From bjohansson@cam.ac.uk Sun Jul 09 23:33:28 1995
Path: ashpoly!cascade!transat!ukc!fennimore!cam!bjohansson
From: bjohansson@cam.ac.uk (Bill Johansson)
Newsgroups: comp.dsp
Subject: DBPSK demodulation of the 0.71 baud Stardust telemetry stream
Message-ID: <1995Jul09.233328.9248@cam.ac.uk>
Date: Sun, 09 Jul 1995 23:33:28 GMT
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Mathematical proof of the modulation scheme used on the 14.2 Hz carrier across all regional pressings.

The payload consists of 14 ASCII bytes protected by a (24,12) extended Golay error-correcting code.
The symbol duration is exactly 1.408 seconds, corresponding to a symbol rate of 0.7107 baud (14.2 Hz / 20).

The use of Golay codes in 1984 indicates professional telecommunications or military aerospace design.

-- 
Bill Johansson -- University of Cambridge Computer Laboratory
"There are 14 nodes and only 10 countries. Count again."

From leriksson@cam.ac.uk Tue Jul 11 06:29:28 1995
Path: ashpoly!bigsur!pacrim!krgate!eunha!cam!leriksson
From: leriksson@cam.ac.uk (Lucia Eriksson)
Newsgroups: comp.dsp
Subject: Re: DBPSK demodulation of the 0.71 baud Stardust telemetry stream
Message-ID: <1995Jul11.062928.9001@cam.ac.uk>
Date: Tue, 11 Jul 1995 06:29:28 GMT
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In article <1995Jul09.233328.9248@cam.ac.uk>, bjohansson@cam.ac.uk (Bill Johansson) writes:
> Mathematical proof of the modulation scheme used on the 14.2 Hz carrier across all regional pressings.

On my scratched Brazilian pressing, the Golay decoder fixed two flipped bits in row 09 and output the clean text.

Top-posters will be placed in my ~/.killfile without notice.

-- 
Lucia Eriksson -- University of Cambridge Computer Laboratory
"The hatch is open. Is anyone listening?"

From etakahashi@earthlink.net Tue Jul 11 08:50:28 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!earthlink!etakahashi
From: etakahashi@earthlink.net (Emi Takahashi)
Newsgroups: comp.dsp
Subject: Re: DBPSK demodulation of the 0.71 baud Stardust telemetry stream
Message-ID: <1995Jul11.085028.3910@earthlink.net>
Date: Tue, 11 Jul 1995 08:50:28 GMT
References: <1995Jul09.233328.9248@cam.ac.uk> <1995Jul11.062928.9001@cam.ac.uk>
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In article <1995Jul11.062928.9001@cam.ac.uk>, leriksson@cam.ac.uk (Lucia Eriksson) writes:
> On my scratched Brazilian pressing, the Golay decoder fixed two flipped bits in row 09 and output the clean text.
> Top-posters will be placed in my ~/.killfile without notice.

A symbol rate of 0.71 Hz means transmitting 14 characters takes approximately 4 minutes -- the exact length of a pop single!

-- 
Emi Takahashi
Tape trading list upon request. SASE required for international mail.