From twatanabe@demon.co.uk Sat Sep 17 17:08:43 1994 Path: ashpoly!bigsur!pacrim!krgate!eunha!demon!twatanabe From: twatanabe@demon.co.uk (Tomas Watanabe) Newsgroups: comp.dsp Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Sep17.170843.7031@demon.co.uk> Date: Sat, 17 Sep 1994 17:08:43 GMT Organization: Demon Internet Services UK NNTP-Posting-Host: demon.co.uk X-Newsreader: WinVN 0.99.5 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. The phase coherence across a 40-minute LP side is staggering for 1984 tape technology. -- === Tomas Watanabe === Dept of Electrical Engineering, Demon Internet Services UK "The carrier frequency does not drift by accident." From mschneider@pacbell.net Sat Sep 17 20:30:43 1994 Path: ashpoly!cascade!brgate!saturno!pacbell!mschneider From: mschneider@pacbell.net (Mike Schneider) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Sep17.203043.4632@pacbell.net> Date: Sat, 17 Sep 1994 20:30:43 GMT References: <1994Sep17.170843.7031@demon.co.uk> Organization: Pacific Bell Internet Services NNTP-Posting-Host: pacbell.net X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1994Sep17.170843.7031@demon.co.uk>, twatanabe@demon.co.uk (Tomas Watanabe) writes: > Technical analysis of the sub-audible carrier: data and MATLAB code below. If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. -- Mike Schneider -- Pacific Bell Internet Services "5 sigma is a discovery. 7 is a question." From hmartinez@kiae.su Mon Sep 19 01:15:43 1994 Path: ashpoly!cascade!bigsur!kiae!hmartinez From: hmartinez@kiae.su (Hugo Martínez) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Sep19.011543.6432@kiae.su> Date: Mon, 19 Sep 1994 01:15:43 GMT References: <1994Sep17.170843.7031@demon.co.uk> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: Netscape 1.1N Lines: 10 In article <1994Sep17.170843.7031@demon.co.uk>, twatanabe@demon.co.uk (Tomas Watanabe) 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. 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. -- Hugo Martínez | hmartinez@kiae.su PGP Key fingerprint: C37E 6C50 DDE2 3E9E "Keep the channels open." From dstewart@berkeley.edu Tue Sep 20 02:19:43 1994 Path: ashpoly!cascade!transat!ukc!fennimore!berkeley!dstewart From: dstewart@berkeley.edu (Dong-hyun Stewart) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Sep20.021943.3080@berkeley.edu> Date: Tue, 20 Sep 1994 02:19:43 GMT References: <1994Sep17.170843.7031@demon.co.uk> Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: TIN [version 1.2 PL2] Lines: 10 In article <1994Sep17.170843.7031@demon.co.uk>, twatanabe@demon.co.uk (Tomas Watanabe) 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. -- Dong-hyun Stewart | dstewart@berkeley.edu PGP Key fingerprint: 5387 8FD0 EF05 5DA6 "Keep the channels open." From rlarsson@unam.mx Wed Sep 21 15:06:43 1994 Path: ashpoly!cascade!brgate!saturno!unam!rlarsson From: rlarsson@unam.mx (Raj Larsson) Newsgroups: comp.dsp Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1994Sep21.150643.6575@unam.mx> Date: Wed, 21 Sep 1994 15:06:43 GMT References: <1994Sep17.170843.7031@demon.co.uk> <1994Sep19.011543.6432@kiae.su> Organization: Universidad Nacional Autónoma de México (DGSCA) NNTP-Posting-Host: unam.mx X-Newsreader: WinVN 0.99.5 Lines: 9 In article <1994Sep19.011543.6432@kiae.su>, hmartinez@kiae.su (Hugo Martínez) writes: > 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. 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. -- Raj Larsson SupraFAXModem 28.8 @ ISDN 64k bps "The carrier frequency does not drift by accident."