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Showing papers on "Impulse noise published in 1982"


Book Chapter
01 Jan 1982

38 citations


Journal ArticleDOI
TL;DR: The effects of slow and nonselective signal fading on the performance of multilevel noucoherent FSK (NCFSK) systems in an additive mixture of Gaussian and highly impulsive noise are analyzed.
Abstract: The effects of slow and nonselective signal fading on the performance of multilevel noucoherent FSK (NCFSK) systems in an additive mixture of Gaussian and highly impulsive noise are analyzed. For binary systems the bit error rate is derived; for M -ary NCFSK systems upper and lower bounds of the character error probability are obtained. The analysis is performed considering the maximum likelihood receiver for additive white Gaussian noise.

25 citations




Journal ArticleDOI
TL;DR: In this paper, the authors used the Savitzky and Golay smoothing method to remove noise spikes from a spectrum numerically, but the results showed that the smooth method simply transforms them to the impulse response of the filter function itself.
Abstract: Sensitive absorption measurements may be contaminated by the presence of particulates in the sample. Scattering by these particles can generate impulse noise (spikes) on the spectrum. This problem is especially serious in spectroscopy with a focused laser source, since the laser probes a small cross section of the sample. Often, this noise ruins an otherwise usable spectrum. If the data are stored digitally, however, it is often possible to remove noise spikes from a spectrum numerically. The commonly used smooth method of Savitzky and Golay does a poor job of removing these spikes. Since they are isolated and unidirectional errors, the smooth method simply transforms them to the impulse response of the filter function itself. Similarly, other low pass digital filters will also transform spikes into bands which may interfere with the analysis of real spectral features.

16 citations



Journal ArticleDOI
TL;DR: Generalized spectral methods have been evaluated by means of an impulse simulation applied to a mathematical model of the human hearing mechanism and the results fully support the proposed rating methods.
Abstract: Damage-risk criteria for impulse noise does not presently take the spectrum of the impulse into account; however, it is known that the human auditory system is spectrally tuned. The present paper advocates the extension to impulse noise of the noise dose concept which is widely used for continuous noise. This approach is based upon sound exposure instead of sound pressure. An A-weighting filter or an octave band analysis can then be used to take the spectral content of the impulses into account. The equipment needed for applying these procedures for impulse noise is an integrating sound level meter or a digital Fourier processor. Generalized spectral methods have been evaluated by means of an impulse simulation applied to a mathematical model of the human hearing mechanism. The results of this simulation agree with the most recent experiments on impulse noise and fully support the proposed rating methods. This conclusion must be emphasized as it leads the derivation of a uniform procedure for predicting loudness and damage risk for hearing which is applicable for continuous noise as well as for impulse noise.

11 citations


Journal ArticleDOI
TL;DR: Simulation results indicate that the AINC provides a very effective suppression of impulse noise, however, conditions in a real communication channel may be quite different from those chosen for simulation, therefore, further research remains to be done before the A INC can be recommended for practical applications.
Abstract: A non-recursive adaptive impulse noise canceller (AINC) is investigated. The AINC is designed to suppress long impulsive interferences which are a primary source of errors in many communication systems. Performance of the AINC depends upon the input filter of the receiver. It is shown that the optimum input filter is LPF; the optimum LPF bandwidth exists which provides the minimum error rate of the receiver. The system error rate is studied by means of a computer simulation. Simulation results indicate that the AINC provides a very effective suppression of impulse noise. However, conditions in a real communication channel may be quite different from those chosen for simulation. Therefore, further research remains to be done before the AINC can be recommended for practical applications.

8 citations


Patent
12 Jan 1982
TL;DR: In this paper, a music signal having an impulse noise from an input terminal is applied to a voltage controlled type LPF filter via signal delay circuit 11 and the impulse noise component included in the said music signal is detected at a noise detecting circuit 13 and it is converted into a pulse width signal having a pulsewidth corresponding to the duration time at a pulse forming circuit 14.
Abstract: PURPOSE:To effectively reject impulse noises without much damage to an original signal, by changing a cutoff frequency of a variable filter added with the original signal in accordance with the duration time of the impulse noises. CONSTITUTION:A music signal having an impulse noise from an input terminal is applied to a voltage controlled type LPF filter 12 via signal delay circuit 11. On the other hand, the impulse noise component included in the said music signal is detected at a noise detecting circuit 13 and it is converted into a pulse width signal having a pulse width corresponding to the duration time at a pulse forming circuit 14. Further, this pulse width signal is converted into a DC voltage corresponding to the pulse width at a pulse width/voltage converting circuit 15 and applied to a control terminal of the said voltage variable type LPF filter 12. Thus, if the duration time of impulse noise is short, the cutoff frequency of the LPF filter 12 is higher and inversely, if the duration time of the impulse noise is longer, the cutoff frequency becomes lower.

5 citations



Journal ArticleDOI
TL;DR: In this paper, the authors discuss the developing information with respect to the issues inherent in the measurement of noise, such as high and low-frequency cutoffs, temporal factors, trading ratios, and limits on the dynamic range.
Abstract: In designing a system to measure noise there are many interacting considerations, among them the electrical/acoustical state‐of‐the‐art, regulatory requirements, administrative concerns, and economic issues. In contrast to these fluctuant elements, the structure of the auditory system is for all practical purposes fixed and establishes limits to many technical issues. Although theoretical work in the noise effects area is in its infancy, this paper will discuss the developing information with respect to the issues inherent in the measurement of noise, such as high‐ and low‐frequency cutoffs, temporal factors, “trading ratios,” and limits on the dynamic range.

01 Feb 1982
TL;DR: In this paper, a balanced active antenna and an impulse noise blanker were used to reduce the detrimental effects of negative-corona generated impulse noise on Raydist T radio navigation equipment.
Abstract: : Erratic operation of Raydist T radio navigation equipment aboard mine countermeasures helicopters has been traced to fuselage-tow cable interactions with the Raydist receiving antenna and to negative-corona generated impulse noise. The development of a balanced active antenna and an impulse noise blanker which have proved successful in reducing these detrimental effects are described. The final system is described in detail and the results of laboratory tests are presented (Author).

Journal ArticleDOI
TL;DR: In this article, a theory is presented in which the percentile sound levels in a room are given as a function of reverberation time and the time between impulses, which may enable "pressure" damage risk criteria to be applied to situations where isolated pulses occur in an enclosure.