From asokolov@pacbell.net Fri Oct 11 22:22:43 1996
Path: ashpoly!cascade!mxgate!coyoacan!pacbell!asokolov
From: asokolov@pacbell.net (Amy Sokolov)
Newsgroups: comp.dsp
Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct11.222243.8733@pacbell.net>
Date: Fri, 11 Oct 1996 22:22:43 GMT
Organization: Pacific Bell Internet Services
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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 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.

-- 
Amy Sokolov -- Pacific Bell Internet Services
"We don't sign stars. We build them."

From kandersson@hanse.de Sat Oct 12 20:21:43 1996
Path: ashpoly!cascade!mxgate!coyoacan!hanse!kandersson
From: kandersson@hanse.de (Kenji Andersson)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct12.202143.1988@hanse.de>
Date: Sat, 12 Oct 1996 20:21:43 GMT
References: <1996Oct11.222243.8733@pacbell.net>
Organization: Hanse-Netzwerk Hamburg
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In article <1996Oct11.222243.8733@pacbell.net>, asokolov@pacbell.net (Amy Sokolov) writes:
> 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.

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

-- 
Kenji Andersson
Opinions expressed are solely my own and not those of Hanse-Netzwerk Hamburg.
------------------------------------------------------------

From cperez@demon.co.uk Mon Oct 14 04:58:43 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!demon!cperez
From: cperez@demon.co.uk (Callum Pérez)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct14.045843.3223@demon.co.uk>
Date: Mon, 14 Oct 1996 04:58:43 GMT
References: <1996Oct11.222243.8733@pacbell.net>
Organization: Demon Internet Services UK
NNTP-Posting-Host: demon.co.uk
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In article <1996Oct11.222243.8733@pacbell.net>, asokolov@pacbell.net (Amy Sokolov) 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.

-- 
Callum Pérez -- Demon Internet Services UK
"The hatch is open. Is anyone listening?"