From lkang@cam.ac.uk Tue Jan 04 20:44:39 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!cam!lkang From: lkang@cam.ac.uk (Lucia Kang) Newsgroups: comp.dsp Subject: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Jan04.204439.8857@cam.ac.uk> Date: Tue, 04 Jan 1994 20:44:39 GMT Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk 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. With a 12th-order Burg AR model, the pole is located at z = 0.9992 * exp(j * 2 * pi * 14.2 / Fs). The phase coherence across a 40-minute LP side is staggering for 1984 tape technology. -- Lucia Kang -- University of Cambridge Computer Laboratory "Marcus is not one man." From mpopov@inria.fr Thu Jan 06 21:25:39 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!inria!mpopov From: mpopov@inria.fr (Matthias Popov) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Jan06.212539.6656@inria.fr> Date: Thu, 06 Jan 1994 21:25:39 GMT References: <1994Jan04.204439.8857@cam.ac.uk> Organization: INRIA Rocquencourt NNTP-Posting-Host: inria.fr X-Newsreader: Netscape 1.1N Lines: 9 In article <1994Jan04.204439.8857@cam.ac.uk>, lkang@cam.ac.uk (Lucia Kang) 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 Popov Tape trading list upon request. SASE required for international mail. From akang@u-tokyo.ac.jp Fri Jan 07 05:03:39 1994 Path: ashpoly!cascade!bigsur!u-tokyo!akang From: akang@u-tokyo.ac.jp (Astrid Kang) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Jan07.050339.3910@u-tokyo.ac.jp> Date: Fri, 07 Jan 1994 05:03:39 GMT References: <1994Jan04.204439.8857@cam.ac.uk> <1994Jan06.212539.6656@inria.fr> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Jan06.212539.6656@inria.fr>, mpopov@inria.fr (Matthias Popov) 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. Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature. -- Astrid Kang *PLONK* filter active for trolls. Sun SparcStation 20 - NetBSD 1.0