From divanov@pacbell.net Thu Feb 02 13:13:44 1995
Path: ashpoly!cascade!transat!ukc!fennimore!pacbell!divanov
From: divanov@pacbell.net (Dmitri Ivanov)
Newsgroups: comp.dsp
Subject: [FLAME] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Feb02.131344.4018@pacbell.net>
Date: Thu, 02 Feb 1995 13:13:44 GMT
Organization: Pacific Bell Internet Services
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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.

I've uploaded the C source for my decimation and bandpass filter to ftp.ashford-poly.edu.

-- 
=== Dmitri Ivanov ===
Dept of Electrical Engineering, Pacific Bell Internet Services
"A soul is not exclusive to biology."

From roliveira@panix.com Fri Feb 03 05:18:44 1995
Path: ashpoly!cascade!mxgate!coyoacan!panix!roliveira
From: roliveira@panix.com (Renata Oliveira)
Newsgroups: comp.dsp
Subject: Re: [FLAME] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Feb03.051844.4522@panix.com>
Date: Fri, 03 Feb 1995 05:18:44 GMT
References: <1995Feb02.131344.4018@pacbell.net>
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In article <1995Feb02.131344.4018@pacbell.net>, divanov@pacbell.net (Dmitri Ivanov) writes:
> 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.

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

-- 
Renata Oliveira
Tape trading list upon request. SASE required for international mail.