Ultrasonic detection of interface in multilayers: Theory and adaptive noise canceling

The analytic expression of the received echo in multilayers NDT (Non-Destruction Evaluation) is derived. Then based on the analytic solution, interface signals are analyzed; and it is concluded that the received ultrasonic echo of mulilayers is composed of all the interface signals. By using the adaptive canceling of the signals from interfaces 0 and 1, the signals from interface 2 can be extracted. The method is applied to simulated and real echoes of multilayers,and the signals from interface 2 is separated successfully Based on the amplitude and arrival time of the signal from interface 2, the bond quality and depth of the interface can be evaluated

Advanced surface coil layout with intrinsic noise cancellation properties for surface-NMR applications

A recent study demonstrated that in small-scale prepolarized surface nuclear magnetic resonance(SNMR-PP)measurements with a footprint of a few square meters,customized PP switch-off ramps can serve as an efficient excitation mechanism,eliminating the requirement for a conventional oscillating excitation pulse.This approach enables the detection of short relaxation signals from the unsaturated soil zone and can,therefore,be used to directly provide soil moisture and pore geometry information.Because ultimately such small-scale SNMR-PP setups are intended for a mobile application,it is necessary to develop strategies that allow for speedy measurement progress and do not require noise cancellation protocols based on reference stations.Hence,we developed a new concentric figure-of-eight(cFOE)loop layout that combines the direction independence of a circular loop with the intrinsic noise cancellation properties of a classical FOE-loop.This approach significantly decreases the measurement time because suitable signal-to-noise ratios are reached much faster compared to a classical circular loop and will bring us one step further toward fast and non-invasive soil moisture mapping applications.

Frequency-Domain Wideband Acoustic Noise Cancellation System

When building an adaptive noise cancellation system for wideband acoustic signals, one can meet some difficulties in practical implementation of such a system. The major problem is related to the necessity of using real-time signal generation and processing. In this paper the active noise control system which utilizes adaptation in frequency domain is considered. It is shown that the proposed algorithms simplify practical implementation of a noise cancellation system. The results of computer simulations and prototype experiments show the effectiveness of the proposed methods. .

Practical Considerations for Implementing Adaptive Acoustic Noise Cancellation in Commercial Earbuds

Active noise cancellation has become a prominent feature in contemporary in-ear personal audio devices.However,due to constraints related to component arrangement,power consumption,and manufacturing costs,most commercial products utilize fixed-type controller systems as the basis for their active noise control algorithms.These systems offer robust performance and a straightforward structure,which is achievable with cost-effective digital signal processors.Nonetheless,a major drawback of fixed-type controllers is their inability to adapt to changes in acoustic transfer paths,such as variations in earpiece fitting conditions.Therefore,adaptive-type active noise control systems that employ adaptive digital filters are considered as the alternative.To address the increasing system complexity,design concepts and implementation strategies are discussed with respect to actual hardware limitations.To illustrate these considerations,a case study showcasing the implementation of a filtered-x least mean square-based active noise control algorithm is presented.A commercial evaluation board accommodating a low-cost,fixed-point digital signal processor is used to simplify operation and provide programming access.The earbuds are obtained from a commercial product designed for noise cancellation.This study underscores the importance of addressing hardware constraints when implementing adaptive active noise cancellation,providing valuable insights for real-world applications.

Coherent optical frequency transfer via 972-km fiber link

We demonstrate coherent optical frequency dissemination over a distance of 972 km by cascading two spans where the phase noise is passively compensated for.Instead of employing a phase discriminator and a phase locking loop in the conventional active phase control scheme,the passive phase noise cancellation is realized by feeding double-trip beat-note frequency to the driver of the acoustic optical modulator at the local site.This passive scheme exhibits fine robustness and reliability,making it suitable for long-distance and noisy fiber links.An optical regeneration station is used in the link for signal amplification and cascaded transmission.The phase noise cancellation and transfer instability of the 972-km link is investigated,and transfer instability of 1.1×10^(-19)at 10^(4)s is achieved.This work provides a promising method for realizing optical frequency distribution over thousands of kilometers by using fiber links.

Time-shared channel identification for adaptive noise cancellation in breath sound extraction

Noise artifacts are one of the key obstacles in applying continuous monitoring and computer-assisted analysis of lung sounds. Traditional adaptive noise cancellation (ANC) methodologies work reasonably well when signal and noise are stationary and independent. Clinical lung sound auscultation encounters an acoustic environment in which breath sounds are not stationary and often correlate with noise. Consequendy, capability of ANC becomes significantly compromised. This paper introduces a new methodology for extracting authentic lung sounds from noise-corrupted measurements. Unlike traditional noise cancellation methods that rely on either frequency band separation or signal/noise independence to achieve noise reduction, this methodology combines the traditional noise canceling methods with the unique feature of time-split stages in breathing sounds. By employing a multi-sensor system, the method first employs a high-pass filter to eliminate the off-band noise, and then performs time-shared blind identification and noise cancellation with recursion from breathing cycle to cycle. Since no frequency separation or signal/noise independence is required, this method potentially has a robust and reliable capability of noise reduction, complementing the traditional methods.

Multi-channel differencing adaptive noise cancellation with multi-kernel method

Although a various of existing techniques are able to improve the performance of detection of the weak interesting sig- nal, how to adaptively and efficiently attenuate the intricate noises especially in the case of no available reference noise signal is still the bottleneck to be overcome. According to the characteristics of sonar arrays, a multi-channel differencing method is presented to provide the prerequisite reference noise. However, the ingre- dient of obtained reference noise is too complicated to be used to effectively reduce the interference noise only using the clas- sical linear cancellation methods. Hence, a novel adaptive noise cancellation method based on the multi-kernel normalized least- mean-square algorithm consisting of weighted linear and Gaussian kernel functions is proposed, which allows to simultaneously con- sider the cancellation of linear and nonlinear components in the reference noise. The simulation results demonstrate that the out- put signal-to-noise ratio （SNR） of the novel multi-kernel adaptive filtering method outperforms the conventional linear normalized least-mean-square method and the mono-kernel normalized least- mean-square method using the realistic noise data measured in the lake experiment.

A High Gain, Noise Cancelling 2515-4900 MHz CMOS LNA for China Mobile 5G Communication Application

With the development of the times,people’s requirements for communication technology are becoming higher and higher.4G communication technology has been unable to meet development needs,and 5G communication technology has emerged as the times require.This article proposes the design of a low-noise amplifier(LNA)that will be used in the 5G band of China Mobile Communications.A low noise amplifier for mobile 5G communication is designed based on Taiwan Semiconductor Manufacturing Company(TSMC)0.13μm Radio Frequency(RF)Complementary Metal Oxide Semiconductor(CMOS)process.The LNA employs self-cascode devices in current-reuse configuration to enable lower supply voltage operation without compromising the gain.This design uses an active feedback amplifier to achieve input impedance matching,avoiding the introduction of resistive negative feedback to reduce gain.A common source(CS)amplifier is used as the input of the low noise amplifier.In order to achieve the low power consumption of LNA,current reuse technology is used to reduce power consumption.Noise cancellation techniques are used to eliminate noise.The simulation results in a maximum power gain of 22.783,the reverse isolation(S12)less than-48.092 dB,noise figure(NF)less than 1.878 dB,minimum noise figure(NFmin)=1.203 dB,input return loss(S11)and output return loss(S22)are both less than-14.933 dB in the frequency range of 2515-4900 MHz.The proposed Ultra-wideband(UWB)LNA consumed 1.424 mW without buffer from a 1.2 V power supply.

Least mean square error difference minimum criterion for adaptive chaotic noise canceller

The least mean square error difference （LMS-ED） minimum criterion for an adaptive chaotic noise canceller is proposed in this paper. Different from traditional least mean square error minimum criterion in which the error is uncorrelated with the input vector, the proposed LMS-ED minimum criterion tries to minimize the correlation between the error difference and input vector difference. The novel adaptive LMS-ED algorithm is then derived to update the weights of adaptive noise canceller. A comparison between cancelling performances of adaptive least mean square （LMS）, normalized LMS （NLMS） and proposed LMS-ED algorithms is simulated by using three kinds of chaotic noises. The simulation results clearly show that the proposed algorithm outperforms the LMS and NLMS algorithms in achieving small values of steady-state excess mean square error. Moreover, the computational complexity of the proposed LMS-ED algorithm is the same as that of the standard LMS algorithms.

Design of Background Noise Suppression Circuit for Mobile Phones

With the purpose of reducing the influence of background noise on the call quality of mobile phones, background noise suppression circuit is designed based on the principle of self-adaptive noise cancellation. Because this method is not involved in the nature of the noise itself, it can be used both for stationary noise cancellation and quasi-stationary noise cancellation. The working principle and circuit design of the system are introduced in detail. Simulated experiment was conducted in the lab, and its experimental results were analyzed. The experimental results show that the circuit works well with low cost, and has a broad prospect of application and popularization.

Error suppression techniques for energy-efficient high-resolution SAR ADCs

The successive approximation register(SAR)is one of the most energy-efficient analog-to-digital converter(ADC)architecture for medium-resolution applications.However,its high energy efficiency quickly diminishes when the target resolution increases.This is because a SAR ADC suffers from several major error source,including the sampling kT/C noise,the comparator noise,and the DAC mismatch.These errors are increasing hard to address in high-resolution SAR ADCs.This paper reviews recent advances on error suppression techniques for SAR ADCs,including the sampling kT/C noise reduction,the noise-shaping(NS)SAR,and the mismatch error shaping(MES).These techniques aim to boost the resolution of SAR ADCs while maintaining their superior energy efficiency.

An Efficient Reference Free Adaptive Learning Process for Speech Enhancement Applications

In issues like hearing impairment,speech therapy and hearing aids play a major role in reducing the impairment.Removal of noise signals from speech signals is a key task in hearing aids as well as in speech therapy.During the transmission of speech signals,several noise components contaminate the actual speech components.This paper addresses a new adaptive speech enhancement(ASE)method based on a modified version of singular spectrum analysis(MSSA).The MSSA generates a reference signal for ASE and makes the ASE is free from feeding reference component.The MSSA adopts three key steps for generating the reference from the contaminated speech only.These are decomposition,grouping and reconstruction.The generated reference is taken as a reference for variable size adaptive learning algorithms.In this work two categories of adaptive learning algorithms are used.They are step variable adaptive learning(SVAL)algorithm and time variable step size adaptive learning(TVAL).Further,sign regressor function is applied to adaptive learning algorithms to reduce the computational complexity of the proposed adaptive learning algorithms.The performance measures of the proposed schemes are calculated in terms of signal to noise ratio improvement(SNRI),excess mean square error(EMSE)and misadjustment(MSD).For cockpit noise these measures are found to be 29.2850,-27.6060 and 0.0758 dB respectively during the experiments using SVAL algorithm.By considering the reduced number of multiplications the sign regressor version of SVAL based ASE method is found to better then the counter parts.

A 0.18μm CMOS inductorless complementary-noise-canceling-LNA for TV tuner applications

This paper presents an inductorless complementary-noise-canceling LNA （CNCLNA） for TV tuners. The CNCLNA exploits single-to-differential topology, which consists of a common gate stage and a common source stage. The complementary topology can save power and improve the noise figure. Linearity is also enhanced by employing a multiple gated transistors technique. The chip is implemented in SMIC 0.18 μm CMOS technology. Measurement shows that the proposed CNCLNA achieves 13.5-16 dB voltage gain from 50 to 860 MHz, the noise figure is below 4.5 dB and has a minimum value of 2.9 dB, and the best PIdB is -7.5 dBm at 860 MHz. The core consumes 6 mA current with a supply voltage of 1.8 V, while the core area is only 0.2 ×0.2 mm2.

Enhancing optomechanical force sensing via precooling and quantum noise cancellation

We theoretically investigate optomechanical force sensing via precooling and quantum noise cancellation in two coupled cavity optomechanical systems.We show that force sensing based on the reduction of noise can be used to dramatically enhance the force sensing and that the precooling process can eifectively improve the quantum noise cancellation.Specifically,we examine the effect of optomechanical cooling and noise reduction on the spectral density of the noise of the force measurement;these processes can significantly enhance the performance of optomechanical force sensing,and setting up the system in the resolved sideband regime can lead to an optimization of the cooling processes in a hybrid system.Such a scheme serves as a promising platform for quantum back-action-evading measurements of the motion and a framework for an optomechanical force sensor.

Salt and pepper noise removal in surveillance video based on low-rank matrix recovery

This paper proposes a new algorithm based on low-rank matrix recovery to remove salt &pepper noise from surveillance video. Unlike single image denoising techniques, noise removal from video sequences aims to utilize both temporal and spatial information. By grouping neighboring frames based on similarities of the whole images in the temporal domain, we formulate the problem of removing salt &pepper noise from a video tracking sequence as a lowrank matrix recovery problem. The resulting nuclear norm and L1-norm related minimization problems can be efficiently solved by many recently developed methods. To determine the low-rank matrix, we use an averaging method based on other similar images. Our method can not only remove noise but also preserve edges and details. The performance of our proposed approach compares favorably to that of existing algorithms and gives better PSNR and SSIM results.

Phase noise approximation analysis for the OFDM system

The influence of phase noise（PN） present at the access point（AP） and mobile terminator（MT） may degrade the performance in orthogonal frequency division multiplexing （OFDM） system, because the OFDM system is sensitive to the PN. The method of PN approximation based on the PN power spectrum was proposed to combat the influence of the PN present. The idea of the PN cancellation is the PN is approximated for the sum of the different frequency between the AP and the MT as well as Doppler shift supposing that the fixed different frequency during several OFDM symbols are identical, so the variable phase may be considered as the combination of the fixed partition and the random partition. The approximation method is utilized to remove the fixed and the random phase partition so that the signal-to-noise ratio （SNR） may be improved. The analysis and the simtilation proposed show that the method may effectively improve the performance of the OFDM system.

A wideband CMOS inductorless low noise amplifier employing noise cancellation for digital TV tuner applications

A wideband inductorless low noise amplifier for digital TV tuner applications is presented. The proposed LNA scheme uses a composite NMOS/PMOS cross-coupled transistor pair to provide partial cancellation of noise generated by the input transistors. The chip is implemented in SMIC 0.18 #m CMOS technology. Measurement shows that the proposed LNA achieves 12.2-15.2 dB voltage gain from 300 to 900 MHz, the noise figure is below 3.1 dB and has a minimum value of 2.3 dB, and the best input-referred 1-dB compression point （IPldB） is - 17 dBm at 900 MHz. The core consumes 7 mA current with a supply voltage of 1.8 V and occupies an area of 0.5 x 0.35 mm2.

Experimental Study on the Lattice-End-Mirror Vibration Noise Cancellation of Ytterbium Clock Laser

In this paper,we describe an optical path stabilization method in order to keep the phase of the clock laser fixed during the interrogation.The phase noise along the optical path of the clock laser is extracted from the heterodyne beat signals.Then an acousto-optic modulator(AOM)driven by direct digital synthesizer(DDS)receives a feedback signal to cancel the phase noise.The experimental results show that our system can effectively suppress additional phase noise.The fractional frequency instability is dropped to 1.76×10^-17/τ at 1 s,which is improved by two orders of magnitude than before.In the case of Rabi excitation with a pulse duration T=50 ms,frequency shift is 7.9 mHz due to the feedback system relock process.For phase noise from different frequency,the system has a good suppression effect on low frequency phase noise.

A 0.18μm CMOS Gilbert low noise mixer with noise cancellation

This paper presents a broadband Gilbert low noise mixer implemented with noise cancellation technique operating between 10 MHz and 0.9 GHz.The Gilbert mixer is known for its perfect port isolation and bad noise performance.The noise cancellation technique of LNA can be applied here to have a better NF.The chip is implemented in SMIC 0.18μm CMOS technology.Measurement shows that the proposed low noise mixer has a 13.7-19.5 dB voltage gain from 10 MHz to 0.9 GHz,an average noise figure of 5 dB and a minimum value of 4.3 dB.The core area is 0.6 x 0.45 mm;.

Real-time adaptive noise cancelling for signal-to-noise enhancement in direct absorption spectroscopy

An adaptive filter for cancelling noise contained in the direct absorption spectra is reported. This technique takes advantage of the periodical nature of the repetitively scanned spectral signal, and requires no prior knowledge of the detailed properties of noises. An experimental system devised for measuring CH4 is used to test the performance of the filter. The measurement results show that the signal-to-noise （S/N） value is improved by a factor of 2. A higher enhancement factor of the S/N value of 5.4 is obtained through open-air measurement owing to higher distortions of the raw data. In addition, the response time of this filter, which characterizes the real-time detection ability of the system, is nine times shorter than that of a conventional signal averaging solution, under the condition that the filter order is 100.