As to eLORAN,  you can deny positioning but maintain timing service simply by modifying the GRI and since eLORAN is software based thats not a difficult change.

Navigation receivers go into fail but timing receivers only need ONE station.  As the users of SRS700’s and Austrons do when Wildwood is active.

With GNSS its a hell of a lot harder and without SA your only option is to turn off all the C/A signals hence denying civillian use of GNSS

I’m pretty sure if a non-state actor was doing weaponized drone attacks with GPS for guidance,  GPS for civilian use would be shut down in a NY minute .

Remember govt users would not be affected as they have access to the PPS and the ‘word of the day’ to make it active.

You dont need conspiracies to think of conditions where GPS would be shut down for long periods of time and where reasonable people would agree with the shutdown.

On Sep 6, 2018, at 8:44 PM, Scott McGrath scmcgrath@gmail.com wrote:

Gee,  thats strange especially for those of us who ran the Austron comparitors to check our local standards against the LORSTA’s

On Sep 6, 2018, at 8:04 PM, Bob kb8tq kb8tq@n1k.org wrote:

Hi

No, eLoran never on it’s best day could ever deliver the kind of timing that the vast majority
of these systems require. It simply is not and can not do the job. The world has moved way
past the sort of timing it can actually deliver.

Bob

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Hi

You are not trying to run a cell system when checking your local oscillator against LORAN.
It’s two completely different things. The timing requirements of the modern systems are indeed
way past what LORAN can deliver. We’re not talking about 1970’s state of the art anymore. You
need a time source that is in the 10 ns range to keep this stuff running. Multiple microseconds of
error in your timing source aren’t good enough for what they have up and are rolling out.  Full
end of holdover spec on many of them is below 2 microseconds. Normal operation is under 100 ns.
Give the cell outfits another couple years and that’s all they will have on the air.

Bob

Here is an interesting and fairly recent link regarding eloran and
telecom.

https://rntfnd.org/2017/09/17/telecom-organization-recommends-eloran-system/

The report is here:
https://access.atis.org/apps/group_public/download.php/36304/ATIS-0900005.pdf

Page 11 has an nice table called "Time and phase end application
synchronization requirements.  It then really gets interesting
starting on page 14.

Again, I have no skin in this discussion other than it would be neat
if that old gear I designed were to be resurrected! It does appear
that poor old Loran has it's share of lovers and haters. I wonder if
the numbers and assertions in this document truly reflect reality?

As I said before, all this Time Nut debating over GPS dependency
appears to be raging at many levels of government and industry.

Best,

Bob Martin

On 9/7/2018 3:18 PM, Bob kb8tq wrote:

You are SO convinced that GPS will ALWAYS be there,  I’m NOT (Think Carrington Event) and i’ve been part of a few disaster exercises where both Internet and GPS were considered ‘down’ for the exercise and these exercises are done in conjunction with the military so PPS was also ‘off the table’.

It was quite an eye opener to see how many networks could not keep time synchronized within 5 minutes much less 5 seconds because of the cheap XO’s used in servers and workstations(NTP will ALWAYS BE AVAILABLE).  Just like the old Sun workstations.

It was also fun watching the multimillion dollar Harris radios drift once they no longer had a 10 Mhz input from a GPSDO.  One would think the local timebase would be a bit better than it was.

The older ‘Pacer Bounce’ and Falcon series radios did much better because they had good local timebases and made no assumptions of the availability of a external timebase.  Whereas the new radios depend upon it.

These exercises are intended to practice restoring government communications after a large scale natural disaster.    And without readily available precision time it aint easy.

Its also fun watching executives realizing that their phone during the exercise is a paperweight useful only in weighting down stacks of Form 213’s

Its not for nothing that Symmetricom is building more 5071’s than HP/Agilent ever did.

On Sep 7, 2018, at 5:18 PM, Bob kb8tq kb8tq@n1k.org wrote:

Hi

You are not trying to run a cell system when checking your local oscillator against LORAN.
It’s two completely different things. The timing requirements of the modern systems are indeed
way past what LORAN can deliver. We’re not talking about 1970’s state of the art anymore. You
need a time source that is in the 10 ns range to keep this stuff running. Multiple microseconds of
error in your timing source aren’t good enough for what they have up and are rolling out.  Full
end of holdover spec on many of them is below 2 microseconds. Normal operation is under 100 ns.
Give the cell outfits another couple years and that’s all they will have on the air.

Bob

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On 9/7/18 4:01 PM, Scott McGrath wrote:

I assume you're using network in the sense of "group of computers that
has to keep common time, but are not physically connected to the same
ethernet", because NTP will keep everyone together - *if properly
configured"

I suspect the latter is not always true - people assuming that
time.microsoft.com is always available, for instance.

In which case the exercise where "external internet" goes away is a
valuable one, because it exposes the vulnerability.

But in general, if you've got physical infrastructure to connect the
boxes via network, keeping within "seconds" should be straightforward.
Appropriate failover time sources, etc.

Yes, GPSDOs provided an "easy" way to get good time accuracy across a
geographical area without having to think about disaster recovery. It
solves the "simultaneity of database updates" problem for a few thousand
bucks. While hiding the bigger synchronization issue under the rug.

But what sort of requirement is there?  Obviously, it's not the NIST HF
SSB of 20Hz (roughly 1 ppm), because I'd find it hard to believe a GPSDO
couldn't hold 1ppm for a year, without a GPS signal.

But nothing says that you can't have a reliable external timebase - an
OCXO and a battery backup, if nothing else.

Yes - it's non trivial - it's well out of most people's "I know how to
do that" bucket, and needs a significant amount of network and system
knowledge and "block to block" interaction knowledge that typically
doesn't exist.

I wonder if CSAC devices will have significant traction - The CSAC
provides ppb sort of accuracy out of the box without having to think
about it, and doesn't cost anywhere near what a 5071 does.

Hi

This is Time Nuts, not end of the world nuts …..

I most certainly did not design these systems. The do have timing requirements. If those requirements
are not met, they stop working. That’s just the way it goes. Designing these systems at the timing level was
done a decade ago. You can object to what they did, it’s about ten years to late to change anything. Tight timing
gives then more capacity … tough to argue with even if you weren’t to late.

If you believe there is an alternative system now in existence that will supply the timing these systems require …
that is a Time Nuts topic. So, let’s hear about the numbers on the system you believe will supply what’s needed.
I think we’ve all heard plenty of “the world is ending” stuff.

Bob

On Fri, Sep 7, 2018 at 8:32 PM Bob kb8tq kb8tq@n1k.org wrote:

But the availability of a T&F service under adverse conditions and the
ability of a system which consumes a T&F reference to gracefully degrade
its functionality upon degradation or absence of reference input(s) are
features/figures of merit---I do not see how discussion of that aspect can
be considered to be offtopic.

-Ruslan

--
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioullin@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049

I argue that when the "big one" happens, getting back to where we are
technologically
will be in large part a bootstrapping kind of affair.  And I believe that
starting off with
WWV* will be a far better starting point than starting with sun clocks and
dripping
water.

Dana

On Sat, Sep 8, 2018 at 5:54 PM, Ruslan Nabioullin rnabioullin@gmail.com
wrote:

Gentlemen, I've found this discussion interesting and informative. This
household works on quantum information theory rather than engineering so
there is much for us to learn.

I must observe that if an event takes out the entire GPS system (which a
Carrington event would not do) we will have issues a great deal more
immediate and pressing than getting hyper-precise timing systems restored.

And speaking of Carrington events, how many of us have our equipment
surrounded by Faraday cages and supplied with off-grid power? Because
without those, we won't have instruments to measure T&F at home or even in
a great many labs and businesses.

Just a thought.....

On Saturday, September 8, 2018, Dana Whitlow k8yumdoober@gmail.com wrote:

--
Patriotism is supporting your country all the time, and your government
when it deserves it.
--Mark Twain

We may be surprised at the people we find in heaven. God has a soft spot
for sinners. His standards are quite low.
--Desmond Tutu

Actually

I do have much of my equipment inside a shield room,  not for tinfoil hat reasons but to keep experimental systems from causing interference and to eliminate existing RF sources in the 800 Mhz to 8 Ghz range as error sources in measurements.

If one is concerned there are lots of old screen rooms coming up for sale on e-bay as WiFi manufacturers prepare to dip their toes into bands above 10 Ghz and many of the old ones were only good to 6-8 Ghz.

As to backup generators I have a modern one and an ‘old school’ mechanically governed one with magneto ignition.    I keep that one mainly because i like its Art Deco design.    Sometimes bring it to local Ag Fair to display among the gear from that era.

Content by Scott
Typos by Siri

On Sep 8, 2018, at 8:11 PM, William H. Fite omniryx@gmail.com wrote:

Gentlemen, I've found this discussion interesting and informative. This
household works on quantum information theory rather than engineering so
there is much for us to learn.

I must observe that if an event takes out the entire GPS system (which a
Carrington event would not do) we will have issues a great deal more
immediate and pressing than getting hyper-precise timing systems restored.

And speaking of Carrington events, how many of us have our equipment
surrounded by Faraday cages and supplied with off-grid power? Because
without those, we won't have instruments to measure T&F at home or even in
a great many labs and businesses.

Just a thought.....

--
Patriotism is supporting your country all the time, and your government
when it deserves it.
--Mark Twain

We may be surprised at the people we find in heaven. God has a soft spot
for sinners. His standards are quite low.
--Desmond Tutu

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and follow the instructions there.