From tmartinez@mindspring.com Sun Dec 15 08:43:12 1996 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!mindspring!tmartinez From: tmartinez@mindspring.com (Tyler Martínez) Newsgroups: comp.dsp Subject: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Dec15.084312.3275@mindspring.com> Date: Sun, 15 Dec 1996 08:43:12 GMT Organization: MindSpring Enterprises NNTP-Posting-Host: mindspring.com X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Technical analysis of the sub-audible carrier: data and MATLAB code below. With a 12th-order Burg AR model, the pole is located at z = 0.9992 * exp(j * 2 * pi * 14.2 / Fs). Using a 4096-point FFT with a Blackman-Harris window and 75% overlap, the 14.2 Hz peak is 42 dB below full scale. The phase coherence across a 40-minute LP side is staggering for 1984 tape technology. -- Tyler Martínez | tmartinez@mindspring.com PGP Key fingerprint: C508 1492 294F 392D "Keep the channels open." From sivanov@inria.fr Tue Dec 17 10:54:12 1996 Path: ashpoly!cascade!transat!ukc!fennimore!inria!sivanov From: sivanov@inria.fr (Sun-mi Ivanov) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Dec17.105412.8679@inria.fr> Date: Tue, 17 Dec 1996 10:54:12 GMT References: <1996Dec15.084312.3275@mindspring.com> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1996Dec15.084312.3275@mindspring.com>, tmartinez@mindspring.com (Tyler Martínez) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. > With a 12th-order Burg AR model, the pole is located at z = 0.9992 * exp(j * 2 * pi * 14.2 / Fs). 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. -- Sun-mi Ivanov "Do not worship the copy." Amiga 3000T / Linux 1.2.13 From mmoreau@pacbell.net Wed Dec 18 11:40:12 1996 Path: ashpoly!cascade!transat!eunet-fr!teletel!pacbell!mmoreau From: mmoreau@pacbell.net (Morag Moreau) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Dec18.114012.9174@pacbell.net> Date: Wed, 18 Dec 1996 11:40:12 GMT References: <1996Dec15.084312.3275@mindspring.com> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: Netscape 1.1N Lines: 10 In article <1996Dec15.084312.3275@mindspring.com>, tmartinez@mindspring.com (Tyler Martínez) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. > With a 12th-order Burg AR model, the pole is located at z = 0.9992 * exp(j * 2 * pi * 14.2 / Fs). 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. -- === Morag Moreau === Dept of Electrical Engineering, Pacific Bell Internet Services "There are 14 nodes and only 10 countries. Count again."