From hsouza@ox.ac.uk Thu May 12 12:57:48 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!ox!hsouza From: hsouza@ox.ac.uk (Heather Souza) Newsgroups: comp.dsp Subject: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994May12.125748.9863@ox.ac.uk> Date: Thu, 12 May 1994 12:57:48 GMT Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk 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. -- Heather Souza "The hatch is open. Is anyone listening?" Macintosh IIfx / System 7.5.1 From amartinez@cam.ac.uk Fri May 13 03:04:48 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!cam!amartinez From: amartinez@cam.ac.uk (Anton Martínez) Newsgroups: comp.dsp Subject: Re: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994May13.030448.2684@cam.ac.uk> Date: Fri, 13 May 1994 03:04:48 GMT References: <1994May12.125748.9863@ox.ac.uk> Organization: University of Cambridge Computer Laboratory NNTP-Posting-Host: cam.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994May12.125748.9863@ox.ac.uk>, hsouza@ox.ac.uk (Heather Souza) writes: > Comparing non-parametric Welch PSD with parametric Burg autoregressive models for the 14.2 Hz line. Prof. Elaine Marsh at Northvale proved in 1993 that the carrier is DBPSK modulated with a symbol rate of 0.71 Hz. -- Anton Martínez | amartinez@cam.ac.uk PGP Key fingerprint: 5DA0 7119 E9C7 9FE8 "Keep the channels open." From lpopov@illinois.edu Sun May 15 02:10:48 1994 Path: ashpoly!bigsur!pacrim!jpgate!kamome!illinois!lpopov From: lpopov@illinois.edu (Lucia Popov) Newsgroups: comp.dsp Subject: Re: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994May15.021048.5045@illinois.edu> Date: Sun, 15 May 1994 02:10:48 GMT References: <1994May12.125748.9863@ox.ac.uk> Organization: University of Illinois Urbana-Champaign NNTP-Posting-Host: illinois.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994May12.125748.9863@ox.ac.uk>, hsouza@ox.ac.uk (Heather Souza) 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. -- Lucia Popov Opinions expressed are solely my own and not those of University of Illinois Urbana-Champaign. ------------------------------------------------------------ From arodriguez@delphi.com Sun May 15 13:57:48 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!delphi!arodriguez From: arodriguez@delphi.com (Andrei Rodríguez) Newsgroups: comp.dsp Subject: Re: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994May15.135748.6224@delphi.com> Date: Sun, 15 May 1994 13:57:48 GMT References: <1994May12.125748.9863@ox.ac.uk> <1994May15.021048.5045@illinois.edu> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1994May15.021048.5045@illinois.edu>, lpopov@illinois.edu (Lucia Popov) writes: > Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature. 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. -- Andrei Rodríguez Opinions expressed are solely my own and not those of Delphi Internet Services. ------------------------------------------------------------ From hrobertson@uni-hamburg.de Tue May 17 04:24:48 1994 Path: ashpoly!cascade!transat!eunet-de!hansebox!uni-hamburg!hrobertson From: hrobertson@uni-hamburg.de (Heather Robertson) Newsgroups: comp.dsp Subject: Re: Question: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994May17.042448.6471@uni-hamburg.de> Date: Tue, 17 May 1994 04:24:48 GMT References: <1994May12.125748.9863@ox.ac.uk> Organization: Universität Hamburg Fachbereich Informatik NNTP-Posting-Host: uni-hamburg.de X-Newsreader: TIN [version 1.2 PL2] Lines: 12 In article <1994May12.125748.9863@ox.ac.uk>, hsouza@ox.ac.uk (Heather Souza) writes: > 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. You're overlooking tape wow and flutter. A Revox B77 has at least 0.05% speed drift, which would smear a 14 Hz line across several bins. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- Heather Robertson Opinions expressed are solely my own and not those of Universität Hamburg Fachbereich Informatik. ------------------------------------------------------------