[LEAPSECS] DUT1

[Gerard Ashton]

One does not use the 100 Hz tone, one counts doubled ticks in
the first 16 seconds of each minute. Right now ticks 9, 10, and
11 are doubled, so DUT1 is -0.3 s. See
http://www.nist.gov/pml/div688/grp40/wwv_format.cfm#ut1
for more details.

I made an error when I wrote WWVB, I meant WWVH.

Of course, one would need optics to make solar or star observations,
when I said no equipment beyond a stopwatch, I meant no additional
timekeeping equipment beyond a shortwave receiver, which I thought
was a given for this discussion.

As for "Define "valid" then. If a government is spending taxpayer money
for a data service that citizens haven't used for decades", if indeed 
citizens
haven't used it for decades, that would be a valid reason to drop it. 
I'm just
saying that the absence of new commercial equipment to automatically
derive DUT1 from WWV or WWVH does not prove that no one is obtaining
DUT1 from those stations.

On 8/4/2011 9:45 AM, Tom Van Baak wrote:

>> It is not necessary, at least in the case of WWV and WWVB, to have 

>> special

>> equipment beyond a short wave radio to decode DUT1. It can be done by

>> ear.

>

> In 1975 short-wave radios were common, but today a short-wave

> radio qualifies as "special equipment".

>

> Even with a SW radio, when was the last time you listened to the

> *subcode* of WWV? These are not the famous 1 second ticks

> we're talking about; it's the low 100 Hz audio tone that is hidden

> below the ticks. It often takes quality headphones or instrument

> grade SW radio to hear this. The subcode doesn't come through

> on the cheap plastic handheld SW radios.

>

> As for WWVB, that's a LF transmission (60 kHz) not short-wave

> and there's no audio to hear. WWVB receivers are plentiful (in

> so-called atomic clocks and watches), but none of them decode

> DUT1.

>

>> Timings of sun and star observations can be done with a hand-operated

>> stop watch to a precision of 0.1 s, the same precision as DUT1. (Not

>> to say there won't be personal errors in excess of 0.1 s, but those 

>> errors

>> will probably be well under 1 s.)

>

> Can you send me a link describing this procedure. I'm surprised

> it can be done with just a stopwatch and no optics.

>

>> I suspect the other reasons to drop DUT1 will be persuasive, but the 

>> lack

>> of commercial decoders is not a valid reason to drop it.

>

> Define "valid" then. If a government is spending taxpayer money

> for a data service that citizens haven't used for decades, then it

> seems to me there is some validity for dropping the service. Or,

> at least replacing that vintage service with something modern.

> You can get DUT1 on the web now with 1000x greater precision

> of WWV/WWVB.

>

> /tvb

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