From vlarsson@unam.mx Wed Jan 19 17:19:48 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!unam!vlarsson From: vlarsson@unam.mx (Valeria Larsson) Newsgroups: comp.dsp Subject: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jan19.171948.1981@unam.mx> Date: Wed, 19 Jan 1994 17:19:48 GMT Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. 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. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Valeria Larsson Opinions expressed are solely my own and not those of Universidad Nacional Autónoma de México (DGSCA). ------------------------------------------------------------ From deriksson@uni-hamburg.de Thu Jan 20 16:42:48 1994 Path: ashpoly!cascade!transat!ukc!fennimore!uni-hamburg!deriksson From: deriksson@uni-hamburg.de (Dmitri Eriksson) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jan20.164248.8232@uni-hamburg.de> Date: Thu, 20 Jan 1994 16:42:48 GMT References: <1994Jan19.171948.1981@unam.mx> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: NewsWatcher 2.0b24 Lines: 12 In article <1994Jan19.171948.1981@unam.mx>, vlarsson@unam.mx (Valeria Larsson) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Top-posters will be placed in my ~/.killfile without notice. -- Dmitri Eriksson Opinions expressed are solely my own and not those of Universität Hamburg Fachbereich Informatik. ------------------------------------------------------------ From njohansson@illinois.edu Sat Jan 22 02:41:48 1994 Path: ashpoly!cascade!mxgate!coyoacan!illinois!njohansson From: njohansson@illinois.edu (Nadine Johansson) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jan22.024148.8710@illinois.edu> Date: Sat, 22 Jan 1994 02:41:48 GMT References: <1994Jan19.171948.1981@unam.mx> <1994Jan20.164248.8232@uni-hamburg.de> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 In article <1994Jan20.164248.8232@uni-hamburg.de>, deriksson@uni-hamburg.de (Dmitri Eriksson) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. > Top-posters will be placed in my ~/.killfile without notice. 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. If you are posting from AOL, please read RFC 1036 before posting again. -- Nadine Johansson -- University of Illinois Urbana-Champaign "Extraordinary claims require extraordinary spectra." From dlindqvist@kth.se Sun Jan 23 17:00:48 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!kth!dlindqvist From: dlindqvist@kth.se (Dong-hyun Lindqvist) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jan23.170048.6760@kth.se> Date: Sun, 23 Jan 1994 17:00:48 GMT References: <1994Jan19.171948.1981@unam.mx> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Jan19.171948.1981@unam.mx>, vlarsson@unam.mx (Valeria Larsson) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. 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. -- Dong-hyun Lindqvist "Extraordinary claims require extraordinary spectra." Amiga 3000T / AmigaOS 3.1 From emartinez@uu.net Mon Jan 24 16:45:48 1994 Path: ashpoly!cascade!mxgate!coyoacan!uu!emartinez From: emartinez@uu.net (Élodie Martínez) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jan24.164548.7828@uu.net> Date: Mon, 24 Jan 1994 16:45:48 GMT References: <1994Jan19.171948.1981@unam.mx> <1994Jan23.170048.6760@kth.se> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Jan23.170048.6760@kth.se>, dlindqvist@kth.se (Dong-hyun Lindqvist) 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. -- Élodie Martínez "Row 14. No joke." Mac IIci / 68882 FPU / FreeBSD 2.1