ANAVRE sends us the following information on the RECOGNIZATION OF THE NORMALIZED SERVICE OF DETERMINATION OF THE SITUATION OF THE WORLD SYSTEM OF DETERMINATION OF THE SITUATION (GPS- SPS) AS A COMPONENT OF THE WORLD RADIONAVEGATION SYSTEM:

Possible GPS problems due to the week counter zero on 6 April 2019

1 At the request of the United States Government, the following information is made available to Member States and international organizations.

2 Reference is made to the Recognition of the Standard Status Assessment Service of the Global Situation Assessment System (GPS- SPS) as a component of the Global Radionavegation System (circular SN / Circ.182, dated 13 June 1996). On 6 April 2019 the GPS- SPS week counter will be put to zero, which may affect some of the oldest GPS receivers.

3 The GPS system transmits the time to GPS receivers using the time and week format that was launched on 6 January 1980. The data field of the navigation message sent by GPS satellites contains the number of weeks that have passed since the start date, and this figure is limited to a maximum of 1,023 weeks. When the GPS system reaches week 1 024, the system recounts from week zero.

4 It is known that some GPS receptors are not able to make the transition from week 1 023 to week 1 024. If the GPS receiver is already a certain age, or if the necessary updates have not been made, the receiver will return to the zero week as if it were August 1999. During this phase, the internal watches of these GPS receivers will experience an absolute lack of reference, and it is possible that they give the wrong time and situation or that they are permanently blocked.

5 Some of these GPS receivers can be repaired with updates and others will become unusable. Users are asked to check with their GPS manufacturers about the status of their receiver.

6 Member States are invited to make this information available to all interested parties.