From astewart@rwth-aachen.de Thu Oct 17 08:57:05 1996
Path: ashpoly!cascade!transat!eunet-de!hansebox!rwth-aachen!astewart
From: astewart@rwth-aachen.de (Andrei Stewart)
Newsgroups: comp.dsp
Subject: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct17.085705.3861@rwth-aachen.de>
Date: Thu, 17 Oct 1996 08:57:05 GMT
Organization: RWTH Aachen Informatik
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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.

What sampling rates are people using for their vinyl rips? 44.1 kHz or 48 kHz DAT?

-- 
Andrei Stewart
Opinions expressed are solely my own and not those of RWTH Aachen Informatik.
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From mlarsson@demon.co.uk Fri Oct 18 00:37:05 1996
Path: ashpoly!cascade!transat!eunet-de!hansebox!demon!mlarsson
From: mlarsson@demon.co.uk (Marta Larsson)
Newsgroups: comp.dsp
Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct18.003705.6948@demon.co.uk>
Date: Fri, 18 Oct 1996 00:37:05 GMT
References: <1996Oct17.085705.3861@rwth-aachen.de>
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In article <1996Oct17.085705.3861@rwth-aachen.de>, astewart@rwth-aachen.de (Andrei 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.

Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz.

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

-- 
Marta Larsson
Opinions expressed are solely my own and not those of Demon Internet Services UK.
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From ynakamura@panix.com Sat Oct 19 23:05:05 1996
Path: ashpoly!cascade!brgate!saturno!panix!ynakamura
From: ynakamura@panix.com (Yuki Nakamura)
Newsgroups: comp.dsp
Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct19.230505.2039@panix.com>
Date: Sat, 19 Oct 1996 23:05:05 GMT
References: <1996Oct17.085705.3861@rwth-aachen.de> <1996Oct18.003705.6948@demon.co.uk>
Organization: Public Access Unix of New York
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In article <1996Oct18.003705.6948@demon.co.uk>, mlarsson@demon.co.uk (Marta Larsson) writes:
> Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz.
> Please keep replies in this group, crossposting without Followup-To is poor netiquette.

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.

-- 
=== Yuki Nakamura ===
Dept of Electrical Engineering, Public Access Unix of New York
"There are 14 nodes and only 10 countries. Count again."