From gwatanabe@purdue.edu Thu Jan 26 03:56:18 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!purdue!gwatanabe From: gwatanabe@purdue.edu (Göran Watanabe) Newsgroups: comp.dsp Subject: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jan26.035618.5207@purdue.edu> Date: Thu, 26 Jan 1995 03:56:18 GMT Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. At 14.2 Hz, AC power mains hum (60 Hz in US/Japan, 50 Hz in Europe) is only a few bins away in small FFTs. MATLAB script available upon request via email. -- Göran Watanabe Opinions expressed are solely my own and not those of Purdue University Engineering Computer Network. ------------------------------------------------------------ From tsokolov@kiae.su Thu Jan 26 08:01:18 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!kiae!tsokolov From: tsokolov@kiae.su (Tyler Sokolov) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jan26.080118.2203@kiae.su> Date: Thu, 26 Jan 1995 08:01:18 GMT References: <1995Jan26.035618.5207@purdue.edu> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Jan26.035618.5207@purdue.edu>, gwatanabe@purdue.edu (Göran Watanabe) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Tyler Sokolov *PLONK* filter active for trolls. PC-9821Ap2 (NEC) - NetBSD 1.0 From jramirez@pipeline.com Sat Jan 28 06:25:18 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!pipeline!jramirez From: jramirez@pipeline.com (Ji-woo Ramírez) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jan28.062518.1493@pipeline.com> Date: Sat, 28 Jan 1995 06:25:18 GMT References: <1995Jan26.035618.5207@purdue.edu> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Jan26.035618.5207@purdue.edu>, gwatanabe@purdue.edu (Göran Watanabe) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. Don't forget that if you downsample to 64 Hz first, your FFT resolution jumps to 0.015 Hz per bin with a modest 4096-point transform. -- Ji-woo Ramírez "Hardware is temporary. The signal survives." Acorn RiscPC 600 / Linux 1.2.13