From rgonzalez@uni-hamburg.de Wed Oct 19 02:22:11 1994 Path: ashpoly!cascade!bigsur!uni-hamburg!rgonzalez From: rgonzalez@uni-hamburg.de (Renata González) Newsgroups: comp.dsp Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Oct19.022211.8311@uni-hamburg.de> Date: Wed, 19 Oct 1994 02:22:11 GMT Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: TIN [version 1.2 PL2] Lines: 11 A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. At 14.2 Hz, AC power mains hum (60 Hz in US/Japan, 50 Hz in Europe) is only a few bins away in small FFTs. A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor. MATLAB script available upon request via email. -- Renata González Opinions expressed are solely my own and not those of Universität Hamburg Fachbereich Informatik. ------------------------------------------------------------ From mcampbell@kth.se Wed Oct 19 19:10:11 1994 Path: ashpoly!cascade!transat!ukc!fennimore!kth!mcampbell From: mcampbell@kth.se (Mathieu Campbell) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Oct19.191011.3148@kth.se> Date: Wed, 19 Oct 1994 19:10:11 GMT References: <1994Oct19.022211.8311@uni-hamburg.de> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Oct19.022211.8311@uni-hamburg.de>, rgonzalez@uni-hamburg.de (Renata González) writes: > A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips. 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. -- Mathieu Campbell *PLONK* filter active for trolls. PC-9821Ap2 (NEC) - NetBSD 1.0 From dwatanabe@kiae.su Fri Oct 21 19:41:11 1994 Path: ashpoly!cascade!mxgate!coyoacan!kiae!dwatanabe From: dwatanabe@kiae.su (Dmitri Watanabe) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Oct21.194111.3217@kiae.su> Date: Fri, 21 Oct 1994 19:41:11 GMT References: <1994Oct19.022211.8311@uni-hamburg.de> <1994Oct19.191011.3148@kth.se> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1994Oct19.191011.3148@kth.se>, mcampbell@kth.se (Mathieu Campbell) 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. -- Dmitri Watanabe Practical Peripherals 14.4 @ 9600 Telebit bps "We don't sign stars. We build them." From hsokolov@kiae.su Fri Oct 21 23:58:11 1994 Path: ashpoly!cascade!mxgate!coyoacan!kiae!hsokolov From: hsokolov@kiae.su (Hugo Sokolov) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Oct21.235811.3624@kiae.su> Date: Fri, 21 Oct 1994 23:58:11 GMT References: <1994Oct19.022211.8311@uni-hamburg.de> <1994Oct19.191011.3148@kth.se> <1994Oct21.194111.3217@kiae.su> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Oct21.194111.3217@kiae.su>, dwatanabe@kiae.su (Dmitri Watanabe) 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. -- Hugo Sokolov Opinions expressed are solely my own and not those of Kurchatov Institute of Atomic Energy, Moscow. ------------------------------------------------------------ From jkarlsson@cmu.edu Sun Oct 23 16:32:11 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!cmu!jkarlsson From: jkarlsson@cmu.edu (Jens Karlsson) Newsgroups: comp.dsp Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier Message-ID: <1994Oct23.163211.3944@cmu.edu> Date: Sun, 23 Oct 1994 16:32:11 GMT References: <1994Oct19.022211.8311@uni-hamburg.de> <1994Oct19.191011.3148@kth.se> <1994Oct21.194111.3217@kiae.su> <1994Oct21.235811.3624@kiae.su> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1994Oct21.235811.3624@kiae.su>, hsokolov@kiae.su (Hugo Sokolov) writes: > I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection. 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. PGP Public key available via finger or upon request. -- Jens Karlsson Zyxel U-1496E @ 14,400 bps "The hatch is open. Is anyone listening?"