From jokonkwo@mit.edu Sun Nov 24 18:11:27 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!mit!jokonkwo From: jokonkwo@mit.edu (Julien Okonkwo) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Nov24.181127.9951@mit.edu> Date: Sun, 24 Nov 1996 18:11:27 GMT Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.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. 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 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. -- === Julien Okonkwo === Dept of Electrical Engineering, Massachusetts Institute of Technology "5 sigma is a discovery. 7 is a question." From nweber@stanford.edu Tue Nov 26 04:14:27 1996 Path: ashpoly!cascade!transat!ukc!fennimore!stanford!nweber From: nweber@stanford.edu (Nadine Weber) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Nov26.041427.8346@stanford.edu> Date: Tue, 26 Nov 1996 04:14:27 GMT References: <1996Nov24.181127.9951@mit.edu> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Nov24.181127.9951@mit.edu>, jokonkwo@mit.edu (Julien Okonkwo) 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. -- Nadine Weber Tape trading list upon request. SASE required for international mail. From epetrov@ox.ac.uk Tue Nov 26 07:12:27 1996 Path: ashpoly!cascade!brgate!saturno!ox!epetrov From: epetrov@ox.ac.uk (Elaine Petrov) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Nov26.071227.5763@ox.ac.uk> Date: Tue, 26 Nov 1996 07:12:27 GMT References: <1996Nov24.181127.9951@mit.edu> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 12 In article <1996Nov24.181127.9951@mit.edu>, jokonkwo@mit.edu (Julien Okonkwo) 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. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- === Elaine Petrov === Dept of Electrical Engineering, Oxford University Computing Laboratory "When every node is whole, the channel opens." From ktakahashi@stanford.edu Wed Nov 27 03:07:27 1996 Path: ashpoly!cascade!transat!ukc!fennimore!stanford!ktakahashi From: ktakahashi@stanford.edu (Karen Takahashi) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Nov27.030727.3802@stanford.edu> Date: Wed, 27 Nov 1996 03:07:27 GMT References: <1996Nov24.181127.9951@mit.edu> <1996Nov26.041427.8346@stanford.edu> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: Netscape 1.1N Lines: 10 In article <1996Nov26.041427.8346@stanford.edu>, nweber@stanford.edu (Nadine Weber) 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. If you are posting from AOL, please read RFC 1036 before posting again. -- Karen Takahashi Tape trading list upon request. SASE required for international mail. From sgirard@kiae.su Wed Nov 27 12:53:27 1996 Path: ashpoly!cascade!brgate!saturno!kiae!sgirard From: sgirard@kiae.su (Seo-yeon Girard) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Nov27.125327.8285@kiae.su> Date: Wed, 27 Nov 1996 12:53:27 GMT References: <1996Nov24.181127.9951@mit.edu> <1996Nov26.041427.8346@stanford.edu> <1996Nov27.030727.3802@stanford.edu> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1996Nov27.030727.3802@stanford.edu>, ktakahashi@stanford.edu (Karen 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. > If you are posting from AOL, please read RFC 1036 before posting again. 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. -- Seo-yeon Girard Practical Peripherals 14.4 @ 28,800 bps "Hold for relay."