Careful where you step. You may just get sucked into time nuts and it never stops. Get a good crystal, then its an RB, next you know your paying shipping for a 100 Lbs Cesium. Evil stuff. Or you can just skip all the distractions and get a good GPSDO. Not as much fun learning on the way. But depends on your end goal. Regards Paul WB8TSL
On Sat, Mar 1, 2014 at 9:04 PM, Bob Albert <[email protected]> wrote: > All this is very interesting. However, my interest is frequency. In > other words, I want to know that my standard oscillators are as close to > desired frequency as possible, and how close that turns out to be. > > > Yes, the Internet gives me time of day as close as I care to know. I have > an 'atomic' clock from LaCrosse that resets itself nightly, although it's > fussy about where in the house I put it. If I put it where I'd like, it > won't receive WWVB, so I put it across the room. I called the company > inquiring about augmenting the internal antenna but they were of no help. > > > While watching the clock and listening to WWV, it seems the clock is a > fraction of a second behind. Even that doesn't matter, but calibrating the > counter time base is another kind of thing. > > I am trying to understand how this is done. Should I ever get a rubidium > standard, I'd want to check its calibration, and that's not a trivial > exercise. > > Bob > > > > > On Saturday, March 1, 2014 4:56 PM, Paul Alfille <[email protected]> > wrote: > > There are WWVB clocks with serial output. Arcron made one that I added > linux ntp support for some years back. > http://www.atomictimeclock.com/radsynarcron.htm > > http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver27.html > > 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 <[email protected]> wrote: > > > Hi > > > > 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. > > > > Bob > > > > On Feb 23, 2014, at 5:21 PM, Tom Van Baak <[email protected]> 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 > > > > > > _______________________________________________ > > > time-nuts mailing list -- [email protected] > > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
