GPS receiver clocks reset April 6
Remember the excitement surrounding the year 2000, and concerns that the year change could cause electronic equipment to fail? On April 6, 2019, GPS will experience a week number rollover (WNRO)—the system’s week number, which uses a 10-bit binary code, will reach its limit of 1,024 weeks and will reset to week 0.
The initial week 0 started on Jan. 6, 1980, and the first week rollover occurred on Aug. 21, 1999. Most GPS receiver manufacturers understand the rollover well and have prepared for it, although older equipment that has not received a firmware update could experience problems.
According to the U.S. Naval Observatory, displayed Coordinated Universal Time (UTC) timing and/or time tags of receiver data could jump by 19.7 years. Any month/year conversions also could fail. “Navigation solution should be OK, but associated time tags could be incorrect,” the observatory said in a statement.
Garmin, which makes a large number of GPS receivers used in general aviation aircraft, said its hardware is prepared for the week number rollover. “For GPS devices that are affected, after the rollover occurs, an incorrect date and time will be displayed,” Garmin said in a statement. “This incorrect time will also be used to timestamp track logs, compute sunrise and sunset, and other functions that rely upon the correct date and time. However, the positioning accuracy will not be affected. The device will continue to deliver the same positioning performance as before the rollover.”
Garmin said it has anticipated and prepared for this event for years. “Regardless, Garmin has been performing exhaustive testing of current and legacy devices to determine if they will be affected by the GPS week number rollover,” the statement continued. “Our testing shows the vast majority of Garmin GPS devices will handle the WNRO without issues.”
Anyone experiencing issues with the GPS week number rollover should contact the manufacturer of that equipment for advice.
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