[time-nuts] Another "atomic" clock question
paul.alfille at gmail.com
Sat Mar 1 19:24:53 EST 2014
There are WWVB clocks with serial output. Arcron made one that I added
linux ntp support for some years back.
As I recall, it was under $100, quite nicely styled, and is sitting here on
my desk. (Reception on the East Coast can be spotty, so I've switched to
standard internet net time source).
On Mon, Feb 24, 2014 at 7:44 AM, Bob Camp <lists at rtty.us> wrote:
> Ok, so 0.1 second at the sync point is indeed a reasonable estimate. If
> that's all you need to deal with (you correct out the crystal offset one
> way or the other) then:
> At 1 day you have 11.5 ppm accuracy. Roughly a 100 Hz beat note with WWV
> at 10 MHz.
> At 10 days you have 1.15 ppm. Roughly a 1 Hz beat note at 10 MHz.
> At 100 days you have 0.115 ppm. That would be about a 10 second period
> beat note.
> None of that is to say that a beat note is all there is to getting
> accuracy off of WWV or that the two approaches deliver the same net
> accuracy. Yes I've done the 10 second beat thing, it can be done with care
> and a good stable WWV signal.
> On Feb 23, 2014, at 5:21 PM, Tom Van Baak <tvb at LeapSecond.com> wrote:
> >> Now that you have brought up this subject, do you know of any way to
> use these LaCrosse clocks to calibrate frequency standards?
> > I suggest using a direct electric (1.5 VDC high-Z) or indirect magnetic
> (high gain) pickup on the coil to get the +/- pulse per second. Compare
> this time with your local frequency standard and over several days you
> should get accuracy better than 10 ms per day (1e-7). Here's an example of
> a raw phase plot:
> > http://leapsecond.com/pages/Junghans/
> > /tvb
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