Users in certain parts of the world may experience a very short period of high Dilution of Precision (DOP >6) in the vicinity of Western Sahara and Morocco at their border and within a large area offshore the United Kingdom and Ireland in the Atlantic from 052117Z – 052120Z Mar 2015 (three minutes), due to satellite maintenance (NANU 2015013, below). DOP depends only on the geometry of the four satellites used by the user equipment to determine its position and time and is a multiplier. Simply speaking, Signal-in-Space error (how much accuracy the signal lost during its travel from the satellite to your receiver) plus Receiver Error (inherent in the manufacture of the device) multiplied by the DOP equals Navigation Error (how far off you can expect the position to be within). Graph illustration of the predicted event can be seen at: http://navcen.uscg.gov/?pageName=degradation_05302015
Predictions are based on a "Best Four" analysis to illustrate the worst case scenario and are provided for situational awareness only.
Please report any outages through the NAVCEN "Report a GPS Problem" page.
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NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2015013
SUBJ: SVN41 (PRN14) FORECAST OUTAGE JDAY 064/1500 – JDAY 065/0300
1. NANU TYPE: FCSTDV
NANU NUMBER: 2015013
NANU DTG: 271807Z FEB 2015
REFERENCE NANU: N/A
REF NANU DTG: N/A
SVN: 41
PRN: 14
START JDAY: 064
START TIME ZULU: 1500
START CALENDAR DATE: 05 MAR 2015
STOP JDAY: 065
STOP TIME ZULU: 0300
STOP CALENDAR DATE: 06 MAR 2015
2. CONDITION: GPS SATELLITE SVN41 (PRN14) WILL BE UNUSABLE ON JDAY 064
(05 MAR 2015) BEGINNING 1500 ZULU UNTIL JDAY 065 (06 MAR 2015)
ENDING 0300 ZULU.
3. POC: CIVILIAN – NAVCEN AT 703-313-5900, HTTP://WWW.NAVCEN.USCG.GOV
MILITARY – GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE – JOINT SPACE OPERATIONS CENTER, DSN 276-3514,
COMM 805-606-3514, JSPOCCOMBATOPS@VANDENBERG.AF.MIL