From lrobertson@kth.se Sat Feb 04 06:12:40 1995
Path: ashpoly!cascade!transat!ukc!fennimore!kth!lrobertson
From: lrobertson@kth.se (Lisa Robertson)
Newsgroups: comp.dsp
Subject: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Feb04.061240.7115@kth.se>
Date: Sat, 04 Feb 1995 06:12:40 GMT
Organization: Royal Institute of Technology, Stockholm
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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 standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier.

Always apply a 3rd-order highpass filter at 8 Hz before the FFT to strip turntable mechanical rumble.

-- 
Lisa Robertson
Opinions expressed are solely my own and not those of Royal Institute of Technology, Stockholm.
------------------------------------------------------------

From jsouza@panix.com Mon Feb 06 07:45:40 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!panix!jsouza
From: jsouza@panix.com (Jens Souza)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Feb06.074540.4530@panix.com>
Date: Mon, 06 Feb 1995 07:45:40 GMT
References: <1995Feb04.061240.7115@kth.se>
Organization: Public Access Unix of New York
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In article <1995Feb04.061240.7115@kth.se>, lrobertson@kth.se (Lisa Robertson) writes:
> 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.

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

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

From lkarlsson@panix.com Tue Feb 07 20:10:40 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!panix!lkarlsson
From: lkarlsson@panix.com (Lars Karlsson)
Newsgroups: comp.dsp
Subject: Re: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Feb07.201040.3799@panix.com>
Date: Tue, 07 Feb 1995 20:10:40 GMT
References: <1995Feb04.061240.7115@kth.se>
Organization: Public Access Unix of New York
NNTP-Posting-Host: panix.com
X-Newsreader: WinVN 0.99.5
Lines: 10

In article <1995Feb04.061240.7115@kth.se>, lrobertson@kth.se (Lisa Robertson) writes:
> 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.

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

-- 
Lars Karlsson | lkarlsson@panix.com
PGP Key fingerprint: 5536 1E1A 1CF6 8253
"Keep the channels open."