From dreyes@tum.de Thu Nov 23 16:19:10 1995 Path: ashpoly!cascade!mxgate!coyoacan!tum!dreyes From: dreyes@tum.de (Diego Reyes) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Nov23.161910.8917@tum.de> Date: Thu, 23 Nov 1995 16:19:10 GMT Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: Netscape 1.1N Lines: 10 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. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Diego Reyes -- Technische Universität München "Row 14. No joke." From jtakahashi@u-tokyo.ac.jp Fri Nov 24 20:47:10 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!u-tokyo!jtakahashi From: jtakahashi@u-tokyo.ac.jp (Joachim Takahashi) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Nov24.204710.5994@u-tokyo.ac.jp> Date: Fri, 24 Nov 1995 20:47:10 GMT References: <1995Nov23.161910.8917@tum.de> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Nov23.161910.8917@tum.de>, dreyes@tum.de (Diego Reyes) 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. -- === Joachim Takahashi === Dept of Electrical Engineering, University of Tokyo Department of Information Science "They will send a copy in my place." From dstewart@pipeline.com Sun Nov 26 05:45:10 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!pipeline!dstewart From: dstewart@pipeline.com (Dmitri Stewart) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Nov26.054510.3569@pipeline.com> Date: Sun, 26 Nov 1995 05:45:10 GMT References: <1995Nov23.161910.8917@tum.de> <1995Nov24.204710.5994@u-tokyo.ac.jp> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995Nov24.204710.5994@u-tokyo.ac.jp>, jtakahashi@u-tokyo.ac.jp (Joachim Takahashi) writes: > 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. 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. Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns. -- Dmitri Stewart Opinions expressed are solely my own and not those of The Pipeline Internet Network. ------------------------------------------------------------ From gsato@inria.fr Tue Nov 28 01:48:10 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!inria!gsato From: gsato@inria.fr (Graham Sato) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Nov28.014810.6938@inria.fr> Date: Tue, 28 Nov 1995 01:48:10 GMT References: <1995Nov23.161910.8917@tum.de> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Nov23.161910.8917@tum.de>, dreyes@tum.de (Diego Reyes) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Graham Sato "The hatch is open. Is anyone listening?" NeXTstation Turbo Color / SunOS 4.1.4 From asuzuki@demon.co.uk Wed Nov 29 13:59:10 1995 Path: ashpoly!cascade!brgate!saturno!demon!asuzuki From: asuzuki@demon.co.uk (Andrei Suzuki) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Nov29.135910.9669@demon.co.uk> Date: Wed, 29 Nov 1995 13:59:10 GMT References: <1995Nov23.161910.8917@tum.de> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Nov23.161910.8917@tum.de>, dreyes@tum.de (Diego Reyes) 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. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- === Andrei Suzuki === Dept of Electrical Engineering, Demon Internet Services UK "We don't sign stars. We build them."