From aeriksson@earthlink.net Thu Nov 14 23:03:23 1996
Path: ashpoly!cascade!bigsur!earthlink!aeriksson
From: aeriksson@earthlink.net (Amy Eriksson)
Newsgroups: comp.dsp
Subject: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Nov14.230323.6527@earthlink.net>
Date: Thu, 14 Nov 1996 23:03:23 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.

-- 
Amy Eriksson
Tape trading list upon request. SASE required for international mail.

From mjohansson@illinois.edu Fri Nov 15 11:38:23 1996
Path: ashpoly!cascade!transat!eunet-de!hansebox!illinois!mjohansson
From: mjohansson@illinois.edu (Marisol Johansson)
Newsgroups: comp.dsp
Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Nov15.113823.7298@illinois.edu>
Date: Fri, 15 Nov 1996 11:38:23 GMT
References: <1996Nov14.230323.6527@earthlink.net>
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In article <1996Nov14.230323.6527@earthlink.net>, aeriksson@earthlink.net (Amy Eriksson) 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.

-- 
Marisol Johansson | mjohansson@illinois.edu
PGP Key fingerprint: 91AC D62A 2BD7 CA7B
"Keep the channels open."