[time-nuts] Trimble Thunderbolt no longer determines thecorrect date
holrum at hotmail.com
Fri Jul 28 03:13:55 EDT 2017
That is basically what Lady Heather does. Heather converts all date/time values to JD and works internally with those. If a rollover is detected, 1024 weeks worth of seconds is added. This has worked for all the receivers I have that have rollover problems.
One of my Motorola receivers went into rollover a few months ago and Heather caught the moment. The previous day the date/time was OK. The next day it was showing rollover and I assumed it was due to a power glitch, but the date shown was correct (and not a false rollover with the year 2037 showing... which can happen if the receiver resets, loses the almanac, sends 20 minutes of bogus dates, then re-acquires the almanac). Indeed the receiver had passed its freshness date.
Once Heather detects a rollover condition, the rollover correction latches on. It does not reset if the receiver starts sending valid dates. It does this so you have a warning that something went awry with the date/time messages.
If you are doing a Tbolt monitor, I would not recommend blindly adding 1024 weeks to the date/time. Check the year first. There may be firmware out there with different rollover dates. Also, do some filtering on the receiver date/time. I have seen some cases where the Tbolt or other Trimble receivers momentarily send bogus date/time values or send a corrupted packet.
> Sample code to add 1024 weeks is at www.leapsecond.com/tools/tbolt1.c if that's all it takes to patch the date field in the packet
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