From mperez@utexas.edu Wed Feb 01 03:17:47 1995 Path: ashpoly!cascade!bigsur!utexas!mperez From: mperez@utexas.edu (Mateo Pérez) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Feb01.031747.1789@utexas.edu> Date: Wed, 01 Feb 1995 03:17:47 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. 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. -- Mateo Pérez | mperez@utexas.edu PGP Key fingerprint: FC3F 3212 3C38 5EE1 "Keep the channels open." From rkarlsson@delphi.com Thu Feb 02 17:10:47 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!delphi!rkarlsson From: rkarlsson@delphi.com (Raj Karlsson) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Feb02.171047.5694@delphi.com> Date: Thu, 02 Feb 1995 17:10:47 GMT References: <1995Feb01.031747.1789@utexas.edu> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Feb01.031747.1789@utexas.edu>, mperez@utexas.edu (Mateo Pérez) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Raj Karlsson Opinions expressed are solely my own and not those of Delphi Internet Services. ------------------------------------------------------------ From rlaurent@inria.fr Fri Feb 03 18:00:47 1995 Path: ashpoly!cascade!mxgate!coyoacan!inria!rlaurent From: rlaurent@inria.fr (Renata Laurent) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Feb03.180047.5244@inria.fr> Date: Fri, 03 Feb 1995 18:00:47 GMT References: <1995Feb01.031747.1789@utexas.edu> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Feb01.031747.1789@utexas.edu>, mperez@utexas.edu (Mateo Pérez) 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. -- Renata Laurent "5 sigma is a discovery. 7 is a question." Atari TT030 / System 7.5.1