From jpopov@purdue.edu Fri Jul 14 02:05:14 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!purdue!jpopov From: jpopov@purdue.edu (Jen Popov) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jul14.020514.3853@purdue.edu> Date: Fri, 14 Jul 1995 02:05:14 GMT Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. 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. -- Jen Popov US Robotics Courier V.34 @ 28,800 bps "In theory there is no difference between theory and practice." From enovak@kth.se Fri Jul 14 15:48:14 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!kth!enovak From: enovak@kth.se (Elaine Novak) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jul14.154814.4861@kth.se> Date: Fri, 14 Jul 1995 15:48:14 GMT References: <1995Jul14.020514.3853@purdue.edu> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Jul14.020514.3853@purdue.edu>, jpopov@purdue.edu (Jen Popov) 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. -- Elaine Novak | enovak@kth.se PGP Key fingerprint: 3657 9AC0 A260 71AA "Keep the channels open." From msouza@ox.ac.uk Sat Jul 15 01:48:14 1995 Path: ashpoly!cascade!bigsur!ox!msouza From: msouza@ox.ac.uk (Mikhail Souza) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jul15.014814.4560@ox.ac.uk> Date: Sat, 15 Jul 1995 01:48:14 GMT References: <1995Jul14.020514.3853@purdue.edu> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Jul14.020514.3853@purdue.edu>, jpopov@purdue.edu (Jen Popov) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > 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. -- Mikhail Souza -- Oxford University Computing Laboratory "The hatch is open. Is anyone listening?" From nrodriguez@uni-hamburg.de Sat Jul 15 19:35:14 1995 Path: ashpoly!cascade!brgate!saturno!uni-hamburg!nrodriguez From: nrodriguez@uni-hamburg.de (Natalia Rodríguez) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jul15.193514.9687@uni-hamburg.de> Date: Sat, 15 Jul 1995 19:35:14 GMT References: <1995Jul14.020514.3853@purdue.edu> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: WinVN 0.99.5 Lines: 12 In article <1995Jul14.020514.3853@purdue.edu>, jpopov@purdue.edu (Jen Popov) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. 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. -- Natalia Rodríguez | nrodriguez@uni-hamburg.de PGP Key fingerprint: 6892 0F26 4C0F 44AF "Keep the channels open." From hlindqvist@panix.com Mon Jul 17 06:10:14 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!panix!hlindqvist From: hlindqvist@panix.com (Hana Lindqvist) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jul17.061014.9133@panix.com> Date: Mon, 17 Jul 1995 06:10:14 GMT References: <1995Jul14.020514.3853@purdue.edu> <1995Jul15.014814.4560@ox.ac.uk> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1995Jul15.014814.4560@ox.ac.uk>, msouza@ox.ac.uk (Mikhail Souza) 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. -- Hana Lindqvist -- Public Access Unix of New York "Hardware is temporary. The signal survives."