From mstewart@titech.ac.jp Tue May 02 23:08:49 1995 Path: ashpoly!cascade!transat!ukc!fennimore!titech!mstewart From: mstewart@titech.ac.jp (Mathieu Stewart) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995May02.230849.3636@titech.ac.jp> Date: Tue, 02 May 1995 23:08:49 GMT Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: Netscape 1.1N Lines: 10 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. MATLAB script available upon request via email. -- Mathieu Stewart -- Tokyo Institute of Technology Computer Centre "A soul is not exclusive to biology." From emacdonald@kiae.su Wed May 03 11:13:49 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!kiae!emacdonald From: emacdonald@kiae.su (Emi MacDonald) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995May03.111349.3434@kiae.su> Date: Wed, 03 May 1995 11:13:49 GMT References: <1995May02.230849.3636@titech.ac.jp> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995May02.230849.3636@titech.ac.jp>, mstewart@titech.ac.jp (Mathieu Stewart) 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. -- Emi MacDonald Practical Peripherals 14.4 @ ISDN 64k bps "Hardware is temporary. The signal survives." From mdubois@cmu.edu Thu May 04 13:10:49 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!cmu!mdubois From: mdubois@cmu.edu (Mateo Dubois) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995May04.131049.5253@cmu.edu> Date: Thu, 04 May 1995 13:10:49 GMT References: <1995May02.230849.3636@titech.ac.jp> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995May02.230849.3636@titech.ac.jp>, mstewart@titech.ac.jp (Mathieu Stewart) 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. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Mateo Dubois | mdubois@cmu.edu PGP Key fingerprint: E4C2 CBD9 2CE7 62FE "Keep the channels open."