Most Recent Advisory
25 Jun 2022
Can different satellites sometimes exhibit inconsistencies in the Least Significant Bit (LSB) of certain broadcast almanac values when the Week Number and Time of Applicability are the same? And if so, why?
What is the mission of the GPS Warfighter Collaboration Cell (GWCC)?
In the YUMA almanac, what is the Right Ascension referenced to?
How do satellite (SV) positions vary with the age of an almanac?  Will my receiver still be able to lock up on SVs with an old almanac?
Can a single point prediction be used to predict GPS accuracy over an entire region?
What are SEP and CEP?
Who controls the Notice Advisory to Navstar User (NANU) process?
How can I determine the age of a navigation upload?
Will upper ionosphere disturbances (such as those caused by solar activity) which affect HF/UHF communications also impact the GPS signal?
How do I determine when a Leap Second is scheduled to be added or removed from the international time standard or the history of past Leap Seconds?
How do I get access to GPS Interface Control Documents (ICDs)?
Why do I get an error when accessing this site saying "There is a problem with this website's securtity certificate"?
Where can I find prescise ephemeris and daily NGA EOPP bulletins?

When a forecast NANU states that a Delta-V maneuver will be conducted, what is the usual duration between changing the health bit in the navigation message and the actual start time of the satellite maneuver?

Q. Is there an official requirement for DoD users of GPS to use the encrypted GPS receivers and signal?