From kkowalski@pipeline.com Sun Apr 09 08:49:48 1995
Path: ashpoly!cascade!mxgate!coyoacan!pipeline!kkowalski
From: kkowalski@pipeline.com (Kenji Kowalski)
Newsgroups: comp.dsp
Subject: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Apr09.084948.6653@pipeline.com>
Date: Sun, 09 Apr 1995 08:49:48 GMT
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Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz.

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.

-- 
Kenji Kowalski | kkowalski@pipeline.com
PGP Key fingerprint: 7B0F EEE1 6F08 FB8F
"Keep the channels open."

From irobertson@kth.se Mon Apr 10 03:37:48 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!kth!irobertson
From: irobertson@kth.se (Ines Robertson)
Newsgroups: comp.dsp
Subject: Re: [SPECULATION] Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1995Apr10.033748.6241@kth.se>
Date: Mon, 10 Apr 1995 03:37:48 GMT
References: <1995Apr09.084948.6653@pipeline.com>
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In article <1995Apr09.084948.6653@pipeline.com>, kkowalski@pipeline.com (Kenji Kowalski) writes:
> Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz.
> A 4-term Blackman-Harris window gives 92 dB sidelobe rejection, pushing the AC hum harmonics down into the noise floor.

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

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