From dmacdonald@rwth-aachen.de Sun Jun 25 17:02:09 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!rwth-aachen!dmacdonald From: dmacdonald@rwth-aachen.de (Dave MacDonald) Newsgroups: comp.dsp Subject: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jun25.170209.7056@rwth-aachen.de> Date: Sun, 25 Jun 1995 17:02:09 GMT Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: Netscape 1.1N Lines: 10 Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Dave MacDonald Tape trading list upon request. SASE required for international mail. From aandersson@pacbell.net Mon Jun 26 06:29:09 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!pacbell!aandersson From: aandersson@pacbell.net (Andrei Andersson) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jun26.062909.3440@pacbell.net> Date: Mon, 26 Jun 1995 06:29:09 GMT References: <1995Jun25.170209.7056@rwth-aachen.de> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Jun25.170209.7056@rwth-aachen.de>, dmacdonald@rwth-aachen.de (Dave MacDonald) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. 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. -- Andrei Andersson *PLONK* filter active for trolls. Sun SparcStation 20 - NetBSD 1.0 From sivanov@illinois.edu Mon Jun 26 22:33:09 1995 Path: ashpoly!cascade!brgate!saturno!illinois!sivanov From: sivanov@illinois.edu (Steve Ivanov) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jun26.223309.1482@illinois.edu> Date: Mon, 26 Jun 1995 22:33:09 GMT References: <1995Jun25.170209.7056@rwth-aachen.de> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 12 In article <1995Jun25.170209.7056@rwth-aachen.de>, dmacdonald@rwth-aachen.de (Dave MacDonald) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- === Steve Ivanov === Dept of Electrical Engineering, University of Illinois Urbana-Champaign "Do not worship the copy." From trobertson@mindspring.com Tue Jun 27 10:59:09 1995 Path: ashpoly!cascade!transat!ukc!fennimore!mindspring!trobertson From: trobertson@mindspring.com (Takeshi Robertson) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jun27.105909.6432@mindspring.com> Date: Tue, 27 Jun 1995 10:59:09 GMT References: <1995Jun25.170209.7056@rwth-aachen.de> <1995Jun26.223309.1482@illinois.edu> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1995Jun26.223309.1482@illinois.edu>, sivanov@illinois.edu (Steve Ivanov) 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. Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin! -- === Takeshi Robertson === Dept of Electrical Engineering, MindSpring Enterprises "Marcus is not one man." From osouza@uu.net Wed Jun 28 14:13:09 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!uu!osouza From: osouza@uu.net (Olga Souza) Newsgroups: comp.dsp Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Jun28.141309.5739@uu.net> Date: Wed, 28 Jun 1995 14:13:09 GMT References: <1995Jun25.170209.7056@rwth-aachen.de> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Jun25.170209.7056@rwth-aachen.de>, dmacdonald@rwth-aachen.de (Dave MacDonald) writes: > Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files. > A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. 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. -- Olga Souza Tape trading list upon request. SASE required for international mail.