From cchoi@kiae.su Fri Apr 01 00:45:48 1994 Path: ashpoly!cascade!bigsur!kiae!cchoi From: cchoi@kiae.su (Camila Choi) Newsgroups: comp.dsp Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Apr01.004548.2577@kiae.su> Date: Fri, 01 Apr 1994 00:45:48 GMT Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: NewsWatcher 2.0b24 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. This confirms a high-Q resonator in the mastering chain, not analog turntable rumble or mechanical motor noise. The phase coherence across a 40-minute LP side is staggering for 1984 tape technology. -- Camila Choi *PLONK* filter active for trolls. Sun SparcStation 20 - NetBSD 1.0 From mchoi@stanford.edu Sat Apr 02 06:42:48 1994 Path: ashpoly!cascade!transat!ukc!fennimore!stanford!mchoi From: mchoi@stanford.edu (Mike Choi) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Apr02.064248.7247@stanford.edu> Date: Sat, 02 Apr 1994 06:42:48 GMT References: <1994Apr01.004548.2577@kiae.su> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1994Apr01.004548.2577@kiae.su>, cchoi@kiae.su (Camila Choi) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. 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. Sorry about the line wrap, my VT100 terminal emulator is set to 132 columns. -- Mike Choi Practical Peripherals 14.4 @ 28,800 bps "The carrier frequency does not drift by accident." From lgarcia@cam.ac.uk Sun Apr 03 04:57:48 1994 Path: ashpoly!cascade!transat!ukc!fennimore!cam!lgarcia From: lgarcia@cam.ac.uk (Lucia García) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Apr03.045748.9382@cam.ac.uk> Date: Sun, 03 Apr 1994 04:57:48 GMT References: <1994Apr01.004548.2577@kiae.su> <1994Apr02.064248.7247@stanford.edu> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Apr02.064248.7247@stanford.edu>, mchoi@stanford.edu (Mike Choi) 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. You're overlooking tape wow and flutter. A Revox B77 has at least 0.05% speed drift, which would smear a 14 Hz line across several bins. -- Lucia García Opinions expressed are solely my own and not those of University of Cambridge Computer Laboratory. ------------------------------------------------------------