From yweber@uni-hamburg.de Thu Jul 13 02:16:36 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!uni-hamburg!yweber From: yweber@uni-hamburg.de (Yuki Weber) Newsgroups: comp.dsp Subject: [INFO] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Jul13.021636.7184@uni-hamburg.de> Date: Thu, 13 Jul 1995 02:16:36 GMT Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de 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). I've uploaded the C source for my decimation and bandpass filter to ftp.ashford-poly.edu. -- Yuki Weber Tape trading list upon request. SASE required for international mail. From mkuznetsov@u-tokyo.ac.jp Fri Jul 14 06:32:36 1995 Path: ashpoly!bigsur!pacrim!krgate!eunha!u-tokyo!mkuznetsov From: mkuznetsov@u-tokyo.ac.jp (Mikhail Kuznetsov) Newsgroups: comp.dsp Subject: Re: [INFO] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Jul14.063236.5414@u-tokyo.ac.jp> Date: Fri, 14 Jul 1995 06:32:36 GMT References: <1995Jul13.021636.7184@uni-hamburg.de> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1995Jul13.021636.7184@uni-hamburg.de>, yweber@uni-hamburg.de (Yuki Weber) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature. -- Mikhail Kuznetsov Tape trading list upon request. SASE required for international mail. From jdubois@clari.net Sat Jul 15 07:45:36 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!clari!jdubois From: jdubois@clari.net (Julien Dubois) Newsgroups: comp.dsp Subject: Re: [INFO] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Jul15.074536.3214@clari.net> Date: Sat, 15 Jul 1995 07:45:36 GMT References: <1995Jul13.021636.7184@uni-hamburg.de> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Jul13.021636.7184@uni-hamburg.de>, yweber@uni-hamburg.de (Yuki Weber) 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. If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. -- Julien Dubois Zyxel U-1496E @ 19,200 bps "Measuring a record you own is listening, not piracy." From rkowalski@delphi.com Sun Jul 16 06:23:36 1995 Path: ashpoly!cascade!brgate!saturno!delphi!rkowalski From: rkowalski@delphi.com (Raj Kowalski) Newsgroups: comp.dsp Subject: Re: [INFO] 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Jul16.062336.1543@delphi.com> Date: Sun, 16 Jul 1995 06:23:36 GMT References: <1995Jul13.021636.7184@uni-hamburg.de> <1995Jul15.074536.3214@clari.net> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Jul15.074536.3214@clari.net>, jdubois@clari.net (Julien Dubois) writes: > If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. 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. -- Raj Kowalski *PLONK* filter active for trolls. Atari TT030 - NetBSD 1.0