[time-nuts] WWVB Signal Generator

Bob kb8tq kb8tq at n1k.org
Sun Aug 26 14:34:42 EDT 2018


Hi

The gotcha is if you have neighbors two or three doors away that *also* put up one of
these devices. You then have a real problem with the neighbor(s) in the middle. The 
wavelength is long enough that Raleigh issues won’t get you. You still have the two
signals ( at slightly different frequencies) beating against each other. The result is
going to show up as who knows what to this or that receiver. With a precision receiver, 
you might even have issues from the guy two houses away …...

Bob

> On Aug 26, 2018, at 1:08 PM, paul swed <paulswedb at gmail.com> wrote:
> 
> Agree with the conversation. With respect to neighbors when the day comes
> they may ask you to boost your signal. :-)
> Granted maybe the day won't come but at least having your local clocks work
> is nice.
> Regards
> Paul
> WB8TSL
> 
> On Sat, Aug 25, 2018 at 10:29 PM, Dana Whitlow <k8yumdoober at gmail.com>
> wrote:
> 
>> 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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