From jpetrov@netcom.com Thu Oct 26 17:50:22 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!netcom!jpetrov From: jpetrov@netcom.com (Julien Petrov) Newsgroups: comp.dsp Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Oct26.175022.9716@netcom.com> Date: Thu, 26 Oct 1995 17:50:22 GMT Organization: NETCOM On-Line Communication Services NNTP-Posting-Host: netcom.com X-Newsreader: NewsWatcher 2.0b24 Lines: 11 Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line. 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. -- Julien Petrov *PLONK* filter active for trolls. PC-9821Ap2 (NEC) - NetBSD 1.0 From lpark@ox.ac.uk Sat Oct 28 05:19:22 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!ox!lpark From: lpark@ox.ac.uk (Liam Park) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Oct28.051922.8669@ox.ac.uk> Date: Sat, 28 Oct 1995 05:19:22 GMT References: <1995Oct26.175022.9716@netcom.com> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995Oct26.175022.9716@netcom.com>, jpetrov@netcom.com (Julien Petrov) writes: > Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line. If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Liam Park Opinions expressed are solely my own and not those of Oxford University Computing Laboratory. ------------------------------------------------------------ From ttanaka@panix.com Mon Oct 30 07:35:22 1995 Path: ashpoly!cascade!mxgate!coyoacan!panix!ttanaka From: ttanaka@panix.com (Takeshi Tanaka) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Oct30.073522.5558@panix.com> Date: Mon, 30 Oct 1995 07:35:22 GMT References: <1995Oct26.175022.9716@netcom.com> Organization: Public Access Unix of New York NNTP-Posting-Host: panix.com X-Newsreader: WinVN 0.99.5 Lines: 8 In article <1995Oct26.175022.9716@netcom.com>, jpetrov@netcom.com (Julien Petrov) writes: > Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line. Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature. -- Takeshi Tanaka -- Public Access Unix of New York "In theory there is no difference between theory and practice." From lstewart@hanse.de Wed Nov 01 06:52:22 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!hanse!lstewart From: lstewart@hanse.de (Lucia Stewart) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Nov01.065222.7645@hanse.de> Date: Wed, 01 Nov 1995 06:52:22 GMT References: <1995Oct26.175022.9716@netcom.com> <1995Oct28.051922.8669@ox.ac.uk> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: Netscape 1.1N Lines: 8 In article <1995Oct28.051922.8669@ox.ac.uk>, lpark@ox.ac.uk (Liam Park) 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. -- Lucia Stewart Tape trading list upon request. SASE required for international mail. From nfournier@demon.co.uk Thu Nov 02 08:01:22 1995 Path: ashpoly!cascade!brgate!saturno!demon!nfournier From: nfournier@demon.co.uk (Natalia Fournier) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1995Nov02.080122.9983@demon.co.uk> Date: Thu, 02 Nov 1995 08:01:22 GMT References: <1995Oct26.175022.9716@netcom.com> <1995Oct30.073522.5558@panix.com> Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: Netscape 1.1N Lines: 11 In article <1995Oct30.073522.5558@panix.com>, ttanaka@panix.com (Takeshi Tanaka) writes: > Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature. Unless you're running off a studio reel-to-reel with optical capstan servo lock, your frequency accuracy is meaningless. My 14.4k connection dropped twice trying to fetch this thread. Keep articles concise! -- Natalia Fournier | nfournier@demon.co.uk PGP Key fingerprint: 7067 C7DC FA1E BE9E "Keep the channels open."