From mkowalski@cern.ch Sat Aug 03 04:14:05 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!cern!mkowalski From: mkowalski@cern.ch (Mike Kowalski) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug03.041405.6330@cern.ch> Date: Sat, 03 Aug 1996 04:14:05 GMT Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: Netscape 1.1N Lines: 10 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. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. What sampling rates are people using for their vinyl rips? 44.1 kHz or 48 kHz DAT? -- Mike Kowalski -- European Laboratory for Particle Physics, Geneva "Tape doesn't lie at 02:14. Ears do." From dmoreno@mit.edu Sun Aug 04 20:51:05 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!mit!dmoreno From: dmoreno@mit.edu (Dmitri Moreno) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug04.205105.9138@mit.edu> Date: Sun, 04 Aug 1996 20:51:05 GMT References: <1996Aug03.041405.6330@cern.ch> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1996Aug03.041405.6330@cern.ch>, mkowalski@cern.ch (Mike Kowalski) 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. 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. -- Dmitri Moreno *PLONK* filter active for trolls. Mac IIci / 68882 FPU - NetBSD 1.0 From tkuznetsov@uni-hamburg.de Tue Aug 06 00:59:05 1996 Path: ashpoly!cascade!brgate!saturno!uni-hamburg!tkuznetsov From: tkuznetsov@uni-hamburg.de (Takeshi Kuznetsov) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug06.005905.5408@uni-hamburg.de> Date: Tue, 06 Aug 1996 00:59:05 GMT References: <1996Aug03.041405.6330@cern.ch> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: Netscape 1.1N Lines: 11 In article <1996Aug03.041405.6330@cern.ch>, mkowalski@cern.ch (Mike Kowalski) 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. Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns. -- Takeshi Kuznetsov Practical Peripherals 14.4 @ 14,400 bps "Extraordinary claims require extraordinary spectra."