The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A fundamental problem in stereophonic acoustic echo cancellation for teleconferencing is the possibility to identify the true impulse responses of the acoustic echo paths. This problem arises from the correlation between the two signals picked up in the remote room. We demonstrate by simple theoretical considerations and experiments that in real situations, due to the characteristics of the acoustic...
In image contrast enhancement [2, 4, 5], quadratic and more generally polynomial filters are a very popular class of nonlinear filters. These filters exhibit good performances in terms of visual quality, but present some drawbacks such as the elimination of usefull information when using a fixed filter. In this paper we propose a new family of adaptive quadratic filters, where a weighted filter mask...
In this paper we propose a new adaptive weighted dα filter. The filter is adaptive regarding noise amplitude distribution, orientation of structures and anisotropy measures. The filter coefficient are chosen according to structure orientation and anisotropy measures. α value is chosen according to the result of local noise distribution and anisotropy coefficient estimations. Some experimental results...
Aliasing is often generated in critically decimated subband schemes which can reduce the performance of subband adaptive algorithms. This paper investigates non-critical decimation schemes in which the generation of aliasing in the subbands is avoided by down-sampling the subband signals by a smaller factor than would normally be expected, thereby allowing for analysis filters with finite transition...
Sparse estimation has received a lot of attention due to its broad applicability. In sparse channel estimat ion, the parameter vector with sparsity characteristic can be well estimated from noisy measurements through sparse adaptive filters. In previous studies, most works use the mean square error (MSE) based cost to develop sparse filters, which is rat ional under the assumption of Gaussian distributions...
The Feedback active noise control (FBANC) scheme is widely used in portable ANC applications. But the FBANC has un-stability problem caused by the modeling error of the electro-acoustic path in its feedback mechanism. To analyze the stability problem, we propose a new stability analysis method utilizing the magnitude component of the open loop frequency response of the FBANC. With the proposed method,...
In this paper, a delayless speech enhancement scheme with zero phase distortion is proposed. It is based on a cascade of adaptive filters that predicts periodic components with a significant auto-correlation for lags larger than a value D. The adaptive filter is positioned at the output of a speech enhancement algorithm, to adjust the phase of the periodic components to the noisy signal, and to remove...
Using EEG signals to estimate cognitive state has drawn increasing attention in recently years, especially in the context of brain-computer interface (BCI) design. However, this goal is extremely difficult because, in addition to the complex relationships between the cognitive state and EEG signals that yields the non-stationarity of the features extracted from EEG signals, there are artefacts introduced...
A method for the suppression of acoustic howling is developed, based on adaptive notch filters (ANF) with regularization (RANF). The method features three RANFs working in parallel to achieve frequency tracking, howling detection and suppression. The ANF-based approach to howling suppression introduces minimal processing delay and minimal complexity, in contrast to non-parametric frame-based methods...
Problem associated with biomedical signal like ECG is to extract noise cause by high frequency interference, electromagnetic fields, power line interference and body movement. It is difficult to apply filters with fixed coefficients to reduce random noises. Adaptive filter technique is required to overcome this problem. This paper presents an innovative technique for estimation of ECG waves using...
Here an attempt has been made for environmental noise cancellation using adaptive Neuro fuzzy inference system for mobile communication. The aim of present work is to reduce the environmental noise during the speech communication by using Adaptive Neuro Fuzzy Filtering. Now a day's many people are using mobile phones during their journey, as received signal is continuously corrupted by environmental...
The implementation of analog adaptive median filters for image processing is presented. The adaptive median filter is based on transconductance comparators, which saturation current is adapted to act as a local weight operator. Transistor level simulations, using 1.2mm parameters, have shown excellent results in high removing incidence noise. An image with 249 × 209 corrupted with 35% salt and pepper...
Adaptive filters with suitable nonlinear devices are very effective in suppressing the adverse effect due to impulse noise. In a previous work, the authors have proposed a new class of nonlinear adaptive filters using the concept of robust statistics [1,2]. The robust M-estimator is used as the objective function, instead of the mean square errors, to suppress the impulse noise. The optimal coefficient...
This paper will focus on a new approach, which was derived from the multi-band ANC concept. The proposed structures referred as Fast Multi-Band ANCs (FMB-ANC) are immune to crosstalk, allowing higher robustness to instability and faster convergence than the CrossTalk Resistant ANC approach (CTRANC). The method is efficient for speech enhancement because it removes reasonably the correlation between...
In this paper, we propose a frequency domain active noise control (ANC) system without a secondary path model. The proposed system is based on the frequency domain simultaneous perturbation (FDSP) method we have proposed. In this system, the coefficients of the adaptive filter are updated only by error signals. The conventional ANC system using the filtered-x algorithm becomes unstable due to the...
Image filtering in moving window in DCT domain has proven its capability in image edge preserving denosing. For the highest noise suppression capability, such a filtering requires, in principle, optimal selection of the size of the moving window for each particular image. In order to overcome this drawback, a combination of signal wavelet expansion (sub band decomposition) and moving window filtering...
Based on the adaptive filtering mode, we discussed and analyzed how to improve the quality of microphone array speech enhancement and reduce the complexity of the algorithm. This paper described a new variable step least mean square (LMS) algorithm which could reduce the effect of input noise to step factor, improve the performance of the algorithm. The algorithm smoothed the step factor in time domain...
Electrocardiogram (ECG) signals are affected by various types of noises that are differed based on frequency content. In order to improve accuracy and reliability, it is essential to remove such a disturbance. The denoising of ECG signals is challenging as it is difficult to apply filters with fixed coefficients. Adaptive filtering techniques can be used, in which the filter coefficients can be modified...
In this paper, low complexity reconfigurable hardware architecture for adaptive median filter is proposed and a comparative study of hardware based median and adaptive median filter is presented. An efficient development of median & adaptive median filter is presented for removal of impulse noise mainly salt & pepper noise from digital Images. Performance measurement of mean square error (MSE)...
An Adaptive Divided Difference filter has been proposed for the systems with non additive Gaussian noise in the situations when noise statistics is unknown. In face of unknown noise statistics the proposed filter can adapt the unknown measurement noise covariance (Ü) incorporating the steps for adaptation in the non adaptive algorithm of Divided Difference filter. Satisfactory estimation performance...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.