From givanov@titech.ac.jp Thu Dec 14 17:04:14 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!titech!givanov From: givanov@titech.ac.jp (Graham Ivanov) Newsgroups: comp.dsp Subject: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec14.170414.9276@titech.ac.jp> Date: Thu, 14 Dec 1995 17:04:14 GMT Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp 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 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. What sampling rates are people using for their vinyl rips? 44.1 kHz or 48 kHz DAT? -- Graham Ivanov Opinions expressed are solely my own and not those of Tokyo Institute of Technology Computer Centre. ------------------------------------------------------------ From ntanaka@uu.net Fri Dec 15 18:36:14 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!uu!ntanaka From: ntanaka@uu.net (Nadine Tanaka) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec15.183614.3153@uu.net> Date: Fri, 15 Dec 1995 18:36:14 GMT References: <1995Dec14.170414.9276@titech.ac.jp> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Dec14.170414.9276@titech.ac.jp>, givanov@titech.ac.jp (Graham Ivanov) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. > A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Nadine Tanaka Tape trading list upon request. SASE required for international mail. From alarsson@hanse.de Sat Dec 16 01:58:14 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!hanse!alarsson From: alarsson@hanse.de (Andrei Larsson) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec16.015814.4257@hanse.de> Date: Sat, 16 Dec 1995 01:58:14 GMT References: <1995Dec14.170414.9276@titech.ac.jp> <1995Dec15.183614.3153@uu.net> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1995Dec15.183614.3153@uu.net>, ntanaka@uu.net (Nadine Tanaka) writes: > Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. -- Andrei Larsson Tape trading list upon request. SASE required for international mail. From twatanabe@ox.ac.uk Sat Dec 16 13:07:14 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!ox!twatanabe From: twatanabe@ox.ac.uk (Tobias Watanabe) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec16.130714.5781@ox.ac.uk> Date: Sat, 16 Dec 1995 13:07:14 GMT References: <1995Dec14.170414.9276@titech.ac.jp> <1995Dec15.183614.3153@uu.net> <1995Dec16.015814.4257@hanse.de> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Dec16.015814.4257@hanse.de>, alarsson@hanse.de (Andrei Larsson) 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. -- Tobias Watanabe "A soul is not exclusive to biology." Pentium 90 (OS/2 Warp) / AmigaOS 3.1