From asantos@kth.se Fri Dec 01 16:08:29 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!kth!asantos From: asantos@kth.se (Astrid Santos) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec01.160829.9144@kth.se> Date: Fri, 01 Dec 1995 16:08:29 GMT Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: TIN [version 1.2 PL2] 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. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. MATLAB script available upon request via email. -- Astrid Santos "Hardware is temporary. The signal survives." Amiga 3000T / System 7.5.1 From adubois@cmu.edu Sat Dec 02 08:29:29 1995 Path: ashpoly!cascade!transat!ukc!fennimore!cmu!adubois From: adubois@cmu.edu (Anton Dubois) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec02.082929.3209@cmu.edu> Date: Sat, 02 Dec 1995 08:29:29 GMT References: <1995Dec01.160829.9144@kth.se> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: WinVN 0.99.5 Lines: 12 In article <1995Dec01.160829.9144@kth.se>, asantos@kth.se (Astrid Santos) writes: > 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. 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. Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Anton Dubois *PLONK* filter active for trolls. Sun 3/60 (SunOS 4.1.1) - NetBSD 1.0 From handersson@mindspring.com Sat Dec 02 18:39:29 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!mindspring!handersson From: handersson@mindspring.com (Heather Andersson) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec02.183929.4299@mindspring.com> Date: Sat, 02 Dec 1995 18:39:29 GMT References: <1995Dec01.160829.9144@kth.se> Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Dec01.160829.9144@kth.se>, asantos@kth.se (Astrid Santos) writes: > 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. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Heather Andersson "We don't sign stars. We build them." Atari TT030 / Linux 1.2.13 From lfournier@cmu.edu Sun Dec 03 19:46:29 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!cmu!lfournier From: lfournier@cmu.edu (Lars Fournier) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Dec03.194629.9033@cmu.edu> Date: Sun, 03 Dec 1995 19:46:29 GMT References: <1995Dec01.160829.9144@kth.se> <1995Dec02.082929.3209@cmu.edu> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Dec02.082929.3209@cmu.edu>, adubois@cmu.edu (Anton Dubois) 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. -- Lars Fournier *PLONK* filter active for trolls. Atari TT030 - NetBSD 1.0