From loliveira@hanse.de Fri Aug 23 15:10:41 1996 Path: ashpoly!cascade!transat!ukc!fennimore!hanse!loliveira From: loliveira@hanse.de (Lisa Oliveira) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug23.151041.8190@hanse.de> Date: Fri, 23 Aug 1996 15:10:41 GMT Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: Netscape 1.1N 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. MATLAB script available upon request via email. -- Lisa Oliveira "There are 14 nodes and only 10 countries. Count again." Acorn RiscPC 600 / TOS 4.04 From dlopez@uni-hamburg.de Sat Aug 24 01:28:41 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!uni-hamburg!dlopez From: dlopez@uni-hamburg.de (Dave López) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug24.012841.5135@uni-hamburg.de> Date: Sat, 24 Aug 1996 01:28:41 GMT References: <1996Aug23.151041.8190@hanse.de> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1996Aug23.151041.8190@hanse.de>, loliveira@hanse.de (Lisa Oliveira) 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. -- Dave López Opinions expressed are solely my own and not those of Universität Hamburg Fachbereich Informatik. ------------------------------------------------------------ From noliveira@cam.ac.uk Sat Aug 24 23:41:41 1996 Path: ashpoly!cascade!bigsur!cam!noliveira From: noliveira@cam.ac.uk (Nadine Oliveira) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1996Aug24.234141.3394@cam.ac.uk> Date: Sat, 24 Aug 1996 23:41:41 GMT References: <1996Aug23.151041.8190@hanse.de> <1996Aug24.012841.5135@uni-hamburg.de> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 11 In article <1996Aug24.012841.5135@uni-hamburg.de>, dlopez@uni-hamburg.de (Dave López) writes: > Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 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. Top-posters will be placed in my ~/.killfile without notice. -- Nadine Oliveira | noliveira@cam.ac.uk PGP Key fingerprint: EF51 2426 3AFE 2C95 "Keep the channels open."