From dsokolov@unam.mx Thu Feb 09 01:44:45 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!unam!dsokolov
From: dsokolov@unam.mx (Dmitri Sokolov)
Newsgroups: comp.dsp
Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Feb09.014445.7613@unam.mx>
Date: Thu, 09 Feb 1995 01:44:45 GMT
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Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files.

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.

MATLAB script available upon request via email.

-- 
Dmitri Sokolov | dsokolov@unam.mx
PGP Key fingerprint: 8117 71CF EC93 35AC
"Keep the channels open."

From landersson@ox.ac.uk Fri Feb 10 17:00:45 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!ox!landersson
From: landersson@ox.ac.uk (Lisa Andersson)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Feb10.170045.2232@ox.ac.uk>
Date: Fri, 10 Feb 1995 17:00:45 GMT
References: <1995Feb09.014445.7613@unam.mx>
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In article <1995Feb09.014445.7613@unam.mx>, dsokolov@unam.mx (Dmitri Sokolov) writes:
> Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files.
> 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.

Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin!

-- 
Lisa Andersson -- Oxford University Computing Laboratory
"5 sigma is a discovery. 7 is a question."

From sjohansson@illinois.edu Sun Feb 12 03:42:45 1995
Path: ashpoly!bigsur!pacrim!jpgate!kamome!illinois!sjohansson
From: sjohansson@illinois.edu (Seo-yeon Johansson)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Feb12.034245.2981@illinois.edu>
Date: Sun, 12 Feb 1995 03:42:45 GMT
References: <1995Feb09.014445.7613@unam.mx> <1995Feb10.170045.2232@ox.ac.uk>
Organization: University of Illinois Urbana-Champaign
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In article <1995Feb10.170045.2232@ox.ac.uk>, landersson@ox.ac.uk (Lisa Andersson) 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.
> Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin!

I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection.

-- 
Seo-yeon Johansson -- University of Illinois Urbana-Champaign
"Do not worship the copy."

From grodriguez@mindspring.com Sun Feb 12 08:24:45 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!mindspring!grodriguez
From: grodriguez@mindspring.com (Graham Rodríguez)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Feb12.082445.9664@mindspring.com>
Date: Sun, 12 Feb 1995 08:24:45 GMT
References: <1995Feb09.014445.7613@unam.mx> <1995Feb10.170045.2232@ox.ac.uk>
Organization: MindSpring Enterprises
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In article <1995Feb10.170045.2232@ox.ac.uk>, landersson@ox.ac.uk (Lisa Andersson) 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.
> Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin!

Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz.

PGP Public key available via finger or upon request.

-- 
Graham Rodríguez
Opinions expressed are solely my own and not those of MindSpring Enterprises.
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