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

[Tom Van Baak]

Hi Andy,

No, there's nothing about 0200Z. Correct, WWVB doesn't know your local zone.

WWVB itself doesn't "switch" to/from DST. It always only transmits UTC. It is up to your receiver-clock to translate UTC to local time for the user display. This is why most of WWVB radio controlled clocks have a little PMCE (Pacific / Mountain / Central / Eastern) switch.

The WWVB data format also includes bits which announce if DST change will occur. It is up to the receiver-clock to decode these bits and make the 1 hour adjustment at the appropriate time (usually 2 am local time).

See also:
https://en.wikipedia.org/wiki/WWVB
http://tf.nist.gov/general/pdf/2422.pdf
http://www.nist.gov/pml/div688/grp40/radioclocks.cfm

/tvb

----- Original Message ----- 
From: "Andy" <AI.egrps+tn at gmail.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Sunday, March 13, 2016 7:21 PM
Subject: Re: [time-nuts] When does NIST change to DST?


> I wonder if WWVB switches to DST around 0200Z, maybe?  Since it can't
> tell where your local zone is.
> 
> Andy
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