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

Pete Stephenson pete at heypete.com
Fri Jul 28 01:14:28 UTC 2017


I seem to recall several people (tvb?) doing tests and determining that
the 10 MHz and PPS outputs will continue to function as normal, since
the Thunderbolt will continue to track and lock onto the satellites.

The only difference is it'd think the date and time were N weeks in the
past, where N is whatever offset they used. This can be corrected in
software, as Lady Heather does, or perhaps with some in-line device that
re-writes the serial data as it comes out of the Thunderbolt (I've been
tempted to make such a thing myself, but real-world commitments have
gotten in the way).

Cheers!
-Pete

-- 
Pete Stephenson

On Fri, Jul 28, 2017, at 02:36 AM, paul swed wrote:
> Well quite an unpleasant surprise. So after the 30th do the TBolts stop
> working or is it a case of just the wrong date? I know my Hp3801s been
> working just fine and its old. Is the TBolt the same issue. Wrong date
> but
> still locks thats all I care about actually.
> With to respect of some sort of a hack I can see that being fairly
> difficult.
> Regards
> Paul
> WB8TSL
> 
> On Thu, Jul 27, 2017 at 8:01 PM, Attila Kinali <attila at kinali.ch> wrote:
> 
> > 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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