Potentially Catastrophic GPS Rollover Due 6th April

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Potentially Catastrophic GPS Rollover Due 6th April

Postby toucana on March 10th, 2019, 7:02 am 


April 6th 2019 might be a poor day to take an airline flight according to some pundits, as the American GPS system is due to undergo an epoch rollover on that day.


Older satnavs and such devices won't be able to use America's Global Positioning System properly after April 6 unless they've been suitably updated or designed to handle a looming epoch rollover.

GPS signals from satellites include a timestamp, needed in part to calculate one's location, that stores the week number using ten binary bits. That means the week number can have 2^10 or 1,024 integer values, counting from zero to 1,023 in this case. Every 1,024 weeks, or roughly every 20 years, the counter rolls over from 1,023 to zero.

The first Saturday in April will mark the end of the 1,024th week, after which the counter will spill over from 1,023 to zero. The last time the week number overflowed like this was on August 21st 1999, nearly two decades on from the first epoch in January 1980. On that occasion there were barely any disruption. 

If devices in use today are not designed or patched to handle this latest rollover, they will revert to an earlier year after that 1,024th week in April, causing attempts to calculate position to potentially fail. System and navigation data could even be corrupted, we're warned.
GPS devices with a poorly implemented GPS Time-to-UTC conversion algorithm may provide incorrect UTC following a week number rollover," US Homeland Security explained in its write-up (PDF) of the issue this week.

"Additionally, some GPS devices that calculate the week number value from a device-specific date rather than the start of the current GPS Time Epoch may provide incorrect UTC at some other device-specific date."

Smartphones are unlikely to be affected because they are based on more modern GPS technology. However, Bill Malik, vice-president of Trend Micro, a cyber security company, has said he is not prepared to fly on April 6 because of the dangers.

In a worst case scenario it is claimed the problem could affect the navigation systems of ships and older aircraft and the digital timekeeping used by websites, electrical grids, financial markets, data centres and computer networks.
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