From dandersson@uni-hamburg.de Wed Nov 02 15:53:47 1994 Path: ashpoly!cascade!brgate!saturno!uni-hamburg!dandersson From: dandersson@uni-hamburg.de (Dmitri Andersson) Newsgroups: comp.dsp Subject: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov02.155347.9357@uni-hamburg.de> Date: Wed, 02 Nov 1994 15:53:47 GMT Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. 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. -- === Dmitri Andersson === Dept of Electrical Engineering, Universität Hamburg Fachbereich Informatik "Hold for relay." From jkowalski@hanse.de Fri Nov 04 07:50:47 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!hanse!jkowalski From: jkowalski@hanse.de (Julien Kowalski) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov04.075047.9780@hanse.de> Date: Fri, 04 Nov 1994 07:50:47 GMT References: <1994Nov02.155347.9357@uni-hamburg.de> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Nov02.155347.9357@uni-hamburg.de>, dandersson@uni-hamburg.de (Dmitri Andersson) 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. -- Julien Kowalski *PLONK* filter active for trolls. Decstation 5000/200 - NetBSD 1.0 From epetrov@mit.edu Fri Nov 04 17:21:47 1994 Path: ashpoly!cascade!bigsur!mit!epetrov From: epetrov@mit.edu (Élodie Petrov) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov04.172147.1028@mit.edu> Date: Fri, 04 Nov 1994 17:21:47 GMT References: <1994Nov02.155347.9357@uni-hamburg.de> <1994Nov04.075047.9780@hanse.de> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Nov04.075047.9780@hanse.de>, jkowalski@hanse.de (Julien Kowalski) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Élodie Petrov | epetrov@mit.edu PGP Key fingerprint: 8022 40DD ED01 06FC "Keep the channels open." From mgirard@cam.ac.uk Sun Nov 06 20:27:47 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!cam!mgirard From: mgirard@cam.ac.uk (Morag Girard) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov06.202747.7072@cam.ac.uk> Date: Sun, 06 Nov 1994 20:27:47 GMT References: <1994Nov02.155347.9357@uni-hamburg.de> <1994Nov04.075047.9780@hanse.de> <1994Nov04.172147.1028@mit.edu> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Nov04.172147.1028@mit.edu>, epetrov@mit.edu (Élodie Petrov) writes: > Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 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. -- Morag Girard | mgirard@cam.ac.uk PGP Key fingerprint: F8D5 E51D 6571 5899 "Keep the channels open."