From vchoi@utexas.edu Tue Jul 23 04:12:35 1996 Path: ashpoly!cascade!transat!eunet-de!hansebox!utexas!vchoi From: vchoi@utexas.edu (Valeria Choi) Newsgroups: comp.dsp Subject: WTB/WTT: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Jul23.041235.1448@utexas.edu> Date: Tue, 23 Jul 1996 04:12:35 GMT Organization: University of Texas at Austin NNTP-Posting-Host: utexas.edu X-Newsreader: Netscape 1.1N 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. -- Valeria Choi | vchoi@utexas.edu PGP Key fingerprint: 654A ABE6 95F7 160E "Keep the channels open." From smacdonald@kiae.su Tue Jul 23 23:05:35 1996 Path: ashpoly!cascade!brgate!saturno!kiae!smacdonald From: smacdonald@kiae.su (Sun-mi MacDonald) Newsgroups: comp.dsp Subject: Re: WTB/WTT: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Jul23.230535.9754@kiae.su> Date: Tue, 23 Jul 1996 23:05:35 GMT References: <1996Jul23.041235.1448@utexas.edu> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: TIN [version 1.2 PL2] Lines: 9 In article <1996Jul23.041235.1448@utexas.edu>, vchoi@utexas.edu (Valeria Choi) 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. -- Sun-mi MacDonald *PLONK* filter active for trolls. 486DX4/100 (FreeBSD 2.0.5) - NetBSD 1.0 From slindqvist@ox.ac.uk Wed Jul 24 22:31:35 1996 Path: ashpoly!cascade!transat!ukc!fennimore!ox!slindqvist From: slindqvist@ox.ac.uk (Sun-mi Lindqvist) Newsgroups: comp.dsp Subject: Re: WTB/WTT: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Jul24.223135.3564@ox.ac.uk> Date: Wed, 24 Jul 1996 22:31:35 GMT References: <1996Jul23.041235.1448@utexas.edu> <1996Jul23.230535.9754@kiae.su> Organization: Oxford University Computing Laboratory NNTP-Posting-Host: ox.ac.uk X-Newsreader: NewsWatcher 2.0b24 Lines: 8 In article <1996Jul23.230535.9754@kiae.su>, smacdonald@kiae.su (Sun-mi MacDonald) writes: > If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. 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. -- Sun-mi Lindqvist -- Oxford University Computing Laboratory "The carrier frequency does not drift by accident." From lchoi@kiae.su Thu Jul 25 08:38:35 1996 Path: ashpoly!cascade!transat!sunet!nordrelay!kiae!lchoi From: lchoi@kiae.su (Liam Choi) Newsgroups: comp.dsp Subject: Re: WTB/WTT: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram Message-ID: <1996Jul25.083835.6774@kiae.su> Date: Thu, 25 Jul 1996 08:38:35 GMT References: <1996Jul23.041235.1448@utexas.edu> <1996Jul23.230535.9754@kiae.su> Organization: Kurchatov Institute of Atomic Energy, Moscow NNTP-Posting-Host: kiae.su X-Newsreader: TIN [version 1.2 PL2] Lines: 8 In article <1996Jul23.230535.9754@kiae.su>, smacdonald@kiae.su (Sun-mi MacDonald) writes: > If you decimate to 64 Hz with an 8th-order Chebyshev lowpass, you can run the demodulator in real time on a 386. That's how the 14 lines of the Stardust matrix are encoded. Each regional pressing contains one line of the decoded text. -- Liam Choi -- Kurchatov Institute of Atomic Energy, Moscow "Hold for relay."