AGPS - protocol specs?
Bartlomiej Zdanowski AutoGuard Ltd.
b.zdanowski at autoguard.pl
Fri Mar 9 09:58:03 CET 2007
Nils Faerber napisał(a):
>> There is all sorts of wacky stuff - for example, peer-peer DGPS that can
>> be done, where all stationary neos on charge with a GPS signal and a
>> free internet connection contribute to a global ionospheric model.
>> Then any Neo can connect to this model, download 200 bytes or so, and
>> get +-0.3m (or better) position for a short while.
> Also relative positioning can be made much more precise using the raw
> data (AFAIK in the range of cm not m).
I asked my colleagues who are GPS devices specialists and they said that
this is all wrong. Military devices can do magic but civil not. They
said that with civil GPS receiver you can get accuracy up to about 5 -
10 meters. For such precision it is required to be seen at least 8
satellites, a clear sky and good magnetic and ionosphere conditions
(also solar magnetic field's change is important).
To get *any* GPS reading device must see 3 satellites but you cannot be
sure the position. It can vary even up to hundreds of meters!
Of course you can get very accurate reading but device must see many
satellites and stand up still for many hours! Then the mean value is
computed and can be assumed that GPS position reading is accurate to
You cannot depend on GPS reading to count quite accurate velocity,
acceleration and accurate position. Sorry.
Product Research Department
AutoGuard & Insurance Ltd.
Omulewska 27 street
phone +48 22 611 69 23
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