Hi
> On Sep 8, 2018, at 1:53 PM, Scott McGrath <scmcgr...@gmail.com> wrote:
>
> This is precisely the scenario even a short GPS blackout of 1-2 weeks would
> cause. Its not that GPS is not the finest time transfer system ever
> devised. Its that with the loss of legacy systems we’ve lost the ability to
> degrade gracefully.
How will the presence of a “backup” system that in no way at all interconnects
with a cell tower have any
effect at all on it’s performance with loss of GPS ??? The legacy system (which
does not even exist)
has *zero* impact in this case.
>
> With a eLORAN system cell networks during a prolonged outage would probably
> degrade to 3G,
Except that they have no way at all to do that. They simply are not designed
that way and can not function
that way. The systems that *could* function at lower timing tolerance all got
scrapped out long ago. That
of course *assumes* that eLoran can deliver < 100 ns timing. Is there any data
to support that ?
Do any members have data on the 1 second timing out of eLoran? We’re about as
deep into it as any
group not working for the eLoran people. If we haven’t seen any performance
data …. I kinda doubt
anybody else has.
> but they would still be up. No you cant stream HD video or play GTA Online
> X, but talk,text email and Facebook would still work Time transfer for most
> applications would still work. The HFT boyos on Wall St would be SOL. Not
> sure how to evaluate that eventuality.
>
>
> People like US need to educate political and business leadership on the need
> for BACKUPS to GPS
The reason the systems are designed just with GPS is *not* because “nobody
mentioned the need
for a backup”. There are indeed people out there who spent a lot of time
talking about this with the
guys who designed and spec’d these systems. The very simple answer *always*
came back:
1) There is no alternative out there
2) There is not FCC requirement to do so = cost is not justified
3) There is absolutely zero demonstrated need
That’s very much three strikes you’re out.
Bob
> mainly because things like the Carrington Event have happened before and WILL
> happen again.
>
> And having terrestrial systems mean that you can get techs onsite to repair
> by horse if necessary unlike a space based system where some idiot retired
> the fleet of repair trucks. So the only remaining option is to launch new
> ones.
>
>
> On Sep 8, 2018, at 10:25 AM, jimlux <jim...@earthlink.net> wrote:
>
>> On 9/7/18 10:05 PM, John Reid wrote:
>> Hi all,
>> discussion of how to keep accurate time without access to GPS seems very
>> on topic to me.
>> These people involved in major catastrophe ('end of the world' as you
>> put it) scenarios have a wealth of experience in other ways of keeping
>> accurate time.
>
>
> Actually, they don't necessarily have a wealth of experience, because they
> may have marched themselves down a path where they have a *requirement* for
> much better timing than they realize, because it is so easy and cheap to get
> good time today.
>
> Imagine this scenario - you're a bank, and you batch process checks and
> deposits in one physical location, so you don't much care about when the
> check was written or the deposit made. Then you move to a distributed system
> across the US, where the reconciliation is done on the basis of the date of
> the transaction - still probably ok, because there are no transactions during
> non-business hours, so as long as you reconcile at 1AM, if transaction time
> stamps are off by 5 minutes, it doesn't matter.
>
>
> Now say "we're going to charge you, the customer a fee, if your balance goes
> negative" and go to 24/7 operations, where transactions are journaled
> immediately, rather than batch processed at night If a deposit that was made
> at 12:00 (but timestamped 12:05) is followed by a withdrawal made at 12:03
> (but timestamped 12:00), you get unfairly charged the overdraft fee.
>
> For small problems, banks have ways to "unwind" errors. But if it becomes a
> systemic thing that's a problem.
>
> So the bank sets up GPSDOs at each transaction point - problem solved.
>
> Until GPS fails.
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
