[time-nuts] WWVB Signal Generator

Dana Whitlow k8yumdoober at gmail.com
Sat Aug 25 22:29:13 EDT 2018


With the watch being physically close to the faux WWVB "transmitter", one
is in
the so-called "near field" regime, where the field strength (V/m) falls as
the inverse
cube of the distance.  If one is putting the watch, say, within a few
inches of the
transmitter, reliable reception should be available yet the signal should
be literally
undetectable by any practical receiving device more than a few feet away.
Hence,
meeting the FCC field strength limit should be trivial.if the device is
used as pictured.
However, if one cranks up the power enough to reliably cover one's entire
house,
then there might be a problem depending how close the nearest neighbor
lives,
even at levels well within the FCC limit he quotes.

Taking the near field relationship in hand, 40 uV/m at 300m would translate
into
a whopping 0.135 V/m at 20 meters range, more than enough to feed most
peoples'
entire house.  So the pragmatic issue would again be- neighbors.  On the
other
hand, most of them would never be aware of the local signal as long as they
get good
time settings, unless they live close enough to Ft. Collins for the two
signals to
contend with each other.

It looks to me like the ferrite rod antenna is considerable overkill.  Even
with no
purposeful antenna I'd expect leakage to yield sufficient signal for at
least a few
inches.

Dana


On Sat, Aug 25, 2018 at 8:11 PM Wayne Holder <wayne.holder at gmail.com> wrote:

> This guy has what looks like a well thought out design using a Sirf-Based
> GPS and ATTiny44A chip to generate a signal to update his watch:
>
>   https://www.anishathalye.com/2016/12/26/micro-wwvb/
>
> Unfortunately, he doesn't seem to have published a schematic or his source
> code.  But, he covers enough detail that I think it wouldn't be too hard to
> replicate what he's done.  Or, perhaps he would disclose these details if
> contacted.
>
> Wayne
>
> On Sat, Aug 25, 2018 at 4:33 AM, D. Resor <organlists at pacbell.net> wrote:
>
> > I thought I would search in a different way for a WWVB signal generator
> > design.  I found this item.  While the designer explains it isn't as
> > accurate as WWVB it may be another starting point.
> >
> > http://www.tauntek.com/wwvbgen-low-cost-wwvb-time-signal-generator.htm
> >
> >
> >
> > Donald R. Resor Jr. T. W. & T. C. Svc. Co.
> > http://hammondorganservice.com
> > Hammond USA warranty service
> > "Most people don't have a sense of humor. They think they do, but they
> > don't." --Jonathan Winters
> >
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