[time-nuts] WWVB Signal Generator

Fri Aug 31 06:45:12 UTC 2018

> Wayne very good progress. You can actually feed the loop coild that exists
> with the cap it should resonate.
> Thats my plan at least.

Thanks, Paul.  Actually, after running a few more tests, the BALDR seems to
now set quite reliably with the wire just wrapped around the ferrite rod as
long as the clock is with 2 inches of the ferrite rod.  I'm using the WWVB
receiver module in another experiment, so I don't want to risk damaging the
module by applying a 5 volt PVM signal to the coil.  But, I have a another
WWVB receiver module on order so, once it arrives, I'll try out your
suggestion.  I've also ordered some ferrite rods in order try my hand at
rolling a 60 kHz antenna from scratch, so that will be another adventure.

Wayne

On Thu, Aug 30, 2018 at 8:04 PM paul swed <paulswedb at gmail.com> wrote:

> Wayne very good progress. You can actually feed the loop coild that exists
> with the cap it should resonate.
> Thats my plan at least.
> Regards
> Paul
> WB8TSL
>
> On Thu, Aug 30, 2018 at 9:44 PM, Wayne Holder <wayne.holder at gmail.com>
> wrote:
>
> > I've had some luck improving things with my ATTiny85-based WWVB Simulator
> > design by replacing the crappy, 8 MHz internal oscillator with an 8 MHz
> > crystal and removing the tweaked timer values I had previously used.  In
> > addition, based on a suggestion from Paul Swed, I tried looping the
> antenna
> > wire a few times around the ferrite rod of a WWVB receiver module I
> > happened to have lying around and this also greatly improved things (see
> > photo on web page at
> > https://sites.google.com/site/wayneholder/controlling-time).  In fact,
> > with
> > the ferrite rod in place, the BALDR clock now syncs even when completely
> > disconnected from being grounded to the ATTiny85 and the scope.
> >
> > I've updated my web page, and the source code at the bottom of the page,
> > accordingly.  BTW, the SYNC output is now moved to pin 7 and the PPS
> output
> > is currently disabled in the code. In addition, I've added some
> additional
> > info on my web page about how to compile and download the program to an
> > ATTiny85 using ATTinyCore by Spence Konde.
> >
> > I've ordered a 15.36 MHz crystal to try, as that should let the ATTiny85
> > generate a true, 60,000 Hz output but, so far, the 8 MHz crystal has
> helped
> > improve things quite a bit.  In addition, I plan to do more tests on
> > different types of antennas in order to see if I can make things even
> more
> > reliable and stable.
> >
> > I still plan on reworking the code so it can also run on a 328-based
> > Arduino board but, currently, the Arduino IDE has no easy way to work
> with
> > boards that don't use a standard, 16 MHz crystal, as this frequency is
> used
> > by the serial port and, in turn, by the boot loader, so altering it can
> > break the ability to upload code.  This has actually caused some issues
> for
> > some of my other projects, so I'm investigating how this issue might be
> > handled.
> >
> > Also, if anyone is interested in trying out other modulation schemes, I
> can
> > easily add a compile option t the code that will let it output a binary
> > low/high modulation signal instead of the PWM signal.
> >
> > Wayne
> >
> > On Thu, Aug 30, 2018 at 8:53 AM paul swed <paulswedb at gmail.com> wrote:
> >
> > > Wayne as I work through the chronverter I do know the good phase
> tracking
> > > clocks really demand on frequency behavior. As I measured its +/- .6 Hz
> > at
> > > 60 KHz. I believe the cheapy wall clocks are a bit wider, but not sure
> as
> > > they are hard to actually measure. They do use a small tuning fork
> > crystal
> > > and from experience these are sharp. When I experimented with them they
> > > were maybe 5 Hz. Indeed the Chinese website had 25 X 60 KHz crystals
> for
> > > maybe $2.
> > > With respect to the antenna. My thinking is a loopstick resonated on 60
> > KHz
> > > and most likely driving it push pull or single ended. Thats 1
> transistor
> > if
> > > single ended as common collector if I had to guess. The reason is the
> > > micros put out a fair level of signal so its a case of upping current
> > into
> > > the antenna. But it really will be a bit of experimenting.
> > > I did look at your code and that was so nice it opened up straight into
> > the
> > > arduino IDE.
> > > Regards
> > > Paul
> > > WB8TSL
> > >
> > > On Thu, Aug 30, 2018 at 5:12 AM, Wayne Holder <wayne.holder at gmail.com>
> > > wrote:
> > >
> > > > For anyone trying out my ATTiny85 code, I've done some additional
> tests
> > > and
> > > > find that placement of the antenna near the clock is very finicky
> and,
> > so
> > > > far, the only way to get a reliable decode of the time in the clock
> is
> > by
> > > > using a scope to monitor the demodulated output and then moving the
> > > antenna
> > > > around until the demodulated signal lines up cleanly with modulated
> > > carrier
> > > > and there are no intra bit glitches.  This can take a bit of
> patience,
> > so
> > > > clearly a better solution needs to be found.  I've found that any
> type
> > of
> > > > glitch in the demodulated signal seems to prevent the clock chip from
> > > > decoding the time.
> > > >
> > > > It's possible the difficultly with locking onto my simulated WWVB
> > signal
> > > > may be partially due to the design of the clock (from my location
> it's
> > > > never been able to to lock onto the real WWVB signal), but I have no
> > > > reference to compare it against so, for now, I have conclude that the
> > > > PWM-based modulation scheme my code uses may also be suboptimal for
> > this
> > > > application.  To make testing even more frustrating, the BALDR clock
> > I'm
> > > > using will only look for a signal for about 6 minutes before it goes
> to
> > > > sleep and I have to then power cycle the clock to get it to listen
> > again.
> > > >
> > > > So, keep this in mind if you're going to try and replicate my
> results.
> > > >
> > > > Wayne
> > > >
> > > > On Wed, Aug 29, 2018 at 6:03 PM Wayne Holder <wayne.holder at gmail.com
> >
> > > > wrote:
> > > >
> > > > > For those that have asked for my to publish the source code for my
> > > > > ATTiny85-based WWVB simulator, I have put up a somewhat hurriedly
> > > written
> > > > > page on my google site at:
> > > > >
> > > > >   https://sites.google.com/site/wayneholder/controlling-time
> > > > >
> > > > > that describes a bit about how the code works, how to compile it
> > using
> > > > the
> > > > > Arduino IDE, how I tested it, some issues I have observed in
> testing
> > it
> > > > > and, at the bottom of the page, a downloadable zip file that
> contains
> > > the
> > > > > complete source code.
> > > > >
> > > > > Note: as mentioned at the top of this page, this is currently a
> work
> > in
> > > > > process, so I'm not yet going to link the article to my main
> website
> > > > page,
> > > > > so you'll need to link in this post to find it.  Also, as draft,
> I'm
> > > > going
> > > > > to continue to revise the page until I feel the project is complete
> > > > enough
> > > > > to publish.  That means the source code zip file is going to
> > > potentially
> > > > > change from time to time, too.
> > > > >
> > > > > Wayne
> > > > >
> > > > > On Wed, Aug 29, 2018 at 1:35 AM Wayne Holder <
> wayne.holder at gmail.com
> > >
> > > > > wrote:
> > > > >
> > > > >> As a follow up, I now have a simple WWVB simulator written in C
> > that's
> > > > >> now running an an ATTiny85 using nothing more than the internal, 8
> > > > >> mHz oscillator and about a 6 inch length of wire connected to one
> of
> > > the
> > > > >> pins as an antenna.  It generates an approximate 60 kHz signal
> using
> > > > PWM on
> > > > >> timer 1.  I tweaked the timer value a bit to correct for some
> > variance
> > > > in
> > > > >> the internal oscillator, but I' not even sure that was necessary,
> as
> > > my
> > > > >> target is just a  BALDR Model B0114ST, consumer grade "Atomic"
> > clock.
> > > > >> Modulation is done by varying the duty cycle of the PWM to
> > approximate
> > > > the
> > > > >> -17 dBr drop on the carrier.  But, again, I don't think this value
> > is
> > > > >> critical with a consumer clock chip.  I tapped the demodulated
> > output
> > > > >> inside the clock and displayed it on my scope along with the
> > generated
> > > > >> signal and I got good, steady demodulation with the wire antenna
> > just
> > > > >> placed near clock.  The next step is to connect up a GPS module
> and
> > > add
> > > > >> code to use it to set the time.  I'm also going to change the code
> > to
> > > > use
> > > > >> the PPS signal from the GPS to drive the output timing rather than
> > the
> > > > test
> > > > >> code I have now that uses timer 0 to generate the PPS interrupt.
> > I'm
> > > > happy
> > > > >> to share details if anyone is interested.
> > > > >>
> > > > >> Wayne
> > > > >>
> > > > >>
> > > > >>
> > > > >> On Sun, Aug 26, 2018 at 2:51 PM, paul swed <paulswedb at gmail.com>
> > > wrote:
> > > > >>
> > > > >>> That would be a great neighbor to have but I can tell you around
> > here
> > > > its
> > > > >>> the phone. Not to concerned about someone putting up a wwvb
> > > > replacement.
> > > > >>> And I can always up the power. Chickle.
> > > > >>> Regards
> > > > >>> Paul
> > > > >>>
> > > > >>> On Sun, Aug 26, 2018 at 2:34 PM, Bob kb8tq <kb8tq at n1k.org>
> wrote:
> > > > >>>
> > > > >>> > 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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