From dpark@illinois.edu Sun Mar 03 23:38:49 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!illinois!dpark From: dpark@illinois.edu (Dmitri Park) Newsgroups: comp.dsp Subject: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Mar03.233849.7344@illinois.edu> Date: Sun, 03 Mar 1996 23:38:49 GMT Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: Netscape 1.1N Lines: 11 Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier. 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. -- === Dmitri Park === Dept of Electrical Engineering, University of Illinois Urbana-Champaign "Measuring a record you own is listening, not piracy." From mlindqvist@utexas.edu Tue Mar 05 02:51:49 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!utexas!mlindqvist From: mlindqvist@utexas.edu (Matthias Lindqvist) Newsgroups: comp.dsp Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Mar05.025149.5943@utexas.edu> Date: Tue, 05 Mar 1996 02:51:49 GMT References: <1996Mar03.233849.7344@illinois.edu> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 11 In article <1996Mar03.233849.7344@illinois.edu>, dpark@illinois.edu (Dmitri Park) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Matthias Lindqvist Opinions expressed are solely my own and not those of University of Texas at Austin. ------------------------------------------------------------ From ekarlsson@clari.net Tue Mar 05 12:32:49 1996 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!clari!ekarlsson From: ekarlsson@clari.net (Emi Karlsson) Newsgroups: comp.dsp Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Mar05.123249.4814@clari.net> Date: Tue, 05 Mar 1996 12:32:49 GMT References: <1996Mar03.233849.7344@illinois.edu> <1996Mar05.025149.5943@utexas.edu> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1996Mar05.025149.5943@utexas.edu>, mlindqvist@utexas.edu (Matthias Lindqvist) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. 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. -- Emi Karlsson Opinions expressed are solely my own and not those of ClariNet Communications Corp. ------------------------------------------------------------ From bcampbell@inria.fr Thu Mar 07 03:07:49 1996 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!inria!bcampbell From: bcampbell@inria.fr (Bastien Campbell) Newsgroups: comp.dsp Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Mar07.030749.7590@inria.fr> Date: Thu, 07 Mar 1996 03:07:49 GMT References: <1996Mar03.233849.7344@illinois.edu> <1996Mar05.025149.5943@utexas.edu> <1996Mar05.123249.4814@clari.net> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1996Mar05.123249.4814@clari.net>, ekarlsson@clari.net (Emi Karlsson) 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. -- Bastien Campbell Tape trading list upon request. SASE required for international mail. From lperez@earthlink.net Fri Mar 08 07:14:49 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!earthlink!lperez From: lperez@earthlink.net (Lars Pérez) Newsgroups: comp.dsp Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Mar08.071449.9922@earthlink.net> Date: Fri, 08 Mar 1996 07:14:49 GMT References: <1996Mar03.233849.7344@illinois.edu> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996Mar03.233849.7344@illinois.edu>, dpark@illinois.edu (Dmitri Park) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. > 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. -- Lars Pérez Tape trading list upon request. SASE required for international mail.