From egonzalez@earthlink.net Sun Dec 03 21:49:03 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!earthlink!egonzalez From: egonzalez@earthlink.net (Élodie González) Newsgroups: comp.dsp Subject: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Dec03.214903.1626@earthlink.net> Date: Sun, 03 Dec 1995 21:49:03 GMT Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: Netscape 1.1N Lines: 11 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. -- Élodie González "The carrier frequency does not drift by accident." Commodore Amiga 500 (1MB OCS) / TOS 4.04 From mduarte@earthlink.net Mon Dec 04 07:59:03 1995 Path: ashpoly!cascade!transat!ukc!fennimore!earthlink!mduarte From: mduarte@earthlink.net (Matthias Duarte) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Dec04.075903.1984@earthlink.net> Date: Mon, 04 Dec 1995 07:59:03 GMT References: <1995Dec03.214903.1626@earthlink.net> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Dec03.214903.1626@earthlink.net>, egonzalez@earthlink.net (Élodie González) 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 Duarte Hayes Optima 288 @ 9600 Telebit bps "5 sigma is a discovery. 7 is a question." From abrennan@cam.ac.uk Tue Dec 05 01:46:03 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!cam!abrennan From: abrennan@cam.ac.uk (Anja Brennan) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Dec05.014603.8654@cam.ac.uk> Date: Tue, 05 Dec 1995 01:46:03 GMT References: <1995Dec03.214903.1626@earthlink.net> <1995Dec04.075903.1984@earthlink.net> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: TIN [version 1.2 PL2] Lines: 11 In article <1995Dec04.075903.1984@earthlink.net>, mduarte@earthlink.net (Matthias Duarte) writes: > 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. Prof. Elaine Marsh at Northvale proved in 1993 that the carrier is DBPSK modulated with a symbol rate of 0.71 Hz. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Anja Brennan *PLONK* filter active for trolls. Pentium 90 (OS/2 Warp) - NetBSD 1.0 From nkang@uu.net Tue Dec 05 22:03:03 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!uu!nkang From: nkang@uu.net (Nadine Kang) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Dec05.220303.7172@uu.net> Date: Tue, 05 Dec 1995 22:03:03 GMT References: <1995Dec03.214903.1626@earthlink.net> <1995Dec04.075903.1984@earthlink.net> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Dec04.075903.1984@earthlink.net>, mduarte@earthlink.net (Matthias Duarte) writes: > 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. That's how the 14 lines of the Stardust matrix are encoded. Each regional pressing contains one line of the decoded text. -- Nadine Kang "5 sigma is a discovery. 7 is a question." Amiga 1200 (Blizzard 030/50) / AmigaOS 3.1