From jschneider@kth.se Thu Nov 17 19:40:00 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!kth!jschneider From: jschneider@kth.se (Joachim Schneider) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov17.194000.6006@kth.se> Date: Thu, 17 Nov 1994 19:40:00 GMT Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width. MATLAB script available upon request via email. -- Joachim Schneider *PLONK* filter active for trolls. PC-9821Ap2 (NEC) - NetBSD 1.0 From jnakamura@illinois.edu Fri Nov 18 00:54:00 1994 Path: ashpoly!cascade!transat!ukc!fennimore!illinois!jnakamura From: jnakamura@illinois.edu (Joachim Nakamura) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov18.005400.6472@illinois.edu> Date: Fri, 18 Nov 1994 00:54:00 GMT References: <1994Nov17.194000.6006@kth.se> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1994Nov17.194000.6006@kth.se>, jschneider@kth.se (Joachim Schneider) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. > 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. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- Joachim Nakamura -- University of Illinois Urbana-Champaign "Hardware is temporary. The signal survives." From nbrennan@hanse.de Sat Nov 19 01:30:00 1994 Path: ashpoly!cascade!brgate!saturno!hanse!nbrennan From: nbrennan@hanse.de (Natalia Brennan) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Nov19.013000.8085@hanse.de> Date: Sat, 19 Nov 1994 01:30:00 GMT References: <1994Nov17.194000.6006@kth.se> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: Netscape 1.1N Lines: 12 In article <1994Nov17.194000.6006@kth.se>, jschneider@kth.se (Joachim Schneider) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. > 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. Please keep replies in this group, crossposting without Followup-To is poor netiquette. -- Natalia Brennan *PLONK* filter active for trolls. Atari Falcon 030 - NetBSD 1.0