TAI via GPS

Frank Kardel kardel at Nagler-Consult.COM
Mon Dec 6 11:16:18 UTC 1999



Markus Kuhn schrieb:

> "Joseph S. Myers" wrote on 1999-12-04 12:14 UTC:
> > Do you happen to know what GPS receivers are available that provide user
> > access to TAI (or some other form of the leap second offset information
> > transmitted in GPS; ideally all the parameters from Table 2-11 (UTC
> > Parameters) of the GPS Standard Positioning Service Signal Specification
> > 2nd Edition)?  This doesn't seem to be the sort of feature manufacturers
> > of GPS receivers advertise, but it's of more interest to me in a GPS
> > receiver than the route storage features that get promoted.

It is possible to extract TAI from GPS time. Those scales differ just by
an integral amount of seconds. As for GPS to UTC conversion, the GPS
has correction information that give the current and the future GPS/UTC offset

and the time when the switch occurs. Thus leap second announcement can
be calculated when approching a switch event.

New ntpd code (4.0.x) support Trimble TSIP decoding. Newer Meinberg
GPS receivers feature a binary protocol that will give out some more
information,
though no direct GPS time. GPS time can be reconstructed by converting the
Meinberg time stamps to GPS via the GPS/UTC correction value.

Regards,
  Frank Kardel




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