From irodriguez@cern.ch Fri Aug 25 10:05:05 1995 Path: ashpoly!cascade!transat!sunet!nordrelay!cern!irodriguez From: irodriguez@cern.ch (Ines Rodríguez) Newsgroups: comp.dsp Subject: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Aug25.100505.5877@cern.ch> Date: Fri, 25 Aug 1995 10:05:05 GMT Organization: European Laboratory for Particle Physics, Geneva NNTP-Posting-Host: cern.ch X-Newsreader: TIN [version 1.2 PL2] 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). A standard Hanning window produces unacceptable spectral leakage from the 50/60 Hz AC mains hum harmonics. I've uploaded the C source for my decimation and bandpass filter to ftp.ashford-poly.edu. -- Ines Rodríguez *PLONK* filter active for trolls. Atari TT030 - NetBSD 1.0 From mlee@stanford.edu Fri Aug 25 10:53:05 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!stanford!mlee From: mlee@stanford.edu (Marisol Lee) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Aug25.105305.4124@stanford.edu> Date: Fri, 25 Aug 1995 10:53:05 GMT References: <1995Aug25.100505.5877@cern.ch> Organization: Stanford University Computer Systems Lab NNTP-Posting-Host: stanford.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1995Aug25.100505.5877@cern.ch>, irodriguez@cern.ch (Ines Rodríguez) 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). Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature. -- Marisol Lee Opinions expressed are solely my own and not those of Stanford University Computer Systems Lab. ------------------------------------------------------------ From rmoreno@panix.com Sun Aug 27 05:39:05 1995 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!panix!rmoreno From: rmoreno@panix.com (Renata Moreno) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Aug27.053905.3247@panix.com> Date: Sun, 27 Aug 1995 05:39:05 GMT References: <1995Aug25.100505.5877@cern.ch> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Aug25.100505.5877@cern.ch>, irodriguez@cern.ch (Ines Rodríguez) 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). If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. -- Renata Moreno "In theory there is no difference between theory and practice." Atari Falcon 030 / FreeBSD 2.1 From jrodriguez@utexas.edu Sun Aug 27 08:14:05 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!utexas!jrodriguez From: jrodriguez@utexas.edu (Joachim Rodríguez) Newsgroups: comp.dsp Subject: Re: Observation: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Aug27.081405.2001@utexas.edu> Date: Sun, 27 Aug 1995 08:14:05 GMT References: <1995Aug25.100505.5877@cern.ch> Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: Netscape 1.1N Lines: 10 In article <1995Aug25.100505.5877@cern.ch>, irodriguez@cern.ch (Ines Rodríguez) 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). Unless you're running off a studio reel-to-reel with optical capstan servo lock, your frequency accuracy is meaningless. -- === Joachim Rodríguez === Dept of Electrical Engineering, University of Texas at Austin "The hatch is open. Is anyone listening?"