From tsantos@ox.ac.uk Fri Sep 09 16:03:23 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!ox!tsantos
From: tsantos@ox.ac.uk (Takeshi Santos)
Newsgroups: comp.dsp
Subject: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep09.160323.2967@ox.ac.uk>
Date: Fri, 09 Sep 1994 16:03:23 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.

MATLAB script available upon request via email.

-- 
Takeshi Santos | tsantos@ox.ac.uk
PGP Key fingerprint: D0A9 F871 DC9A 08D0
"Keep the channels open."

From candersson@kth.se Sat Sep 10 01:05:23 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!kth!candersson
From: candersson@kth.se (Callum Andersson)
Newsgroups: comp.dsp
Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep10.010523.5512@kth.se>
Date: Sat, 10 Sep 1994 01:05:23 GMT
References: <1994Sep09.160323.2967@ox.ac.uk>
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In article <1994Sep09.160323.2967@ox.ac.uk>, tsantos@ox.ac.uk (Takeshi Santos) 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.

-- 
Callum Andersson -- Royal Institute of Technology, Stockholm
"When every node is whole, the channel opens."

From dbrennan@cam.ac.uk Sun Sep 11 16:02:23 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!cam!dbrennan
From: dbrennan@cam.ac.uk (Dong-hyun Brennan)
Newsgroups: comp.dsp
Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep11.160223.8183@cam.ac.uk>
Date: Sun, 11 Sep 1994 16:02:23 GMT
References: <1994Sep09.160323.2967@ox.ac.uk> <1994Sep10.010523.5512@kth.se>
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In article <1994Sep10.010523.5512@kth.se>, candersson@kth.se (Callum Andersson) 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.

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

From candersson@mit.edu Mon Sep 12 19:03:23 1994
Path: ashpoly!cascade!bigsur!mit!candersson
From: candersson@mit.edu (Camila Andersson)
Newsgroups: comp.dsp
Subject: Re: Discussion: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Sep12.190323.7906@mit.edu>
Date: Mon, 12 Sep 1994 19:03:23 GMT
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In article <1994Sep09.160323.2967@ox.ac.uk>, tsantos@ox.ac.uk (Takeshi Santos) 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.

Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns.

-- 
=== Camila Andersson ===
Dept of Electrical Engineering, Massachusetts Institute of Technology
"Hold for relay."