[time-nuts] When does NIST change to DST?

[Nick Sayer]

Well, they flip the “warning” bit at 0h UTC (4PM PST the afternoon before), so I think the explanation is that my clock was able to sync up at that time, and it reacted to the warning bit rather than using that as a cue to make the change at 0200J like it should have. Either that, or the receiver erroneously received a ’11’ rather than a ’10’, or WWVB transmitted the bits wrong (which I’d think unlikely, except that it wasn’t just my clock that reacted early).

> On Mar 14, 2016, at 8:23 PM, Andy <AI.egrps+tn at gmail.com> wrote:
> 
> Yes, what I meant by "switch to DST" was that it flips the DST bit.
> Not that the timecode itself changes.
> 
> Since the time many clocks use to sync up with WWVB is (from what I
> recall) around 2AM, it seems kind of dicey whether they would make the
> change on the right day.
> 
> I think that doesn't explain the change happening at 2000J -- unless
> your receiver was receiving and syncing to WWVB at that time and they
> had already flipped the bit.
> 
> Andy
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