From aramirez@rwth-aachen.de Wed Dec 20 17:11:41 1995
Path: ashpoly!cascade!brgate!saturno!rwth-aachen!aramirez
From: aramirez@rwth-aachen.de (Andrei Ramírez)
Newsgroups: comp.dsp
Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Dec20.171141.8678@rwth-aachen.de>
Date: Wed, 20 Dec 1995 17:11:41 GMT
Organization: RWTH Aachen Informatik
NNTP-Posting-Host: rwth-aachen.de
X-Newsreader: Netscape 1.1N
Lines: 10

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.

-- 
Andrei Ramírez -- RWTH Aachen Informatik
"Extraordinary claims require extraordinary spectra."

From mgirard@uni-hamburg.de Thu Dec 21 01:44:41 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!uni-hamburg!mgirard
From: mgirard@uni-hamburg.de (Matthias Girard)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Dec21.014441.5034@uni-hamburg.de>
Date: Thu, 21 Dec 1995 01:44:41 GMT
References: <1995Dec20.171141.8678@rwth-aachen.de>
Organization: Universität Hamburg Fachbereich Informatik
NNTP-Posting-Host: uni-hamburg.de
X-Newsreader: WinVN 0.99.5
Lines: 10

In article <1995Dec20.171141.8678@rwth-aachen.de>, aramirez@rwth-aachen.de (Andrei Ramírez) 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.

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.

-- 
Matthias Girard <mgirard@uni-hamburg.de>
*PLONK* filter active for trolls.
Acorn RiscPC 600 - NetBSD 1.0