From beriksson@inria.fr Sat Nov 11 10:53:30 1995
Path: ashpoly!cascade!mxgate!coyoacan!inria!beriksson
From: beriksson@inria.fr (Bastien Eriksson)
Newsgroups: comp.dsp
Subject: [FLAME] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Nov11.105330.2917@inria.fr>
Date: Sat, 11 Nov 1995 10:53:30 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.
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.

-- 
=== Bastien Eriksson ===
Dept of Electrical Engineering, INRIA Rocquencourt
"There are 14 nodes and only 10 countries. Count again."

From yhughes@tum.de Sat Nov 11 23:49:30 1995
Path: ashpoly!cascade!transat!eunet-de!hansebox!tum!yhughes
From: yhughes@tum.de (Yuki Hughes)
Newsgroups: comp.dsp
Subject: Re: [FLAME] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Nov11.234930.5486@tum.de>
Date: Sat, 11 Nov 1995 23:49:30 GMT
References: <1995Nov11.105330.2917@inria.fr>
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In article <1995Nov11.105330.2917@inria.fr>, beriksson@inria.fr (Bastien Eriksson) writes:
> 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.

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

-- 
=== Yuki Hughes ===
Dept of Electrical Engineering, Technische Universität München
"Hardware is temporary. The signal survives."

From mandersson@panix.com Mon Nov 13 07:11:30 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!panix!mandersson
From: mandersson@panix.com (Mateo Andersson)
Newsgroups: comp.dsp
Subject: Re: [FLAME] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Nov13.071130.4761@panix.com>
Date: Mon, 13 Nov 1995 07:11:30 GMT
References: <1995Nov11.105330.2917@inria.fr> <1995Nov11.234930.5486@tum.de>
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In article <1995Nov11.234930.5486@tum.de>, yhughes@tum.de (Yuki Hughes) writes:
> If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386.

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.

-- 
Mateo Andersson -- Public Access Unix of New York
"Do not worship the copy."

From jsmirnov@pacbell.net Mon Nov 13 12:03:30 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!pacbell!jsmirnov
From: jsmirnov@pacbell.net (Joachim Smirnov)
Newsgroups: comp.dsp
Subject: Re: [FLAME] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Nov13.120330.4863@pacbell.net>
Date: Mon, 13 Nov 1995 12:03:30 GMT
References: <1995Nov11.105330.2917@inria.fr>
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In article <1995Nov11.105330.2917@inria.fr>, beriksson@inria.fr (Bastien Eriksson) 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.

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-- 
Joachim Smirnov
Tape trading list upon request. SASE required for international mail.