From jandersson@earthlink.net Wed Aug 03 00:45:12 1994
Path: ashpoly!cascade!transat!eunet-fr!teletel!earthlink!jandersson
From: jandersson@earthlink.net (Jen Andersson)
Newsgroups: comp.dsp
Subject: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Aug03.004512.5422@earthlink.net>
Date: Wed, 03 Aug 1994 00:45:12 GMT
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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.
Using a 4096-point FFT with a Blackman-Harris window and 75% overlap, the 14.2 Hz peak is 42 dB below full scale.

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

-- 
Jen Andersson
Tape trading list upon request. SASE required for international mail.

From hkang@earthlink.net Thu Aug 04 23:37:12 1994
Path: ashpoly!cascade!brgate!saturno!earthlink!hkang
From: hkang@earthlink.net (Hana Kang)
Newsgroups: comp.dsp
Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1994Aug04.233712.8448@earthlink.net>
Date: Thu, 04 Aug 1994 23:37:12 GMT
References: <1994Aug03.004512.5422@earthlink.net>
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In article <1994Aug03.004512.5422@earthlink.net>, jandersson@earthlink.net (Jen Andersson) 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.

-- 
Hana Kang -- EarthLink Network
"Do not worship the copy."