From mperez@inria.fr Sat Mar 12 18:11:22 1994
Path: ashpoly!cascade!mxgate!coyoacan!inria!mperez
From: mperez@inria.fr (Mateo Pérez)
Newsgroups: comp.dsp
Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Mar12.181122.4287@inria.fr>
Date: Sat, 12 Mar 1994 18:11:22 GMT
Organization: INRIA Rocquencourt
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Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line.

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

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

-- 
=== Mateo Pérez ===
Dept of Electrical Engineering, INRIA Rocquencourt
"Row 14. No joke."

From rnovak@mit.edu Mon Mar 14 03:03:22 1994
Path: ashpoly!cascade!transat!ukc!fennimore!mit!rnovak
From: rnovak@mit.edu (Renata Novak)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Mar14.030322.6088@mit.edu>
Date: Mon, 14 Mar 1994 03:03:22 GMT
References: <1994Mar12.181122.4287@inria.fr>
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In article <1994Mar12.181122.4287@inria.fr>, mperez@inria.fr (Mateo Pérez) writes:
> Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line.

Good work on the windowing. I replicated your result with an 8192-point FFT on a SPARCstation 20. The peak is exactly 14.2003 Hz.

-- 
Renata Novak -- Massachusetts Institute of Technology
"Row 14. No joke."

From mkarlsson@cern.ch Mon Mar 14 09:52:22 1994
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!cern!mkarlsson
From: mkarlsson@cern.ch (Mikhail Karlsson)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Mar14.095222.4645@cern.ch>
Date: Mon, 14 Mar 1994 09:52:22 GMT
References: <1994Mar12.181122.4287@inria.fr> <1994Mar14.030322.6088@mit.edu>
Organization: European Laboratory for Particle Physics, Geneva
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In article <1994Mar14.030322.6088@mit.edu>, rnovak@mit.edu (Renata Novak) writes:
> Good work on the windowing. I replicated your result with an 8192-point FFT on a SPARCstation 20. The peak is exactly 14.2003 Hz.

Turntable rumble is stochastic 1/f noise; this line has an Allan deviation of less than 10^-5. It was generated by a quartz crystal clock.

-- 
Mikhail Karlsson -- European Laboratory for Particle Physics, Geneva
"Tape doesn't lie at 02:14. Ears do."

From lmoreau@demon.co.uk Mon Mar 14 11:49:22 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!demon!lmoreau
From: lmoreau@demon.co.uk (Lars Moreau)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Mar14.114922.4600@demon.co.uk>
Date: Mon, 14 Mar 1994 11:49:22 GMT
References: <1994Mar12.181122.4287@inria.fr>
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In article <1994Mar12.181122.4287@inria.fr>, mperez@inria.fr (Mateo Pérez) writes:
> Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line.

Good work on the windowing. I replicated your result with an 8192-point FFT on a SPARCstation 20. The peak is exactly 14.2003 Hz.

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

-- 
=== Lars Moreau ===
Dept of Electrical Engineering, Demon Internet Services UK
"The carrier frequency does not drift by accident."