A Two-Dimensional Clustering Approach to the Analysis of Audible Noises Induced at Telephone Terminals

Masao MASUGI
Kimihiro TAJIMA
Hiroshi YAMANE
Kazuo MURAKAWA

Publication
IEICE TRANSACTIONS on Communications   Vol.E89-B    No.5    pp.1662-1671
Publication Date: 2006/05/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.5.1662
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electromagnetic Compatibility(EMC)
Keyword: 
audible noise,  electromagnetic interference,  self-organizing,  clustering,  

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Summary: 
This paper describes a two-dimensional clustering scheme-based analysis of audible noises induced at telephone terminals. To analyze EMI sources that cause telephone-audible noise, we use a self-organizing map, which provides a way to map high-dimensional data onto a two-dimensional domain. Also, in order to discriminate EMI sources without using particular resonance frequencies that have peaks in the frequency domain, we use the energy spectra of telephone-audible noises as input for training the self-organizing map. In applying this method in actual environments, we measured ten kinds of telephone-audible noises (due to Radio waves and cross-talk noises, etc.) and then derived their energy spectra for eight frequency bands: 1-250 Hz, 250-500 Hz, 500-1 kHz, 1 k-1.5 kHz, 1.5 k-2 kHz, 2 k-3 kHz, 3 k-4 kHz, and over 4 kHz. We visually confirmed that the measured telephone-audible noise data could be projected onto the map in accordance with their properties, resulting in a combined depiction of the composition of derived energy spectra in the frequency bands. The proposed method can deal with multi-dimensional parameters, projecting its results onto a two-dimensional space in which the projected data positions give us an effective depiction of EMI sources that cause disturbances at telephone terminals.