From tnakamura@uni-hamburg.de Sat Jun 01 10:22:25 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!uni-hamburg!tnakamura From: tnakamura@uni-hamburg.de (Tyler Nakamura) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Jun01.102225.3071@uni-hamburg.de> Date: Sat, 01 Jun 1996 10:22:25 GMT Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: WinVN 0.99.5 Lines: 11 A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. 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. -- Tyler Nakamura *PLONK* filter active for trolls. Atari Falcon 030 - NetBSD 1.0 From iperez@inria.fr Mon Jun 03 03:28:25 1996 Path: ashpoly!cascade!mxgate!coyoacan!inria!iperez From: iperez@inria.fr (Ines Pérez) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Jun03.032825.4559@inria.fr> Date: Mon, 03 Jun 1996 03:28:25 GMT References: <1996Jun01.102225.3071@uni-hamburg.de> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Jun01.102225.3071@uni-hamburg.de>, tnakamura@uni-hamburg.de (Tyler Nakamura) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Ines Pérez Opinions expressed are solely my own and not those of INRIA Rocquencourt. ------------------------------------------------------------ From psuzuki@stanford.edu Tue Jun 04 15:01:25 1996 Path: ashpoly!cascade!brgate!saturno!stanford!psuzuki From: psuzuki@stanford.edu (Pavel Suzuki) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Jun04.150125.6190@stanford.edu> Date: Tue, 04 Jun 1996 15:01:25 GMT References: <1996Jun01.102225.3071@uni-hamburg.de> <1996Jun03.032825.4559@inria.fr> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1996Jun03.032825.4559@inria.fr>, iperez@inria.fr (Ines Pérez) 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. -- Pavel Suzuki Tape trading list upon request. SASE required for international mail. From afournier@pacbell.net Tue Jun 04 22:42:25 1996 Path: ashpoly!cascade!bigsur!pacbell!afournier From: afournier@pacbell.net (Aiko Fournier) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Jun04.224225.2083@pacbell.net> Date: Tue, 04 Jun 1996 22:42:25 GMT References: <1996Jun01.102225.3071@uni-hamburg.de> <1996Jun03.032825.4559@inria.fr> <1996Jun04.150125.6190@stanford.edu> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Jun04.150125.6190@stanford.edu>, psuzuki@stanford.edu (Pavel Suzuki) 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. -- Aiko Fournier *PLONK* filter active for trolls. NeXTstation Turbo Color - NetBSD 1.0