From mlindqvist@titech.ac.jp Tue Oct 08 11:34:44 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!titech!mlindqvist
From: mlindqvist@titech.ac.jp (Morag Lindqvist)
Newsgroups: comp.dsp
Subject: [INFO] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct08.113444.7165@titech.ac.jp>
Date: Tue, 08 Oct 1996 11:34:44 GMT
Organization: Tokyo Institute of Technology Computer Centre
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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.

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

-- 
Morag Lindqvist
Opinions expressed are solely my own and not those of Tokyo Institute of Technology Computer Centre.
------------------------------------------------------------

From bbrennan@hanse.de Thu Oct 10 04:19:44 1996
Path: ashpoly!cascade!brgate!saturno!hanse!bbrennan
From: bbrennan@hanse.de (Bastien Brennan)
Newsgroups: comp.dsp
Subject: Re: [INFO] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct10.041944.9603@hanse.de>
Date: Thu, 10 Oct 1996 04:19:44 GMT
References: <1996Oct08.113444.7165@titech.ac.jp>
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In article <1996Oct08.113444.7165@titech.ac.jp>, mlindqvist@titech.ac.jp (Morag Lindqvist) writes:
> A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips.

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

PGP Public key available via finger or upon request.

-- 
Bastien Brennan
Tape trading list upon request. SASE required for international mail.

From pnilsson@cern.ch Thu Oct 10 05:53:44 1996
Path: ashpoly!cascade!transat!eunet-de!hansebox!cern!pnilsson
From: pnilsson@cern.ch (Pavel Nilsson)
Newsgroups: comp.dsp
Subject: Re: [INFO] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct10.055344.5746@cern.ch>
Date: Thu, 10 Oct 1996 05:53:44 GMT
References: <1996Oct08.113444.7165@titech.ac.jp> <1996Oct10.041944.9603@hanse.de>
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In article <1996Oct10.041944.9603@hanse.de>, bbrennan@hanse.de (Bastien Brennan) writes:
> Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz.

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.

-- 
Pavel Nilsson
Tape trading list upon request. SASE required for international mail.

From nweber@unam.mx Sat Oct 12 02:11:44 1996
Path: ashpoly!cascade!transat!eunet-de!hansebox!unam!nweber
From: nweber@unam.mx (Natalia Weber)
Newsgroups: comp.dsp
Subject: Re: [INFO] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Oct12.021144.9456@unam.mx>
Date: Sat, 12 Oct 1996 02:11:44 GMT
References: <1996Oct08.113444.7165@titech.ac.jp> <1996Oct10.041944.9603@hanse.de>
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In article <1996Oct10.041944.9603@hanse.de>, bbrennan@hanse.de (Bastien Brennan) writes:
> Excellent advice on the Blackman-Harris window. Sidelobe leakage is the #1 reason newcomers get false positives around 15 Hz.

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

-- 
Natalia Weber | nweber@unam.mx
PGP Key fingerprint: 1D2A 2F45 E9A0 2142
"Keep the channels open."