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Old 14-02-2019, 03:40   #1
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IS your GPS ready the 20 year rollover?

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 210 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 in 1999, nearly two decades on from the first epoch in January 1980. You can see where this is going. 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.

https://ics-cert.us-cert.gov/sites/d...n_GPS_2019.pdf
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Old 14-02-2019, 05:25   #2
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Re: IS your GPS ready the 20 year rollover?

From my perspective as a developer, GPS should still work on these devices, but you might have to turn back its time as it might recognize the positions as "too old to use". Which is a lot worse if you do not know why this is happening and are mid-voyage. Then you have a device that lives in the past and so do your gpx tracks

Not all manufacturers have to be affected as they might know how to map the field, but you should check. The good thing is your phone and iPad should still work.
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Old 14-02-2019, 05:51   #3
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Re: IS your GPS ready the 20 year rollover?

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The good thing is your phone and iPad should still work.
A good thing?
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Old 14-02-2019, 06:09   #4
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Re: IS your GPS ready the 20 year rollover?

I'd rather have that as a nav than none at all if I get this problem in the middle of a multi-day passage.
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Old 14-02-2019, 06:16   #5
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Re: IS your GPS ready the 20 year rollover?

LOL—— talk about de ja vu!!! Sounds like Y2K all over again.
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Old 14-02-2019, 06:19   #6
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Re: IS your GPS ready the 20 year rollover?

Phones and tablets are good for navigation.
I have had my furuno GPS not being able to get position fix for 2 hours while phone was working and never the opposite , ofcourse is better to have both just in case .
My furuno gp 32 doesn't seem to be effected , here is the list of furuno GPS that will be effected:
https://www.furuno.co.jp/en/news/not...53&dispmid=965
If it does I am not ready to pay 500 for a new GPS specially if it has the same issue in 20 years .
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Old 14-02-2019, 06:23   #7
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Will let you know in April when my GPS Puck, Nav Program and Spot are due for their next outing..
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Old 14-02-2019, 08:07   #8
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Re: IS your GPS ready the 20 year rollover?

Just a thought...

If your unit worked in 1999, it should work this time around, too. And if you have one which was built since 1999, the developers would have known about this issue.

Right?
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Old 14-02-2019, 08:45   #9
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Re: IS your GPS ready the 20 year rollover?

Well, there goes my Trimble I pulled out of the garbage in 2002!
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Old 14-02-2019, 09:37   #10
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Re: IS your GPS ready the 20 year rollover?

Does not bother me, My Tamaya Jupiter, Patek Phillipe pocket watch (manual winding) and paper charts will still be working after all humanity is gone let alone GPS.
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Old 14-02-2019, 11:02   #11
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Re: IS your GPS ready the 20 year rollover?

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Just a thought...

If your unit worked in 1999, it should work this time around, too. And if you have one which was built since 1999, the developers would have known about this issue.

Right?
Unfortunately no. These are somewhat similar, but not really.

Y2K was an issue with years which only used the last 2 digits of the year during the 20th century. This caused confusion between 1901 and 2001, since both would be defined as "01".

The Epoch Time (Unix Time) has to do with how Unix records time. Epoch time starts at midnight GMT on January 1st 1970 and counts each second that has elapsed since that time.

02/14/19 @ 18:58:40 GMT = 1550170720 (Epoch Time).

Epoch time stores the week number using ten binary bits. That means the week number can have 210 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.
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Old 14-02-2019, 11:14   #12
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Re: IS your GPS ready the 20 year rollover?

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Unfortunately no. These are somewhat similar, but not really.

Y2K was an issue with years which only used the last 2 digits of the year during the 20th century. This caused confusion between 1901 and 2001, since both would be defined as "01".

The Epoch Time (Unix Time) has to do with how Unix records time. Epoch time starts at midnight GMT on January 1st 1970 and counts each second that has elapsed since that time.

02/14/19 @ 18:58:40 GMT = 1550170720 (Epoch Time).

Epoch time stores the week number using ten binary bits. That means the week number can have 210 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.
He was not commenting on the Y2K 1999 issue. He was saying if your GPS made it through the 1999 epoch it should make it through this one
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Old 14-02-2019, 16:32   #13
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Re: IS your GPS ready the 20 year rollover?

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LOL—— talk about de ja vu!!! Sounds like Y2K all over again.
I understand and absolutely agree. Y2K was mostly a non-event and this should be too. The fact that there are any GPS units built after 1999 that don't handle the rollover gracefully is just a massive indictment of their designers - that first rollover event sent shockwaves through the navigation industry and so to ignore it in future designs is stunning incompetence.

For background, I was underway on that day in 1999 when my GPS ceased to function. IIRC I had two different units and both failed. When I came into the marina that evening everyone was desperate to get them going again. The problem was that the old ephemeris data was still in the GPS while the new satellite data seemed to refer to 1024 weeks earlier. The fix was to do a factory reset so all of the data would be acquired in the new epoch. Most GPS receivers were put back to full functionality with this simple fix - the hard part was to work out how to do the reset for each model as they were different. The Furuno listing doesn't state the year of introduction but I suspect that many are pre-1999 designs. Anyway this just shouldn't be happening, and most likely a factory reset will cure it if it does.

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Old 14-02-2019, 16:42   #14
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Re: IS your GPS ready the 20 year rollover?

John Harrison will roll over in his grave on the same day. LOL
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Old 14-02-2019, 16:54   #15
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Re: IS your GPS ready the 20 year rollover?

Newer devices already handle this. At least for this rollover. If it's more than 5 years old, worry. Some older devices can be updated.
If your device can't/won't be updated, it's worthless, except for charts.
I know, sucks.
Given the recent changes in magnetic north, anything that can't be updated is in trouble.
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