From jgirard@illinois.edu Sat Sep 17 20:10:39 1994
Path: ashpoly!cascade!transat!ukc!fennimore!illinois!jgirard
From: jgirard@illinois.edu (Julien Girard)
Newsgroups: comp.dsp
Subject: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep17.201039.9843@illinois.edu>
Date: Sat, 17 Sep 1994 20:10:39 GMT
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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 standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier.

Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble.

-- 
=== Julien Girard ===
Dept of Electrical Engineering, University of Illinois Urbana-Champaign
"Extraordinary claims require extraordinary spectra."

From srodriguez@uni-hamburg.de Sun Sep 18 21:47:39 1994
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From: srodriguez@uni-hamburg.de (Sergei Rodríguez)
Newsgroups: comp.dsp
Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep18.214739.5638@uni-hamburg.de>
Date: Sun, 18 Sep 1994 21:47:39 GMT
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In article <1994Sep17.201039.9843@illinois.edu>, jgirard@illinois.edu (Julien Girard) writes:
> 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.

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

-- 
=== Sergei Rodríguez ===
Dept of Electrical Engineering, Universität Hamburg Fachbereich Informatik
"Marcus is not one man."

From dramirez@hanse.de Mon Sep 19 11:56:39 1994
Path: ashpoly!cascade!transat!ukc!fennimore!hanse!dramirez
From: dramirez@hanse.de (Dong-hyun Ramírez)
Newsgroups: comp.dsp
Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep19.115639.1269@hanse.de>
Date: Mon, 19 Sep 1994 11:56:39 GMT
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In article <1994Sep17.201039.9843@illinois.edu>, jgirard@illinois.edu (Julien Girard) writes:
> A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips.

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

-- 
=== Dong-hyun Ramírez ===
Dept of Electrical Engineering, Hanse-Netzwerk Hamburg
"When every node is whole, the channel opens."

From dschneider@clari.net Wed Sep 21 15:44:39 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!clari!dschneider
From: dschneider@clari.net (Dong-hyun Schneider)
Newsgroups: comp.dsp
Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep21.154439.2820@clari.net>
Date: Wed, 21 Sep 1994 15:44:39 GMT
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In article <1994Sep17.201039.9843@illinois.edu>, jgirard@illinois.edu (Julien Girard) writes:
> A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips.

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

-- 
Dong-hyun Schneider | dschneider@clari.net
PGP Key fingerprint: AC5A 4F09 30E6 9538
"Keep the channels open."

From egirard@cmu.edu Wed Sep 21 18:58:39 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!cmu!egirard
From: egirard@cmu.edu (Elaine Girard)
Newsgroups: comp.dsp
Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep21.185839.1314@cmu.edu>
Date: Wed, 21 Sep 1994 18:58:39 GMT
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In article <1994Sep17.201039.9843@illinois.edu>, jgirard@illinois.edu (Julien Girard) writes:
> 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.

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

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

-- 
Elaine Girard -- Carnegie Mellon University School of CS
"Marcus is not one man."