[time-nuts] WWVB Chronverter update progress

Bob kb8tq kb8tq at n1k.org
Mon Aug 27 15:21:53 EDT 2018


One of the “interesting” things about the phase modulation on WWVB is that it does not get converted to 
AM (and thus mess things up) in the front end filters of the typical watches and clocks. The filters also do
not strip off the AM modulation sidebands of the signal. One would *guess* that the filters have to be at least
20Hz wide (+/- 10 Hz relative to 60,000 Hz)  to make this happen. 


> On Aug 27, 2018, at 2:26 PM, Larry McDavid <lmcdavid at lmceng.com> wrote:
> Tim, there is indeed a consumer clock that uses only the BPSK modulation on WWVB. It is an "ULTRATOMIC" clock by La Crosse and has available on Amazon for over a year now. I have two of these clocks. They are *vastly* more sensitive than the usual "atomic" AM clocks. My actual experience is that these clocks will sync to WWVB within 10 minutes any time of day, completely unlike the usual AM "atomic" clocks.
> Several years ago I had radiant barrier thermal insulation installed in my home attic; it forms essentially an aluminum umbrella over my home, an unexpected result. I had to relocate all my AM "atomic" clocks to (the inside of) outside walls for them to sync overnight. However, the ULTRATOMIC clocks will sync within 10 minutes any time of day, anywhere within my home.
> But, so far as I can determine, this one rather large analog-display La Crosse clock is the only consumer BPSK clock available. It uses two or four C-cells for power and claims up to 6 years "battery" life. I installed two C-cells and they were only slightly depleted after one year. The clock can be configured for time zone and to inhibit motion of the second hand between midnight and 5 am. For me, one advantage is that the clock face is large enough that I can read it without my glasses!
> Look here:
> https://www.amazon.com/Crosse-Technology-404-1235UA-SS-UltrAtomic-Stainless/dp/B01CCHXTE2/ref=sr_1_3?ie=UTF8&qid=1535393731&sr=8-3&keywords=la+crosse+ultratomic
> or search ULTRATOMIC La Crosse on Amazon.
> Tom Van Baak did a tear-down has many pictures posted on his website; look here:
> http://www.leapsecond.com/pages/ultratomic/
> Larry
> On 8/27/2018 8:12 AM, Tim Shoppa wrote:
> ...
>> Now, if this is a fancy-pants consumer WWVB wall clock that also expects
>> the phase shift keying (not just amplitude keying) then I have no idea how
>> it'll respond to just plain amplitude keying for the time code. You might
>> think the WWVB BPSK chip will respond to loud and clear amplitude
>> modulation but I have no experience with this. Nor do I even know if a
>> single consumer clock was ever sold with BPSK ability.
>> Tim N3QE...
> -- 
> Best wishes,
> Larry McDavid W6FUB
> Anaheim, California  (SE of Los Angeles, near Disneyland)
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