[time-nuts] Kinemetrics/Truetime WWVB model 60-dc?

[Bob Camp]

Hi

They changed the modulation format on WWVB back a while. It does not impact the “wall clock” receivers
but it will not work with the carrier recovery (phase tracking) older receivers. That’s regardless of the antenna
you happen to use. About the only solution is to run a device ahead of the older box that receives the new
format and generates a “clean” carrier for the older box. There are various people on the list who have played 
a bit with doing this.

Bob


> On Apr 29, 2016, at 7:12 PM, Rob Seaman <seaman at noao.edu> wrote:
> 
> Howdy,
> 
> We’re in the process of upgrading our telescopes in various ways, including deploying spiffy new GNSS clocks. While rummaging around the shelves of old equipment, I came across the WWVB time code generators that had been retired themselves a dozen years ago or more (in favor of NTP and/or GPS equipment). These are Kinemetrics/Truetime model 60-dc. They appears to power up ok to the point of displaying the colons and flickering keep-alive LEDs (see p.51 of http://www.to-way.com/tf/60dc.pdf). It would be cool to bring them back to life, if only to serve as retro wall clocks.
> 
> It turns out the old 60 KHz antenna (same manufacturer, model A-60FS) was still mounted on the building, but I wasn’t able to get either of the two devices to lock when connected to it. The antenna had been repaired at some point, so I have no confidence that it's still in working condition after many years out in the weather after the case had been opened.
> 
> Now I’ve come across this notice from Spectracom:
> 
> 	http://spectracom.com/sites/default/files/document-files/Pending%20Changes%20in%20the%20WWVB%20Radio%20Signal%20Affects%20Precision%20Frequency%20and%20Timing%20Reference.pdf
> 
> which suggests that other vendors’ devices might also "no longer operate as intended as a result of the WWVB signal change” after July 2012.
> 
> If so, bummer!
> 
> If not, suggestions for acquiring a functioning antenna?
> 
> Many thanks for any information on these or similar devices. I should note that another telescope elsewhere on the mountain appears to still be using a Datum model 9100 (via Forth software!) nightly (though with WWV, not WWVB?)*  Does anybody have a manual for that unit?
> 
> Rob Seaman
> University of Arizona
> —
> * there were even some IRIG wall clocks
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