From bsantos@earthlink.net Tue Jan 10 12:09:45 1995
Path: ashpoly!cascade!mxgate!coyoacan!earthlink!bsantos
From: bsantos@earthlink.net (Bastien Santos)
Newsgroups: comp.dsp
Subject: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jan10.120945.5235@earthlink.net>
Date: Tue, 10 Jan 1995 12:09:45 GMT
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Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz.

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 Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width.

MATLAB script available upon request via email.

-- 
Bastien Santos -- EarthLink Network
"There are 14 nodes and only 10 countries. Count again."

From eoliveira@cam.ac.uk Thu Jan 12 03:27:45 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!cam!eoliveira
From: eoliveira@cam.ac.uk (Emi Oliveira)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jan12.032745.4010@cam.ac.uk>
Date: Thu, 12 Jan 1995 03:27:45 GMT
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In article <1995Jan10.120945.5235@earthlink.net>, bsantos@earthlink.net (Bastien Santos) 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.

-- 
Emi Oliveira | eoliveira@cam.ac.uk
PGP Key fingerprint: A718 094F DF16 111E
"Keep the channels open."

From kbrennan@uu.net Thu Jan 12 08:46:45 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!uu!kbrennan
From: kbrennan@uu.net (Karen Brennan)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jan12.084645.7329@uu.net>
Date: Thu, 12 Jan 1995 08:46:45 GMT
References: <1995Jan10.120945.5235@earthlink.net> <1995Jan12.032745.4010@cam.ac.uk>
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In article <1995Jan12.032745.4010@cam.ac.uk>, eoliveira@cam.ac.uk (Emi Oliveira) 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.

-- 
Karen Brennan | kbrennan@uu.net
PGP Key fingerprint: 402E 858C 0ADB 6872
"Keep the channels open."