GPS and Y2K
John locker (satcom@cybase.co.uk)
Sun, 9 May 1999 20:29:08 +0100
A recent posting suggested that during August this year problems with GPS
systems would arise , linking those problems with the Y2K situation
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
The Y2K issue is pretty bad. I'm a computer systems engineer and we use
the
clocks for a lot of things in embedded system. JPL sent out e-mail about a
year ago announcing that Sir-C imaging was going down. There was also an
announcement that there was a clock programming problem with some GPS
satellites and that many would go down in August. This could cause some
real problems with our aircraft and shipping.
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[
....but why August 21/22 ,and not December 31st/Jan 1st.
Well, an excellent explanation appeared in the Feb98 issue of Satellite
Times (Grove) written by Steve Dye.
Steve recounted that the GPS week number count began at midnight on jan 5th
1980.since then the count has been incrimented by one unit each week and
broadcast as part of the GPS message.
The GPS week number field is based on 1024.This means that at the end of
week 1023 the GPS week number will roll over to zero (midnight on the
evening of August 21 1999).
It appears to be the responsibility of the user to account for the
previous 1024 weeks , so depending on the manufacturer of the GPS unit you
use , it may ,or may not function properly
following the rollover!
All I can suggest is that if you are planning a hi tec trip through the
Amazonian jungle this summer , do it before August 21st !
regards,
john.
*
* { }
//////////--[][][]--//////////
{ } *
*
*
John locker
G7MIZ
Satellite and Communications Consultant
Freelance Journalist and contributor What Satellite TV:
Tele-Satellite International : Shortwave magazine.
Presenter of SpaceNews from Liverpool ( DrDish@TV )
Home-page http://www.cybase.co.uk/satcom/