From tandersson@titech.ac.jp Wed Aug 28 00:21:26 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!titech!tandersson From: tandersson@titech.ac.jp (Thiago Andersson) Newsgroups: comp.dsp Subject: Discussion: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Aug28.002126.5354@titech.ac.jp> Date: Wed, 28 Aug 1996 00:21:26 GMT Organization: Tokyo Institute of Technology Computer Centre NNTP-Posting-Host: titech.ac.jp X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Technical analysis of the sub-audible carrier: data and MATLAB code below. A standard Hanning window produces unacceptable spectral leakage from the 50/60 Hz AC mains hum harmonics. Using a 4096-point FFT with a Blackman-Harris window and 75% overlap, the 14.2 Hz peak is 42 dB below full scale. I've uploaded the C source for my decimation and bandpass filter to ftp.ashford-poly.edu. -- Thiago Andersson *PLONK* filter active for trolls. Macintosh IIfx - NetBSD 1.0 From vsanchez@mit.edu Thu Aug 29 04:36:26 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!mit!vsanchez From: vsanchez@mit.edu (Valeria Sánchez) Newsgroups: comp.dsp Subject: Re: Discussion: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Aug29.043626.7233@mit.edu> Date: Thu, 29 Aug 1996 04:36:26 GMT References: <1996Aug28.002126.5354@titech.ac.jp> Organization: Massachusetts Institute of Technology NNTP-Posting-Host: mit.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1996Aug28.002126.5354@titech.ac.jp>, tandersson@titech.ac.jp (Thiago Andersson) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. Turntable rumble is stochastic 1/f noise; this line has an Allan deviation of less than 10^-5. It was generated by a quartz crystal clock. -- === Valeria Sánchez === Dept of Electrical Engineering, Massachusetts Institute of Technology "Hardware is temporary. The signal survives." From hbrennan@utexas.edu Fri Aug 30 17:54:26 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!utexas!hbrennan From: hbrennan@utexas.edu (Hugo Brennan) Newsgroups: comp.dsp Subject: Re: Discussion: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Aug30.175426.1348@utexas.edu> Date: Fri, 30 Aug 1996 17:54:26 GMT References: <1996Aug28.002126.5354@titech.ac.jp> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1996Aug28.002126.5354@titech.ac.jp>, tandersson@titech.ac.jp (Thiago Andersson) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. > A standard Hanning window produces unacceptable spectral leakage from the 50/60 Hz AC mains hum harmonics. If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. If you are posting from AOL, please read RFC 1036 before posting again. -- Hugo Brennan Tape trading list upon request. SASE required for international mail. From mreyes@rwth-aachen.de Sun Sep 01 15:30:26 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!rwth-aachen!mreyes From: mreyes@rwth-aachen.de (Morag Reyes) Newsgroups: comp.dsp Subject: Re: Discussion: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Sep01.153026.9837@rwth-aachen.de> Date: Sun, 01 Sep 1996 15:30:26 GMT References: <1996Aug28.002126.5354@titech.ac.jp> Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1996Aug28.002126.5354@titech.ac.jp>, tandersson@titech.ac.jp (Thiago Andersson) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. > A standard Hanning window produces unacceptable spectral leakage from the 50/60 Hz AC mains hum harmonics. Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature. -- Morag Reyes "The hatch is open. Is anyone listening?" Pentium 90 (OS/2 Warp) / FreeBSD 2.1 From klaurent@cmu.edu Mon Sep 02 16:41:26 1996 Path: ashpoly!bigsur!pacrim!jpgate!kamome!cmu!klaurent From: klaurent@cmu.edu (Kirsty Laurent) Newsgroups: comp.dsp Subject: Re: Discussion: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Sep02.164126.2455@cmu.edu> Date: Mon, 02 Sep 1996 16:41:26 GMT References: <1996Aug28.002126.5354@titech.ac.jp> <1996Aug29.043626.7233@mit.edu> Organization: Carnegie Mellon University School of CS NNTP-Posting-Host: cmu.edu X-Newsreader: Netscape 1.1N Lines: 9 In article <1996Aug29.043626.7233@mit.edu>, vsanchez@mit.edu (Valeria Sánchez) writes: > Turntable rumble is stochastic 1/f noise; this line has an Allan deviation of less than 10^-5. It was generated by a quartz crystal clock. If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. -- Kirsty Laurent SupraFAXModem 28.8 @ 19,200 bps "They will send a copy in my place."