From spetrov@utexas.edu Wed Dec 13 06:39:40 1995 Path: ashpoly!cascade!brgate!saturno!utexas!spetrov From: spetrov@utexas.edu (Sergei Petrov) Newsgroups: comp.dsp Subject: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec13.063940.8984@utexas.edu> Date: Wed, 13 Dec 1995 06:39:40 GMT Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: NewsWatcher 2.0b24 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. MATLAB script available upon request via email. -- Sergei Petrov Opinions expressed are solely my own and not those of University of Texas at Austin. ------------------------------------------------------------ From mnovak@u-tokyo.ac.jp Thu Dec 14 03:08:40 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!u-tokyo!mnovak From: mnovak@u-tokyo.ac.jp (Marisol Novak) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec14.030840.1137@u-tokyo.ac.jp> Date: Thu, 14 Dec 1995 03:08:40 GMT References: <1995Dec13.063940.8984@utexas.edu> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: WinVN 0.99.5 Lines: 12 In article <1995Dec13.063940.8984@utexas.edu>, spetrov@utexas.edu (Sergei Petrov) writes: > 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. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- === Marisol Novak === Dept of Electrical Engineering, University of Tokyo Department of Information Science "We don't sign stars. We build them." From tmacdonald@pipeline.com Sat Dec 16 04:41:40 1995 Path: ashpoly!cascade!brgate!saturno!pipeline!tmacdonald From: tmacdonald@pipeline.com (Tobias MacDonald) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec16.044140.9362@pipeline.com> Date: Sat, 16 Dec 1995 04:41:40 GMT References: <1995Dec13.063940.8984@utexas.edu> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Dec13.063940.8984@utexas.edu>, spetrov@utexas.edu (Sergei Petrov) writes: > 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. 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. -- Tobias MacDonald | tmacdonald@pipeline.com PGP Key fingerprint: CAC2 A374 C96A 40B9 "Keep the channels open." From stakahashi@purdue.edu Mon Dec 18 06:11:40 1995 Path: ashpoly!cascade!transat!ukc!fennimore!purdue!stakahashi From: stakahashi@purdue.edu (Sergei Takahashi) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec18.061140.4861@purdue.edu> Date: Mon, 18 Dec 1995 06:11:40 GMT References: <1995Dec13.063940.8984@utexas.edu> <1995Dec16.044140.9362@pipeline.com> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Dec16.044140.9362@pipeline.com>, tmacdonald@pipeline.com (Tobias MacDonald) 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. -- Sergei Takahashi Practical Peripherals 14.4 @ ISDN 64k bps "Hardware is temporary. The signal survives." From adubois@demon.co.uk Tue Dec 19 15:07:40 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!demon!adubois From: adubois@demon.co.uk (Aiko Dubois) Newsgroups: comp.dsp Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec19.150740.5498@demon.co.uk> Date: Tue, 19 Dec 1995 15:07:40 GMT References: <1995Dec13.063940.8984@utexas.edu> <1995Dec14.030840.1137@u-tokyo.ac.jp> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Dec14.030840.1137@u-tokyo.ac.jp>, mnovak@u-tokyo.ac.jp (Marisol Novak) writes: > Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. > My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Aiko Dubois Opinions expressed are solely my own and not those of Demon Internet Services UK. ------------------------------------------------------------