http://en.wikipedia.org/wiki/Sinc_filter brick-wall brick-wall filter sinc filter Sinc filter sinc filters en.wikipedia.org/wiki/Sinc_filter English English 英語版 Sinc filter English 英語版 brick-wall filter sinc en.wikipedia.org/wiki/Sinc_filter Sinc filter brick-wall Ideal filters English English http://en.wikipedia.org/wiki/Sinc_filter