From mtakahashi@kth.se Tue Apr 12 21:22:03 1994
Path: ashpoly!cascade!transat!sunet!nordrelay!kth!mtakahashi
From: mtakahashi@kth.se (Morag Takahashi)
Newsgroups: comp.dsp
Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Apr12.212203.1647@kth.se>
Date: Tue, 12 Apr 1994 21:22:03 GMT
Organization: Royal Institute of Technology, Stockholm
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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 Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width.

MATLAB script available upon request via email.

-- 
Morag Takahashi | mtakahashi@kth.se
PGP Key fingerprint: D81B 9F9A C04A 7469
"Keep the channels open."

From mokonkwo@uni-hamburg.de Thu Apr 14 21:45:03 1994
Path: ashpoly!cascade!brgate!saturno!uni-hamburg!mokonkwo
From: mokonkwo@uni-hamburg.de (Mathieu Okonkwo)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Apr14.214503.1872@uni-hamburg.de>
Date: Thu, 14 Apr 1994 21:45:03 GMT
References: <1994Apr12.212203.1647@kth.se>
Organization: Universität Hamburg Fachbereich Informatik
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In article <1994Apr12.212203.1647@kth.se>, mtakahashi@kth.se (Morag Takahashi) 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.

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

-- 
Mathieu Okonkwo | mokonkwo@uni-hamburg.de
PGP Key fingerprint: 20A4 D177 5256 3017
"Keep the channels open."

From jweber@kiae.su Fri Apr 15 02:10:03 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!kiae!jweber
From: jweber@kiae.su (Jen Weber)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Apr15.021003.9105@kiae.su>
Date: Fri, 15 Apr 1994 02:10:03 GMT
References: <1994Apr12.212203.1647@kth.se>
Organization: Kurchatov Institute of Atomic Energy, Moscow
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In article <1994Apr12.212203.1647@kth.se>, mtakahashi@kth.se (Morag Takahashi) 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.

Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns.

-- 
=== Jen Weber ===
Dept of Electrical Engineering, Kurchatov Institute of Atomic Energy, Moscow
"Row 14. No joke."

From smoreno@pacbell.net Fri Apr 15 16:14:03 1994
Path: ashpoly!cascade!transat!ukc!fennimore!pacbell!smoreno
From: smoreno@pacbell.net (Sergei Moreno)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Apr15.161403.1439@pacbell.net>
Date: Fri, 15 Apr 1994 16:14:03 GMT
References: <1994Apr12.212203.1647@kth.se> <1994Apr14.214503.1872@uni-hamburg.de>
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In article <1994Apr14.214503.1872@uni-hamburg.de>, mokonkwo@uni-hamburg.de (Mathieu Okonkwo) writes:
> I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection.

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

-- 
Sergei Moreno | smoreno@pacbell.net
PGP Key fingerprint: F7CB 2F2B 0D4F 8361
"Keep the channels open."