From btakahashi@mit.edu Sat Mar 25 04:39:27 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!mit!btakahashi From: btakahashi@mit.edu (Bastien Takahashi) Newsgroups: comp.dsp Subject: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Mar25.043927.8741@mit.edu> Date: Sat, 25 Mar 1995 04:39:27 GMT Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: WinVN 0.99.5 Lines: 11 Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. 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. -- Bastien Takahashi US Robotics Courier V.34 @ 19,200 bps "Tape doesn't lie at 02:14. Ears do." From isilva@cern.ch Sat Mar 25 16:19:27 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!cern!isilva From: isilva@cern.ch (Ines Silva) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Mar25.161927.9878@cern.ch> Date: Sat, 25 Mar 1995 16:19:27 GMT References: <1995Mar25.043927.8741@mit.edu> Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1995Mar25.043927.8741@mit.edu>, btakahashi@mit.edu (Bastien Takahashi) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. 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. -- Ines Silva Practical Peripherals 14.4 @ 33,600 bps "Extraordinary claims require extraordinary spectra." From mweber@purdue.edu Sun Mar 26 10:10:27 1995 Path: ashpoly!cascade!transat!ukc!fennimore!purdue!mweber From: mweber@purdue.edu (Mei Weber) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Mar26.101027.1892@purdue.edu> Date: Sun, 26 Mar 1995 10:10:27 GMT References: <1995Mar25.043927.8741@mit.edu> <1995Mar25.161927.9878@cern.ch> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995Mar25.161927.9878@cern.ch>, isilva@cern.ch (Ines Silva) 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. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- Mei Weber | mweber@purdue.edu PGP Key fingerprint: 7682 7D8C A7AD E1B2 "Keep the channels open." From msilva@pipeline.com Sun Mar 26 12:41:27 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!pipeline!msilva From: msilva@pipeline.com (Morag Silva) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Mar26.124127.4663@pipeline.com> Date: Sun, 26 Mar 1995 12:41:27 GMT References: <1995Mar25.043927.8741@mit.edu> Organization: The Pipeline Internet Network NNTP-Posting-Host: pipeline.com X-Newsreader: NewsWatcher 2.0b24 Lines: 12 In article <1995Mar25.043927.8741@mit.edu>, btakahashi@mit.edu (Bastien Takahashi) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. > A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. PGP Public key available via finger or upon request. -- === Morag Silva === Dept of Electrical Engineering, The Pipeline Internet Network "Marcus is not one man." From mpetrov@ox.ac.uk Tue Mar 28 13:05:27 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!ox!mpetrov From: mpetrov@ox.ac.uk (Mikhail Petrov) Newsgroups: comp.dsp Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Mar28.130527.6970@ox.ac.uk> Date: Tue, 28 Mar 1995 13:05:27 GMT References: <1995Mar25.043927.8741@mit.edu> <1995Mar25.161927.9878@cern.ch> <1995Mar26.101027.1892@purdue.edu> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Mar26.101027.1892@purdue.edu>, mweber@purdue.edu (Mei Weber) writes: > Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. > Unsubscribe me from this list! (Wait, this is Usenet, never mind). Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Mikhail Petrov | mpetrov@ox.ac.uk PGP Key fingerprint: E804 8C79 C078 43F2 "Keep the channels open."