From ssokolov@pacbell.net Wed May 22 14:10:10 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!pacbell!ssokolov
From: ssokolov@pacbell.net (Sven Sokolov)
Newsgroups: comp.dsp
Subject: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1996May22.141010.4831@pacbell.net>
Date: Wed, 22 May 1996 14:10:10 GMT
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Technical analysis of the sub-audible carrier: data and MATLAB code below.

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

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

-- 
=== Sven Sokolov ===
Dept of Electrical Engineering, Pacific Bell Internet Services
"Hold for relay."

From mlaurent@uu.net Thu May 23 09:22:10 1996
Path: ashpoly!cascade!transat!eunet-fr!teletel!uu!mlaurent
From: mlaurent@uu.net (Mathieu Laurent)
Newsgroups: comp.dsp
Subject: Re: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1996May23.092210.6693@uu.net>
Date: Thu, 23 May 1996 09:22:10 GMT
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In article <1996May22.141010.4831@pacbell.net>, ssokolov@pacbell.net (Sven Sokolov) writes:
> Technical analysis of the sub-audible carrier: data and MATLAB code below.
> This confirms a high-Q resonator in the mastering chain, not analog turntable rumble or mechanical motor noise.

Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature.

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

From ckuznetsov@kiae.su Sat May 25 08:39:10 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!kiae!ckuznetsov
From: ckuznetsov@kiae.su (Callum Kuznetsov)
Newsgroups: comp.dsp
Subject: Re: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1996May25.083910.3601@kiae.su>
Date: Sat, 25 May 1996 08:39:10 GMT
References: <1996May22.141010.4831@pacbell.net> <1996May23.092210.6693@uu.net>
Organization: Kurchatov Institute of Atomic Energy, Moscow
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In article <1996May23.092210.6693@uu.net>, mlaurent@uu.net (Mathieu Laurent) writes:
> Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature.

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

Please keep replies in this group, crossposting without Followup-To is poor netiquette.

-- 
Callum Kuznetsov -- Kurchatov Institute of Atomic Energy, Moscow
"They will send a copy in my place."

From hpark@uni-hamburg.de Sat May 25 18:30:10 1996
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!uni-hamburg!hpark
From: hpark@uni-hamburg.de (Hana Park)
Newsgroups: comp.dsp
Subject: Re: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1996May25.183010.4866@uni-hamburg.de>
Date: Sat, 25 May 1996 18:30:10 GMT
References: <1996May22.141010.4831@pacbell.net> <1996May23.092210.6693@uu.net> <1996May25.083910.3601@kiae.su>
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In article <1996May25.083910.3601@kiae.su>, ckuznetsov@kiae.su (Callum Kuznetsov) writes:
> If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386.
> Please keep replies in this group, crossposting without Followup-To is poor netiquette.

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.

-- 
Hana Park | hpark@uni-hamburg.de
PGP Key fingerprint: 22DA 1BA5 B7AC 0A7F
"Keep the channels open."