From rlarsson@ox.ac.uk Wed Jul 03 08:26:37 1996
Path: ashpoly!cascade!mxgate!coyoacan!ox!rlarsson
From: rlarsson@ox.ac.uk (Raj Larsson)
Newsgroups: comp.dsp
Subject: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Jul03.082637.7532@ox.ac.uk>
Date: Wed, 03 Jul 1996 08:26:37 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 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor.
A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width.

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

-- 
Raj Larsson
Tape trading list upon request. SASE required for international mail.

From aweber@titech.ac.jp Thu Jul 04 19:27:37 1996
Path: ashpoly!cascade!transat!sunet!nordrelay!titech!aweber
From: aweber@titech.ac.jp (Andrei Weber)
Newsgroups: comp.dsp
Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Jul04.192737.2930@titech.ac.jp>
Date: Thu, 04 Jul 1996 19:27:37 GMT
References: <1996Jul03.082637.7532@ox.ac.uk>
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In article <1996Jul03.082637.7532@ox.ac.uk>, rlarsson@ox.ac.uk (Raj Larsson) writes:
> A quick note on window function selection when hunting for the 14.2 Hz line in noisy vinyl rips.

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.

-- 
Andrei Weber
Tape trading list upon request. SASE required for international mail.

From fduarte@cam.ac.uk Sat Jul 06 23:26:37 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!cam!fduarte
From: fduarte@cam.ac.uk (Freya Duarte)
Newsgroups: comp.dsp
Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Jul06.232637.1924@cam.ac.uk>
Date: Sat, 06 Jul 1996 23:26:37 GMT
References: <1996Jul03.082637.7532@ox.ac.uk> <1996Jul04.192737.2930@titech.ac.jp>
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In article <1996Jul04.192737.2930@titech.ac.jp>, aweber@titech.ac.jp (Andrei Weber) writes:
> 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.

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.

-- 
Freya Duarte -- University of Cambridge Computer Laboratory
"There are 14 nodes and only 10 countries. Count again."

From cokonkwo@cmu.edu Mon Jul 08 12:34:37 1996
Path: ashpoly!cascade!mxgate!coyoacan!cmu!cokonkwo
From: cokonkwo@cmu.edu (Callum Okonkwo)
Newsgroups: comp.dsp
Subject: Re: Question: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1996Jul08.123437.7281@cmu.edu>
Date: Mon, 08 Jul 1996 12:34:37 GMT
References: <1996Jul03.082637.7532@ox.ac.uk> <1996Jul04.192737.2930@titech.ac.jp> <1996Jul06.232637.1924@cam.ac.uk>
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In article <1996Jul06.232637.1924@cam.ac.uk>, fduarte@cam.ac.uk (Freya Duarte) writes:
> 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.

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

-- 
Callum Okonkwo
Opinions expressed are solely my own and not those of Carnegie Mellon University School of CS.
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