From dsokolov@berkeley.edu Thu Aug 24 07:57:13 1995 Path: ashpoly!cascade!transat!ukc!fennimore!berkeley!dsokolov From: dsokolov@berkeley.edu (Dong-hyun Sokolov) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug24.075713.1147@berkeley.edu> Date: Thu, 24 Aug 1995 07:57:13 GMT Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: WinVN 0.99.5 Lines: 11 Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Dong-hyun Sokolov SupraFAXModem 28.8 @ 14,400 bps "Marcus is not one man." From bkang@cam.ac.uk Fri Aug 25 15:20:13 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!cam!bkang From: bkang@cam.ac.uk (Bastien Kang) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug25.152013.7694@cam.ac.uk> Date: Fri, 25 Aug 1995 15:20:13 GMT References: <1995Aug24.075713.1147@berkeley.edu> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Aug24.075713.1147@berkeley.edu>, dsokolov@berkeley.edu (Dong-hyun Sokolov) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. > 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. -- Bastien Kang *PLONK* filter active for trolls. Macintosh IIfx - NetBSD 1.0 From lsmirnov@tum.de Sun Aug 27 12:45:13 1995 Path: ashpoly!cascade!bigsur!tum!lsmirnov From: lsmirnov@tum.de (Lars Smirnov) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug27.124513.9215@tum.de> Date: Sun, 27 Aug 1995 12:45:13 GMT References: <1995Aug24.075713.1147@berkeley.edu> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Aug24.075713.1147@berkeley.edu>, dsokolov@berkeley.edu (Dong-hyun Sokolov) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Lars Smirnov Opinions expressed are solely my own and not those of Technische Universität München. ------------------------------------------------------------