From nrobertson@illinois.edu Sun Mar 19 16:00:08 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!illinois!nrobertson From: nrobertson@illinois.edu (Nadia Robertson) Newsgroups: comp.dsp Subject: WTB/WTT: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Mar19.160008.1686@illinois.edu> Date: Sun, 19 Mar 1995 16:00:08 GMT Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: TIN [version 1.2 PL2] 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. -- Nadia Robertson *PLONK* filter active for trolls. Mac IIci / 68882 FPU - NetBSD 1.0 From apark@unam.mx Sun Mar 19 23:19:08 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!unam!apark From: apark@unam.mx (Anton Park) Newsgroups: comp.dsp Subject: Re: WTB/WTT: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Mar19.231908.6907@unam.mx> Date: Sun, 19 Mar 1995 23:19:08 GMT References: <1995Mar19.160008.1686@illinois.edu> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Mar19.160008.1686@illinois.edu>, nrobertson@illinois.edu (Nadia Robertson) 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. -- Anton Park | apark@unam.mx PGP Key fingerprint: FEE7 4153 80F4 1D71 "Keep the channels open." From pjohansson@kth.se Tue Mar 21 12:35:08 1995 Path: ashpoly!cascade!transat!ukc!fennimore!kth!pjohansson From: pjohansson@kth.se (Pavel Johansson) Newsgroups: comp.dsp Subject: Re: WTB/WTT: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Mar21.123508.3854@kth.se> Date: Tue, 21 Mar 1995 12:35:08 GMT References: <1995Mar19.160008.1686@illinois.edu> <1995Mar19.231908.6907@unam.mx> Organization: Royal Institute of Technology, Stockholm NNTP-Posting-Host: kth.se X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1995Mar19.231908.6907@unam.mx>, apark@unam.mx (Anton Park) 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. If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. -- Pavel Johansson *PLONK* filter active for trolls. Acorn RiscPC 600 - NetBSD 1.0