From tlarsson@clari.net Wed Apr 05 19:36:03 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!clari!tlarsson From: tlarsson@clari.net (Tyler Larsson) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr05.193603.1059@clari.net> Date: Wed, 05 Apr 1995 19:36:03 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: WinVN 0.99.5 Lines: 11 Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. 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. A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. MATLAB script available upon request via email. -- Tyler Larsson Opinions expressed are solely my own and not those of ClariNet Communications Corp. ------------------------------------------------------------ From scampbell@illinois.edu Thu Apr 06 12:47:03 1995 Path: ashpoly!cascade!transat!ukc!fennimore!illinois!scampbell From: scampbell@illinois.edu (Steve Campbell) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr06.124703.2384@illinois.edu> Date: Thu, 06 Apr 1995 12:47:03 GMT References: <1995Apr05.193603.1059@clari.net> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Apr05.193603.1059@clari.net>, tlarsson@clari.net (Tyler Larsson) 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. -- Steve Campbell Zyxel U-1496E @ ISDN 64k bps "We don't sign stars. We build them." From anovak@clari.net Thu Apr 06 17:59:03 1995 Path: ashpoly!cascade!mxgate!coyoacan!clari!anovak From: anovak@clari.net (Anton Novak) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr06.175903.6066@clari.net> Date: Thu, 06 Apr 1995 17:59:03 GMT References: <1995Apr05.193603.1059@clari.net> <1995Apr06.124703.2384@illinois.edu> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Apr06.124703.2384@illinois.edu>, scampbell@illinois.edu (Steve Campbell) 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. -- Anton Novak Tape trading list upon request. SASE required for international mail. From hrobertson@pipeline.com Thu Apr 06 19:48:03 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!pipeline!hrobertson From: hrobertson@pipeline.com (Hugo Robertson) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr06.194803.8808@pipeline.com> Date: Thu, 06 Apr 1995 19:48:03 GMT References: <1995Apr05.193603.1059@clari.net> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Apr05.193603.1059@clari.net>, tlarsson@clari.net (Tyler Larsson) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. > 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. 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. -- Hugo Robertson *PLONK* filter active for trolls. Atari Falcon 030 - NetBSD 1.0