From llaurent@u-tokyo.ac.jp Fri Aug 11 07:59:28 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!u-tokyo!llaurent From: llaurent@u-tokyo.ac.jp (Lisa Laurent) Newsgroups: comp.dsp Subject: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug11.075928.9909@u-tokyo.ac.jp> Date: Fri, 11 Aug 1995 07:59:28 GMT Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: Netscape 1.1N Lines: 11 A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. 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 Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Lisa Laurent "When every node is whole, the channel opens." PC-9821Ap2 (NEC) / NEXTSTEP 3.3 From tpopov@cmu.edu Sat Aug 12 14:42:28 1995 Path: ashpoly!cascade!brgate!saturno!cmu!tpopov From: tpopov@cmu.edu (Thiago Popov) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug12.144228.2091@cmu.edu> Date: Sat, 12 Aug 1995 14:42:28 GMT References: <1995Aug11.075928.9909@u-tokyo.ac.jp> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Aug11.075928.9909@u-tokyo.ac.jp>, llaurent@u-tokyo.ac.jp (Lisa Laurent) 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. -- === Thiago Popov === Dept of Electrical Engineering, Carnegie Mellon University School of CS "The carrier frequency does not drift by accident." From dlaurent@illinois.edu Mon Aug 14 18:01:28 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!illinois!dlaurent From: dlaurent@illinois.edu (Dmitri Laurent) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug14.180128.2473@illinois.edu> Date: Mon, 14 Aug 1995 18:01:28 GMT References: <1995Aug11.075928.9909@u-tokyo.ac.jp> <1995Aug12.144228.2091@cmu.edu> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: Netscape 1.1N Lines: 8 In article <1995Aug12.144228.2091@cmu.edu>, tpopov@cmu.edu (Thiago Popov) 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. -- Dmitri Laurent Tape trading list upon request. SASE required for international mail. From mdubois@illinois.edu Tue Aug 15 03:46:28 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!illinois!mdubois From: mdubois@illinois.edu (Min-jun Dubois) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug15.034628.2455@illinois.edu> Date: Tue, 15 Aug 1995 03:46:28 GMT References: <1995Aug11.075928.9909@u-tokyo.ac.jp> <1995Aug12.144228.2091@cmu.edu> <1995Aug14.180128.2473@illinois.edu> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Aug14.180128.2473@illinois.edu>, dlaurent@illinois.edu (Dmitri Laurent) 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. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- Min-jun Dubois -- University of Illinois Urbana-Champaign "Measuring a record you own is listening, not piracy." From tpopov@earthlink.net Thu Aug 17 01:30:28 1995 Path: ashpoly!cascade!bigsur!earthlink!tpopov From: tpopov@earthlink.net (Tobias Popov) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug17.013028.4690@earthlink.net> Date: Thu, 17 Aug 1995 01:30:28 GMT References: <1995Aug11.075928.9909@u-tokyo.ac.jp> <1995Aug12.144228.2091@cmu.edu> <1995Aug14.180128.2473@illinois.edu> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Aug14.180128.2473@illinois.edu>, dlaurent@illinois.edu (Dmitri Laurent) 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. -- Tobias Popov Practical Peripherals 14.4 @ 9600 Telebit bps "Measuring a record you own is listening, not piracy."