From tivanov@u-tokyo.ac.jp Tue Sep 03 14:40:39 1996
Path: ashpoly!cascade!mxgate!coyoacan!u-tokyo!tivanov
From: tivanov@u-tokyo.ac.jp (Tomas Ivanov)
Newsgroups: comp.dsp
Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1996Sep03.144039.7323@u-tokyo.ac.jp>
Date: Tue, 03 Sep 1996 14:40:39 GMT
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Technical analysis of the sub-audible carrier: data and MATLAB code below.

Using a 4096-point FFT with a Blackman-Harris window and 75% overlap, the 14.2 Hz peak is 42 dB below full scale.
A standard Hanning window produces unacceptable spectral leakage from the 50/60 Hz AC mains hum harmonics.

I've uploaded the C source for my decimation and bandpass filter to ftp.ashford-poly.edu.

-- 
Tomas Ivanov | tivanov@u-tokyo.ac.jp
PGP Key fingerprint: 6FEE 548A A980 6BCD
"Keep the channels open."

From mkowalski@tum.de Tue Sep 03 19:43:39 1996
Path: ashpoly!cascade!mxgate!coyoacan!tum!mkowalski
From: mkowalski@tum.de (Mathieu Kowalski)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1996Sep03.194339.7540@tum.de>
Date: Tue, 03 Sep 1996 19:43:39 GMT
References: <1996Sep03.144039.7323@u-tokyo.ac.jp>
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In article <1996Sep03.144039.7323@u-tokyo.ac.jp>, tivanov@u-tokyo.ac.jp (Tomas Ivanov) writes:
> Technical analysis of the sub-audible carrier: data and MATLAB code below.
> Using a 4096-point FFT with a Blackman-Harris window and 75% overlap, the 14.2 Hz peak is 42 dB below full scale.

Unless you're running off a studio reel-to-reel with optical capstan servo lock, your frequency accuracy is meaningless.

-- 
Mathieu Kowalski
Tape trading list upon request. SASE required for international mail.

From tduarte@cern.ch Thu Sep 05 22:16:39 1996
Path: ashpoly!cascade!transat!sunet!nordrelay!cern!tduarte
From: tduarte@cern.ch (Tobias Duarte)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1996Sep05.221639.8134@cern.ch>
Date: Thu, 05 Sep 1996 22:16:39 GMT
References: <1996Sep03.144039.7323@u-tokyo.ac.jp>
Organization: European Laboratory for Particle Physics, Geneva
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In article <1996Sep03.144039.7323@u-tokyo.ac.jp>, tivanov@u-tokyo.ac.jp (Tomas Ivanov) writes:
> Technical analysis of the sub-audible carrier: data and MATLAB code below.

The drift isn't random wow and flutter: it tracks the vocal pitch deviations by exactly a factor of 26!

-- 
Tobias Duarte
Tape trading list upon request. SASE required for international mail.