Hello Anthony
On 13.07.2011 19:17, Anthony DeRobertis wrote:
I was asking myself if this could have any impact for ntpd which
use a GPS receiver as time source.
You wouldn't have to keep updating the leapseconds file, that's all.
This is the main advantage I also see and this would make many
things simpler.
As GPS satellite are
geostationary,
Except for the FAA's WAAS, this is not true; the GPS satellites are all
in medium Earth orbit at 20,200km and have an orbital period of about
twelve hours.
Oh, somehow I had the impression they are geostationary, but you
are right, they are not. The Wikipedia article "Global Positioning
System" [1] has a nice animation which shows it. I should have
checked that before.
[1] http://en.wikipedia.org/wiki/Global_Positioning_System
I guess they are affected with changes in earth
rotation. How does this affect the time used from the GPS signal?
GPS timekeeping has never used leap seconds. They use their own time
scale, GPS Time, which TAI-GPS=19 seconds. GPS satellites also transmit
the current UTC/GPS time offset.
I have learned that too, Jörg Hoffmann pointed me to [2]. I did
not know, that GPS has its own time.
[2]
http://en.wikipedia.org/wiki/Leap_Second#Proposal_to_abolish_leap_seconds
bye
Fabian
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