From knilsson@uu.net Thu Aug 10 16:31:25 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!uu!knilsson From: knilsson@uu.net (Karen Nilsson) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug10.163125.4239@uu.net> Date: Thu, 10 Aug 1995 16:31:25 GMT Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net 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 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. -- Karen Nilsson *PLONK* filter active for trolls. Macintosh IIfx - NetBSD 1.0 From jnakamura@purdue.edu Sat Aug 12 12:04:25 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!purdue!jnakamura From: jnakamura@purdue.edu (Ji-woo Nakamura) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug12.120425.4500@purdue.edu> Date: Sat, 12 Aug 1995 12:04:25 GMT References: <1995Aug10.163125.4239@uu.net> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1995Aug10.163125.4239@uu.net>, knilsson@uu.net (Karen Nilsson) 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. -- Ji-woo Nakamura Tape trading list upon request. SASE required for international mail. From asantos@uni-hamburg.de Mon Aug 14 03:44:25 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!uni-hamburg!asantos From: asantos@uni-hamburg.de (Amy Santos) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug14.034425.5528@uni-hamburg.de> Date: Mon, 14 Aug 1995 03:44:25 GMT References: <1995Aug10.163125.4239@uu.net> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1995Aug10.163125.4239@uu.net>, knilsson@uu.net (Karen Nilsson) 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. -- Amy Santos Opinions expressed are solely my own and not those of Universität Hamburg Fachbereich Informatik. ------------------------------------------------------------ From mmartinez@cmu.edu Wed Aug 16 01:23:25 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!cmu!mmartinez From: mmartinez@cmu.edu (Marisol Martínez) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug16.012325.1464@cmu.edu> Date: Wed, 16 Aug 1995 01:23:25 GMT References: <1995Aug10.163125.4239@uu.net> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1995Aug10.163125.4239@uu.net>, knilsson@uu.net (Karen Nilsson) writes: > Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz. Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz. -- Marisol Martínez SupraFAXModem 28.8 @ 9600 Telebit bps "Row 14. No joke." From mkarlsson@cam.ac.uk Fri Aug 18 03:22:25 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!cam!mkarlsson From: mkarlsson@cam.ac.uk (Marta Karlsson) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1995Aug18.032225.8899@cam.ac.uk> Date: Fri, 18 Aug 1995 03:22:25 GMT References: <1995Aug10.163125.4239@uu.net> <1995Aug16.012325.1464@cmu.edu> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Aug16.012325.1464@cmu.edu>, mmartinez@cmu.edu (Marisol Martínez) 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. -- === Marta Karlsson === Dept of Electrical Engineering, University of Cambridge Computer Laboratory "Row 14. No joke."