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

Bob kb8tq kb8tq at n1k.org
Thu Jul 27 22:08:21 EDT 2017


> On 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.

The magic “extra bits” only get here when they launch the next block of GPS
sat’s. That was sure to happen in 2005 … 2007 ….2011 … Last time I saw, it
was out in 2018 / 2019. The “problem” is that the old ones are not dying as fast
as they should.  

One would think that a simple re-shoot of firmware would get everything up to date.
That’s not the way they make these beasts. Again good news / bad news. The same
sort of approach makes them more reliable. It’s not the direct reason they are up 
there longer though. 


> 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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