From candersson@inria.fr Sun May 14 16:34:56 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!inria!candersson From: candersson@inria.fr (Callum Andersson) Newsgroups: comp.dsp Subject: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995May14.163456.6826@inria.fr> Date: Sun, 14 May 1995 16:34:56 GMT Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N 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. MATLAB script available upon request via email. -- Callum Andersson Opinions expressed are solely my own and not those of INRIA Rocquencourt. ------------------------------------------------------------ From shughes@ox.ac.uk Mon May 15 09:18:56 1995 Path: ashpoly!cascade!brgate!saturno!ox!shughes From: shughes@ox.ac.uk (Sven Hughes) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995May15.091856.9069@ox.ac.uk> Date: Mon, 15 May 1995 09:18:56 GMT References: <1995May14.163456.6826@inria.fr> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995May14.163456.6826@inria.fr>, candersson@inria.fr (Callum Andersson) 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. Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns. -- Sven Hughes -- Oxford University Computing Laboratory "There are 14 nodes and only 10 countries. Count again." From ngirard@utexas.edu Tue May 16 13:28:56 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!utexas!ngirard From: ngirard@utexas.edu (Nadine Girard) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995May16.132856.3441@utexas.edu> Date: Tue, 16 May 1995 13:28:56 GMT References: <1995May14.163456.6826@inria.fr> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1995May14.163456.6826@inria.fr>, candersson@inria.fr (Callum Andersson) 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. -- Nadine Girard | ngirard@utexas.edu PGP Key fingerprint: E9B0 92CB 25E2 B176 "Keep the channels open." From bandersson@uni-hamburg.de Thu May 18 06:12:56 1995 Path: ashpoly!cascade!mxgate!coyoacan!uni-hamburg!bandersson From: bandersson@uni-hamburg.de (Brian Andersson) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995May18.061256.5138@uni-hamburg.de> Date: Thu, 18 May 1995 06:12:56 GMT References: <1995May14.163456.6826@inria.fr> <1995May15.091856.9069@ox.ac.uk> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: NewsWatcher 2.0b24 Lines: 12 In article <1995May15.091856.9069@ox.ac.uk>, shughes@ox.ac.uk (Sven Hughes) 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. > Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- Brian Andersson "5 sigma is a discovery. 7 is a question." PC-9821Ap2 (NEC) / FreeBSD 2.1