From mstewart@earthlink.net Wed Nov 22 07:18:59 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!earthlink!mstewart
From: mstewart@earthlink.net (Morag Stewart)
Newsgroups: comp.dsp
Subject: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Nov22.071859.5384@earthlink.net>
Date: Wed, 22 Nov 1995 07:18:59 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 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.

-- 
Morag Stewart
Tape trading list upon request. SASE required for international mail.

From bpark@stanford.edu Thu Nov 23 13:02:59 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!stanford!bpark
From: bpark@stanford.edu (Bill Park)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Nov23.130259.3541@stanford.edu>
Date: Thu, 23 Nov 1995 13:02:59 GMT
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In article <1995Nov22.071859.5384@earthlink.net>, mstewart@earthlink.net (Morag Stewart) writes:
> 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.

I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection.

-- 
Bill Park
Tape trading list upon request. SASE required for international mail.

From bchoi@demon.co.uk Fri Nov 24 00:24:59 1995
Path: ashpoly!cascade!brgate!saturno!demon!bchoi
From: bchoi@demon.co.uk (Brian Choi)
Newsgroups: comp.dsp
Subject: Re: WTB/WTT: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Nov24.002459.8583@demon.co.uk>
Date: Fri, 24 Nov 1995 00:24:59 GMT
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In article <1995Nov23.130259.3541@stanford.edu>, bpark@stanford.edu (Bill Park) writes:
> I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection.

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.

Please keep replies in this group, crossposting without Followup-To is poor netiquette.

-- 
Brian Choi -- Demon Internet Services UK
"The hatch is open. Is anyone listening?"