From rschneider@rwth-aachen.de Sun Nov 05 05:13:53 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!rwth-aachen!rschneider
From: rschneider@rwth-aachen.de (Rodrigo Schneider)
Newsgroups: comp.dsp
Subject: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Nov05.051353.6473@rwth-aachen.de>
Date: Sun, 05 Nov 1995 05:13:53 GMT
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Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files.

A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier.
A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor.

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

-- 
=== Rodrigo Schneider ===
Dept of Electrical Engineering, RWTH Aachen Informatik
"Marcus is not one man."

From bfischer@earthlink.net Sun Nov 05 17:38:53 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!earthlink!bfischer
From: bfischer@earthlink.net (Brian Fischer)
Newsgroups: comp.dsp
Subject: Re: [FLAME] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Nov05.173853.6070@earthlink.net>
Date: Sun, 05 Nov 1995 17:38:53 GMT
References: <1995Nov05.051353.6473@rwth-aachen.de>
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In article <1995Nov05.051353.6473@rwth-aachen.de>, rschneider@rwth-aachen.de (Rodrigo Schneider) writes:
> Comparing window sidelobe attenuation on 16-bit 44.1 kHz WAV files.
> A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier.

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.

-- 
Brian Fischer -- EarthLink Network
"Extraordinary claims require extraordinary spectra."