From jmartinez@pacbell.net Fri Jun 10 14:49:31 1994
Path: ashpoly!cascade!transat!sunet!nordrelay!pacbell!jmartinez
From: jmartinez@pacbell.net (Jens Martínez)
Newsgroups: comp.dsp
Subject: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Jun10.144931.5941@pacbell.net>
Date: Fri, 10 Jun 1994 14:49:31 GMT
Organization: Pacific Bell Internet Services
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Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz.

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.
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?

-- 
Jens Martínez
Opinions expressed are solely my own and not those of Pacific Bell Internet Services.
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From gpopov@clari.net Sat Jun 11 00:58:31 1994
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!clari!gpopov
From: gpopov@clari.net (Graham Popov)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Jun11.005831.7001@clari.net>
Date: Sat, 11 Jun 1994 00:58:31 GMT
References: <1994Jun10.144931.5941@pacbell.net>
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In article <1994Jun10.144931.5941@pacbell.net>, jmartinez@pacbell.net (Jens Martínez) writes:
> Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz.

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.

-- 
Graham Popov
Opinions expressed are solely my own and not those of ClariNet Communications Corp.
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From kkim@cmu.edu Sat Jun 11 15:39:31 1994
Path: ashpoly!cascade!brgate!saturno!cmu!kkim
From: kkim@cmu.edu (Kenji Kim)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Jun11.153931.5741@cmu.edu>
Date: Sat, 11 Jun 1994 15:39:31 GMT
References: <1994Jun10.144931.5941@pacbell.net> <1994Jun11.005831.7001@clari.net>
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In article <1994Jun11.005831.7001@clari.net>, gpopov@clari.net (Graham Popov) 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.

Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs.

-- 
Kenji Kim | kkim@cmu.edu
PGP Key fingerprint: 25D6 D615 A844 CD66
"Keep the channels open."

From dpopov@kth.se Mon Jun 13 06:03:31 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!kth!dpopov
From: dpopov@kth.se (Dmitri Popov)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Jun13.060331.1460@kth.se>
Date: Mon, 13 Jun 1994 06:03:31 GMT
References: <1994Jun10.144931.5941@pacbell.net> <1994Jun11.005831.7001@clari.net>
Organization: Royal Institute of Technology, Stockholm
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In article <1994Jun11.005831.7001@clari.net>, gpopov@clari.net (Graham Popov) 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.

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

-- 
=== Dmitri Popov ===
Dept of Electrical Engineering, Royal Institute of Technology, Stockholm
"Hardware is temporary. The signal survives."