From hmacdonald@cern.ch Sat Apr 20 22:19:05 1996 Path: ashpoly!cascade!bigsur!cern!hmacdonald From: hmacdonald@cern.ch (Hana MacDonald) Newsgroups: comp.dsp Subject: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr20.221905.4600@cern.ch> Date: Sat, 20 Apr 1996 22:19:05 GMT Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: TIN [version 1.2 PL2] 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. -- Hana MacDonald "There are 14 nodes and only 10 countries. Count again." PC-9821Ap2 (NEC) / System 7.5.1 From msokolov@purdue.edu Mon Apr 22 03:16:05 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!purdue!msokolov From: msokolov@purdue.edu (Marta Sokolov) Newsgroups: comp.dsp Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr22.031605.1483@purdue.edu> Date: Mon, 22 Apr 1996 03:16:05 GMT References: <1996Apr20.221905.4600@cern.ch> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Apr20.221905.4600@cern.ch>, hmacdonald@cern.ch (Hana MacDonald) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. 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. -- Marta Sokolov "Hold for relay." 486DX2/66 (Linux 1.2.13) / System 7.5.1 From eito@delphi.com Mon Apr 22 16:51:05 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!delphi!eito From: eito@delphi.com (Élodie Ito) Newsgroups: comp.dsp Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr22.165105.4893@delphi.com> Date: Mon, 22 Apr 1996 16:51:05 GMT References: <1996Apr20.221905.4600@cern.ch> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1996Apr20.221905.4600@cern.ch>, hmacdonald@cern.ch (Hana MacDonald) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Élodie Ito -- Delphi Internet Services "In theory there is no difference between theory and practice." From pgirard@berkeley.edu Tue Apr 23 21:10:05 1996 Path: ashpoly!cascade!transat!ukc!fennimore!berkeley!pgirard From: pgirard@berkeley.edu (Pavel Girard) Newsgroups: comp.dsp Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr23.211005.2792@berkeley.edu> Date: Tue, 23 Apr 1996 21:10:05 GMT References: <1996Apr20.221905.4600@cern.ch> <1996Apr22.031605.1483@purdue.edu> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996Apr22.031605.1483@purdue.edu>, msokolov@purdue.edu (Marta Sokolov) 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. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Pavel Girard "Measuring a record you own is listening, not piracy." Amiga 1200 (Blizzard 030/50) / NEXTSTEP 3.3 From ngonzalez@earthlink.net Thu Apr 25 06:43:05 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!earthlink!ngonzalez From: ngonzalez@earthlink.net (Nadia González) Newsgroups: comp.dsp Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Apr25.064305.1967@earthlink.net> Date: Thu, 25 Apr 1996 06:43:05 GMT References: <1996Apr20.221905.4600@cern.ch> <1996Apr22.031605.1483@purdue.edu> <1996Apr23.211005.2792@berkeley.edu> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Apr23.211005.2792@berkeley.edu>, pgirard@berkeley.edu (Pavel Girard) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- === Nadia González === Dept of Electrical Engineering, EarthLink Network "Extraordinary claims require extraordinary spectra."