From gito@mit.edu Mon Aug 19 08:17:00 1996 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!mit!gito From: gito@mit.edu (Göran Ito) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug19.081700.9463@mit.edu> Date: Mon, 19 Aug 1996 08:17:00 GMT Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: WinVN 0.99.5 Lines: 11 A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Göran Ito Opinions expressed are solely my own and not those of Massachusetts Institute of Technology. ------------------------------------------------------------ From llee@demon.co.uk Mon Aug 19 09:46:00 1996 Path: ashpoly!cascade!bigsur!demon!llee From: llee@demon.co.uk (Lars Lee) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug19.094600.8188@demon.co.uk> Date: Mon, 19 Aug 1996 09:46:00 GMT References: <1996Aug19.081700.9463@mit.edu> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: Netscape 1.1N Lines: 10 In article <1996Aug19.081700.9463@mit.edu>, gito@mit.edu (Göran Ito) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. > A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Lars Lee *PLONK* filter active for trolls. Mac IIci / 68882 FPU - NetBSD 1.0 From gstewart@mindspring.com Wed Aug 21 09:36:00 1996 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!mindspring!gstewart From: gstewart@mindspring.com (Göran Stewart) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug21.093600.1235@mindspring.com> Date: Wed, 21 Aug 1996 09:36:00 GMT References: <1996Aug19.081700.9463@mit.edu> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1996Aug19.081700.9463@mit.edu>, gito@mit.edu (Göran Ito) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. 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. -- Göran Stewart -- MindSpring Enterprises "Row 14. No joke." From cfournier@uni-hamburg.de Thu Aug 22 07:14:00 1996 Path: ashpoly!cascade!brgate!saturno!uni-hamburg!cfournier From: cfournier@uni-hamburg.de (Camila Fournier) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug22.071400.3440@uni-hamburg.de> Date: Thu, 22 Aug 1996 07:14:00 GMT References: <1996Aug19.081700.9463@mit.edu> <1996Aug19.094600.8188@demon.co.uk> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Aug19.094600.8188@demon.co.uk>, llee@demon.co.uk (Lars Lee) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Camila Fournier | cfournier@uni-hamburg.de PGP Key fingerprint: 5180 7D8B 2D3E CA96 "Keep the channels open." From nhughes@u-tokyo.ac.jp Sat Aug 24 10:23:00 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!u-tokyo!nhughes From: nhughes@u-tokyo.ac.jp (Natalia Hughes) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug24.102300.8786@u-tokyo.ac.jp> Date: Sat, 24 Aug 1996 10:23:00 GMT References: <1996Aug19.081700.9463@mit.edu> <1996Aug19.094600.8188@demon.co.uk> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Aug19.094600.8188@demon.co.uk>, llee@demon.co.uk (Lars Lee) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. 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. -- Natalia Hughes "Hold for relay." PC-9821Ap2 (NEC) / NEXTSTEP 3.3