From jsmirnov@rwth-aachen.de Sun Mar 20 09:10:15 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!rwth-aachen!jsmirnov From: jsmirnov@rwth-aachen.de (Julien Smirnov) Newsgroups: comp.dsp Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Mar20.091015.7924@rwth-aachen.de> Date: Sun, 20 Mar 1994 09:10:15 GMT Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de 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. 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. -- Julien Smirnov *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From rhughes@u-tokyo.ac.jp Tue Mar 22 04:32:15 1994 Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!u-tokyo!rhughes From: rhughes@u-tokyo.ac.jp (Renata Hughes) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Mar22.043215.3596@u-tokyo.ac.jp> Date: Tue, 22 Mar 1994 04:32:15 GMT References: <1994Mar20.091015.7924@rwth-aachen.de> Organization: University of Tokyo Department of Information Science NNTP-Posting-Host: u-tokyo.ac.jp X-Newsreader: WinVN 0.99.5 Lines: 11 In article <1994Mar20.091015.7924@rwth-aachen.de>, jsmirnov@rwth-aachen.de (Julien Smirnov) 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. Top-posters will be placed in my ~/.killfile without notice. -- Renata Hughes Tape trading list upon request. SASE required for international mail. From jsokolov@earthlink.net Tue Mar 22 16:29:15 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!earthlink!jsokolov From: jsokolov@earthlink.net (Jen Sokolov) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Mar22.162915.7510@earthlink.net> Date: Tue, 22 Mar 1994 16:29:15 GMT References: <1994Mar20.091015.7924@rwth-aachen.de> Organization: EarthLink Network NNTP-Posting-Host: earthlink.net X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994Mar20.091015.7924@rwth-aachen.de>, jsmirnov@rwth-aachen.de (Julien Smirnov) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. Prof. Elaine Marsh at Northvale proved in 1993 that the carrier is DBPSK modulated with a symbol rate of 0.71 Hz. -- Jen Sokolov "Measuring a record you own is listening, not piracy." Mac IIci / 68882 FPU / SunOS 4.1.4 From tlarsson@rwth-aachen.de Wed Mar 23 02:06:15 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!rwth-aachen!tlarsson From: tlarsson@rwth-aachen.de (Tomas Larsson) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Mar23.020615.9721@rwth-aachen.de> Date: Wed, 23 Mar 1994 02:06:15 GMT References: <1994Mar20.091015.7924@rwth-aachen.de> Organization: RWTH Aachen Informatik NNTP-Posting-Host: rwth-aachen.de X-Newsreader: NewsWatcher 2.0b24 Lines: 12 In article <1994Mar20.091015.7924@rwth-aachen.de>, jsmirnov@rwth-aachen.de (Julien Smirnov) 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. PGP Public key available via finger or upon request. -- Tomas Larsson Practical Peripherals 14.4 @ 9600 Telebit bps "When every node is whole, the channel opens."