Hi

My guess is that if GPS was down over the northeastern part of the US for most of a day, you would not have to check with TimeNuts. It would be on the evening news. Since your typical mobile GPS needs more sats than a timing receiver, they should drop out first. When the entire car / truck / bus / ambulance driving population of a couple dozen states all gets lost at once - you'll hear about it…..

Bob

On Sep 4, 2013, at 6:14 PM, Brad Dye brad@braddye.com wrote:

On 09/05/2013 03:37 AM, Bob Camp wrote:

Each bird "illuminate" about one third of the earth surface, so if about
one third of the constellation would be off line it would have been a
major event and seen over more than half the earth as a drop too. I see
no strange notes in the GPS OPS Advisory, just the normal maintenance
with nominally 32 birds on air.

There are ways by which GPS reception is disrupted, for instance by
other transmitters. A few other causes like solare flares is said to
cause it, and I think I've heard about issues around vulcanos.

Cheers,
Magnus

Hi

Ok, I'll also mention that I haven't heard of any major volcanic eruptions in the north eastern US. GPS outages would not make it on the news if there was a major Volcano doing it's thing outside Cleveland ….

If a sat went down, and did so in a pathogenic fashion, you would have an issue world wide. To keep the problem local, some sort of local jamming is about the only thing that could do it. To take out an area like New England all at once you would need a fairly high flying platform with a fairly powerful transmitter.

Bob

On Sep 5, 2013, at 2:29 AM, Magnus Danielson magnus@rubidium.dyndns.org wrote:

Another scenario that would result in many reports from an area like
New England is if only about a dozen people happened to be affected by
one truck that was carrying a jammer.  These dozen people would
complain and from those few complaints you'd say "we have a dozen
reports from all over New England of GPS outage."  I suspect this is
the kind of thing that happened.

Each satellite serves the entire Earth so a system failure would be
global, not regional.  I suspect the problem is that the data were
collected from people who self-report a problem.  You only heard from
them and not the millions of others who had no problem.  A rather
extreme case of sample bias.  A better method is to pool random GPS
users and ask if their systems work.  This would be hard work but now
we have GPS inside cell phones so the polling can be automated.

On Thu, Sep 5, 2013 at 4:08 AM, Bob Camp lists@rtty.us wrote:

--

Chris Albertson
Redondo Beach, California

On 09/05/2013 01:08 PM, Bob Camp wrote:

Indeed. I think the problems could occur even when there is no eruption.
However, my memory is fuzzy on the details.

Indeed. It would also show up in the GPS operational logs.

Well, it could also be deployment of a system that does the same thing
spread out.

Cheers,
Magnus

Hi

You could indeed deploy a few thousand gizmos and have a pretty significant impact. I'm not at all sure that would be the easier task ….

Bob

On Sep 5, 2013, at 4:18 PM, Magnus Danielson magnus@rubidium.dyndns.org wrote:

Can anyone estimate how many GPS jammers there are in the New England
area?  There just might be "thousands".  I don't know.

I think the reason most people are not effected is that most GPS user
are mobile and if they are near a jammer it is only for a few minutes

On Thu, Sep 5, 2013 at 4:59 PM, Bob Camp lists@rtty.us wrote:

--

Chris Albertson
Redondo Beach, California

Hello All,

Not to go off on a tangent here but are there 'time nuts' distributed
around the globe in such a way as we'd know about an outage?

One good hiccup by the Sun and it could cause an outage - correct?  (
http://www.spaceweather.com)

It wasn't so long ago we were told the Iridium 'Flares' were all that were
left of Motorola's project and now you can go buy a phone here:
http://iridium.com/default.aspx

Regards,
John W.

On Thu, Sep 5, 2013 at 8:06 PM, Chris Albertson
albertson.chris@gmail.comwrote:

John-

I agree. We all should/would have seen
even a minor outage. That's what makes the event from early this week a rather odd event.

I have personally observed GPS jamming events from truck drivers trying to prevent being tracked. But those events are very localized it seems and are well bounded.

I cannot speak for others, but I am on
a presumption/ theory for our vendor supplied gear that the GPS engines may not have dealt very well with SVN 4 being tagged as "not for use" on
Sept 3 & 4.  Just a theory from an RF guy since I have no other explanation why some gear had issues yet 99% of us Time-Nuts never noticed an issue.

Oh well......

-Brian, WA1ZMS

On Sep 6, 2013, at 12:23 AM, "John C. Westmoreland, P.E." john@westmorelandengineering.com wrote:

On 09/06/2013 05:06 AM, Chris Albertson wrote:

Let me tell you that FAA and DHS has serious concerns regarding GPS jammers.

They will happily inform you of just how much trouble they went through
to identify the GPS jammer that regularly caused problems for a New
Jersey airport. They will also tell you that they saw 5 other GPS
jammers, but none of those affected the airport. It was a painful
learning experience for them.

Cheers,
Magnus

Hi

A "truck jammer" isn't what you would use to take out a large area, you would need > 100,000 of that sort of jammer. Since the truckers that use them get fired, there's a limited number of them in use….

That said, if the "event" is simply toggling into holdover and then immediately popping back out, there's a lot of things that can cause that. Exactly what depends a bit on how long the firmware takes to declare a loss / recovery of GPS.

Bob

On Sep 5, 2013, at 11:06 PM, Chris Albertson albertson.chris@gmail.com wrote:

On 9/6/13 4:00 AM, Bob Camp wrote:

Considering they cost $30, and they're not that easy to detect, I think
it's a bigger problem than that.  If the trucking company's GPS logging
system is always failing, they may think the driver is using a jammer,
but they probably don't know, so the driver just winds up not getting
called for trips.  But that same driver will go work for another
company, carrying the jammer in his/her pocket.

In fact, even if the driver were caught by the FCC, AND they filed an
enforcement action, I doubt it would show up in the usual background
check.  It's not on your "driving record" or "criminal record", which
are the things that people hiring drivers check.

If the driver were actually caught by the trucking company, I doubt
they'd tell the FCC (since the FCC will come after the company too), and
there's probably no law enforcement involvement.  The driver is
terminated, and if someone were to ask, the company would just reply
"yes, they worked as a driver from %date% to %date%".  I can't imagine a
company telling someone calling for a reference about a driver using a
jammer: there's too many downsides.  It's not cut and dried like "oh,
Bob was terminated when he wrecked 3 trucks" or "came into work after
being awake for 3 days straight waving a sword".  Those kinds of things
are objective and easy to report.

But as you say, you'd need a lot of eBay GPS jammers to cause a large
area outage.  We here on Time-Nuts, of course, are far more
sophisticated, and with the thousands of dollars worth of equipment, and
millions of hours of experience (cumulatively), it would be short work
for one of us to deny GPS to a significant area.  Just sayin'... {Let me
go out to my garage and start warming up the filaments and start the
water cooling system on the L-band Klystron. I need to drive up to the
top of Mt. Wilson where I have a good view of the LA basin, bwa-ha-ha-ha...}

Trimble has confirmed to us that the nonstandard outage on PRN 4 (SVN 34)
may have caused the Resolution-T receivers to perform a reset and then
return to normal operation. They are investigating the cause but it does
explain why only some people experienced the event. Other Trimble receivers
and other manufacturers seem unaffected.

On Thu, Sep 5, 2013 at 10:34 PM, Brian, WA1ZMS wa1zms@att.net wrote:

Bill, did you forget your meds or double up on the dosage or something? ;-)

Ed

On 9/6/2013 1:07 PM, Bill Hawkins wrote:

Hi

Ok, here's why the guy gets fired:

The trucking company doesn't do the GPS thing to catch the trucker goofing off. They do it because they get paid to do it. A number of companies will only ship with you if you can real time track the cargo and tell them when it'll get to their dock. Why - they only have to pay the unload crew to be there when there's cargo coming in. They only schedule production when all the parts will be there. No parts / no delivery  - everybody stay home and we don't pay you.

When the tracking goes blank on the truck, the company does not pay the agreed on premium for the service. If the percentage of loads without tracking goes above a (quite low) threshold the truck line gets significantly less business than their competitor.

The trucking companies go after this stuff because it costs them a lot of money, not because of any law that may be broken.

Bob

On Sep 6, 2013, at 9:25 AM, Jim Lux jimlux@earthlink.net wrote:

Lisa,

Thanks for this update.  How many Resolution-T receivers are out there?

Not to go off on another tangent - but I have heard something about 'GPS
jamming during the America's Cup'.  Hmmm.

Regards,
John Westmoreland

On Fri, Sep 6, 2013 at 8:54 AM, Lisa Perdue perdue.lisa@gmail.com wrote:

Fellow Time Nuts:

Is this a site to be trusted?:

http://adn.agi.com/SatelliteOutageCalendar/SOFCalendar.aspx

Regards,
John W.

On Fri, Sep 6, 2013 at 6:41 PM, John C. Westmoreland, P.E. <
john@westmorelandengineering.com> wrote: