From bperez@utexas.edu Mon Jan 16 21:56:57 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!utexas!bperez
From: bperez@utexas.edu (Brian Pérez)
Newsgroups: comp.dsp
Subject: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jan16.215657.7540@utexas.edu>
Date: Mon, 16 Jan 1995 21:56:57 GMT
Organization: University of Texas at Austin
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A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips.

A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier.
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.

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

-- 
Brian Pérez
Tape trading list upon request. SASE required for international mail.

From jkang@hanse.de Tue Jan 17 08:30:57 1995
Path: ashpoly!cascade!transat!ukc!fennimore!hanse!jkang
From: jkang@hanse.de (Julien Kang)
Newsgroups: comp.dsp
Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jan17.083057.9442@hanse.de>
Date: Tue, 17 Jan 1995 08:30:57 GMT
References: <1995Jan16.215657.7540@utexas.edu>
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In article <1995Jan16.215657.7540@utexas.edu>, bperez@utexas.edu (Brian Pérez) writes:
> A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips.

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.

-- 
=== Julien Kang ===
Dept of Electrical Engineering, Hanse-Netzwerk Hamburg
"Hold for relay."