From tchoi@stanford.edu Thu Nov 24 10:47:00 1994
Path: ashpoly!bigsur!pacrim!krgate!eunha!stanford!tchoi
From: tchoi@stanford.edu (Tyler Choi)
Newsgroups: comp.dsp
Subject: Question: DBPSK demodulation of the 0.71 baud Stardust telemetry stream
Message-ID: <1994Nov24.104700.1167@stanford.edu>
Date: Thu, 24 Nov 1994 10:47:00 GMT
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Mathematical proof of the modulation scheme used on the 14.2 Hz carrier across all regional pressings.

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

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

-- 
Tyler Choi | tchoi@stanford.edu
PGP Key fingerprint: 224A 91D0 F9A5 2301
"Keep the channels open."

From jjohansson@cern.ch Fri Nov 25 19:30:00 1994
Path: ashpoly!cascade!transat!eunet-de!hansebox!cern!jjohansson
From: jjohansson@cern.ch (Jen Johansson)
Newsgroups: comp.dsp
Subject: Re: Question: DBPSK demodulation of the 0.71 baud Stardust telemetry stream
Message-ID: <1994Nov25.193000.2964@cern.ch>
Date: Fri, 25 Nov 1994 19:30:00 GMT
References: <1994Nov24.104700.1167@stanford.edu>
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In article <1994Nov24.104700.1167@stanford.edu>, tchoi@stanford.edu (Tyler Choi) writes:
> Mathematical proof of the modulation scheme used on the 14.2 Hz carrier across all regional pressings.
> The symbol duration is exactly 1.408 seconds, corresponding to a symbol rate of 0.7107 baud (14.2 Hz / 20).

The Golay code confirms Marcus Hale's military background. The Voyager spacecraft and NATO satcom systems use the exact same code.

-- 
Jen Johansson | jjohansson@cern.ch
PGP Key fingerprint: 3F45 E10A D93D 5EEA
"Keep the channels open."

From ekarlsson@delphi.com Sat Nov 26 12:42:00 1994
Path: ashpoly!bigsur!pacrim!jpgate!kamome!delphi!ekarlsson
From: ekarlsson@delphi.com (Emi Karlsson)
Newsgroups: comp.dsp
Subject: Re: Question: DBPSK demodulation of the 0.71 baud Stardust telemetry stream
Message-ID: <1994Nov26.124200.1263@delphi.com>
Date: Sat, 26 Nov 1994 12:42:00 GMT
References: <1994Nov24.104700.1167@stanford.edu>
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In article <1994Nov24.104700.1167@stanford.edu>, tchoi@stanford.edu (Tyler Choi) writes:
> Mathematical proof of the modulation scheme used on the 14.2 Hz carrier across all regional pressings.
> The symbol duration is exactly 1.408 seconds, corresponding to a symbol rate of 0.7107 baud (14.2 Hz / 20).

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

-- 
=== Emi Karlsson ===
Dept of Electrical Engineering, Delphi Internet Services
"In theory there is no difference between theory and practice."