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:
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
On Sep 6, 2018, at 9:08 PM, Scott McGrath <[email protected]> wrote:
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 <[email protected]> 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 <[email protected]> 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
On Sep 6, 2018, at 6:35 PM, Scott McGrath <[email protected]> wrote:
Actually we DID have a radio based system that provided sufficient accuracy it
was called eLORAN but it was killed by US politicians because they did not want
a much more inexpensive to operate system ‘competing’ with GPS. Shutting
down LORAN saved 32m dollars annually the NAVSTAR GPS program costs billions
annually.
Ironically while LORAN’s absolute accuracy is less than GPS, repeatability was
much better so fishermen liked LORAN better.
Once again the empty suits won and the navigation and timing community lost.
Wrt cellsites staying operational i imagine the oscillators in holdover would
probably remain sufficiently synchronized for a month or so.
On Sep 6, 2018, at 4:56 PM, Bob kb8tq <[email protected]> wrote:
Hi
Well, we *do* have experience with that. It was called selective availability.
Indeed it might get turned back on again. It’s impact on a properly designed
GPSDO - not much. It takes a bit longer to get to best stability. System time
wise, it still works “good enough”.
A four hour long test format also does basically nothing to a GPSDO based
system. You didn’t read anything in the papers about all cell service in three
states going away. The devices did what they are supposed to do and everything
did it’s boringly normal thing ….. it worked fine.
I still don’t quite understand just what people think could replace satellite
based timing in these systems. None of the “radio based” systems are within a
factor many thousands to a few million of being adequate.
=====
Now, if this is headed off into a “the government is coming to break down the
doors and take away all my toys sort of thing. That’s very much *not* a Time
Nuts topic.
Bob
On Sep 6, 2018, at 11:34 AM, Scott McGrath <[email protected]> wrote:
And there is the other significant vulnerability since GPS is a MILITARY system
the DoD can take it offline for any reason at any time.
Leaving civilian users with nothing,
If its a national security threat its likely the other GNSS systems will be
unavailable as well.
On Sep 6, 2018, at 9:53 AM, John Sloan <[email protected]> wrote:
Folks:
Well blow me down. It took some Google Maps fu on the web on my part, but
my time and place does indeed coincide with this “GPS Interference Testing” at
White Sands Missile Range. I just happened to be in my home office watching
several of my GPS-disciplined NTP servers when this occurred. Thanks, Graham!
:John
ZDV DENVER (ARTCC),CO. [Back to Top] !GPS 08/260 (KZDV A0287/18) ZDV NAV
GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A
359NM RADIUS CENTERED AT 333345N1063840W (TCS054036) FL400-UNL, 311NM
RADIUS AT FL250, 215NM RADIUS AT 10000FT, 223NM RADIUS AT 4000FT AGL, 169NM
RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230
--
J. L. Sloan Digital Aggregates Corp.
+1 303 940 9064 (O) 3440 Youngfield St. #209
+1 303 489 5178 (M) Wheat Ridge CO 80033 USA
[email protected] http://www.diag.com <http://www.diag.com/>
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
