Influence Of Impulsive Noise Research Articles

Robust time–frequency representation based on the signal normalization and concentration measures

An efficient procedure for obtaining time–frequency representations under high influence of impulsive noise is proposed in this paper. The procedure uses the fast Fourier transform based algorithm instead of sorting procedures common in the case of various robust time–frequency representations proposed recently. Concentration measure is used to select a free parameter of the transform.

Impulse noise exposure in early adulthood accelerates age-related hearing loss

The aim of this study was to investigate the influence of impulse noise on age-related hearing loss. The study consisted of two groups. Each group contained 109 men. Group I comprised veterans with normal hearing at the end of 1979 sino-vietnamese war. All these veterans were randomly selected from Guangzhou Military Command. Group II were men with no military experience randomly chosen from the health examination center of Guangzhou General Hospital of Guangzhou Military Command. Pure-tone thresholds of these two groups were measured and compared. The pure-tone thresholds of Group I were poorer than those of Group II at the frequencies of 4, 6 and 8kHz. Thus, impulse noise accelerates age-related hearing loss.

時間サンプルの復元によるＯＦＤＭ信号へのインパルス雑音の影響の軽減

In OFDM transmission, performance is degraded by the existence of time domain impulse noise because this noise has very wide bandwidth, and it affects all the carriers in the OFDM signal. Especially, the influence of impulse noise with large amplitude couse severe degradation[8]. In this paper, a scheme that reduces the influence of impulse noise is proposed. In the proposed scheme, the symbols after decision are re-modulated to generate a time domain OFDM signal to replace the samples that are degraded by the impulse noise in the time domain. The time domain OFDM signal is demodulated again after the influence of the impulse noise is reduced. This results in an improvemed of bit error rate. Moreover, the peformance of the proposed scheme can be further improved by applying it iteratively.

Robust time-frequency distributions based on the robust short time fourier transform

Design of time-frequency distributions (Tfds) that are robust to the impulse noise influence is considered. The robustTfds based on the robust short-time Fourier transform (Stft) are proposed. An efficient procedure to evaluate the robustStft is given. RobustTfds based on the robustStft have better energy concentration around the signal instantaneous frequency (If) than the robustStft itself. Also, theseTfds are more resistant to higher impulse noise than the robustTfds obtained using the local autocorrelation function (Laf) based minimization problem.

Robust adaptive spread-spectrum receiver with neural net preprocessing in non-Gaussian noise

Multiuser communications channels based on code division multiple access (CDMA) technique exhibit non-Gaussian statistics due to the presence of highly structured multiple access interference (MAI) and impulsive ambient noise. Linear adaptive interference suppression techniques are attractive for mitigating MAI under Gaussian noise. However, the Gaussian noise hypothesis has been found inadequate in many wireless channels characterized by impulsive disturbance. Linear finite impulse response (FIR) filters adapted with linear algorithms are limited by their structural formulation as a simple linear combiner with a hyperplanar decision boundary, which are extremely vulnerable to impulsive interference. This raises the issues of devising robust reception algorithms accounting at the design stage the non-Gaussian behavior of the interference. We propose a multiuser receiver that involves an adaptive nonlinear preprocessing front-end based on a multilayer perceptron neural network, which acts as a mechanism to reduce the influence of impulsive noise followed by a postprocessing stage using linear adaptive filters for MAI suppression. Theoretical arguments supported by promising simulation results suggest that the proposed receiver, which combines the relative merits of both nonlinear and linear signal processing, presents an effective approach for joint suppression of MAI and non-Gaussian ambient noise.

Influence of impulse noise on speech transmission index

This paper analyzes the influence of impulse noise impairments in a telecommunication channel on the speech transmission index (STI) value, which was measured using RASTI method. So far STI has not been applied in telecommunications as a speech transmission quality measure. Impulse noise components were formed as IEEE standard impulse streams. Impulse noise amplitude level relative to the level of reference (RASTI) signal as well as the duration between successive impulse events were varied in a channel. Consequently, STI value was determined as a function of these two parameters. In the same channel PB‐Word Score evaluation was also performed. As a result, the correlation between PB‐Word Score and STI value for a telephone channel with impulse noise impairments present was established in this paper.