Re: [time-nuts] GPS receiver local oscillator (was: 1PPS for the beginner)

[Wayne Holder]

> Hene we would need a DAC resolution of 1e-4 or 14bit. That's already a
DAC that has a price
> tag, multiple times that of the TCXO.

 I'm not sure what you consider "low cost' but a 16 bit DAC like the
MAX5216BGUA+

goes for $3.40, quantity one.

Wayne


On Tue, Aug 14, 2018 at 2:33 PM, Attila Kinali  wrote:

> On Tue, 14 Aug 2018 11:05:17 -0400
> Bob kb8tq  wrote:
>
> > > Is there a need to make the math easier?
> > > This is what we have microprocessors for.
> >
> > There is *always* a need to make the math easier if I’m quickly typing
> up an example. For proof I
> > reference the hundreds of posts in the archives where I didn’t quite get
> it right :)
>
> I am pretty sure that the math is less the problem than being able
> to control the oscillator precisely enough while staying at low cost.
>
> The average TCVCXO has a tuning range of...let's say 10ppm = 1e-5
> over a range of 0-3V. Now, we want to be able to shift the phase
> such, that we are within 1ns at the next pulse (actually we want it
> to be better, but lets keep the numbers simple). This means we need
> to control the frequency with a precision of 1e-9. Hene we would need
> a DAC resolution of 1e-4 or 14bit. That's already a DAC that has a price
> tag, multiple times that of the TCXO. Hence it's cheaper just to
> shift the frequency/phase digitally and not touch the TCXO.
>
>
> Attila Kinali
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neal Stephenson
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/
> listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

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  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
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/
> listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

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  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  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  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 
> > > 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
> > >>
> > >

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

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  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  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  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  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 > >
>> > > 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
>&g

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

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  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 
> 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  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  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 

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

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  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 
> 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 
> > 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:
> 

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

> 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  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 
> 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  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 
> > > wrote:
> > >
> > > > For anyone trying out my ATT

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

My 15.36 MHz crystals arrived and using one to replace the 8 MHz crystal
seems to, again, improve the ability of the BALDR clock to lock onto and
decode the signal.  It now reliably syncs if the clock is within 6-7 inches
of the tuned, ferrite rod antenna (still just wrapping the wire around the
rod.)  With just a loose, wire antenna, the clock syncs if the antenna is
with 2-3 inches of the clock, which is also an improvement.

I'm also starting to work on moving the code over to an Arduino using an
old Duemilanove board I had lying around, as ithe crystal it uses is a
standard, HC-49 package, which makes it easer to replace than the surface
mount crystals used on modern Arduino boards (you can also get a cheap clone
of the Duemilanove on eBay
<https://www.ebay.com/itm/Duemilanove-USB-Board-2009-ATMega328P-PU-Microcontroller-Compatible-With-Arduino/182256700970>
for
about $6 + shipping.)  And, as near as I can tell, 15.36 MHz is close
enough to 16 MHz that I didn't have to modify the boot loader and uploads
seem to work ok.  Just swap the crystal and go.  So, that's one less thing
to worry about.

Wayne

On Thu, Aug 30, 2018 at 8:04 PM paul swed  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 
> 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  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 o

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

I've reworked my WWVB Simulator so it can now run on a slightly modified,
328-based Arduino (swapped in a 16.36 MHz crystal for the standard 16 MHz.)
 The new code is also now using a GPS module to set the time from the
GPS $GPRMC message and my BALDR clock just syncs up nicely.  I used a
GlobalTopGPS module (similar to the one used in this Adafruit GPS module
<https://www.adafruit.com/product/746>) but, with minor changes, it should
work with any GPS module.  The main change needed is configuring the
message used to set the module to only send $GPRMC messages (at a 1 second
interval) and suppress the others NMEA messages.

The last step is to to set the DST status bits (57 and 58) in the WWVB
message, but I'm little bit confused as to when to precisely set these
bits.  For reference, the the Java code (below) that I used to prototype
and test the algorithms before converting to C.  The code computes the
starting day of year and ending day of year and the idea is to use these
two DOY values to control to setting bits 57 and 58.  But, it's unclear to
me if I should set starting and ending state (code 2 and 1, respectively)
on the Sunday of the change or on the days before and after this date?  Or,
 are the starting and ending states set on Sunday and the other states on
the following Mondays?  I'm confused.

Wayne

public class DaylightSavings {
  private static final int daysToMonth[][] = {
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 },
{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335 },
  };
  private static final int MARCH = 3;
  private static final int NOVEMBER = 11;

  /*
   *  Compute state and end of Daylight Savings time for specified 4 digit year
   *DST Starts the 2nd Sunday of March at 2:00 AM
   *DST Ends the first Sunday of November at 1:00 AM
   */

  public static void main (String[] args) {
int year = 2018;
int start = getNthSundayOfMonth(2, MARCH, year);  //
Get 2nd Sunday of March
int end = getNthSundayOfMonth(1, NOVEMBER, year); //
Get 1st Sunday of November
int startDoy = getDayOfYear(start, MARCH, isLeapYear(year));
int endDoy = getDayOfYear(end, NOVEMBER, isLeapYear(year));
System.out.println("DST starts: " + MARCH + "/" + start + "/" +
year + " (Day of Year: " + startDoy + ") ");
System.out.println("DST ends:   " + NOVEMBER +  "/" + end + "/" +
year + " (Day of Year: " + endDoy + ")");
  }

  private static int getNthSundayOfMonth (int sundays, int month, int year) {
for (int day = 1; day < 15; day++) {
  if (getDayOfWeek(month, day, year) == 2) {
if (--sundays == 0) {
  return day;
}
  }
}
// Should never get here
return 0;
  }

  private static int getDayOfYear (int day, int month, boolean leapYear) {
return daysToMonth[leapYear ? 1 : 0][month - 1] + day;
  }

  private static boolean isLeapYear (int year) {
return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
  }

  /**
   * Compute Day Of Week (1-7) using Zeller's Method
   * @param month (1-12)
   * @param day (1-n)
   * @param year 4 digit year
   * @return day of week (1 = Sat, 2 = Su, 3 = Mon, 4 = Tue, 5 = Wed,
6 = Thr, 7 = Fri
   */
  private static int getDayOfWeek ( int month, int day, int year) {
int cen = year / 100;
year = year % 100;
if (month == 1) {
  month = 13;
  year--;
} else if (month == 2) {
  month = 14;
  year--;
    }
return (day + 13 * (month + 1) / 5 + year + year / 4 + cen / 4 + 5
* cen) % 7 + 1;
  }
}


On Sat, Sep 1, 2018 at 5:14 PM Wayne Holder  wrote:

> My 15.36 MHz crystals arrived and using one to replace the 8 MHz crystal
> seems to, again, improve the ability of the BALDR clock to lock onto and
> decode the signal.  It now reliably syncs if the clock is within 6-7 inches
> of the tuned, ferrite rod antenna (still just wrapping the wire around the
> rod.)  With just a loose, wire antenna, the clock syncs if the antenna is
> with 2-3 inches of the clock, which is also an improvement.
>
> I'm also starting to work on moving the code over to an Arduino using an
> old Duemilanove board I had lying around, as ithe crystal it uses is a
> standard, HC-49 package, which makes it easer to replace than the surface
> mount crystals used on modern Arduino boards (you can also get a cheap clone
> of the Duemilanove on eBay
> <https://www.ebay.com/itm/Duemilanove-USB-Board-2009-ATMega328P-PU-Microcontroller-Compatible-With-Arduino/182256700970>
>  for
> about $6 + shipping.)  And, as near as I can tell, 15.36 MHz is close
> enough to 16 MHz that I didn't have to modify the boot loader and uploads
> seem to work ok.  Just swap the crystal and go.  So, that's one less thing
> to worry about.
>
> Wayne
&g

Re: [time-nuts] WWVB Signal Generator

[Wayne Holder]

I was able to sort out my issue with the DST bits with the help of the
code Andy Backus recently published.  I believe my code should now be ready
for anyone who's curious to try out.  Complete details are available on the
following page:

  https://sites.google.com/site/wayneholder/controlling-time-2

This new code is a bit simpler than the ATTiny85-based code I published
before, as I've eliminated the use of interrupts and now use the GPS
module's PPS signal to control bit timing and simple calls to the millis()
function to control the timing of the bit modulation.  I still recommend
swapping the 16 MHz crystal for a 15.36 MHz one, but you should be able to
run the code on any ATMega328-based Arduino using a 16 MHz clock, although
with reduced range from the antenna to the clock.

Wayne

On Wed, Sep 5, 2018 at 8:48 AM Mark Sims  wrote:

> If your receiver has it the $GPZDA  can be a better message to use.   They
> usually have better seconds resolution and some receivers give them some
> special love as to when they come out.  But, depending upon your code, this
> may not matter.  Also check to see if your chosen time message comes out
> before or after the 1PPS.
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Observations on how "Atomic" WWVB clocks set time

[Wayne Holder]

Now that I have my WWVB simulator
 up and
running it's allowed me to experiment with the BALDR Model B0114ST clock I
own.  I've always been curious to observe what happens when it detects and
set the time but, typically, this usually happens in the early hours of the
morning when propagation of the WWVB signal is better.  But, with the
simulator, I can observe the time change, over and over again whenever I
want.  And, since I coded a SYNC signal into the simulator that goes high
for one second during the first second of each transmit frame, I can
connect this to an LED to use a reference.  So, I sent about doing some
simple experiments.

First, I wanted to determine how many 1 minute frames of data it requires
before the clock will sync up to the transmission.  This was easy to test
by pulling the battery out of the clock just after the Sync LED lights up
and then putting it back in again in order to put the clock into a state
where it was reset and looking for a signal.  Then, just by watching the
LED and the clock display I was able to watch as each frame was transmitted
and determine that (at least with my BALDR B0114ST), it takes only two
frames of data before the clock is able to sync.

So, next, I decided to see if the clock would sync if I altered the
simulator code to send a valid time, but the same exact time sent for each
frame with no advancement of the minutes.  As I had expected when I was
first working on code for the simulator, the clock is never able to sync.
So, I reasoned that, even though the time code format doesn't include any
type of checksum, it probably uses the time difference between successive
frames to determine when it has seen two valid frames of data.

To test this theory, I changed the code to repeat the minutes value for
both odd and even frames (ANDing minutes with 0xFE to send the sequence 0,
0, 2, 2, 4, 4, 6, 6, etc.)  To my surprise, the clock was still able to
sync to the correct time.  However, on thinking about it a bit, I realized
that the clock probably saw the repeated frame as an error, but then saw
the next frame as valid time the fit with the sequence (for example 0, 0, 2
could be seen as 0, err, 1).  And, given that the signal strength of WWVB
is marginal in many areas, this improves the clock's ability to sync.  Very
clever.

BTW, has anyone ever seen a WWVB-based clock that displays the year?  I
don't suppose it's needed, as most people are aware of what year it is, but
I'm curious if any clocks that do show the year were ever built.
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

[Wayne Holder]

The oscillator mentioned in the article is a SiT1532 made by SiTime
.  It's sold in a chip scale package that's only 1.5mm x
.9mm, which means it'a no much more than a chip of silicon with some solder
balls attached.  The data sheet indicates there is a "polymer" coating on
the back side of the chip, but the working surface would be in the bottom
where the solder balls are.  There is a rectangular protrusion shown on the
"Dimensions and Patterns" section (page 12) that's right over where the
MEMS mechanism would sit that might be some type of seal, but there is no
descriptive text.

The curious thing to me is that some iPhones are said not to recover from
exposure to helium but, as an essentially mechanical device, I can think of
no reason that the SiT1532 would not recover from exposure to helium after
the gas had migrated out.  I wonder off the iPhone could be damaged by an
oscillator failure, o one that's running off frequency? The devices sell
for about $1.25 at Mouser and I have a tank of helium in the garage, so I'm
thinking about doing an experiment.  The only problems is finding a way to
solder wires to such a small part?  Might have to make a PCB, instead.

Wayne

On Wed, Oct 31, 2018 at 12:51 PM Mark Sims  wrote:

> https://ifixit.org/blog/11986/iphones-are-allergic-to-helium/
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] More ES100 WWVB Measurements

[Wayne Holder]

While reading this thread and pondering whether to buy and fool around with
an ES100-based module from Universal Solder, I suddenly found myself
wondering if there was any advantage to using the time received from WWVB
vs just using an inexpensive GPS receiver.  The ES100  module costs about
$70, but I can get a GPS receiver, with antenna, for far less than that and
I've had no trouble receiving GPS signals indoors with most modern receiver
modules.

I suppose the low power requirements of the ES100 might be an advantage
when building battery powered clocks to mount on the wall, but it seems
like some of the newer, ultra low power GPS modules intended for use in
smart watches could also work in a battery-powered wall clock, especially
if the receiver was only powered on a few times a day to update the time.

And, finally, if GPS modules are (or will some become) a suitable
replacement for WWVB receiver modules, do we really need WWVB in the modern
age?  Perhaps there's some critical advantage to using WWVB to get the time
but, offhand, I cannot think of it.  What am I missing?

Wayne

On Mon, Dec 31, 2018 at 4:30 PM Brooke Clarke  wrote:

> Hi Joseph:
>
> Thanks for the patent link.  I've added it to my WWVB phase modulation
> info at:
> https://prc68.com/I/Loop.shtml#La_Crosse_UltrAtomic
>
> --
> Have Fun,
>
> Brooke Clarke
> https://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> axioms:
> 1. The extent to which you can fix or improve something will be limited by
> how well you understand how it works.
> 2. Everybody, with no exceptions, holds false beliefs.
>
>  Original Message 
> > On Mon, 31 Dec 2018 12:00:02 -0500, time-nuts-requ...@lists.febo.com
> > wrote:
> >
> >>   time-nuts Digest, Vol 173, Issue 44
> >> Message: 7
> >> Date: Mon, 31 Dec 2018 04:04:22 -0800
> >> From: "Tom Van Baak" 
> >> To: "Discussion of precise time and frequency measurement"
> >>  
> >> Subject: Re: [time-nuts] More ES100 WWVB Measurements
> >> Message-ID: <96BB388753294278A9CDE96C1EA7D9AE@pc52>
> >> Content-Type: text/plain;charset="UTF-8"
> >>
> >> Hi Graham,
> >>
> >> That's very nice work. And you have uncovered several unusual effects
> >> in the ES100. Bugs? Features? If we time nuts keep up the good work
> >> to evaluate this chip, we are likely at some point to get an
> >> informative response from the guys who designed it. They read
> >> time-nuts.
> > I didn't see this mentioned, but I think I have found the relevant US
> > patent application: US20130051184A1, Real-time clock integrated circuit
> > with time code receiver, method of operation thereof and devices
> > incorporating the same, Oren Eliezer et al, Oren Eliezer et al, filed
> > 2013-02-28.
> >
> > .
> >
> > Found this by chasing stuff from the EverSet website:
> > .<
> http://everset-tech.com/wp-content/uploads/2014/11/ReceiverRadioClocks.pdf
> >.
> >
> > Joe Gwinn
> >
> >
> >> So now both you and Tim have observed the off-by-one-second (or
> >> off-by-N-seconds) effect in the ES100. I wonder if this explains why
> >> some of my ES100-based La Crosse 1235UA Ultratomic wall clocks are
> >> off by a second sometimes.
> >>
> >> My main question: in your "Time Plot.PNG" plot, what is the cause of
> >> the sawtooth pattern? The points are almost all on a clear negative
> >> slope, though bounded by roughly +/- 75ms. Looking on the far left, I
> >> see a time drift of +50 ms to -25 ms over an hour, which is
> >> equivalent to a -20 ppm frequency offset; about -2 seconds/day.
> >>
> >> Do you think this is due to the 16 MHz onboard xtal? If so, how about
> >> changing the temperature of the eval board by a lot (say, several
> >> tens of degrees) for an extended time (say, 4 hours) and see if the
> >> sawtooth slope changes convincingly.
> >>
> >> Also, just to be sure, can you put a known independent timing signal
> >> (e.g., GPS/1PPS) into your complex BeagleBone Black / Debian 9.4 /
> >> ntpd time server / Python 3 / Excel stack to establish the validity
> >> of your measurement methodology? Very likely you did it right, but I
> >> always cringe when I hear "Linux" or "NTP" and "precise time" in the
> >> same sentence. Yes, sorry, forgive me; I grew up in the "trust, but
> >> verify" generation [1]. It applies pretty well to metrology also ;-)
> >>
> >> /tvb
> >>
> >> [1] https://en.wikipedia.org/wiki/Trust,_but_verify
> >>
> >>
> >> End of time-nuts Digest, Vol 173, Issue 44
> >> **
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
> >
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follo

Re: [time-nuts] More ES100 WWVB Measurements

[Wayne Holder]

> If you are fairly deep inside a building, GPS isn’t going to get there.
WWVB likely
> will make it to an internal location.

Interesting thought. I wonder if anyone has tested WWVB reception in a
deep underground location such as a sub sub level in a building or parking
garage?

Wayne

On Mon, Dec 31, 2018 at 5:29 PM Bob kb8tq  wrote:

> Hi
>
> If you are fairly deep inside a building, GPS isn’t going to get there.
> WWVB likely
> will make it to an internal location.
>
> If you are convinced that WWVB is un-jamable and that GPS is easily
> jammed, WWVB
> would be more robust.
>
> That’s about it.
>
> Bob
>
> > On Dec 31, 2018, at 7:56 PM, Wayne Holder 
> wrote:
> >
> > While reading this thread and pondering whether to buy and fool around
> with
> > an ES100-based module from Universal Solder, I suddenly found myself
> > wondering if there was any advantage to using the time received from WWVB
> > vs just using an inexpensive GPS receiver.  The ES100  module costs about
> > $70, but I can get a GPS receiver, with antenna, for far less than that
> and
> > I've had no trouble receiving GPS signals indoors with most modern
> receiver
> > modules.
> >
> > I suppose the low power requirements of the ES100 might be an advantage
> > when building battery powered clocks to mount on the wall, but it seems
> > like some of the newer, ultra low power GPS modules intended for use in
> > smart watches could also work in a battery-powered wall clock, especially
> > if the receiver was only powered on a few times a day to update the time.
> >
> > And, finally, if GPS modules are (or will some become) a suitable
> > replacement for WWVB receiver modules, do we really need WWVB in the
> modern
> > age?  Perhaps there's some critical advantage to using WWVB to get the
> time
> > but, offhand, I cannot think of it.  What am I missing?
> >
> > Wayne
> >
> > On Mon, Dec 31, 2018 at 4:30 PM Brooke Clarke 
> wrote:
> >
> >> Hi Joseph:
> >>
> >> Thanks for the patent link.  I've added it to my WWVB phase modulation
> >> info at:
> >> https://prc68.com/I/Loop.shtml#La_Crosse_UltrAtomic
> >>
> >> --
> >> Have Fun,
> >>
> >> Brooke Clarke
> >> https://www.PRC68.com
> >> http://www.end2partygovernment.com/2012Issues.html
> >> axioms:
> >> 1. The extent to which you can fix or improve something will be limited
> by
> >> how well you understand how it works.
> >> 2. Everybody, with no exceptions, holds false beliefs.
> >>
> >>  Original Message 
> >>> On Mon, 31 Dec 2018 12:00:02 -0500, time-nuts-requ...@lists.febo.com
> >>> wrote:
> >>>
> >>>>  time-nuts Digest, Vol 173, Issue 44
> >>>> Message: 7
> >>>> Date: Mon, 31 Dec 2018 04:04:22 -0800
> >>>> From: "Tom Van Baak" 
> >>>> To: "Discussion of precise time and frequency measurement"
> >>>> 
> >>>> Subject: Re: [time-nuts] More ES100 WWVB Measurements
> >>>> Message-ID: <96BB388753294278A9CDE96C1EA7D9AE@pc52>
> >>>> Content-Type: text/plain;charset="UTF-8"
> >>>>
> >>>> Hi Graham,
> >>>>
> >>>> That's very nice work. And you have uncovered several unusual effects
> >>>> in the ES100. Bugs? Features? If we time nuts keep up the good work
> >>>> to evaluate this chip, we are likely at some point to get an
> >>>> informative response from the guys who designed it. They read
> >>>> time-nuts.
> >>> I didn't see this mentioned, but I think I have found the relevant US
> >>> patent application: US20130051184A1, Real-time clock integrated circuit
> >>> with time code receiver, method of operation thereof and devices
> >>> incorporating the same, Oren Eliezer et al, Oren Eliezer et al, filed
> >>> 2013-02-28.
> >>>
> >>> .<https://patents.google.com/patent/US20130051184>
> >>>
> >>> Found this by chasing stuff from the EverSet website:
> >>> .<
> >>
> http://everset-tech.com/wp-content/uploads/2014/11/ReceiverRadioClocks.pdf
> >>> .
> >>>
> >>> Joe Gwinn
> >>>
> >>>
> >>>> So now both you and Tim have observed the off-by-one-second (or
> >>>> off-by-N-seconds) effect in the ES100. I wonder if this explains wh

Re: [time-nuts] 4.19 MHz xtal

[Wayne Holder]

The following wikipedia article:

  https://en.wikipedia.org/wiki/Omega_Marine_Chronometer

mentions a "*Marine Chronometer clock using an advanced 4.19 MHz quartz
resonator giving an unparalleled accuracy of less than 5 seconds per year
under calibre 1525*."  My guess is that this crystal technology eventually
found its way into consumer clocks.

Wayne

On Sun, Mar 31, 2019 at 3:02 PM Neville Michie  wrote:

> Hi,
> I have a Philips quartz clock that runs on 4.19 MHz.
> In spite of the high frequency it still runs for years
> on a C cell.
> Can any of the quartz crystal gurus explain why this
> frequency was chosen? I believe that this clock was
> supposed to have better than usual accuracy.
> Philips always had a high level of engineering excellence.
>
> cheers,
> Neville Michie
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] WWVB Disciplined Oscillator

[Wayne Holder]

Perhaps this has been mention before, but I found the following document
while researching some details on WWVB and thought it might interest the
group:

  https://www.kevincroissant.com/WWVB/WWVB_PTTI_2018.pdf

I know that Spectracom once made a WWVB Disciplined Oscillator in the form
of the Model 8164, but I figured that this approach probably was obsolete
in the era of GPS and network-based time. However, the author seems to have
produced some interesting results.  Has anyone else built, or tried to
build a WWVB Disciplined Oscillator?

Wayne
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] WWVB Disciplined Oscillator

[Wayne Holder]

> Hi Wayne,
> Great to see you found my presentation!
> The paper is available here:
>  https://www.kevincroissant.com/WWVB/WWVB_PTTI_2018_paper.pdf

Kevin, thanks for the link to the paper.  I'd like to know more about how
correlation works and how you were able to use to to sync with the WWVB
bitstream.  From what I read in your paper, I'm guessing that the "local"
code you use for correlation is generated by prediction once the receiver
has locked on the broadcast code and these two bit streams are then
"compared" in some way via multiplication...  But, I don't really
understand how this is done at a practical level as it would seem that his
would require multiple passes over the code with some type of sliding time
offset that advances with each pass? Or, are there simpler techniques?  Can
you suggest a reference where I can learn more?

BTW, for everyone else following the WWW/WWVB/WWVH defunding saga, a post
on this web page:

   http://cqnewsroom.blogspot.com

claims that "*Congress has restored full funding for WWV, WWVB and WWVH,
despite a budget proposal from the National Institute of Standards and
Technology to shut down the three standard time and frequency radio
stations. The Consolidated Appropriations Act of 2019 included some $725
million for NIST's Scientific and Technical Research and Services (STRS),
the budget category that includes the stations' funding, according to NIST
Public Affairs Director Gail Porter. The conference report accompanying the
budget bill notes that "(t)he agreement rejects the proposed terminations
and reductions for all STRS programs" and includes "not less than fiscal
year 2018 funding" for several services, including "Time and Fundamental
Measurement Dissemination."*

The article then adds: *"With the shutdown threat ended, preparations
continue for marking WWV's centennial this fall. According to the ARRL
Letter, the Northern Colorado Amateur Radio Club will be operating a
special event station from the WWV transmitter site from September 28
through October 2, using the callsign WW0WWV."*

Wayne




Wayne

Wayne

On Sat, Apr 6, 2019 at 9:00 PM Kevin Croissant 
wrote:

> Hi Wayne,
>
> Great to see you found my presentation!
> The paper is available here:
> https://www.kevincroissant.com/WWVB/WWVB_PTTI_2018_paper.pdf
> I traveled to CO and met with NIST people there and gathered more data
> then. We're planning to put out another paper soon (I'm finishing up my
> bachelor's right now so I'm a bit preoccupied though).
> I think LF timing is still very relevant in this day and age, and WWVB
> still shows promise as a national timing source.
>
> Let me know if you have any questions.
> Best,
> Kevin
>
> On Sat, Apr 6, 2019 at 10:00 PM paul swed  wrote:
>
> > Wayne good read on the paper.
> > All of the spectracoms and such were rendered useless by the new BPSK
> > modulation. Though now that 5 years or so have passed not so new. Unless
> > the modulation is accounted for they can't track the carrier. There are
> > external modifications and other approaches that have been suggested. I
> > have design and tested numbers of them with a final approach using the
> > cheat'n d-psk-r. Won't go into that as its been shared here on time-nuts
> > enough. A lot depends on your location and signal strength. Clearly
> taking
> > advantage of the new modulation for carrier prediction has advantage. But
> > the fact is even I am now spoiled by GPSDOs.
> > I also built a far simplere approach called a remodulator for simply
> > allowing the spectracoms to get time. They are nice displays. Not sure
> you
> > can get even those piece parts any longer.
> > Regards
> > Paul
> > WB8TSL
> >
> > On Sat, Apr 6, 2019 at 8:00 PM Wayne Holder 
> > wrote:
> >
> > > Perhaps this has been mention before, but I found the following
> document
> > > while researching some details on WWVB and thought it might interest
> the
> > > group:
> > >
> > >   https://www.kevincroissant.com/WWVB/WWVB_PTTI_2018.pdf
> > >
> > > I know that Spectracom once made a WWVB Disciplined Oscillator in the
> > form
> > > of the Model 8164, but I figured that this approach probably was
> obsolete
> > > in the era of GPS and network-based time. However, the author seems to
> > have
> > > produced some interesting results.  Has anyone else built, or tried to
> > > build a WWVB Disciplined Oscillator?
> > >
> > > Wayne
> > > ___
> > > time-nuts mailing list -- time-nuts@lists.febo.com
> > > To unsubscrib

Re: [time-nuts] WWVB Disciplined Oscillator

[Wayne Holder]

jimlux,
thanks for the info cross correlation.  That's sort of how i imagined it
should work, but I wasn't sure.  I guess it really helps that we live in
the age of fast computation.

Wayne

On Sun, Apr 7, 2019 at 10:00 AM jimlux  wrote:

> On 4/7/19 4:30 AM, Wayne Holder wrote:
> >> Hi Wayne,
> >> Great to see you found my presentation!
> >> The paper is available here:
> >>   https://www.kevincroissant.com/WWVB/WWVB_PTTI_2018_paper.pdf
> >
> > Kevin, thanks for the link to the paper.  I'd like to know more about how
> > correlation works and how you were able to use to to sync with the WWVB
> > bitstream.  From what I read in your paper, I'm guessing that the "local"
> > code you use for correlation is generated by prediction once the receiver
> > has locked on the broadcast code and these two bit streams are then
> > "compared" in some way via multiplication...  But, I don't really
> > understand how this is done at a practical level as it would seem that
> his
> > would require multiple passes over the code with some type of sliding
> time
> > offset that advances with each pass? Or, are there simpler techniques?
> Can
> > you suggest a reference where I can learn more?
> >
>
>
> One thing that helps is that you know the structure and content of the
> bitstream after the fact - that is, the SNR needed to decode the bits is
> lower than that to recover precision timing.  So you take the "known"
> bitstream and do a cross correlation against the received signal.
>
> pseudocode for the cross correlation is something like this:
>
> for lag=0:N
> sum=0
> for i=0:M-1
> sum = sum + input[i]*reference[i+lag]
> end for
> crosscorrel[lag] = sum/M
> end for
>
> this is a O(N*M) number of operations, so most folks use a technique
> using FFTs: FFT each of them, multiply term by term, then inverse FFT
> back.  That's O(3*M*log2(M) +M operations)
>
>
> You'll get something that has a peak in the middle, which corresponds to
> the point of "maximum alignment" between the two data streams.
>
> There's all sorts of things one can do to get "sub sample" resolution -
> essentially by interpolating.  Zero padding the data set before FFTing
> is one way.
>
> The other thing that might save computational burden is that you don't
> need to try ALL possible time lags - you have an estimate, and so you
> can slide around just that
>
>
>
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Lars GPSDO

[Wayne Holder]

> We have agreed that I will do a board and make Gerber file available. Any
comments or recommendations please off list.

Perhaps put the DAC and the OCVCXO on a daughter board using .1" headers as
an interconnect (like an Arduino shield) so that different DAC/Osc designs
can be swapped in and out.

Wayne

On Sun, Apr 7, 2019 at 12:01 PM ew via time-nuts 
wrote:

> A few more tests on the Lars GPSDO to better understand. The data is
> reduced to 2 and 6 hours to reduce data volume. overwhelms our PC's but
> tells us what Jim and we are looking for. We have agreed that I will do a
> board and make Gerber file available. Most likely two Lars with pulse width
> DAC and Jim's with a DAC.
> Any comments or recommendations please off list.As part of our related
> tests we found little change between Furuno GN87 and GT87 when used in a
> GPSDO.
> Bert___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Pioneering Deep-Space Atomic Clock Taking Flight This Month

[Wayne Holder]

Perhaps also of interest:
https://ws680.nist.gov/publication/get_pdf.cfm?pub_id=105138

Wayne

On Thu, Jun 6, 2019 at 3:15 PM jimlux  wrote:

> On 6/6/19 12:36 PM, JULIAN TOPOLSKI wrote:
> > Interesting article but no description of the clock.
> >
> >
> https://www.space.com/nasa-atomic-clock-falcon-heavy-launch.html?utm_source=twitter&utm_medium=social&utm_campaign=dlvr.it
> > ___
>
> It's DSAC..
>
> https://en.wikipedia.org/wiki/Deep_Space_Atomic_Clock
>
> an order of magnitude better than a space Rb
> an order of magnitude better than a Cassini USO at 1000 second tau
>
>
>
>
> https://ieeexplore.ieee.org/abstract/document/7437483
> R. L. Tjoelker et al., "Mercury Ion Clock for a NASA Technology
> Demonstration Mission," in IEEE Transactions on Ultrasonics,
> Ferroelectrics, and Frequency Control, vol. 63, no. 7, pp. 1034-1043,
> July 2016.
> doi: 10.1109/TUFFC.2016.2543738
>
>
> https://ieeexplore.ieee.org/document/8304787
> IEEE Trans Ultrason Ferroelectr Freq Control. 2018 Jun;65(6):950-961.
> doi: 10.1109/TUFFC.2018.2808269.
> Using the Deep Space Atomic Clock for Navigation and Science.
> Ely TA, Burt EA, Prestage JD, Seubert JM, Tjoelker RL.
> Abstract
> Routine use of one-way radiometric tracking for deep space navigation
> and radio science is not possible today because spacecraft frequency and
> time references that use state-of-the-art ultrastable oscillators
> introduce errors from their intrinsic drift and instability on
> timescales past 100 s. The Deep Space Atomic Clock (DSAC), currently
> under development as a NASA Technology Demonstration Mission, is an
> advanced prototype of a space-flight suitable, mercury-ion atomic clock
> that can provide an unprecedented frequency and time stability in a
> space-qualified clock. Indeed, the ground-based results of the DSAC
> space demonstration unit have already achieved an Allan deviation of
> 2E-15 at one day; space performance on this order will enable the use of
> one-way radiometric signals for deep space navigation and radio science.
>
>
> http://issfd.org/ISSFD_2012/ISSFD23_OD1_2.pdf
>
>
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Is there anyone local to me with an 8.5 digit multimeter?

[Wayne Holder]

Not that I'm an expert on this but, in the 10 Meg and 100 Meg ranges, I
believe a variety of issues, including the triboelectric effect, humidity
and surface contamination are going to be big factors, especially if you
expect to maintain anything close to 8.5 digit accuracy.

  https://ims-resistors.com/wp-content/uploads/2017/03/TN-006.pdf

Wayne

On Tue, Jun 11, 2019 at 11:05 AM Dr. David Kirkby <
drkir...@kirkbymicrowave.co.uk> wrote:

> I'm located in Althorne, Essex (CM3 6DT). I'd like to get a couple of
> resistors (10 M and 100 M) measured on an 8.5 digit meter, then compare
> them to what a 34970A data acquisition unit says. I don't want to spend a
> fortune on very high-end resistors, so bringing the unit to a 3458A, and
> measuring the resistor on two meters reasonably close in time, should be
> enough.
>
> There are some issues with these data acquisition meters, which impacts
> their stability. It does not help the fact that there's no S/N on it, so i
> don't now if it has any particular fault.
>
> --
> Dr David Kirkby Ph.D C.Eng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
> Essex, CM3 6DT, United Kingdom.
> Registered in England and Wales as company number 08914892
> https://www.kirkbymicrowave.co.uk/
> Tel 01621-680100 / +44 1621-680100
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.