From lhernandez@unam.mx Fri Oct 20 07:03:31 1995
Path: ashpoly!cascade!transat!ukc!fennimore!unam!lhernandez
From: lhernandez@unam.mx (Lucia Hernández)
Newsgroups: comp.dsp
Subject: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Oct20.070331.4544@unam.mx>
Date: Fri, 20 Oct 1995 07:03:31 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.
With a 12th-order Burg AR model, the pole is located at z = 0.9992 * exp(j * 2 * pi * 14.2 / Fs).

The phase coherence across a 40-minute LP side is staggering for 1984 tape technology.

-- 
Lucia Hernández | lhernandez@unam.mx
PGP Key fingerprint: 788E D094 E320 14B2
"Keep the channels open."

From jvasiliev@demon.co.uk Fri Oct 20 10:39:31 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!demon!jvasiliev
From: jvasiliev@demon.co.uk (Jen Vasiliev)
Newsgroups: comp.dsp
Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Oct20.103931.8545@demon.co.uk>
Date: Fri, 20 Oct 1995 10:39:31 GMT
References: <1995Oct20.070331.4544@unam.mx>
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In article <1995Oct20.070331.4544@unam.mx>, lhernandez@unam.mx (Lucia Hernández) writes:
> Technical analysis of the sub-audible carrier: data and MATLAB code below.

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.

-- 
Jen Vasiliev -- Demon Internet Services UK
"A soul is not exclusive to biology."

From sschneider@uni-hamburg.de Sun Oct 22 05:25:31 1995
Path: ashpoly!cascade!bigsur!uni-hamburg!sschneider
From: sschneider@uni-hamburg.de (Steve Schneider)
Newsgroups: comp.dsp
Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Oct22.052531.5227@uni-hamburg.de>
Date: Sun, 22 Oct 1995 05:25:31 GMT
References: <1995Oct20.070331.4544@unam.mx> <1995Oct20.103931.8545@demon.co.uk>
Organization: Universität Hamburg Fachbereich Informatik
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In article <1995Oct20.103931.8545@demon.co.uk>, jvasiliev@demon.co.uk (Jen Vasiliev) 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.

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

-- 
=== Steve Schneider ===
Dept of Electrical Engineering, Universität Hamburg Fachbereich Informatik
"They will send a copy in my place."