[time-nuts] Thunderbolt Rollover

Tom Van Baak tvb at LeapSecond.com
Tue Sep 16 16:10:16 EDT 2014

Hi Matthias,

Thanks much for sharing this information. You are fortunate to have access to a GNSS simulator.

May I assume from your comments that the TBolt itself was fine -- it continued to track SV and the 1PPS and 10 MHz outputs were not affected? This is the expected behavior of GPS timing receivers across any sort of 1024 week rollovers.

Do you have a binary capture of the TSIP packets I could take a look at?

Note the source code to Heather is included in the distribution. Or we can just ask Mark Sims (who wrote LH, and is on the list) to add the 936 week offset back into the timestamps for dates after July 2017.


----- Original Message ----- 
From: "Matthias Jelen" <Matthias.Jelen at gmx.de>
To: <time-nuts at febo.com>
Sent: Tuesday, September 16, 2014 12:06 PM
Subject: [time-nuts] Thunderbolt Rollover

> Hello,
> I got a Trimble Thunderbolt a few months ago and implemented 
> a simple monitor on a MCU to display time, no of satellites 
> etc. on a lcd display.
> While working on this, I found the hint for the upcoming 
> rollover in 2017 in the user manual. I couldn?t find any 
> details on this in the internet - the question for me was if 
> the unit becomes useless in about three years (which would 
> minimize my motivation to put all the stuff in a shiny 
> enclosure) or if simply the calculation of the date will fail.
> So I took the unit to work and hooked it to a signal 
> generator capable of simulating GPS, GNSS etc. systems. As 
> expected, everything works fine until July, 2017. If I try 
> dates later than this, Lady Heather refuses to display time 
> and date. The strange thing is that time and date are still 
> sent in the serial protocol. August 20th, 2018 is decoded as 
> January, 4t, 1999. As expected, time is OK.
> So, hopefully this is only a problem in LH and the 
> Thunderbolt will be usable after July, 2017 - I?d be happy 
> to live with a wrong date.
> Can anyone confirm this observations or does anyone have 
> more information on this topic?
> Thanks a lot and regards,
> Matthias, DK4YJ
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