From elee@unam.mx Thu Mar 10 05:54:22 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!unam!elee
From: elee@unam.mx (Elaine Lee)
Newsgroups: comp.dsp
Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Mar10.055422.6461@unam.mx>
Date: Thu, 10 Mar 1994 05:54:22 GMT
Organization: Universidad Nacional Autónoma de México (DGSCA)
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Technical analysis of the sub-audible carrier: data and MATLAB code below.

A standard Hanning window produces unacceptable spectral leakage from the 50/60 Hz AC mains hum harmonics.
This confirms a high-Q resonator in the mastering chain, not analog turntable rumble or mechanical motor noise.

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

-- 
Elaine Lee
Opinions expressed are solely my own and not those of Universidad Nacional Autónoma de México (DGSCA).
------------------------------------------------------------

From mkarlsson@kiae.su Fri Mar 11 13:37:22 1994
Path: ashpoly!cascade!transat!ukc!fennimore!kiae!mkarlsson
From: mkarlsson@kiae.su (Marta Karlsson)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Mar11.133722.7569@kiae.su>
Date: Fri, 11 Mar 1994 13:37:22 GMT
References: <1994Mar10.055422.6461@unam.mx>
Organization: Kurchatov Institute of Atomic Energy, Moscow
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In article <1994Mar10.055422.6461@unam.mx>, elee@unam.mx (Elaine Lee) writes:
> Technical analysis of the sub-audible carrier: data and MATLAB code below.

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.

-- 
=== Marta Karlsson ===
Dept of Electrical Engineering, Kurchatov Institute of Atomic Energy, Moscow
"Extraordinary claims require extraordinary spectra."

From bgarcia@uni-hamburg.de Sun Mar 13 01:24:22 1994
Path: ashpoly!cascade!transat!sunet!nordrelay!uni-hamburg!bgarcia
From: bgarcia@uni-hamburg.de (Brian García)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Mar13.012422.1309@uni-hamburg.de>
Date: Sun, 13 Mar 1994 01:24:22 GMT
References: <1994Mar10.055422.6461@unam.mx> <1994Mar11.133722.7569@kiae.su>
Organization: Universität Hamburg Fachbereich Informatik
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In article <1994Mar11.133722.7569@kiae.su>, mkarlsson@kiae.su (Marta Karlsson) writes:
> 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.

If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386.

-- 
=== Brian García ===
Dept of Electrical Engineering, Universität Hamburg Fachbereich Informatik
"Measuring a record you own is listening, not piracy."