I got this from our GPS Network.....any comments??
To: Superior GPS Network users,
Over the past two weeks we have experienced an unusual number of tech support calls related to GPS
Problems. What was most unusual was the fact that ALL calls were related to the same issue. Given the
Variety of GPS brands, models, ages of equipment and software used, it seemed to more than coincidence.
For the first time in GPS history, one central observer (Network administrator), Is able to monitor the status of multiple GPS units in the field, real-time. We began monitoring (as time permitted) when the calls for help starting coming in.
What we noticed was a change of condition from 11/22 through 12/3.
Starting the week of Nov. 22, close monitoring of logged on rovers revealed an unusual situation. All rovers logged on that were near the coast were having problems FIXING a position. All rovers working in-land were not affected. The problem
persisted for the entire morning, and was consistent with coast/inland geography.
It appears to have “peaked” on 12/2 when NONE of the logged on rovers could FIX for any more than a brief period of time. The problem seemed to dissipate as the day progressed, but due to a lack of significant number of users being logged on in the afternoon, we could not verify that definitively.
In an attempt to understand what was happening, we reviewed Mission Planning for that time period, from Topcon and Ashtech, and neither showed potential issues.
Given that Mission Planning only “predicts” Dilution of Precision (DOPS) values based on satellite position and availability,
And that it does not account for any other factors that may have an effect on GPS operation, we started looking at other potential causes.
A review of our NANU messages revealed nothing that should cause this issue: (maybe SVN34??*)
CONDITION: GPS SATELLITE SVN23 (PRN32) WILL BE UNUSABLE ON JDAY 344
(10 DEC 2010) BEGINNING 0115 ZULU UNTIL JDAY 344 (10 DEC 2010)
ENDING 1315 ZULU.
* CONDITION: GPS SATELLITE SVN34 (PRN04) WILL BE UNUSABLE ON JDAY 336
(02 DEC 2010) BEGINNING 1400 ZULU UNTIL JDAY 337 (03 DEC 2010)
ENDING 0200 ZULU.
CONDITION: GPS SATELLITE SVN34 (PRN04) WILL BE UNUSABLE ON JDAY 351
(17 DEC 2010) BEGINNING 0715 ZULU UNTIL JDAY 351 (17 DEC 2010)
ENDING 1915 ZULU.
Revised***
CONDITION: GPS SATELLITE SVN34 (PRN04) WILL BE UNUSABLE ON JDAY 356
(22 DEC 2010) BEGINNING 1300 ZULU UNTIL JDAY 357 (23 DEC 2010)
ENDING 0100 ZULU. PLEASE REFERENCE NANU NUMBER 2010143
DTG 221750Z NOV 2010 FOR THE ORIGINAL OUTAGE TIME.
NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2010144 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS *** The purpose of this notification is to inform users of an upcoming event related to the GPS satellite constellation. The 2nd Space Operations Squadron will be installing new ground software on 1 Dec 10 (J335).
There are no planned GPS satellite outages for this activity, and the broadcast navigation signal will remain IS-GPS-200 compliant. Any military or civil users who encounter user equipment problems after the install should contact the GPSOC (military), NAVCEN (civil,
non-aviation) as soon as possible, or aviation users should file reports consistent with FAA approved procedures.
To Subscribe for these alerts see: http://cgls.uscg.mil/mailman/listinfo/nanu
---------------------------------------------------------
Another potential problem is “space weather”. Jeremy found an article (see below) about a coronal mass ejection.
This CME may have an effect on communications, specifically radio waves, which are the foundation of the GPS
System as we know it.
http://www.spaceweather.com/
AURORA WATCH: NOAA forecasters estimate a 25% to 30% chance of geomagnetic activity on Dec. 3rd when a CME might hit Earth's magnetic field. High-latitude sky watchers should be alert for auroras tonight.
-This is expected to dissipate over the next few days. If the FIX problem also dissipates, we may conclude that this was a contributing factor.
Another search revealed high levels of electron flux yesterday and today. The chart shows a great deal
Of activity during the same time period as most of our tech support calls….
http://www.swpc.noaa.gov/today.html
This should subside with the passing of the CME.
Both of these anomalies are related to the 11 year “solar cycle” which we are on the up hill run to the peak:
Unfortunately for all the research, and all of the data available, we may never know the real cause of the problem.
Next week, if the GPS problems disappear, we may conclude that this was the cause, but until we have more empirical evidence, we are only speculating….
This communication is sent with the intention of helping our GPS customers understand GPS technology in order
To better utilize their equipment. If you prefer to not receive these communications in the future, please reply to
this e-mail with REMOVE in the subject line.
Mork said it first: NANU NANU
FWIW,
In that it is localized, could it be radio signal interference?
Of course, I would expect that any unintentional jamming would cause failure to track rather than degraded tracking. Hmmm.
Interesting.
Cheers,
DMM
No such problem experienced with our state-wide Real Time Network (GULFNet) here in Louisiana.
GPS Anomalies? Comapre With The Long Island Earthquake....
Coronal activity from the sun should affect all the receivers not just the receivers on the coast. Since Connecticut is due North of Long Island I would consider that the CT coast was shimmy shaking. There are earth disturbance due to earthquakes other than just ground and subsurface movement.
Paul in PA