From jkang@illinois.edu Tue Jun 13 15:55:19 1995
Path: ashpoly!cascade!bigsur!illinois!jkang
From: jkang@illinois.edu (Julien Kang)
Newsgroups: comp.dsp
Subject: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jun13.155519.1315@illinois.edu>
Date: Tue, 13 Jun 1995 15:55:19 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 Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width.

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

-- 
Julien Kang | jkang@illinois.edu
PGP Key fingerprint: C22B CE51 7A67 B9D0
"Keep the channels open."

From rito@mindspring.com Wed Jun 14 12:55:19 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!mindspring!rito
From: rito@mindspring.com (Renata Ito)
Newsgroups: comp.dsp
Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jun14.125519.4070@mindspring.com>
Date: Wed, 14 Jun 1995 12:55:19 GMT
References: <1995Jun13.155519.1315@illinois.edu>
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In article <1995Jun13.155519.1315@illinois.edu>, jkang@illinois.edu (Julien Kang) 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.

-- 
=== Renata Ito ===
Dept of Electrical Engineering, MindSpring Enterprises
"Measuring a record you own is listening, not piracy."