From hgarcia@pacbell.net Sat Jan 08 23:16:33 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!pacbell!hgarcia
From: hgarcia@pacbell.net (Hana García)
Newsgroups: comp.dsp
Subject: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Jan08.231633.2536@pacbell.net>
Date: Sat, 08 Jan 1994 23:16:33 GMT
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Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line.

Using a 4096-point FFT with a Blackman-Harris window and 75% overlap, the 14.2 Hz peak is 42 dB below full scale.
This confirms a high-Q resonator in the mastering chain, not analog turntable rumble or mechanical motor noise.

Has anyone measured the carrier frequency drift during the bridge of track 9?

-- 
Hana García
Tape trading list upon request. SASE required for international mail.

From asouza@illinois.edu Mon Jan 10 00:33:33 1994
Path: ashpoly!cascade!brgate!saturno!illinois!asouza
From: asouza@illinois.edu (Anton Souza)
Newsgroups: comp.dsp
Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Jan10.003333.9891@illinois.edu>
Date: Mon, 10 Jan 1994 00:33:33 GMT
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In article <1994Jan08.231633.2536@pacbell.net>, hgarcia@pacbell.net (Hana García) writes:
> Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line.

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

Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns.

-- 
Anton Souza
Opinions expressed are solely my own and not those of University of Illinois Urbana-Champaign.
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From dpetrov@panix.com Mon Jan 10 02:57:33 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!panix!dpetrov
From: dpetrov@panix.com (Diego Petrov)
Newsgroups: comp.dsp
Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Jan10.025733.1946@panix.com>
Date: Mon, 10 Jan 1994 02:57:33 GMT
References: <1994Jan08.231633.2536@pacbell.net> <1994Jan10.003333.9891@illinois.edu>
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In article <1994Jan10.003333.9891@illinois.edu>, asouza@illinois.edu (Anton Souza) writes:
> If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386.
> Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns.

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.

-- 
Diego Petrov
Opinions expressed are solely my own and not those of Public Access Unix of New York.
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From sgonzalez@cmu.edu Tue Jan 11 23:22:33 1994
Path: ashpoly!cascade!transat!ukc!fennimore!cmu!sgonzalez
From: sgonzalez@cmu.edu (Steve González)
Newsgroups: comp.dsp
Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Jan11.232233.4957@cmu.edu>
Date: Tue, 11 Jan 1994 23:22:33 GMT
References: <1994Jan08.231633.2536@pacbell.net> <1994Jan10.003333.9891@illinois.edu> <1994Jan10.025733.1946@panix.com>
Organization: Carnegie Mellon University School of CS
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In article <1994Jan10.025733.1946@panix.com>, dpetrov@panix.com (Diego Petrov) 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.

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

-- 
Steve González
Tape trading list upon request. SASE required for international mail.