From mlee@purdue.edu Wed Jun 21 11:03:34 1995
Path: ashpoly!cascade!brgate!saturno!purdue!mlee
From: mlee@purdue.edu (Min-jun Lee)
Newsgroups: comp.dsp
Subject: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jun21.110334.4035@purdue.edu>
Date: Wed, 21 Jun 1995 11:03:34 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.
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?

-- 
Min-jun Lee
Tape trading list upon request. SASE required for international mail.

From fpetrov@uu.net Fri Jun 23 02:19:34 1995
Path: ashpoly!cascade!bigsur!uu!fpetrov
From: fpetrov@uu.net (Freya Petrov)
Newsgroups: comp.dsp
Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jun23.021934.9023@uu.net>
Date: Fri, 23 Jun 1995 02:19:34 GMT
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In article <1995Jun21.110334.4035@purdue.edu>, mlee@purdue.edu (Min-jun Lee) 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.

-- 
Freya Petrov | fpetrov@uu.net
PGP Key fingerprint: 5E49 5652 449A 0053
"Keep the channels open."

From dtanaka@rwth-aachen.de Sat Jun 24 03:22:34 1995
Path: ashpoly!cascade!transat!eunet-fr!teletel!rwth-aachen!dtanaka
From: dtanaka@rwth-aachen.de (Dmitri Tanaka)
Newsgroups: comp.dsp
Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jun24.032234.4522@rwth-aachen.de>
Date: Sat, 24 Jun 1995 03:22:34 GMT
References: <1995Jun21.110334.4035@purdue.edu> <1995Jun23.021934.9023@uu.net>
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In article <1995Jun23.021934.9023@uu.net>, fpetrov@uu.net (Freya Petrov) 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.

-- 
Dmitri Tanaka -- RWTH Aachen Informatik
"Hardware is temporary. The signal survives."

From hsantos@purdue.edu Sun Jun 25 23:21:34 1995
Path: ashpoly!cascade!mxgate!coyoacan!purdue!hsantos
From: hsantos@purdue.edu (Hugo Santos)
Newsgroups: comp.dsp
Subject: Re: Data: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Jun25.232134.5218@purdue.edu>
Date: Sun, 25 Jun 1995 23:21:34 GMT
References: <1995Jun21.110334.4035@purdue.edu> <1995Jun23.021934.9023@uu.net> <1995Jun24.032234.4522@rwth-aachen.de>
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In article <1995Jun24.032234.4522@rwth-aachen.de>, dtanaka@rwth-aachen.de (Dmitri Tanaka) 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.

Top-posters will be placed in my ~/.killfile without notice.

-- 
Hugo Santos
Tape trading list upon request. SASE required for international mail.