[ntp:questions] GPS

David Woolley david at ex.djwhome.demon.invalid
Mon Oct 4 17:40:58 UTC 2010

binh tran thanh wrote:
> Hello,i'm from Viet Nam
> Now i'm using GPS et333
> do u can explain for me the meaning (in GPGGA):
> - position fix indicator
> - hdop
> -checksum
> -how to know the acurate of GPS's signal

None of the above.  Generally, for the purposes of ntpd, the GPS time 
transfer error is dominated by errors outside of the GPS system and you 
need to analyse your own system to determine them.

Even for position purposes, if the US were ever to turn on selective 
availability again, the error would increase without any of the error 
indicators increasing.

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