At 23:59:42 UTC on 4/6/2019 (Midnight GPS time, which differs by 18 leap-seconds from UTC) , the 10-bit GPS Week Number broadcast by the constellation will reset to zero for the second time since the beginning of GPS on 1/6/1980. The official presentation on the issue from gps.gov details the issue, and the U.S. Department of Homeland Security has issued a bulletin regarding the use of GPS for timing purposes. The purpose of this UNAVCO Knowledge Base article is to educate operators of high-precision GPS receivers about any necessary action. There is also information below regarding some seismological and cellular devices.

Topcon GB-1000 GNSS receiver

As the gps.gov presentation states, the best course of action for all owners of GPS receivers and any other hardware that uses GPS for timing or geolocation is to “Trust but Verify” by directly contacting the manufacturer of any such hardware for advice. In addition to the high-precision receivers such as seismometers, dataloggers, cellular modems, internet routers, etc. may also require firmware updates or hardware replacement in order to properly handle the rollover. Read more…