readout technique for charge-coupled devices (CCD), is gaining popularity in astronomical applications. By using an oversampling ADC and a digital filter, a DCDS system can achieve a better performance than traditional analogue readout techniques at the expense of a more complex system analysis. Several attempts to analyse and optimize a DCDS system have been reported, but most of the work presented in the literature has been experimental. Some approximate analytical tools have been presented for independent parameters of the system, but the overall performance and trade-offs have not been yet modelled. Furthermore, there is disagreement among experimental results that cannot be explained by the analytical tools available. In this work, a theoretical analysis of a generic DCDS readout system is presented, including key aspects such as the signal conditioning stage, the ADC resolution, the sampling frequency and the digital filter implementation. By using a time-domain noise model, the effect of the digital filter is properly modelled as a discrete-time process, thus avoiding the imprecision of continuous-time approximations that have been used so far. As a result, an accurate, closed-form expression for the signal-to-noise ratio at the output of the readout system is reached. This expression can be easily optimized in order to meet a set of specifications for a given CCD, thus providing a systematic design methodology for an optimal readout system. Simulated results are presented to validate the theory, obtained with both time- and frequency-domain noise generation models for completeness.

Effects of Regularisation Priors and Anatomical Partial Volume Correction on Dynamic PET Data

Dynamic PET provides temporal information about the tracer uptake. However, each PET frame has usually low statistics, resulting in noisy images. Furthermore, PET images suffer from partial volume effects. The goal of this study is to understand the effects of prior regularisation on dynamic PET data and subsequent anatomical partial volume correction. The Median Root Prior (MRP) regularisation method was used in this work during reconstruction. The quantification and noise in image-domain and time-domain (time-activity curves) as well as the impact on parametric images is assessed and compared with Ordinary Poisson Ordered Subset Expectation Maximisation (OP-OSEM) reconstruction with and without Gaussian filter. This study shows the improvement in PET images and time-activity curves (TAC) in terms of noise as well as in the parametric images when using prior regularisation in dynamic PET data. Anatomical partial volume correction improves the TAC and consequently, parametric images. Therefore, the use of MRP with anatomical partial volume correction is of interest for dynamic PET studies.

A 3.7 mW Low-Noise Wide-Bandwidth 4.5 GHz Digital Fractional-N PLL Using Time Amplifier-Based TDC

A digital fractional-N PLL that employs a high resolution TDC and a truly ΔΣ fractional divider to achieve low in-band noise with a wide bandwidth is presented. The fractional divider employs a digital-to-time converter (DTC) to cancel out ΔΣ quantization noise in time domain, thus alleviating TDC dynamic range requirements. The proposed digital architecture adopts a narrow range low-power time-amplifier based TDC (TA-TDC) to achieve sub 1 ps resolution. By using TA-TDC in place of a BBPD, the limit cycle behavior that plagues BB-PLLs is greatly suppressed by the TA-TDC, thus permitting wide PLL bandwidth. The proposed architecture is also less susceptible to DTC nonlinearity and has faster settling and tracking behavior compared to a BB-PLL. Fabricated in 65 nm CMOS process, the prototype PLL achieves better than -106 dBc/Hz in-band noise and 3 MHz PLL bandwidth at 4.5 GHz output frequency using 50 MHz reference. The PLL consumes 3.7 mW and achieves better than 490 fs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> integrated jitter. This translates to a FoM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</sub> of -240.5 dB, which is the best among the reported fractional-N PLLs.

The correlation between audible noise and corona current in time domain caused by single positive corona source on the conductor

Audible noise and corona current are two main DC corona effects, and they may both highly depend on the characteristics of space charges generated during corona discharge. However, relatively little investigation has previously been done on the correlation between them especially in time-domain. In the present work, the timedomain waveforms of audible noise and corona current generated by single positive corona source were recorded simultaneously. Their characteristics were carefully analyzed and found to be closely related. It was found that both the audible noise and the corona current consisted of repetitive pulses, and one-to-one relationship in time could be observed and confirmed between them. Furthermore, a linear correlation between the peak-to-peak values of audible noise pulses and the amplitude of corona current pulses was obtained. Empirical formulas with the same forms for them were derived to further prove the linear correlation. The close correlation between the audible noise and the corona current was interpreted qualitatively in the presented work and found to be highly related to the generated space charges.

Convergence Analysis of Wireless Remote Iterative Learning Control Systems with Channel Noise

AbstractChannel noise, including sensor‐to‐controller(SC) noise and controller‐to‐actuator(CA) noise, impacts the convergence of wireless remote iterative learning control (ILC) system significantly. In this paper, the relationship between output error, SC noise and CA noise is obtained firstly by super‐vector formulation, and then the norm of output error vector covariance matrix is employed to analyze the convergence of the system in presence of SC noise and CA noise. Upper bound of the norm at any sample time reveals that the SC noise is accumulated only in iteration domain, while the CA noise is accumulated not only in iteration domain but also in time domain. Furthermore, the accumulated effect of the CA noise in time domain is ruled by system matrices, so the values of which determine the effect of the CA noise is greater or less than that of the SC noise on convergence of the system. Finally, some simulation results are given to illustrate correctness of the result.

Clipping Noise Cancelation for OFDM Systems Using Reliable Observations Based on Compressed Sensing

In this paper, a clipping noise cancelation scheme using compressed sensing (CS) technique is proposed for orthogonal frequency division multiplexing systems. The proposed scheme does not need reserved tones or pilot tones, which is different from the previous works using CS technique. Instead, observations of the clipping noise in data tones are exploited, which leads to no loss of data rate. Also, in contrast with the previous works, the proposed scheme selectively exploits the reliable observations of the clipping noise instead of using whole observations, which results in minimizing the bad influence of channel noise. From the selected reliable observations, the clipping noise in time domain is reconstructed and canceled by using CS technique. Simulation results show that the proposed scheme performs well compared to other conventional clipping noise cancelation schemes and shows the best performance in some cases.

Efficient transient noise analysis of non‐periodic mixed analogue/digital circuits

This paper proposes a numerical method for accurate time-domain noise simulation of mixed analogue/digital electrical circuits that in principle do not admit a periodic steady-state working condition, such as fractional ΔΣ phase-locked loops (PLLs). By means of a tool known as saltation matrix, which allows dealing with non-smooth vector fields, a variational approach is adopted. The power spectral density of a noisy electrical variable is computed by applying the Thomson's multitaper method (MTM) to the numerical solution of the stochastic variational model of the circuit. This allows to resort to a single transient simulation run, thus avoiding cpu time consuming Monte-Carlo-like approaches. The effectiveness of the proposed method is shown by comparing simulation results related to a commercial fractional ΔΣ PLL with experimental data.

Uncertainty Quantification in Deer Spectroscopy using Bayesian Statistical Inversion Methods

Double electron-electron resonance (DEER) spectroscopy is a powerful electron paramagnetic resonance experiment that provides 2-8nm distance measurements between spin-labels in systems varying from small, soluble proteins, to large, membrane-bound complexes. A key strength of DEER is that it reports a distance distribution corresponding to conformational ensembles in frozen solutions. However, in practice its usable information is often limited to the dominant spin-spin distance. Peak widths and shapes, which describe conformational heterogeneity, are highly sensitive to time-domain noise, regularization parameters, and spin-label conformations. A robust method for quantifying uncertainty in DEER distributions does not currently exist, complicating interpretation. Here we demonstrate the use of Bayesian statistical inversion methods to generate conditional covariance estimates and Bayesian credibility sets in DEER data analysis. To decouple true uncertainty from spin-label conformations, we attached spin labels featuring varying flexibilities to maltose binding protein (MBP) and measured using DEER under varying conditions. By determining the contributions to DEER data from both the spin-label and uncertainty, we have taken an important step towards robust assignment of distance distribution features to protein conformations.

SNR Improvement for Energy Detection of Narrow Band Signal in OFDM System

For orthogonal frequency division multiplexing (OFDM) based cognitive systems, the narrow band signal of the primary users (PU) is difficult to detect when it straddles the boundaries of two adjacent subcarriers. In this paper, we propose a novel energy detection (ED) method with time domain noise smoothing to improve the performance of the conventional ED of the OFDM system under the quasi-static multipath channel for detecting the narrow band primary signals. The effect of noise smoothing of the proposed ED method is analyzed. The close-form solution of probability of detection for OFDM system under quasi-static multipath channel is derived and verified by simulations. Simulations show that the proposed ED method can achieve the expected high signal-to-noise ratio (SNR) gain.

Assessment on transient sound radiation of a vibrating steel bridge due to traffic loading

Structure-borne noise induced by vehicle–bridge coupling vibration is harmful to human health and living environment. Investigating the sound pressure level and the radiation mechanism of structure-borne noise is of great significance for the assessment of environmental noise pollution and noise control. In this paper, the transient noise induced by vehicle–bridge coupling vibration is investigated by employing the hybrid finite element method (FEM) and boundary element method (BEM). The effect of local vibration of the bridge deck is taken into account and the sound responses of the structure-borne noise in time domain is obtained. The precision of the proposed method is validated by comparing numerical results to the on-site measurements of a steel girder-plate bridge in service. It implies that the sound pressure level and its distribution in both time and frequency domains may be predicted by the hybrid approach of FEM–BEM with satisfactory accuracy. Numerical results indicate that the vibrating steel bridge radiates high-level noise because of its extreme flexibility and large surface area for sound radiation. The impact effects of the vehicle on the sound pressure when leaving the bridge are observed. The shape of the contour lines in the area around the bridge deck could be explained by the mode shapes of the bridge. The moving speed of the vehicle only affects the sound pressure components with frequencies lower than 10Hz.

Experimental noise filtering by quantum control

Instabilities due to extrinsic interference are routinely faced in systems engineering, and a common solution is to rely on a broad class of $\textit{filtering}$ techniques in order to afford stability to intrinsically unstable systems. For instance, electronic systems are frequently designed to incorporate electrical filters composed of, $\textit{e.g.}$ RLC components, in order to suppress the effects of out-of-band fluctuations that interfere with desired performance. Quantum coherent systems are now moving to a level of complexity where challenges associated with realistic time-dependent noise are coming to the fore. Unfortunately, standard control solutions involving feedback are generally impossible due to the strictures of quantum mechanics, and existing error-suppressing gate constructions generally rely on unphysical bang-bang controls or quasi-static error models that do not reflect realistic laboratory environments. In this work we use the theory of quantum control engineering and experiments with trapped $^{171}$Yb$^{+}$ ions to demonstrate the construction of novel $\textit{noise filters}$ which are specifically designed to mitigate the effect of realistic time-dependent fluctuations on qubits \emph{during useful operations}. Starting with desired filter characteristics and the Walsh basis functions, we use a combination of analytic design rules and numeric search to construct time-domain noise filters tailored to a desired state transformation. Our results validate the generalized filter-transfer function framework for arbitrary quantum control operations, and demonstrate that it can be leveraged as an effective and efficient tool for developing novel robust control protocols.

Planetary Gear Train Used in Wind Driver Generator Based on TCA

By the disadvantage of the speed fluctuations to the gear noise and vibration spectrum in time domain, a new method to measuring the periodic signal was put forward in pulse time domain. The multi-channel simultaneous measurement model were brought out, aimed at analyzing the gear meshing state and its frequency characteristics. Then, the 14 DOF nonlinear vibration equations was derived from kinetic analysis on the planetary gear pair meshing model, which was solved and simulated in Matlab software, containing with transmission error, time-varying mesh stiffness, clearance and other factors. Finally, an integrated platform was constructed for measuring gear noise, vibration and transmission error to verify the effectiveness and feasibility of the analytical.