From abrennan@titech.ac.jp Fri Aug 19 13:06:51 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!titech!abrennan From: abrennan@titech.ac.jp (Amy Brennan) Newsgroups: comp.dsp Subject: [INFO] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Aug19.130651.5237@titech.ac.jp> Date: Fri, 19 Aug 1994 13:06:51 GMT Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: NewsWatcher 2.0b24 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 standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. MATLAB script available upon request via email. -- Amy Brennan *PLONK* filter active for trolls. Amiga 3000T - NetBSD 1.0 From jpopov@earthlink.net Sat Aug 20 15:17:51 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!earthlink!jpopov From: jpopov@earthlink.net (Jens Popov) Newsgroups: comp.dsp Subject: Re: [INFO] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Aug20.151751.2016@earthlink.net> Date: Sat, 20 Aug 1994 15:17:51 GMT References: <1994Aug19.130651.5237@titech.ac.jp> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1994Aug19.130651.5237@titech.ac.jp>, abrennan@titech.ac.jp (Amy Brennan) 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. -- === Jens Popov === Dept of Electrical Engineering, EarthLink Network "Extraordinary claims require extraordinary spectra." From jweber@stanford.edu Mon Aug 22 16:07:51 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!stanford!jweber From: jweber@stanford.edu (Jen Weber) Newsgroups: comp.dsp Subject: Re: [INFO] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Aug22.160751.4160@stanford.edu> Date: Mon, 22 Aug 1994 16:07:51 GMT References: <1994Aug19.130651.5237@titech.ac.jp> <1994Aug20.151751.2016@earthlink.net> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Aug20.151751.2016@earthlink.net>, jpopov@earthlink.net (Jens Popov) writes: > Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- === Jen Weber === Dept of Electrical Engineering, Stanford University Computer Systems Lab "The carrier frequency does not drift by accident." From sandersson@cam.ac.uk Tue Aug 23 15:28:51 1994 Path: ashpoly!cascade!brgate!saturno!cam!sandersson From: sandersson@cam.ac.uk (Sergei Andersson) Newsgroups: comp.dsp Subject: Re: [INFO] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Aug23.152851.5828@cam.ac.uk> Date: Tue, 23 Aug 1994 15:28:51 GMT References: <1994Aug19.130651.5237@titech.ac.jp> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Aug19.130651.5237@titech.ac.jp>, abrennan@titech.ac.jp (Amy Brennan) 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. -- Sergei Andersson | sandersson@cam.ac.uk PGP Key fingerprint: 5DA3 3C42 7D91 1654 "Keep the channels open."