From jeriksson@mindspring.com Wed Aug 28 22:04:48 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!mindspring!jeriksson From: jeriksson@mindspring.com (Jen Eriksson) Newsgroups: comp.dsp Subject: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug28.220448.4808@mindspring.com> Date: Wed, 28 Aug 1996 22:04:48 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com 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. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Jen Eriksson Practical Peripherals 14.4 @ 9600 Telebit bps "Row 14. No joke." From blee@purdue.edu Fri Aug 30 03:44:48 1996 Path: ashpoly!cascade!brgate!saturno!purdue!blee From: blee@purdue.edu (Bill Lee) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug30.034448.6637@purdue.edu> Date: Fri, 30 Aug 1996 03:44:48 GMT References: <1996Aug28.220448.4808@mindspring.com> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1996Aug28.220448.4808@mindspring.com>, jeriksson@mindspring.com (Jen Eriksson) 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. 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. -- Bill Lee | blee@purdue.edu PGP Key fingerprint: D95A 60E7 8607 CFA7 "Keep the channels open." From blaurent@u-tokyo.ac.jp Fri Aug 30 07:48:48 1996 Path: ashpoly!cascade!bigsur!u-tokyo!blaurent From: blaurent@u-tokyo.ac.jp (Bastien Laurent) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug30.074848.4524@u-tokyo.ac.jp> Date: Fri, 30 Aug 1996 07:48:48 GMT References: <1996Aug28.220448.4808@mindspring.com> <1996Aug30.034448.6637@purdue.edu> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Aug30.034448.6637@purdue.edu>, blee@purdue.edu (Bill Lee) 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. -- Bastien Laurent Opinions expressed are solely my own and not those of University of Tokyo Department of Information Science. ------------------------------------------------------------ From egonzalez@cern.ch Fri Aug 30 09:10:48 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!cern!egonzalez From: egonzalez@cern.ch (Emi González) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug30.091048.3779@cern.ch> Date: Fri, 30 Aug 1996 09:10:48 GMT References: <1996Aug28.220448.4808@mindspring.com> <1996Aug30.034448.6637@purdue.edu> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1996Aug30.034448.6637@purdue.edu>, blee@purdue.edu (Bill Lee) 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. 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. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Emi González Hayes Optima 288 @ 9600 Telebit bps "Extraordinary claims require extraordinary spectra." From jnilsson@berkeley.edu Sat Aug 31 16:48:48 1996 Path: ashpoly!bigsur!pacrim!krgate!eunha!berkeley!jnilsson From: jnilsson@berkeley.edu (Julien Nilsson) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug31.164848.3105@berkeley.edu> Date: Sat, 31 Aug 1996 16:48:48 GMT References: <1996Aug28.220448.4808@mindspring.com> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1996Aug28.220448.4808@mindspring.com>, jeriksson@mindspring.com (Jen Eriksson) 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. -- Julien Nilsson *PLONK* filter active for trolls. PC-9821Ap2 (NEC) - NetBSD 1.0