Showing papers on "Impulse noise published in 1989"

Amplitude, width, and interarrival distributions for noise impulses on intrabuilding power line communication networks

Abstract: Estimates are presented of probability distributions for the amplitude, width, and interarrival time of noise impulses. These estimates are based on measurements in both industrial and residential buildings and usefully complement the noise spectral density estimates of others. The results are based on measurements with and without specific electrical loads on the 120-V power line network. All measurements are between line and neutral conductors. The harmful effects of power line impulse noise on digital communications are indicated. Some suggestions for combatting these effects are presented, based on the impulse noise measurement results. >

Impact of non-Gaussian impulsive noise on the performance of high-level QAM

Abstract: The impact of non-Gaussian impulse noise (Middleton's class A noise) combined with Gaussian thermal noise on the performance of high-level QAM (quadrature amplitude modulation) (e.g., 16, 64, and 256 QAM) systems is analyzed. The P(e) (probability of error) performance of the system is evaluated in terms of CNR (carrier-to-noise ratio), impulsive index (A) of the noise, and power ratio of the Gaussian noise to the impulsive noise ( Gamma '). It is shown that, in the high-level QAM, non-Gaussian impulsive noise degrades the system performance significantly, even at high CNR. It is also found that an upper bound on the error probability exists for Gamma ' >

A class of multi-shell min/max median filters

Abstract: A novel extension of median filters from one dimension to higher dimensions is presented. Unlike the standard and separable median filters, this class of filters is able to preserve features of lower dimensionality, such as thin lines in two-dimensional space. Also, unlike the max/median filter, it does not have to trace exhaustively all the possible lines through the central sample. Hence, this class of filters does not blur sharp images while removing impulse noise and is highly computationally efficient. With minor modifications, missing line noise can also be removed with similar performance. Moreover, this class of filters is able to perform feature selective filtering by which isolated features of any particular shape can be removed from an image with a set of custom-tailored shells. >

On the NEXT and impulse noise properties of subscriber loops

Abstract: The transmission range of subscriber loops carrying ISDN (integrated services digital network) signals with a net bit rate of 144 kb/s is limited mainly by the near-end crosstalk (NEXT) between cable pairs and by impulse noise transformed into these loops owing to their imperfect symmetry. In order to be able to predict this transmission range, a considerable amount of experimental and theoretical work was required prior to the introduction of ISDN for a better understanding of the cross-talk and noise phenomena in these loops. The author summarizes NEXT measurement results and modeling methods and reports on impulse noise measurements and the statistical models derived from them. Detailed results of swept-frequency measurements in different cables are considered. Measurement results indicate considerable variation in the density of impulse noises within 24 h, a hyperbolic distribution, interval distribution according to the sum of exponential functions, and steadily increasing amplitude density below 40 kHz. >

Circuit for driving an inductive load

Abstract: A switching transistor for driving an inductive load is switched on and off by a switching signal of a PWM signal or a signal equivalent to the PWM Signal. A frequency band of impulse noise components of the switching signal is above a frequency band used in an apparatus including the inductive load.

Detection of Signals in the Presence of Strong, Signal-Like Interference and Impulse Noise

Abstract: We assume that the noise which interferes with signal detection can be considered to be a mixture of non-stationary, high-amplitude, non-Gaussian components plus a low amplitude Gaussian stationary component. Such a model appears to be widely applicable. The methodology that we propose for signal detection is to identify, categorize, model, and remove the non-Gaussian components in a piece-wise fashion based on their ease of separability from the background Gaussian noise and weak signals. This approach to modeling and processing complicated and non-stationary data is similar to that of experimental physicists going back at least to the time of Newton and perhaps most clearly articulated by Eugene Wigner in his Nobel Prize lecture [1]. Liu and Nolte [2] and Claus, Kadota, and Romain [3] have shown that when the noise is Gaussian and consists of a sum of a strong highly coherent component and a weak component of independent noise samples, then estimation and subtraction of the coherent noise component is nearly optimal. The application of special data smoothers and data cleaners by Martin and Thomson [4] for obtaining robust spectral estimates when the data is contaminated by outliers has provided another motivation for our use of adaptive differential quantization for robust detection.

On a theoretical interpretation of the prevalence rate of noise‐induced annoyance in residential populations—High‐amplitude impulse‐noise environments

Abstract: In a recent paper, Fidell et al. [J. Acoust. Soc. Am. 84, 2109–2113 (1988)] have introduced a theoretical interpretation of the prevalence rate of noise‐induced annoyance in residential populations exposed to common environments consisting of sources such as aircraft, motor vehicles, etc. Their model assumes a compressive transformation of DNL, and they assert that ‘‘the quantity that engenders annoyance must be strongly related to the apparent magnitude of noise exposure.’’ Thus they use the well‐known finding that apparent loudness is proportional to the 0.3 root of acoustic energy. High‐amplitude impulse noise has been shown to be different from typical community noise, in part because it induces vibrations and rattles in structures. So the annoyance response is due both to the audible sound and to the induced vibrations and rattles; the latter should be proportional to the 0.5 power of DNL. In this letter, a compressive transformation coefficient of 0.4 (midway between 0.3 and 0.5) is used for high‐amplitude impulse sound. The results show excellent fit between theory and results. On the one hand, this fit supports the view of the Committee on Hearing Bioacoustics and Biomechanics (CHABA), a view that induced vibrations and rattles (and not only loudness) determine annoyance to high‐amplitude impulse noise, and, on the other hand, this close fit lends further credence to the Fidell model.

Edge preserving filtering by combining nonlinear mean and median filters

Abstract: The authors introduce a very general class of nonlinear filters, called mapping order-statistics filters (MOSFs). A subclass of the MOSFs, called L/sub p/-mean median filters (L/sub p/-MMF), is treated in detail. Theoretical analysis and computer simulations shown that the L/sub p/-MMF removes one kind of impulse noise as well as the nonlinear mean filter and attenuates Gaussian and uniformly distributed noise efficiently. The main advantages of the L/sub p/-MMF are that it can preserve edges as well as the median filter and can remove both the positive and negative impulse noise simultaneously. Further theoretical analysis shows that a finite-length discrete signal always converges to a fixed-point signal (root signal), if the same L/sub p/-MMF is applied iteratively. A necessary condition for a signal to be a root signal is found and proved. This necessary condition is also valid for the FIR-median hybrid filter. >

Properties of the momentum LMS algorithm

Abstract: The momentum least-mean square (MLMS) algorithm, a modified version of the well-known LMS algorithm, has recently been proposed, and an analysis of its basic convergence properties has been given. The authors revise the ranges of the MLMS algorithm's parameters, for which convergence is guaranteed, and provide precise expressions of convergence rate and steady-state performance of the algorithm under slow learning conditions. As a result, it is shown that, with Gaussian inputs and a low adaptation rate, the LMS and MLMS algorithms are equivalent, but, with inputs incorporating impulse noise components, the MLMS algorithm performs better. Due to its increased inertia, the MLMS algorithm becomes preferable for systems with inputs containing impulse noise components. At the expense of increased computational complexity, the MLMS algorithm is more stable against short-term disturbances exhibited by the filter input. >

Effect of impulse noise rejection with median filter on binary digital receiver performance

Abstract: In the letter an analysis of the effect achieved by using a median filter for impulse noise rejection in a binary digital receiver, is carried out. Results have shown that the error probability can be considerably reduced in digital communication systems with a keying speed that is a few times less than is permitted by the channel bandwidth.

Non-contact id card system and identifying device

Abstract: PURPOSE:To reduce a malfunction due to an impulsive noise without deteriorating sensitivity and to reduce the generation of an unnecessary signal and the deterioration of a signal quality by providing a detecting means for detecting the presence and the absence of the noise and a control means for removing the noise at the position of any circuit block after an AM demodulating part. CONSTITUTION:To the constitution of the conventional device, an impulse detecting part 21, a timer part 22 and level control parts 23a, 23b are added. The impulse is detected from the output of an AGC circuit 7 in the impulse detecting part 21 and a level is deteriorated in a level control part 23 only for a constant period by the timer part 22, thereby, a signal by the impulse is not outputted from a detecting circuit 9 but the malfunction due to the impulse noise can be lowered without deteriorating the sensitivity.

Modeling and performance of the North American Broadcast Teletext System with quasi-synchronous detection

Abstract: In vestigial sideband systems the most critical region is the Nyquist region of the receiver response, which is difficult to control in practice, so that synchronous and quasi-synchronous detection are not perfect due to quadrature distortion. The advantages of phase-locked-loop quasi-synchronous detection and the factors influencing their design are discussed. These factors include incidental phase modulation introduced by the Nyquist slope of the receiver IF filter in response to synchronization signals, audio buzz, and the effects of other signal distortions. Analysis, modeling, and computer simulations have been used to study quasi-synchronous detection in Gaussian and impulse noise and multipath environments and to find carrier recovery phase error and teletext system performance curves. Possible improvements to television carrier recovery systems are suggested. It is concluded that well-designed quasi-synchronous carrier recovery loops suffer relatively minor degradations (about 0.5 dB) compared to narrowband (synchronous) carrier recovery, in multipath and noise environments of interest to broadcast teletext application. >

Testing basic access loops for service-affecting impulse noise

Abstract: The implementation of basic access ISDN (integrated services digital network) using the standard Digital Subscriber Line (DSL) will convert the local loop to a digital transport facility. The author suggests procedures for determining whether a basic access loop is subject to service-affecting impulse noise and describes the technical parameters of instruments that would be used to make that determination. The standard DSL will be a robust technology that will be largely immune to the effects of impulse noise. It is recommended that loops carrying DSL signals be tested for impulse noise only when the other maintenance tests have failed to reveal the source of customer trouble. Specifically, it is not recommended that impulse noise testing be part of a routine loop-qualification procedure. Results of impulse noise studies suggest that an errored second objective be used to determine whether impulse noise will affect service on loops carrying DSL signals. The author proposes a measurement procedure that uses currently available impulse noise tests sets to estimate the errored second performance of a DSL on a given loop. >

Digital loop system performance prediction using an impulse noise database

Abstract: A methodology for capturing and reproducing the outside plant impulse noise environment in the laboratory is presented. This methodology permits outside plant impulse noise to be characterized and analyzed and its effects on digital loop systems to be studied in a controlled environment. The ability to subject digital loop systems to actual impulse noise present in the outside plant in this manner will enable loop system designers to acquire a better understanding of how bit errors are caused by impulse noise. It will also allow them to improve their designs during early product development stages through extensive testing, thus reducing the need for costly design changes at later stages of development. In addition, this capability would also be used to develop accurate and reliable loop system deployment guidelines. Accurate and reliable guidelines are essential where digital services have to be provided cost effectively and responsively. >

Bandwidth efficient coding on channels disturbed by jamming and impulse noise

Abstract: Bandwidth efficient data transmission using trellis coded modulation (TCM) can significantly increase a digital communication link's reliability without sacrificing spectral efficiency. In this paper we discuss TCM on channels with impulse noise. The intentional partial band jammer with optimized duty cycle is analyzed analytically and taken as a worst case impulse noise interferer. It is shown that a new code design criterion, the effective length of a code becomes the central code parameter determining the performance of TCM. A number of new TCM codes are presented and their performance is calculated. It is shown that these codes fare significantly better than codes designed for additive white Gaussian noise channels.

Digital image processor

Abstract: PURPOSE: To simultaneously realize the elimination of an impulse noise and the restoration of blurring by changing an image signal to be outputted as necessary. CONSTITUTION: An image processor is composed of a storage circuit 1 storing an image signal, a decision circuit 2 deciding the necessary/unnecessary of the correction of an image and an address circuit 3 designating the address of a picture element signal to be outputted in accordance with the decision result. In the decision circuit 2, noise and a blurred part are recognized, the picture element signal of this part is not outputted as it is, the signal is changed by the most approximate correction unnecessary picture element signal and the signal is outputted. As a result, noise can be eliminated, and at the same time, the contour of a graphic can be made conspicuous.