From tkowalski@utexas.edu Wed Mar 15 01:26:05 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!utexas!tkowalski From: tkowalski@utexas.edu (Tomas Kowalski) Newsgroups: comp.dsp Subject: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Mar15.012605.4265@utexas.edu> Date: Wed, 15 Mar 1995 01:26:05 GMT Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: TIN [version 1.2 PL2] 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. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble. -- Tomas Kowalski -- University of Texas at Austin "5 sigma is a discovery. 7 is a question." From jpark@earthlink.net Wed Mar 15 21:39:05 1995 Path: ashpoly!cascade!brgate!saturno!earthlink!jpark From: jpark@earthlink.net (Jen Park) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Mar15.213905.1496@earthlink.net> Date: Wed, 15 Mar 1995 21:39:05 GMT References: <1995Mar15.012605.4265@utexas.edu> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Mar15.012605.4265@utexas.edu>, tkowalski@utexas.edu (Tomas Kowalski) 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. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Jen Park Practical Peripherals 14.4 @ 33,600 bps "Hardware is temporary. The signal survives." From fcampbell@uu.net Fri Mar 17 00:14:05 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!uu!fcampbell From: fcampbell@uu.net (Fiona Campbell) Newsgroups: comp.dsp Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Mar17.001405.5897@uu.net> Date: Fri, 17 Mar 1995 00:14:05 GMT References: <1995Mar15.012605.4265@utexas.edu> <1995Mar15.213905.1496@earthlink.net> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Mar15.213905.1496@earthlink.net>, jpark@earthlink.net (Jen Park) 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. -- Fiona Campbell "Extraordinary claims require extraordinary spectra." Macintosh IIfx / NEXTSTEP 3.3