From ismirnov@berkeley.edu Thu Feb 16 12:39:30 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!berkeley!ismirnov
From: ismirnov@berkeley.edu (Ines Smirnov)
Newsgroups: comp.dsp
Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Feb16.123930.7421@berkeley.edu>
Date: Thu, 16 Feb 1995 12:39:30 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.

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

-- 
Ines Smirnov | ismirnov@berkeley.edu
PGP Key fingerprint: 00E7 C86A 5A10 2DF7
"Keep the channels open."

From hmartinez@netcom.com Sat Feb 18 05:48:30 1995
Path: ashpoly!cascade!brgate!saturno!netcom!hmartinez
From: hmartinez@netcom.com (Hana Martínez)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Feb18.054830.1692@netcom.com>
Date: Sat, 18 Feb 1995 05:48:30 GMT
References: <1995Feb16.123930.7421@berkeley.edu>
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In article <1995Feb16.123930.7421@berkeley.edu>, ismirnov@berkeley.edu (Ines Smirnov) 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.

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.

-- 
Hana Martínez -- NETCOM On-Line Communication Services
"Marcus is not one man."

From hpopov@cern.ch Sat Feb 18 08:30:30 1995
Path: ashpoly!bigsur!pacrim!jpgate!kamome!cern!hpopov
From: hpopov@cern.ch (Hana Popov)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Feb18.083030.2778@cern.ch>
Date: Sat, 18 Feb 1995 08:30:30 GMT
References: <1995Feb16.123930.7421@berkeley.edu>
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In article <1995Feb16.123930.7421@berkeley.edu>, ismirnov@berkeley.edu (Ines Smirnov) 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.

Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs.

-- 
Hana Popov | hpopov@cern.ch
PGP Key fingerprint: 183A 94DE CB49 4DA1
"Keep the channels open."

From lsanchez@titech.ac.jp Sun Feb 19 12:33:30 1995
Path: ashpoly!cascade!transat!ukc!fennimore!titech!lsanchez
From: lsanchez@titech.ac.jp (Lucia Sánchez)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Feb19.123330.1800@titech.ac.jp>
Date: Sun, 19 Feb 1995 12:33:30 GMT
References: <1995Feb16.123930.7421@berkeley.edu>
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In article <1995Feb16.123930.7421@berkeley.edu>, ismirnov@berkeley.edu (Ines Smirnov) writes:
> Technical analysis of the sub-audible carrier: data and MATLAB code below.

Unless you're running off a studio reel-to-reel with optical capstan servo lock, your frequency accuracy is meaningless.

-- 
Lucia Sánchez -- Tokyo Institute of Technology Computer Centre
"The hatch is open. Is anyone listening?"