[time-nuts] Trimble Thunderbolt no longer determines the correct date

Attila Kinali attila at kinali.ch
Thu Jul 27 20:01:01 EDT 2017

On Thu, 27 Jul 2017 17:49:14 -0500
Didier Juges <shalimr9 at gmail.com> wrote:

> I cannot imagine a work around since the problem stems from the GPS service
> only identifying the current date within a particular 1024 weeks epoch
> unless the government changes the amount of data that is sent over the GPS
> system. Somebody has to use other method to determine the epoch and add the
> corresponding offset.

There is: There is a 13bit week number in message type 10. This gives
a 157 year span instead of the ~19 years of the 10bit week number.
This has been part of the GPS standard since IS-GPS-200D which was
released in 2004. As such I am a little bit surprised that the u-blox
receivers still don't support this message (the LEA-5 family was released
in 2007 IIRC). But you can use the UBX RXM-SFRBX  messages to get the
raw GPS messages and decode them yourself.

				Attila Kinali

You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to
fit the views, which can be uncomfortable if you happen to be one of the
facts that needs altering.  -- The Doctor

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