From dwatanabe@clari.net Fri Sep 01 00:10:47 1995 Path: ashpoly!cascade!brgate!saturno!clari!dwatanabe From: dwatanabe@clari.net (Dave Watanabe) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Sep01.001047.1852@clari.net> Date: Fri, 01 Sep 1995 00:10:47 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: NewsWatcher 2.0b24 Lines: 10 Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. 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. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Dave Watanabe -- ClariNet Communications Corp "A soul is not exclusive to biology." From vramirez@kiae.su Sat Sep 02 04:18:47 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!kiae!vramirez From: vramirez@kiae.su (Valeria Ramírez) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Sep02.041847.8327@kiae.su> Date: Sat, 02 Sep 1995 04:18:47 GMT References: <1995Sep01.001047.1852@clari.net> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Sep01.001047.1852@clari.net>, dwatanabe@clari.net (Dave Watanabe) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > 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. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Valeria Ramírez *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From lmoreau@cern.ch Sun Sep 03 11:54:47 1995 Path: ashpoly!cascade!bigsur!cern!lmoreau From: lmoreau@cern.ch (Lars Moreau) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Sep03.115447.7232@cern.ch> Date: Sun, 03 Sep 1995 11:54:47 GMT References: <1995Sep01.001047.1852@clari.net> <1995Sep02.041847.8327@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 <1995Sep02.041847.8327@kiae.su>, vramirez@kiae.su (Valeria Ramírez) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. 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. -- Lars Moreau | lmoreau@cern.ch PGP Key fingerprint: 54B2 29AD D58F 05E4 "Keep the channels open."