[Elecraft] OT: Changes at WWV, WWVB

[David Anderson]

There seems to be a lot of misinformation and misunderstanding about how consumer WWVB consumer clocks and watches sync and what the changes to the format at WWVB mean to them.

The following which give the details from the horse's mouth

http://www.nist.gov/pml/div688/wwvb-030513.cfm


http://www.nist.gov/pml/div688/grp40/wwvb.cfm


Consumer clocks and watches that sync to WWVB old and new generally are not affected by the changes to the modulation scheme. The changes do affect frequency standard products that phase locked to the carrier, and some specific clocks that used synchronous AM detection, not your Radio Shack atomic desk clock.

The reason WWVB clocks check around midnight is because the reception is generally much better at night and with fewer interference sources switched on there is a better signal to noise available at the receiver. 

I would venture to say that most clocks that have stopped working as well as they did in the past would be because of an increase in interference levels due to our modern digital lifestyles and poor enforcement of EMC standards, not the change of the WWVB modulation to add PSK which is backwards compatible to the old scheme.


73

David Anderson GM4JJJ 

> On 29 Nov 2014, at 02:16, david Moes <dmoes at nexicom.net> wrote:
> 
> I recieved a new la Crosse clock about two months ago  In the instructions it stated that it would only sync a a specific time at night.    And now I know why.
> 
> David Moes
> President: Peterborough Amateur Radio Club.
> dmoes at nexicom.net
> VE3DVY,  VE3SD
> 
>> On 11/28/2014 18:40, Hisashi T Fujinaka wrote:
>> On Fri, 28 Nov 2014, Ken G Kopp wrote:
>> 
>> ...
>> 
>>> Here's the most important info .... as of about a year
>>> ago the modulation scheme on WWVB (60 kHz) was
>>> changed (phase reversal each minute) and this has
>>> rendered most of the end-user equipment inoperative.
>>> Most (all ?) tracking receivers like the HP-117's are
>>> now useless without extensive modification.
>>> 
>>> Most of the "atomic" clocks now in use ->do not<- synch
>>> to the current modulation scheme on the 60 kHz signal.
>>> This will explain the differences in displayed time on
>>> supposedly identical clocks and how some appear to
>>> not be getting sufficient enough signal to synchronize.
>> 
>> I heard from my time-nerd friends that the modulation scheme changes for
>> a short period at night to allow a chance for older equipment to sync
>> up. I don't know that for sure.
>> 
>> Technology Review said there are millions of pieces of equipment that
>> use the older scheme.
> 
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