[time-nuts] More ES100 WWVB Measurements

[David G. McGaw]

It appears Canada tries to match the US to save confusion.  The US 
changed the dates starting in 2007 (making clocks in earlier systems 
like VCRs obsolete) and Canada followed suit.  Who knows what Congress 
will do in the future (abolish DST?  I hope!), so programming a system 
to be good to 2100 seems optimistic!

David N1HAC


On 1/1/19 5:31 PM, Graham / KE9H wrote:
>> Does anybody know how many other places use the same rules?  What does
> Canada do?
>
> https://en.wikipedia.org/wiki/Daylight_saving_time_by_country
>
> --- Graham
>
> ==
>
> On Tue, Jan 1, 2019 at 4:05 PM Hal Murray <hmurray at megapathdsl.net> wrote:
>
>>> GPS has no bits for Daylight Savings.  As far as I know only WWV and WWVB
>>> have those bits. So for a clock displaying local time WWVB is the way to
>> go.
>>
>> WWVB's DST data is targeted at the US.
>>
>> Does anybody know how many other places use the same rules?  What does
>> Canada
>> do?
>>
>> Has anybody looked into how much code it takes to implement DST?  If you
>> are
>> willing to stick to one set of rules, you could pre-compute a small table
>> to
>> cover the next 20 (or 100) years.  That's probably not good enough for a
>> product, but OK for most home brew clocks.  Can I get to 2100 with only 28
>> slots?  (7 for day-of-week, and 4 for leap years)
>>
>> The full Unix time conversion package is pretty big if you are of running
>> it
>> on a tiny SOC.  Has anybody implemented a slimmed down version?  How slim
>> can
>> you get if all you want is DST?
>>
>> Besides, GPS gives you leap second warning.
>>
>> A while ago, somebody asked why use WWVB rather than GPS?  One answer is
>> so we
>> can monitor what it does when a leap second happens.
>>
>>
>>
>>
>> --
>> These are my opinions.  I hate spam.
>>
>>
>>
>>
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