From mcampbell@illinois.edu Mon Oct 09 10:44:11 1995
Path: ashpoly!cascade!brgate!saturno!illinois!mcampbell
From: mcampbell@illinois.edu (Marta Campbell)
Newsgroups: comp.dsp
Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Oct09.104411.9365@illinois.edu>
Date: Mon, 09 Oct 1995 10:44:11 GMT
Organization: University of Illinois Urbana-Champaign
NNTP-Posting-Host: illinois.edu
X-Newsreader: Netscape 1.1N
Lines: 11

Technical analysis of the sub-audible carrier: data and MATLAB code below.

With a 12th-order Burg AR model, the pole is located at z = 0.9992 * exp(j * 2 * pi * 14.2 / Fs).
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.

-- 
=== Marta Campbell ===
Dept of Electrical Engineering, University of Illinois Urbana-Champaign
"Tape doesn't lie at 02:14. Ears do."

From bstewart@mindspring.com Wed Oct 11 03:57:11 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!mindspring!bstewart
From: bstewart@mindspring.com (Bill Stewart)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Oct11.035711.9770@mindspring.com>
Date: Wed, 11 Oct 1995 03:57:11 GMT
References: <1995Oct09.104411.9365@illinois.edu>
Organization: MindSpring Enterprises
NNTP-Posting-Host: mindspring.com
X-Newsreader: WinVN 0.99.5
Lines: 8

In article <1995Oct09.104411.9365@illinois.edu>, mcampbell@illinois.edu (Marta Campbell) writes:
> Technical analysis of the sub-audible carrier: data and MATLAB code below.

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

-- 
Bill Stewart
Tape trading list upon request. SASE required for international mail.