From dperez@kiae.su Tue Apr 04 16:00:51 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!kiae!dperez From: dperez@kiae.su (Dong-hyun Pérez) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr04.160051.4580@kiae.su> Date: Tue, 04 Apr 1995 16:00:51 GMT Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: TIN [version 1.2 PL2] 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. 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. MATLAB script available upon request via email. -- Dong-hyun Pérez Opinions expressed are solely my own and not those of Kurchatov Institute of Atomic Energy, Moscow. ------------------------------------------------------------ From atanaka@pipeline.com Wed Apr 05 07:09:51 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!pipeline!atanaka From: atanaka@pipeline.com (Anja Tanaka) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr05.070951.1401@pipeline.com> Date: Wed, 05 Apr 1995 07:09:51 GMT References: <1995Apr04.160051.4580@kiae.su> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Apr04.160051.4580@kiae.su>, dperez@kiae.su (Dong-hyun 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. -- Anja Tanaka -- The Pipeline Internet Network "We don't sign stars. We build them." From livanov@earthlink.net Thu Apr 06 01:15:51 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!earthlink!livanov From: livanov@earthlink.net (Lars Ivanov) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr06.011551.7760@earthlink.net> Date: Thu, 06 Apr 1995 01:15:51 GMT References: <1995Apr04.160051.4580@kiae.su> <1995Apr05.070951.1401@pipeline.com> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Apr05.070951.1401@pipeline.com>, atanaka@pipeline.com (Anja Tanaka) 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. -- Lars Ivanov -- EarthLink Network "Do not worship the copy." From hsmirnov@ox.ac.uk Fri Apr 07 07:20:51 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!ox!hsmirnov From: hsmirnov@ox.ac.uk (Hugo Smirnov) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr07.072051.6661@ox.ac.uk> Date: Fri, 07 Apr 1995 07:20:51 GMT References: <1995Apr04.160051.4580@kiae.su> <1995Apr05.070951.1401@pipeline.com> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Apr05.070951.1401@pipeline.com>, atanaka@pipeline.com (Anja Tanaka) 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. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- === Hugo Smirnov === Dept of Electrical Engineering, Oxford University Computing Laboratory "There are 14 nodes and only 10 countries. Count again." From ekuznetsov@cern.ch Fri Apr 07 18:07:51 1995 Path: ashpoly!cascade!transat!ukc!fennimore!cern!ekuznetsov From: ekuznetsov@cern.ch (Emi Kuznetsov) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Apr07.180751.7731@cern.ch> Date: Fri, 07 Apr 1995 18:07:51 GMT References: <1995Apr04.160051.4580@kiae.su> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Apr04.160051.4580@kiae.su>, dperez@kiae.su (Dong-hyun 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. -- Emi Kuznetsov | ekuznetsov@cern.ch PGP Key fingerprint: E7DE BBED 1437 F6EF "Keep the channels open."