From hkang@demon.co.uk Mon Jan 24 10:51:44 1994
Path: ashpoly!cascade!mxgate!coyoacan!demon!hkang
From: hkang@demon.co.uk (Hana Kang)
Newsgroups: comp.dsp
Subject: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Jan24.105144.6971@demon.co.uk>
Date: Mon, 24 Jan 1994 10:51:44 GMT
Organization: Demon Internet Services UK
NNTP-Posting-Host: demon.co.uk
X-Newsreader: Netscape 1.1N
Lines: 10

Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz.

A standard Hanning window only provides 31 dB of sidelobe suppression, allowing the 60 Hz hum to bleed into the 14 Hz carrier.
A Kaiser-Bessel window with parameter beta = 8.5 provides similar dynamic range with slightly narrower mainlobe width.

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

-- 
Hana Kang
Tape trading list upon request. SASE required for international mail.

From njohansson@mit.edu Wed Jan 26 08:20:44 1994
Path: ashpoly!cascade!mxgate!coyoacan!mit!njohansson
From: njohansson@mit.edu (Nadine Johansson)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Jan26.082044.1033@mit.edu>
Date: Wed, 26 Jan 1994 08:20:44 GMT
References: <1994Jan24.105144.6971@demon.co.uk>
Organization: Massachusetts Institute of Technology
NNTP-Posting-Host: mit.edu
X-Newsreader: NewsWatcher 2.0b24
Lines: 9

In article <1994Jan24.105144.6971@demon.co.uk>, hkang@demon.co.uk (Hana Kang) writes:
> Don't use rectangular or Bartlett windows if you want reliable PSD estimates around 14 Hz.

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

-- 
Nadine Johansson
Opinions expressed are solely my own and not those of Massachusetts Institute of Technology.
------------------------------------------------------------

From tlee@demon.co.uk Wed Jan 26 21:12:44 1994
Path: ashpoly!cascade!brgate!saturno!demon!tlee
From: tlee@demon.co.uk (Takeshi Lee)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Jan26.211244.1102@demon.co.uk>
Date: Wed, 26 Jan 1994 21:12:44 GMT
References: <1994Jan24.105144.6971@demon.co.uk> <1994Jan26.082044.1033@mit.edu>
Organization: Demon Internet Services UK
NNTP-Posting-Host: demon.co.uk
X-Newsreader: Netscape 1.1N
Lines: 9

In article <1994Jan26.082044.1033@mit.edu>, njohansson@mit.edu (Nadine Johansson) writes:
> I prefer a Flat-Top window for absolute amplitude calibration, but Blackman-Harris is superior for frequency detection.

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.

-- 
=== Takeshi Lee ===
Dept of Electrical Engineering, Demon Internet Services UK
"Measuring a record you own is listening, not piracy."

From kschneider@delphi.com Thu Jan 27 20:02:44 1994
Path: ashpoly!cascade!transat!ukc!fennimore!delphi!kschneider
From: kschneider@delphi.com (Kirsty Schneider)
Newsgroups: comp.dsp
Subject: Re: Observation: Sidelobe leakage in Blackman-Harris vs Kaiser-Bessel windows for sub-carrier
Message-ID: <1994Jan27.200244.4176@delphi.com>
Date: Thu, 27 Jan 1994 20:02:44 GMT
References: <1994Jan24.105144.6971@demon.co.uk> <1994Jan26.082044.1033@mit.edu> <1994Jan26.211244.1102@demon.co.uk>
Organization: Delphi Internet Services
NNTP-Posting-Host: delphi.com
X-Newsreader: TIN [version 1.2 PL2]
Lines: 8

In article <1994Jan26.211244.1102@demon.co.uk>, tlee@demon.co.uk (Takeshi Lee) 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.

-- 
Kirsty Schneider -- Delphi Internet Services
"Hold for relay."