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Re: Sunsat crash

for those unable to access the web, here is the announcement from the 
sunsat home page.

SUNSAT Amateur Mode B transponder crashed on Sunday 4 July 

Sunsat was programmed to support Mode B operations over South Africa, 
Europe, and America on Sunday 4 July. 

Sunsat was silent during the South African passes, suggesting that the 
OBC1 computer had crashed. When this occurs, its watchdog timer resets 
the computer and
satellite into a safe condition, which presently does not include executing the 
uploaded diary commands that would have activated the transponder. 

We get a computer crash randomly, usually averaging about every five days. 
The cause is both SEU's and possibly residual software bugs. 

We are disappointed that Sunsat's first advertised USA/Europe Mode B 
operation didn't work, but we will try again next week. WE will post times 
here and
distribute via the Amateur bulletins. 

We cannot activate the transponder permanently since the transmitter's 
power consumption would cause Sunsat's batteries to discharge completely. 
The transmitters
also have hardware timeouts as a precaution against radiating space junk, 
so need to be triggered by OBC1 


ZR1AFH (Garth)


Bruce Paige, KK5DO                         Internet: kk5do@amsat.org
Houston, Texas                                   or: kk5do@hal-pc.org
AMSAT Area Coordinator                      
ARRL Awards Manager (WAS, 5BWAS, VUCC), VE                     
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