Noise in Telecommunication: Different Types and Methods of dealing with Noise

This article discusses noise in telecommunications: different types and methods of dealing with noise. Noise is arguably a very hated problem because it can interfere with the quality of signal reception and also the reproduction of the signal that will be transmitted. Not only that, but noise can also limit the range of the system to a certain emission power and can affect the sensitivity and sensitivity of the reception signal. Even in some cases, noise can also result in a reduction in the bandwidth of a system. Of course, we've all felt how annoying the noise effect is. For example, when listening to the radio, a hissing sound appears on the loudspeaker due to noise. To overcome noise, it is divided into passive noise control and active noise control. Passive noise control is an effort to overcome noise using components that do not require power. Generally passive noise control uses soundproof materials that act as insulation against noise. The method most commonly used to overcome noise is through increasing the gain. The noise is generally in a specific sound area. Hiss is on high frequencies, while noise and hum are on low frequencies. This is the principle underlying the noise reduction method.

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Design of a Hybrid Acoustic Device Based on Proof-Mass Actuators

Volume 3: Advanced Composite Materials and Processing; Robotics; Information Management and PLM; Design Engineering ◽

10.1115/esda2012-82470 ◽

2012 ◽

Author(s):

Francesco Braghin ◽

Francesco Castelli-Dezza ◽

Simone Cinquemani ◽

Ferruccio Resta

Keyword(s):

High Performance ◽

Proof Mass ◽

Supporting Surface ◽

Low Frequencies ◽

High Frequencies ◽

Sound Reproduction ◽

Different Types ◽

Magnetostrictive Actuator ◽

Acoustic Device

The paper deals with the design of a device for sound reproduction to be fixed to a supporting surface. The device is made up of two different types of acoustic actuators based on different technologies that allow good sound reproduction in the range of frequencies from 20Hz to 20kHz. The generation of sound at high frequencies is demanded to a magnetostrictive actuator, while a more traditional magnetodynamics actuator is used to generate sound at low frequencies. The coupling between these two actuators leads to a device having small overall dimensions and high performance.

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A Review of Active Noise Control Applications on Noise Barrier in Three-Dimensional/Open Space: Myths and Challenges

Fluctuation and Noise Letters ◽

10.1142/s0219477519300027 ◽

2019 ◽

Vol 18 (04) ◽

pp. 1930002 ◽

Cited By ~ 2

Author(s):

Hsiao Mun Lee ◽

Zhaomeng Wang ◽

Kian Meng Lim ◽

Heow Pueh Lee

Keyword(s):

Open Space ◽

Noise Control ◽

Active Noise Control ◽

Three Dimensional ◽

Construction Site ◽

Noise Sources ◽

Current State ◽

Active Noise ◽

Noise Barrier ◽

Passive Noise

Active noise control (ANC), with counteracting sound in exact equal magnitude and opposite phase to the noise to be controlled, is often considered as a potential solution for solving complex noise problems. However, there are both myths and challenges in its implementations. In a crowded city like Singapore, many noise sources from construction site and subway track are located very close to the residential and commercial buildings. It was suggested by few researchers that by placing suitable control speakers at the construction site (working principle of ANC), the noise from the construction site could be prevented from propagating to the surrounding buildings. Similarly, for viaduct or subway track, by placing control speakers along the viaduct or track, the noise generated by the passing trains or vehicles could be reduced based on the principle of ANC technique. However, implementation of ANC technique on these noise issues is not easy as all of these noise control problems involve multiple noise sources with complex or transient frequency spectrum in large three-dimensional/open space. Therefore, the main intention of the present paper is to discuss the current state of the art of this topic as well as to examine the potential application and limitation of the ANC technique in mitigating unwanted noise, particularly in large three-dimensional/open space and with cooperation of passive noise barrier.

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Design and Implementation of Self-Tuning Regulators for Active Noise Control

ASME 1991 Computers in Engineering Conference: Volume 2 — Finite Elements/Computational Geometry; Computers in Education; Robotics and Controls ◽

10.1115/cie1991-0171 ◽

1991 ◽

Author(s):

Rahmat Shoureshi ◽

Yasuhiro Matsuyoshi

Keyword(s):

High Frequency ◽

Noise Control ◽

Acoustic Noise ◽

Active Noise Control ◽

Frequency Noise ◽

Control Methods ◽

Active Noise ◽

Self Tuning ◽

Passive Noise ◽

Industrial Societies

Abstract Acoustic noise has become an increasingly important problem, especially in industrial societies. The main reason being the increase in usage of machines in virtually all aspects of our lives, higher population densities, and concerns about the health consequences of exposure to acoustic noise. Passive noise control methods work well for relatively high frequency noise, but become progressively more expensive and less effective as one considers control of lower frequency noise. Development and implementation of an adaptive active noise controller is presented.

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Hybrid Active and Passive Noise Control of Cavities

Acta Acustica united with Acustica ◽

10.3813/aaa.918455 ◽

2011 ◽

Vol 97 (5) ◽

pp. 752-760 ◽

Cited By ~ 1

Author(s):

Lenin Babu ◽

Chandramouli Padmanabhan

Keyword(s):

Porous Material ◽

Elastic Material ◽

Sound Absorption ◽

Noise Suppression ◽

Noise Control ◽

Active Noise Control ◽

Elastic Materials ◽

Active Noise ◽

Absorption Performance ◽

Passive Noise

In this paper a hybrid active noise control of a cavity with poro-elastic material has been investigated. It has been found that the noise reduction achieved with active noise control in the cavity without poro-elastic material is not significantly altered with the presence of poro-elastic materials. This is shown to be independent of the porous material and its thickness and is true both at lower and mid-frequency ranges. Further, it is seen that macro perforations do not alter the sound absorption performance of the poro-elastic material in the presence of active noise control. The results clearly indicate that one can choose a smaller thickness of the porous material when active noise control is used in a cavity for noise suppression.

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Sound Quality of Exhaust Pipes Through Semi-Active Noise Control

10.4271/2006-01-2575 ◽

2006 ◽

Author(s):

Fernando A.N.C. Pinto ◽

Walace de Souza Pacheco

Keyword(s):

Noise Control ◽

Active Noise Control ◽

Sound Quality ◽

Active Noise

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Vibration Measurements for Active Noise Control in a HVAC System with a Passive Absorber

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.248.49 ◽

2016 ◽

Vol 248 ◽

pp. 49-56

Author(s):

Karol Szumski ◽

Marek Pawelczyk

Keyword(s):

Control System ◽

Noise Control ◽

Active Noise Control ◽

Audio Signal ◽

Passive Component ◽

Frequency Range ◽

Active System ◽

Active Noise ◽

Narrow Frequency Range ◽

Passive Noise

A hybrid active-passive noise control system for a HVAC duct combines both a physicalnoise absorber and an active system. Due to the presence of the passive component, requirements forthe active system can be relaxed, removing the need for detecting and suppressing noise in the frequencyrange already covered by the passive elements. A typical noise measurement system adaptedto working in airflow usually uses a microphone with a housing designed to reduce the noise generateddue to local turbulent flow introduced by the housing itself. Alternatively, there are microphonesspecifically designed to work in the airflow.During work on the hybrid active-passive noise control system both a microphone designed forairflow and a microphone with special housing were tested. While these solutions can be used forresearch, both have issues making them impractical when designing a commercial product. This, alongwith the required narrow frequency range motivated the authors to consider vibration measurementsperformed by appropriately installed accelerometers. An audio signal is then synthesized using thosemeasurements and it is confronted with signals obtained at the same time with microphones.In the paper the proposed method is presented and validated with a laboratory HVAC installation ofa large cross-section and an originally designed passive absorber. Obtained results encourage further research.

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Suitability of Active Noise Barriers for Construction Sites

Applied Sciences ◽

10.3390/app10186160 ◽

2020 ◽

Vol 10 (18) ◽

pp. 6160

Author(s):

Shahin Sohrabi ◽

Teresa Pàmies Gómez ◽

Jordi Romeu Garbí

Keyword(s):

Noise Control ◽

Noise Source ◽

Active Noise Control ◽

Target Area ◽

Construction Sites ◽

Noise Barriers ◽

Active Noise ◽

Noise Barrier ◽

Passive Noise ◽

Suitable Location

Barriers are increasingly used to protect the pedestrian and neighboring buildings from construction noise activities. This study aims to investigate the suitability of applying active noise control on barriers in a construction site to protect the street area and neighboring buildings. Transducers that are simulated in this work are close to the barrier, and their optimal positions are defined in such a way that the control system has the maximum performance at the neighboring areas close to the construction sites. To begin with, the suitable location of the control sources is found when the total squared pressure is minimized at the positions of noise receivers. The suitable location of the error sensors is, then, found when the control sources are fixed at the position of the previous step and the total squared pressure is minimized at the error sensors. The best location for the error sensors is defined when the maximum reduction is achieved in the target area. It is observed that suitable positions for the transducers depend on the location of target areas for noise control, the position of the noise source, and its operating frequency. In this investigation, a unique configuration is proposed for the transducers that achieves a comparable reduction both at the street area and the neighboring buildings, simultaneously. The results show that the active noise barrier with a height of 2.5 m can achieve an extra insertion loss in the street zone, varies from 9.3 to 16.4 dB (in comparison with passive noise barrier) when the distance of the noise source from the barrier changes in the range of 7 to 1 m, respectively. Those values are of the same order for the passive noise attenuation. Furthermore, similar results are achieved when attempting to cancel the shadow zone of a façade 15 m away from the barrier.

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AUTOREGRESSIVE MODELING OF BIOLOGICAL PHENOMENA

Biophysical Reviews and Letters ◽

10.1142/s1793048010001172 ◽

2010 ◽

Vol 05 (03) ◽

pp. 109-128 ◽

Cited By ~ 1

Author(s):

VASILE V. MORARIU ◽

CĂLIN VAMOŞ ◽

ŞTEFAN ŞOLTUZ ◽

ALEXANDRU POP ◽

LUIZA BUIMAGĂ-IARINCA ◽

...

Keyword(s):

Power Laws ◽

Cell Biophysics ◽

Natural Phenomena ◽

Spatial Correlations ◽

Low Frequencies ◽

High Frequencies ◽

Microbial Genomes ◽

First Order ◽

Biological Phenomena ◽

Different Types

Many natural phenomena can be described by power-laws of temporal or spatial correlations. The equivalence in frequency domain is the 1/f spectrum. A closer look at various experimental data reveals more or less significant deviations from a 1/f characteristic. Such deviations are especially evident at low frequencies and less evident at high frequencies where spectra are very noisy. We exemplify such cases with four different types of phenomena offered by molecular biology (series of coding sequence lengths from microbial genomes, series of the atomic mobility of the protein main chain), cell biophysics (flickering of red blood cells), cognitive psychology (mentally generated series of apparent random numbers) and astrophysics (the X-ray flux variability of a galaxy). All these examples appear to be described by autoregressive models of the first-order AR(1) or higher-order models. This further shows that a spectrum needs to be first subjected to averaging as, long ago, suggested by Mandelbrot otherwise the spectra can be more or less easily confused and/or approximated by power-laws.

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Integration of Bass Enhancement and Active Noise Control System in Automobile Cabin

Advances in Acoustics and Vibration ◽

10.1155/2008/869130 ◽

2008 ◽

Vol 2008 ◽

pp. 1-9 ◽

Cited By ~ 4

Author(s):

Liang Wang ◽

Woon Seng Gan ◽

Sen M. Kuo

Keyword(s):

Control System ◽

Noise Suppression ◽

Noise Control ◽

Active Noise Control ◽

Low Frequency ◽

Audio Signal ◽

Digital Signal ◽

Processing Technologies ◽

Active Noise

With the advancement of digital signal processing technologies, consumers are more concerned with the quality of multimedia entertainment in automobiles. In order to meet this demand, an audio enhancement system is needed to improve bass reproduction and cancel engine noise in the cabins. This paper presents an integrated active noise control system that is based on frequency-sampling filters to track and extract the bass information from the audio signal, and a multifrequency active noise equalizer to tune the low-frequency engine harmonics to enhance the bass reproduction. In the noise cancellation mode, a maximum of 3 dB bass enhancement can be achieved with significant noise suppression, while higher bass enhancement can be achieved in the bass enhance mode. The results show that the proposed system is effective for solving both the bass audio reproduction and the noise control problems in automobile cabins.

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