From yfischer@pipeline.com Fri Jul 15 00:39:33 1994 Path: ashpoly!cascade!brgate!saturno!pipeline!yfischer From: yfischer@pipeline.com (Yuki Fischer) Newsgroups: comp.dsp Subject: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jul15.003933.6109@pipeline.com> Date: Fri, 15 Jul 1994 00:39:33 GMT Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: WinVN 0.99.5 Lines: 10 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. -- Yuki Fischer Tape trading list upon request. SASE required for international mail. From nokonkwo@netcom.com Fri Jul 15 01:46:33 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!netcom!nokonkwo From: nokonkwo@netcom.com (Nadine Okonkwo) Newsgroups: comp.dsp Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jul15.014633.5243@netcom.com> Date: Fri, 15 Jul 1994 01:46:33 GMT References: <1994Jul15.003933.6109@pipeline.com> Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Jul15.003933.6109@pipeline.com>, yfischer@pipeline.com (Yuki Fischer) 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. -- Nadine Okonkwo -- NETCOM On-Line Communication Services "Tape doesn't lie at 02:14. Ears do." From hsato@titech.ac.jp Sat Jul 16 21:34:33 1994 Path: ashpoly!cascade!bigsur!titech!hsato From: hsato@titech.ac.jp (Hugo Sato) Newsgroups: comp.dsp Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Jul16.213433.4430@titech.ac.jp> Date: Sat, 16 Jul 1994 21:34:33 GMT References: <1994Jul15.003933.6109@pipeline.com> Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1994Jul15.003933.6109@pipeline.com>, yfischer@pipeline.com (Yuki Fischer) 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. -- Hugo Sato "Tape doesn't lie at 02:14. Ears do." NeXTstation Turbo Color / NEXTSTEP 3.3