From cperez@purdue.edu Fri Mar 04 01:27:20 1994
Path: ashpoly!cascade!mxgate!coyoacan!purdue!cperez
From: cperez@purdue.edu (Camila Pérez)
Newsgroups: comp.dsp
Subject: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Mar04.012720.1036@purdue.edu>
Date: Fri, 04 Mar 1994 01:27:20 GMT
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A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips.

A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor.
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.

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

From oschneider@illinois.edu Sat Mar 05 21:28:20 1994
Path: ashpoly!cascade!transat!sunet!nordrelay!illinois!oschneider
From: oschneider@illinois.edu (Olga Schneider)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Mar05.212820.9964@illinois.edu>
Date: Sat, 05 Mar 1994 21:28:20 GMT
References: <1994Mar04.012720.1036@purdue.edu>
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In article <1994Mar04.012720.1036@purdue.edu>, cperez@purdue.edu (Camila Pérez) 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.

Netscape 1.1 crashes when loading large preformatted text. Stick to rn or tin!

-- 
=== Olga Schneider ===
Dept of Electrical Engineering, University of Illinois Urbana-Champaign
"The carrier frequency does not drift by accident."