# How do I change the clock for DST ending?



## Barry Allen (Apr 18, 2018)

Manually changing the time works. When I select the option for auto setting the clock from a cell signal (OnStar?) it goes back to being an hour forward.

Is the time signal from the cell tower wrong? How do I fix that?


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## snowwy66 (Nov 5, 2017)

You can't change what the cell tower reads. 

I've seen some towers take 24 - 48 hours to update. 

If you live on a time zone. That also causes issues.


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## Barry Allen (Apr 18, 2018)

snowwy66 said:


> You can't change what the cell tower reads.


Cell towers use GPS time, which does't have DST. There must be some sort of internal correction programmed to convert GPS to local time, and it must be late being broadcast. But that makes me wonder why it takes any longer than about a nanosecond to update, because we know exactly when DST starts and ends. It should be already programmed into the cell tower for billing record purposes. That brings to question the accuracy of records if there is ever a criminal case that brings it into question...


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## snowwy66 (Nov 5, 2017)

Barry Allen said:


> Cell towers use GPS time, which does't have DST. There must be some sort of internal correction programmed to convert GPS to local time, and it must be late being broadcast. But that makes me wonder why it takes any longer than about a nanosecond to update, because we know exactly when DST starts and ends. It should be already programmed into the cell tower for billing record purposes. That brings to question the accuracy of records if there is ever a criminal case that brings it into question...


Your clock goes off the cell if that's your setting.
So whatever the cell reads. The clock reads. 
And they DO read time changes.


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## Barry Allen (Apr 18, 2018)

snowwy66 said:


> So whatever the cell reads. The clock reads.
> And they DO read time changes.


Cell towers go by GPS time, which is UTC as of 1980 but does not account for leap seconds (meaning it's diverged by 18 seconds). GPS time does not do DST or time zones - that's up to local clocks to make that calculation. So my question is why the cell tower wouldn't switch off DST right at 0200 local time since it's the exact known moment that DST ends.


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## Barry Allen (Apr 18, 2018)

It's Tuesday afternoon and the clock is still stuck on DST...


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## Barry Allen (Apr 18, 2018)

Hah, it finally changed this afternoon.


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