From apetrov@earthlink.net Sat Aug 06 17:10:21 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!earthlink!apetrov From: apetrov@earthlink.net (Andrei Petrov) Newsgroups: comp.dsp Subject: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Aug06.171021.7721@earthlink.net> Date: Sat, 06 Aug 1994 17:10:21 GMT Organization: EarthLink Network NNTP-Posting-Host: earthlink.net 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. 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. -- Andrei Petrov Opinions expressed are solely my own and not those of EarthLink Network. ------------------------------------------------------------ From epetrov@pacbell.net Sun Aug 07 21:36:21 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!pacbell!epetrov From: epetrov@pacbell.net (Élodie Petrov) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Aug07.213621.3439@pacbell.net> Date: Sun, 07 Aug 1994 21:36:21 GMT References: <1994Aug06.171021.7721@earthlink.net> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Aug06.171021.7721@earthlink.net>, apetrov@earthlink.net (Andrei Petrov) 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. -- Élodie Petrov Hayes Optima 288 @ 9600 Telebit bps "They will send a copy in my place." From bstewart@hanse.de Tue Aug 09 11:31:21 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!hanse!bstewart From: bstewart@hanse.de (Bastien Stewart) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Aug09.113121.8734@hanse.de> Date: Tue, 09 Aug 1994 11:31:21 GMT References: <1994Aug06.171021.7721@earthlink.net> <1994Aug07.213621.3439@pacbell.net> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1994Aug07.213621.3439@pacbell.net>, epetrov@pacbell.net (Élodie Petrov) 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. -- Bastien Stewart -- Hanse-Netzwerk Hamburg "There are 14 nodes and only 10 countries. Count again." From skuznetsov@tum.de Wed Aug 10 02:58:21 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!tum!skuznetsov From: skuznetsov@tum.de (Sven Kuznetsov) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Aug10.025821.1661@tum.de> Date: Wed, 10 Aug 1994 02:58:21 GMT References: <1994Aug06.171021.7721@earthlink.net> <1994Aug07.213621.3439@pacbell.net> <1994Aug09.113121.8734@hanse.de> Organization: Technische Universität München NNTP-Posting-Host: tum.de X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Aug09.113121.8734@hanse.de>, bstewart@hanse.de (Bastien Stewart) 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. -- Sven Kuznetsov | skuznetsov@tum.de PGP Key fingerprint: 386B 84F9 8C7E 88D9 "Keep the channels open."