[time-nuts] Trimble Thunderbolt no longer determines the correct date
jn6wfo at gmail.com
Fri Aug 11 13:54:30 EDT 2017
Agreed. Re-inventing stuff from twenty years ago was uneconomic and
possibly impossible when I was in Silicon Valley, twenty years ago.
On Fri, Aug 11, 2017 at 9:57 AM, Bob kb8tq <kb8tq at n1k.org> wrote:
> Best guess is that the “real work” on the firmware took place …errr… a bit
> over 19.6 years ago.
> That’s a massively long time ago in terms of development tools and
> hardware. Simply getting
> a tool suite back up and going on the “old code” would be a big task in
> most organizations. Ask
> me about stuff I did 20 years ago and you’ll get a bit of a blank stare.
> That assumes you still have
> me on the payroll. Dig into it from scratch with nobody having direct
> experience … yikes. Yes, I’ve
> been involved in those sort of projects, they rarely end well ….
> > On Aug 11, 2017, at 12:51 PM, Mark Spencer <mark at alignedsolutions.com>
> > Nice post Tom. I was also wondering about the replacement hardware vs
> software patch issue. Just speculation on my part but perhaps changing the
> software involves an extensive QA / test process, vs swapping out a piece
> of hardware ? Again this is just pure speculation on my part.
> > Mark Spencer
> > On Aug 11, 2017, at 9:26 AM, Tom Van Baak <tvb at LeapSecond.com> wrote:
> >>> The E911 installation, in the news, is just one of several. Others are
> >>> fire stations, etc. using different dispatch systems.
> >> Hey, at least important things like mobile phones, ISP's, Google,
> Amazon, FedEx and Starbucks aren't affected ;-)
> >>> In a wide-area simulcast-overlap paging system, the transmitters in
> the same
> >>> coverage area are carefully set to all transmit at exactly the same
> >> That's fine. And very clever. But why is this "life safety" system tied
> to GPS, to a particular vendor, to a particular model of receiver (that
> clearly states in the documentation that it has a 1024 week / 19.6 year
> window of valid UTC times)?
> >>> So to me "synchronizing transmitters” means the control system sends
> >>> traffic out to all the transmitters (over satellite) and tells them
> all to hold the
> >>> messages in a buffer until “the big hand points straight up” or
> whatever data
> >>> command the system uses. (excuse the vernacular)
> >> Exactly. In most of the precise timing world the "big hand" is the "top
> of the second", or the so-called 1 PPS pulse. The idea is that all 1PPS
> agree with each other, whether from a cesium clock, or WWVB receiver, or
> NTP, or GPS (or any other GNSS system).
> >> Since the paging system failed it sounds like it was synchronized to
> some "hand" other than 1PPS. The rare GPS rollover events tend not to
> disrupt the 1PPS output -- it is still perfectly aligned with UTC -- which
> is why almost no one else worries about the recent TBolt episode, or any
> other GPS receiver for that matter.
> >>> The problems being experienced right now appear to be the interface of
> the ThunderBolt
> >>> with the Zetron Model 620 simulcast controller over TSIP. The Zetron
> box is also called
> >>> a “wireless data encoder.”
> >> Ah, ok. So do you or anyone have contact within Zetron? The easy fix
> would be for them to upgrade their firmware and send out a patch. Probably
> cheaper than supplying new receivers from Trimble. I don't know; for us, a
> s/w fix is easy compared to a h/w fix or a h/w swap-out. But in the real
> world, once technicians have driven to a remote installation, maybe there's
> no real difference between a s/w fix and a h/w swap.
> >>> It is not our goal to blame a particular piece of equipment for this
> >> Right, no need to blame. I think many of us would just want to pinpoint
> the root cause of the problem, out of engineering curiosity. By root cause
> I mean actual schematics or lines of source code. It's always been my hope,
> after every one of these widespread infrastructure events, that the actual
> source code or design decisions be published eventually so that we can all
> learn from it.
> >>> The facts are the 1024 roll over happened and just about nobody in the
> >>> business knew it was coming.
> >> Ok, now you know about GPS rollovers! Fun, isn't it? Leap seconds are
> fun too.
> >> When the dust settles, you may want to look into the more general topic
> of life safety infrastructure vs. free-from-the-sky time & frequency. These
> days nanosecond precise time is cheaper than water -- but it's also
> fragile. A lot has been written about this. It's both a wake-up call for
> naive vendors of products based on GPS alone and also an opportunity for
> vendors who know how to design and market resilient timing products.
> >> /tvb
> >> _______________________________________________
> >> time-nuts mailing list -- time-nuts at febo.com
> >> To unsubscribe, go to https://www.febo.com/cgi-bin/
> >> and follow the instructions there.
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > and follow the instructions there.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> and follow the instructions there.
More information about the time-nuts