Re: [time-nuts] Lots of Off Topic discussion

[Bob kb8tq]

Hi

I most certainly *have* seen an NTP server that ran off of WWVB and relayed 
the result to the internet. The fun part was that they had entered the “delay” 
number into their config file with the wrong sign on it (or there was a bug in 
the NTP code at that time). The result was that they were …. errr …. a bit 
off time.

So yes, you *can* hook NTP into WWVB, it has been done. It is a way (if you get
the signs right ….) to get into millisecond(s) level accuracy.

Bob

> On Sep 1, 2018, at 2:02 PM, Peter Laws  wrote:
> 
> On Sat, Sep 1, 2018 at 9:15 AM David G. McGaw
>  wrote:
> 
>> available methods of time dissemination.  I am very concerned that
>> factions of NIST consider that this should no longer be part of their
>> mission.
> 
> 
> 1) WWV* systems are not critical to anything I have found other than
> WWVB being used to keep "atomic clocks" in sync and updated for DST.
> I've asked in many places but other than two recent papers that used
> WWV HF signals with the Long Wavelength Array to do some ionospheric
> measurements I can't find any evidence that the signals are critical
> to anything in science.
> 
> 2) Anyone that *needs* accurate time to within a few ms of UTC uses
> NTP.  Anyone who thinks they need more precision than that can look at
> PTP (usually deciding that NTP is plenty good once they see what it
> will cost them for PTP).  All current consumer operating systems (OS
> X, iOS, Android, Windows, etc) have some form of NTP client built in.
> 
> 3) Is no one familiar with the US federal budgeting process?  Really?
> The executive branch (Commerce is a cabinet-level department therein)
> submits to the legislative branch the budget for what they claim they
> will need for the upcoming fiscal year.  This is made up from
> estimates of each cabinet member (and others) who get their numbers
> from the various institutions within their silos (e.g., NIST under
> Commerce).  Because no department head wants their budget cut, they
> ensure that items put up for "cutting" are ones that the public is
> most likely to complain (to congress) about.  A quick google didn't
> tell me when the executive branch last submitted a budget that was
> actually in balance but I'm sure it's been 35 years at least despite
> the alleged cutting.  And it doesn't matter because the executive
> budget is routinely ignored by the body that is actually in charge of
> spending, congress.
> 
> 4) I don't think I've ever seen an NTP server that used WWV* as their
> reference clock (it's listed in the output of the query command)
> because GPS is ubiquitous.  "Yeah, but Carrington!"  I am not certain,
> but given that in the US, the Navstar GPS is a US military system run
> by the US military for US military purposes (which happens to have a
> signal available to civilians) that the designers were not only aware
> of solar physics but used that awareness to make the GPS system as
> resilient as they could to the potential effects of CMEs and flares.
> So for me, the "GPS COULD FAIL!" argument does nothing.
> 
> 
> 
> I'd rather read about Earth tides affecting time measurements.  Or
> proper care and feeding of your Cs oscillator.
> 
> 
> 
> --
> Peter Laws | N5UWY | plaws plaws net | Travel by Train!
> 
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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

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 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

Re: [time-nuts] WWV and legal issues

[Gerhard Hoffmann]

Am 01.09.2018 um 20:40 schrieb Magnus Danielson:

One should first know that there is a lot of papers now on frequency
transfer over fiber. The stability achieved on the best ones so far
greatly below that of the optical clocks that they want to compare.


Please, in a nutshell: what are the worst offenders:

- tranceivers (mechanical, temp, other misfeatures)
- cables ( bending, temp, mechanical stress)
- others?

In the case of transceivers: are there desirable modifications
that would alleviate the problems?

best regards, Gerhard



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Re: [time-nuts] Lots of Off Topic discussion

[Don]

Try receiving wwv or wwvb with your HP3586 SLV and determine precisely
where f(o) is.
It's difficult, ...as propagation and atmospheric conditions will
unwittingly prevail.
This ham prefers my gpsdo's, or my cesium.
Don
N5CID
=
On Sat, 2018-09-01 at 17:04 -0400, William H. Fite wrote:
> With respect, Scott, EVERY ham knows about WWV.
> 
> 
> On Saturday, September 1, 2018, Scott McGrath 
> wrote:
> 
> > 
> > I’m concerned with the science
> > 
> > the WWV/WWVB stations provide invaluable information about the
> > condition
> > of the ionosphere with a baseline of DECADES of data.
> > 
> > Also dont forget that pre PSK the NTP daemon in unix had a
> > interface for
> > Spectracom WWVB receivers and any retrofitted with a D-PSK’er still
> > provide
> > network time within all national banking regulations.
> > 
> > As to GPS Jamming well I think its essential that sophisticated GPS
> > users
> > like this community educate decision makers in their sphere of
> > influence
> > just how FRAGILE a system GPS is.I realize some dont want to
> > hear this
> > but its essential that we as a technological society create backup
> > systems
> > using different techology bases to deliver precise time and
> > frequency in an
> > economical fashion because not everyone can afford a couple of
> > 5071’s.
> > 
> > As to only ‘hams’ using them I dont think many hams unless they are
> > running vintage Collins gear with a WWV position on the bandswitch
> > to align
> > the PTO,  even know about WWV.
> > 
> > Most of the WWV users  I know personally are atmospheric
> > scientists,
> > military and other government users.
> > 
> > 
> > 
> > Content by Scott
> > Typos by Siri
> > 
> > On Sep 1, 2018, at 2:37 PM, Brian Lloyd  wrote:
> > 
> > On Sat, Sep 1, 2018 at 9:13 AM, David G. McGaw <
> > david.g.mc...@dartmouth.edu>
> > wrote:
> > 
> > > 
> > > I consider saving WWV/WWVH/WWVB to be ON topic.  They may not be
> > > as
> > > precise as some on this list like to achieve, but they are
> > > publicly
> > > available methods of time dissemination.  I am very concerned
> > > that
> > factions
> > > 
> > > of NIST consider that this should no longer be part of their
> > > mission.
> > > 
> > I think it is still on-topic for the following reasons:
> > 
> > 1. In many parts of the world, WWV is still a convenient time
> > reference.
> > You can get human-accurate time with nothing more than a $20
> > shortwave
> > receiver.  No, it is not time-nuts accurate but it will do for most
> > things
> > that people do, including celestial navigation and knowing when to
> > come to
> > dinner.
> > 
> > 2. It is a stable RF source for people monitoring changes in the
> > the
> > ionosphere. Whatever else it is, we KNOW they are emitting ON 2.5,
> > 5, 10,
> > 15, 20, and 25 MHz.
> > 
> > I also consider the discussion of GPS jamming to be relevant
> > because, for
> > people who DO want/need time-nuts accuracy, GPS is far and away the
> > most
> > convenient reference. Knowing how it might fail is useful.
> > 
> > YMMV.
> > 
> > --
> > 
> > 
> > 
> > Brian Lloyd
> > 706 Flightline
> > Spring Branch, TX 78070
> > br...@lloyd.aero
> > +1.210.802-8FLY (1.210.802-8359)
> > ___
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> > and follow the instructions there.
> > 
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[time-nuts] Lots of Off Topic discussion

[Mark Sims]

Me too...  that's why Lady Heather can calculate and plot solid earth tide 
displacements.   Also the vertical offset in gravity due to solar/lunar tidal 
effects.

-

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Re: [time-nuts] Lots of Off Topic discussion

[William H. Fite]

With respect, Scott, EVERY ham knows about WWV.


On Saturday, September 1, 2018, Scott McGrath  wrote:

> I’m concerned with the science
>
> the WWV/WWVB stations provide invaluable information about the condition
> of the ionosphere with a baseline of DECADES of data.
>
> Also dont forget that pre PSK the NTP daemon in unix had a interface for
> Spectracom WWVB receivers and any retrofitted with a D-PSK’er still provide
> network time within all national banking regulations.
>
> As to GPS Jamming well I think its essential that sophisticated GPS users
> like this community educate decision makers in their sphere of influence
> just how FRAGILE a system GPS is.I realize some dont want to hear this
> but its essential that we as a technological society create backup systems
> using different techology bases to deliver precise time and frequency in an
> economical fashion because not everyone can afford a couple of 5071’s.
>
> As to only ‘hams’ using them I dont think many hams unless they are
> running vintage Collins gear with a WWV position on the bandswitch to align
> the PTO,  even know about WWV.
>
> Most of the WWV users  I know personally are atmospheric scientists,
> military and other government users.
>
>
>
> Content by Scott
> Typos by Siri
>
> On Sep 1, 2018, at 2:37 PM, Brian Lloyd  wrote:
>
> On Sat, Sep 1, 2018 at 9:13 AM, David G. McGaw <
> david.g.mc...@dartmouth.edu>
> wrote:
>
> > I consider saving WWV/WWVH/WWVB to be ON topic.  They may not be as
> > precise as some on this list like to achieve, but they are publicly
> > available methods of time dissemination.  I am very concerned that
> factions
> > of NIST consider that this should no longer be part of their mission.
> >
>
> I think it is still on-topic for the following reasons:
>
> 1. In many parts of the world, WWV is still a convenient time reference.
> You can get human-accurate time with nothing more than a $20 shortwave
> receiver.  No, it is not time-nuts accurate but it will do for most things
> that people do, including celestial navigation and knowing when to come to
> dinner.
>
> 2. It is a stable RF source for people monitoring changes in the the
> ionosphere. Whatever else it is, we KNOW they are emitting ON 2.5, 5, 10,
> 15, 20, and 25 MHz.
>
> I also consider the discussion of GPS jamming to be relevant because, for
> people who DO want/need time-nuts accuracy, GPS is far and away the most
> convenient reference. Knowing how it might fail is useful.
>
> YMMV.
>
> --
>
>
>
> Brian Lloyd
> 706 Flightline
> Spring Branch, TX 78070
> br...@lloyd.aero
> +1.210.802-8FLY (1.210.802-8359)
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>
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-- 
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when it deserves it.
--Mark Twain

We may be surprised at the people we find in heaven. God has a soft spot
for sinners. His standards are quite low.
--Desmond Tutu
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Re: [time-nuts] WWV and legal issues

[Magnus Danielson]

Hi Bob,

Thanks for the paper.

One should first know that there is a lot of papers now on frequency
transfer over fiber. The stability achieved on the best ones so far
greatly below that of the optical clocks that they want to compare.

Then, for those links able to transfer phase/time, most of them is for
point-to-point systems, many relating to relatively short distances.

Only a few relates to larger distances and some form of network style, mesh.

They fill different purposes, and should not be compared between the
groups, as it changes widely what is meaningful.

I did a presentation some EFTFs ago on some experiences of time-transfer
systems. We had some "interesting" failures where the delay jumped 1 ms.
That is what happens when underlying system re-route one side of a
two-way transfer under the feet of you. These are challenges others
don't see, but that comes with commercial telco setups. For some reason
I know far more about behavior and delays in radio links now than I
thought I would need to, again for reasons that would never show up in
dedicated systems. So, the challenges shifts with the field.

Cheers,
Magnus

On 09/01/2018 08:18 PM, Bob Martin wrote:
> 
> Here is an interesting paper on using fiber:
> 
> https://pdfs.semanticscholar.org/a37e/04164c01a6bfea2154c8f0dd97f49d1673b0.pdf
> 
> 
> I believe it used some of the gear that is(was) used in the GPS ground
> stations around the world.
> 
> Bob Martin
> 
> On 9/1/2018 3:29 AM, Magnus Danielson wrote:
>> Hi,
>>
>> It was very telling when I crashed a research group into the reality of
>> phase/time transfer over fiber compared to frequency transfer. Armed
>> with a whiteboard and pens, I derived the forumulas and showed how they
>> worked and not worked. It's a completely different ball-game and their
>> "known tricks" ain't doing nothing good as it comes to time.
>>
>> I had to figure much of this out myself as I did nation-wide system
>> design to achieve the goal. It's a combination of many skills that goes
>> into designing the full system from scratch and make it fit together.
>> It's not hard stuff, it's just many details one needs to get right.
>>
>> Oh the fun.
>>
>> Cheers,
>> Magnus
>>
>> On 08/31/2018 05:15 PM, Bob kb8tq wrote:
>>> Hi
>>>
>>> That works fine if you are doing things manual to check a local
>>> standard. If you are trying to
>>> disipline a few thousand cell towers 24 hours a day … not so much. It
>>> also works for
>>> checking frequency. What modern systems need is time. That gets you
>>> into a whole
>>> world of resolving and identifying individual edges. The WWVB signal
>>> really was never
>>> set up for this. Loran-C is an example of a signal that was designed
>>> to identify a specific
>>> edge.
>>>
>>> Bob
>>>
 On Aug 31, 2018, at 10:30 AM, Martin VE3OAT  wrote:

 But the diurnal phase shifts at VLF are predictable and largely
 repeatable.  Ignore the phase at night and use only the phase
 records during the day when an all-daylight propagation path
 exists.  You might have to "correct" the absolute phase reading by
 some multiple of the RF period, but with a low rate of local
 standard oscillator drift, this is a simple matter of arithmetic.
 Back in the day, I managed Sulzer crystal oscillators at 5 field
 sites from my office and could maintain phase continuity for weeks
 at a time, until we had to diddle the dial on one or several of them
 to correct for crystal aging.  Then it was just more arithmetic
 again.  Several of the oscillators had such low drift rates that all
 I needed was one daily phase reading from the VLF phase tracking
 receiver (Tracor 599Js) at those sites to know the frequency of the
 Sulzers there.

 ... Martin VE3OAT

 On Thu, 30 Aug 2018 12:27:12 -0400
 Bob kb8tq  wrote:

> WWVB as transmitted ( = right at the input to the antenna) is a
> wonderfully stable signal. As soon as
> that signal hits the real world things start to degrade.
> Propagation between transmit and receive sites
> is a big deal, even at 60 KHz. On top of that, there is a*lot*  of
> manmade noise at 60 KHz. The receive
> signal to noise will never be as good as you might like it to be ?.

> I don't know about WWVB, but for DCF77 it's known that sunrise/sunset
> causes a phase shift of several 100?s at even moderate distances
> (like ~500km). Unfortunately I don't have any measurements at hand.
>     Attila Kinali


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>>>
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Re: [time-nuts] Lots of Off Topic discussion

[Brian Lloyd]

On Sat, Sep 1, 2018 at 9:13 AM, David G. McGaw 
wrote:

> I consider saving WWV/WWVH/WWVB to be ON topic.  They may not be as
> precise as some on this list like to achieve, but they are publicly
> available methods of time dissemination.  I am very concerned that factions
> of NIST consider that this should no longer be part of their mission.
>

I think it is still on-topic for the following reasons:

1. In many parts of the world, WWV is still a convenient time reference.
You can get human-accurate time with nothing more than a $20 shortwave
receiver.  No, it is not time-nuts accurate but it will do for most things
that people do, including celestial navigation and knowing when to come to
dinner.

2. It is a stable RF source for people monitoring changes in the the
ionosphere. Whatever else it is, we KNOW they are emitting ON 2.5, 5, 10,
15, 20, and 25 MHz.

I also consider the discussion of GPS jamming to be relevant because, for
people who DO want/need time-nuts accuracy, GPS is far and away the most
convenient reference. Knowing how it might fail is useful.

YMMV.

-- 



Brian Lloyd
706 Flightline
Spring Branch, TX 78070
br...@lloyd.aero
+1.210.802-8FLY (1.210.802-8359)
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Re: [time-nuts] NIST

[Bob Bownes]

Mark,

That would be most useful and free folks from a few of the proprietary
satellite tracker programs. One could write a 'shim' to consume the output
from a tcp/udp (or serial) port and convert to the proper format for a
chosen polar or az/el rotor.

Bob


On Sat, Sep 1, 2018 at 2:00 PM Mark Sims  wrote:

> I recently added a feature to Lady Heather that can output the sun and
> moon positions to a port.  This was for use by solar trackers and moon
> bounce antennas.   It would be easy to modify that code to output the
> position of a satellite (or all satellites) if you wanted to keep an
> antenna pointed at a specific satellite.
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[time-nuts] NIST

[Mark Sims]

I recently added a feature to Lady Heather that can output the sun and moon 
positions to a port.  This was for use by solar trackers and moon bounce 
antennas.   It would be easy to modify that code to output the position of a 
satellite (or all satellites) if you wanted to keep an antenna pointed at a 
specific satellite.  
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Re: [time-nuts] Effects of Simple GPS jamming on GPSDO's ?

[Mark Goldberg]

On Sat, Sep 1, 2018 at 3:49 AM, Dana Whitlow  wrote:
>
> Question for Mark re metal foil under the antenna:
>
> What's the nature of the improvement?  Between the large tilt angle and
the
> shape of the
> foil piece, I'd certainly not expect any material improvement in the
> multi-path department.

It's just a ground plane. Having a ground plane under the antenna improved
signal strength by 5-10 dB over just putting the antenna in the window.
I covered a box to get the antenna up a little higher and to have the
ground plane be bigger than 1/4 wave at the L1 frequency. It's ugly but it
works.
It's for a Trueposition GPSDO, not that sensitive. Mounting the antenna
inside did not work well.

I've also been known to hold my phone in the upper corner of the balcony on
a cruise ship to use it as a corner reflector to catch wifi from shops on
the dock. That worked surprisingly well too.

>
> Also, are the Venetian blinds seen in the photo made of metal, or plastic
> (or wood)?
> Is there a screen on the window?  If so, ditto question regarding the
> composition.
>

The blinds are metal. There is no screen in the window, which also made a
huge improvement over windows with metal screens.

Regards,

Mark
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Re: [time-nuts] distribution of precision time via fiber networks

[Bob Martin]

Jim,

  You can still find the Deep Space Network fiber-optic 
distribution equipment for sale on the Microsemi website:


https://www.microsemi.com/product-directory/modular-synchronization-systems/4168-time-code-translator

  I designed the hardware for NASA's DSN upgrade while at Timing 
Solutions Corp. I remember having to design and lay out 23 circuit 
boards within about 5 months when we got that contract. The Time 
Code Translator was the hardest to get right because it did so much.


 I never paid much attention to where it went because it was "on to 
the next project" as soon as it was completed. Still it's nice to 
see that it got deployed and (hopefully) worked.


Bob Martin


On 9/1/2018 8:25 AM, jimlux wrote:

On 9/1/18 7:00 AM, Scott McGrath wrote:
There was a paper published when NASA did something similar for 
LC39 and the VAB.    Anyone have a copy because the link i have is 
dead.


As I recall it was some trick and compensating for thermal effects 
on the fiber itself was a large part of the effort.





I don't know about at the Cape (I'm not sure what the *need* for 
precision timing at that level might be, but it could be there).


There's a whole lot of stuff that's been published about 
distributing frequency references and holding tight phase tolerances 
at the Deep Space Network stations, since they do arraying using 
multiple apertures, as well as run of the mill VLBI stuff.


https://deepspace.jpl.nasa.gov/dsndocs/810-005/304/304B.pdf is the 
"production" system for DSN, but as mentioned therein, there are 
various improved schemes in development.


You might search for publications by Bob Tjoelker.


  While there are JPL papers in IEEE sources behind paywalls, almost 
always, they're also available in NTRS (https://ntrs.nasa.gov/) or 
JPL's piece (https://trs.jpl.nasa.gov/). If the paper isn't online 
for free in that location, you can send an email to NASA (there's a 
form at ntrs.nasa.gov) or the JPL librarian (link at the trs site) 
and they'll send it to you.  Another good place to look for DSN 
related stuff is here:


https://ipnpr.jpl.nasa.gov/

The Chinese seem to have been publishing lots of papers on Arxiv 
recently about "joint time and frequency distribution"


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Re: [time-nuts] Lots of Off Topic discussion

[David G. McGaw]

I consider saving WWV/WWVH/WWVB to be ON topic.  They may not be as 
precise as some on this list like to achieve, but they are publicly 
available methods of time dissemination.  I am very concerned that 
factions of NIST consider that this should no longer be part of their 
mission.


David N1HAC


On 9/1/18 9:07 AM, David C. Partridge wrote:

Guys,

The noise level has risen rather high lately.  I really think that
discussions of jamming of GPS and other systems are not relevant.

The loss of WWVx is also mostly OT as I don't believe that anyone seriously
still uses it for a time/frequency reference these days.

Dave




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Re: [time-nuts] WWV and legal issues

[Scott McGrath]

There was a paper published when NASA did something similar for LC39 and the 
VAB.Anyone have a copy because the link i have is dead.

As I recall it was some trick and compensating for thermal effects on the fiber 
itself was a large part of the effort.



On Sep 1, 2018, at 5:29 AM, Magnus Danielson  wrote:

Hi,

It was very telling when I crashed a research group into the reality of
phase/time transfer over fiber compared to frequency transfer. Armed
with a whiteboard and pens, I derived the forumulas and showed how they
worked and not worked. It's a completely different ball-game and their
"known tricks" ain't doing nothing good as it comes to time.

I had to figure much of this out myself as I did nation-wide system
design to achieve the goal. It's a combination of many skills that goes
into designing the full system from scratch and make it fit together.
It's not hard stuff, it's just many details one needs to get right.

Oh the fun.

Cheers,
Magnus

> On 08/31/2018 05:15 PM, Bob kb8tq wrote:
> Hi
> 
> That works fine if you are doing things manual to check a local standard. If 
> you are trying to 
> disipline a few thousand cell towers 24 hours a day … not so much. It also 
> works for 
> checking frequency. What modern systems need is time. That gets you into a 
> whole 
> world of resolving and identifying individual edges. The WWVB signal really 
> was never
> set up for this. Loran-C is an example of a signal that was designed to 
> identify a specific
> edge.
> 
> Bob
> 
>> On Aug 31, 2018, at 10:30 AM, Martin VE3OAT  wrote:
>> 
>> But the diurnal phase shifts at VLF are predictable and largely repeatable.  
>> Ignore the phase at night and use only the phase records during the day when 
>> an all-daylight propagation path exists.  You might have to "correct" the 
>> absolute phase reading by some multiple of the RF period, but with a low 
>> rate of local standard oscillator drift, this is a simple matter of 
>> arithmetic. Back in the day, I managed Sulzer crystal oscillators at 5 field 
>> sites from my office and could maintain phase continuity for weeks at a 
>> time, until we had to diddle the dial on one or several of them to correct 
>> for crystal aging.  Then it was just more arithmetic again.  Several of the 
>> oscillators had such low drift rates that all I needed was one daily phase 
>> reading from the VLF phase tracking receiver (Tracor 599Js) at those sites 
>> to know the frequency of the Sulzers there.
>> 
>> ... Martin VE3OAT
>> 
>> On Thu, 30 Aug 2018 12:27:12 -0400
>> Bob kb8tq  wrote:
>> 
>>> WWVB as transmitted ( = right at the input to the antenna) is a wonderfully 
>>> stable signal. As soon as
>>> that signal hits the real world things start to degrade. Propagation 
>>> between transmit and receive sites
>>> is a big deal, even at 60 KHz. On top of that, there is a*lot*  of manmade 
>>> noise at 60 KHz. The receive
>>> signal to noise will never be as good as you might like it to be ?.
>> 
>>> I don't know about WWVB, but for DCF77 it's known that sunrise/sunset
>>> causes a phase shift of several 100?s at even moderate distances
>>> (like ~500km). Unfortunately I don't have any measurements at hand.
>>>Attila Kinali
>> 
>> 
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[time-nuts] Lots of Off Topic discussion

[David C. Partridge]

Guys,

The noise level has risen rather high lately.  I really think that
discussions of jamming of GPS and other systems are not relevant.

The loss of WWVx is also mostly OT as I don't believe that anyone seriously
still uses it for a time/frequency reference these days.

Dave




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Re: [time-nuts] NIST

[Bob kb8tq]

Hi

> On Sep 1, 2018, at 3:06 AM, Magnus Danielson  
> wrote:
> 
> 
> 
> On 08/31/2018 03:36 PM, Bob kb8tq wrote:
>> Hi
>> 
>> “Backbone timing” gets done by boxes buried deep in systems. Those systems 
>> take years
>> to design. The boxes that go in them similarly take years to get onto the 
>> market. Once designed
>> deployment is far from instantaneous. Operators are always pressed by cost 
>> constraints. Adding
>> anything beyond the minimums … not going to happen.
>> 
>> The result is that there are no systems out there that use WWVB or WWV other 
>> than wrist watches
>> and wall clock like devices. Utilities (cell phones, internet, finance ) run 
>> with something else. Converting
>> them to a secondary “something” is a many years sort of thing, even if it is 
>> technically feasible. 
>> 
>> You can pull a bunch of spare GPS sat’s out of storage and get them in orbit 
>> *way* quicker than you can 
>> rebuild every cell tower in the country. In fact, newer designs run their 
>> timing in a way that a GPS failure 
>> is not that big a deal. How long it’ll take before that sort of design is 
>> common in the US…. years and years …
>> 
>> If you are going to come up with a time source at the ~ 10 ns level, that’s 
>> not going to happen from WWVB
>> or WWV. They never were good enough to get to that level and it’s not on the 
>> transmit end. You would need
>> a very different system. It’s been a long time since any of these services 
>> (internet, finance, cell )  were in the 
>> millisecond or even the microsecond range. The modern stuff in all theses 
>> areas  is  < 100 ns. 
> 
> The actual requirements is usually on the 1-10 us level, but they are
> happy when they have the extra precision.

Well, they are and they aren’t. The newer systems (which rapidly become the 
only system) are at the one microsecond
level after being in holder for many hours ( days?). The assumption is that 
only one tower (or chunk) goes into holdover
at a time and the rest are still at least 10X better than that. Cut them all 
loose an the numbers would have to be tighter.

In order to get them all at the 100 ns level, you need a source that is around 
5 to 10X better than that. The timing source
is not the only source of error and you need to “train” your holdover clock 
with something that is mighty good. The
holdover spec often applies after a very short period of training (a day to 
several days). Indeed, if you put a Cs standard
in every cell tower and every internet node you probably could back off a bit 
on the 10X. With quartz or Rb, you need
the accuracy in training. 

Bob



> 
>> How long would it take to change all this? Well first some random Senior 
>> Member of the IEEE would 
>> have to start writing papers about the various issues. Various organizations 
>> in various countries would 
>> need to hold meeting after meeting after meeting talking things over. 
>> Somebody eventually would have
>> to come up with funds to actually try a few things. Maybe they work in the 
>> real world / maybe they don’t
>> work. 
>> 
>> Once you prove you have a system that can do “good enough", you would need 
>> laws / regulations passed to
>> make the “new thing” part of the required designs. You also need funding 
>> bills to deploy the “source” end 
>> of things and time to get that up and running. Once it’s running, you then 
>> give manufacturers some amount of time 
>> to get it in the field ….. and extensions when that doesn’t happen. Twenty 
>> years? Thirty years? Maybe longer? 
>> This stuff does not go very fast. 
> 
> It's been done for 10+ years now. Some 15+ countries have nation wide
> networks that makes them GPS independent for some applications.
> It has been a fun system to design and deploy.
> 
> Getting more precision isn't all that hard, it just takes more effort in
> the details and hence money and time. If people need 100 ns or 10 ns
> system time, it can be done.
> 
>> Best bet on what the “new thing” would be? Something like IEEE-1588 over 
>> fiber. It cuts out a bunch of this and 
>> that in terms of experiments and testing the basic system. We know most of 
>> *how* to do it already. It’s just a matter 
>> of a  billions of dollars in tax money to get the gaps filled in and then a 
>> few tens of billions in tax money to get
>> the backbone gear in place. Once that’s done you ramp up to the really 
>> expensive part of the deal ….Is it paid
>> for by your tax return in April or by a higher price on every cell call / 
>> transaction you make? … who knows … it’s 
>> a tax that you are paying either way. 
> 
> IEEE 1588 isn't working out at all for WAN, it's stuck in LAN
> environment, which is the dirty little secret of the industry. There is
> trials for dedicated wavelengths with using 1588 or it's extension White
> Rabbit that works great, but in any form of production environment it's
> a mess.
> 
> Network based precision timing takes a number of hurdles to handle. I've
> done my fair 

Re: [time-nuts] News

[Didier Juges]

Congratulations Magnus, a well deserved reward for your contributions. My
boss is a Senior Member and I know they do not just give those away.
Well done!

Didier

On Thu, Aug 30, 2018, 3:40 PM Magnus Danielson 
wrote:

> Hi Bob,
>
> On 08/30/2018 10:33 PM, Bob kb8tq wrote:
> > Hi
> >
> > Magnus … do you have some news you might want to share with the group?
>
> Oh, well, sure:
>
> Today I received a nice email from IEEE starting with:
> "It is a great pleasure to congratulate you on your elevation to the
> grade of IEEE Senior member. IEEE Senior Membership is an honor bestowed
> only to those who have made significant contributions to the profession."
>
> I'm humbled by these words, but proud of the achievement and happy for
> the distinction. This has been a process that has been going on since
> spring when IEEE approached me and pointed out that I should be able to
> become senior member, writing up a modern CV and then being interviewed
> by three Senior Members was interesting, sharing the room with very
> senior engineers, PhDs and professors all seeking to reach the IEEE
> Senior member elevation.
>
> Cheers,
> Magnus
>
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Re: [time-nuts] NIST

[Gerhard Hoffmann]

Am 31.08.2018 um 20:17 schrieb Hal Murray:

att...@kinali.ch said:

I have somewhere a paper (which i cannot find currently, sorry) that used a
dish trained at one of the EGNOS satellites and used it as the only source
for timing. IIRC the results were promising, but not spectacular. The problem
being that all the ionospheric and tropospheric ...

There is another problem in that area.  How accurately is the location of the
satellite known?  published?

Geo-sync satellites actually wander around their nominal positions.  How much
does that effect timing?  I've seen figure-8 pictures of the pattern, but I
don't remember any data on elevation changes.


Geo-stat sats usually do their navigation via their linear transponders,
the rest is in some ground stations, so the added cost for flight hardware
is essentially nil.

The operators know the position of their sats quite precisely since,
for a phone sat as an example, the ground station transmission timing
must be aligned quite carefully to avoid both overlapping and idle time
of the channel. They switch both between cities and to give the phone
user the illusion of a continuous 2 way connection without too much delay.

The absolute position is less important as long as it is known.

Small countries like Luxembourg have just one geostationary parking lot
but operate several sats. They may have a more pronounced need to
keep the positions precise.

Overly precise position shortens the lifetime of a sat since it eats up 
fuel.


The navigation is simply made by PN streams say > 20 dB below the
MPEG data.

I have made the PN generators,  bit / frame generators /synchronizers,
correlators, de/modulators for some of them.

I don't think that the exact position data is published. It is a closed
system, after all.

But a bunch of hams with enough criminal energy could probably
measure it for themselves. The down link is already there in every
household with a SAT TV.  Oh, no, I do not promote that!

best regards,
Gerhard




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Re: [time-nuts] WWV and legal issues

[Magnus Danielson]

Hi,

It was very telling when I crashed a research group into the reality of
phase/time transfer over fiber compared to frequency transfer. Armed
with a whiteboard and pens, I derived the forumulas and showed how they
worked and not worked. It's a completely different ball-game and their
"known tricks" ain't doing nothing good as it comes to time.

I had to figure much of this out myself as I did nation-wide system
design to achieve the goal. It's a combination of many skills that goes
into designing the full system from scratch and make it fit together.
It's not hard stuff, it's just many details one needs to get right.

Oh the fun.

Cheers,
Magnus

On 08/31/2018 05:15 PM, Bob kb8tq wrote:
> Hi
> 
> That works fine if you are doing things manual to check a local standard. If 
> you are trying to 
> disipline a few thousand cell towers 24 hours a day … not so much. It also 
> works for 
> checking frequency. What modern systems need is time. That gets you into a 
> whole 
> world of resolving and identifying individual edges. The WWVB signal really 
> was never
> set up for this. Loran-C is an example of a signal that was designed to 
> identify a specific
> edge.
> 
> Bob
> 
>> On Aug 31, 2018, at 10:30 AM, Martin VE3OAT  wrote:
>>
>> But the diurnal phase shifts at VLF are predictable and largely repeatable.  
>> Ignore the phase at night and use only the phase records during the day when 
>> an all-daylight propagation path exists.  You might have to "correct" the 
>> absolute phase reading by some multiple of the RF period, but with a low 
>> rate of local standard oscillator drift, this is a simple matter of 
>> arithmetic. Back in the day, I managed Sulzer crystal oscillators at 5 field 
>> sites from my office and could maintain phase continuity for weeks at a 
>> time, until we had to diddle the dial on one or several of them to correct 
>> for crystal aging.  Then it was just more arithmetic again.  Several of the 
>> oscillators had such low drift rates that all I needed was one daily phase 
>> reading from the VLF phase tracking receiver (Tracor 599Js) at those sites 
>> to know the frequency of the Sulzers there.
>>
>> ... Martin VE3OAT
>>
>> On Thu, 30 Aug 2018 12:27:12 -0400
>> Bob kb8tq  wrote:
>>
>>> WWVB as transmitted ( = right at the input to the antenna) is a wonderfully 
>>> stable signal. As soon as
>>> that signal hits the real world things start to degrade. Propagation 
>>> between transmit and receive sites
>>> is a big deal, even at 60 KHz. On top of that, there is a*lot*  of manmade 
>>> noise at 60 KHz. The receive
>>> signal to noise will never be as good as you might like it to be ?.
>>
>>> I don't know about WWVB, but for DCF77 it's known that sunrise/sunset
>>> causes a phase shift of several 100?s at even moderate distances
>>> (like ~500km). Unfortunately I don't have any measurements at hand.
>>> Attila Kinali
>>
>>
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>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>> and follow the instructions there.
> 
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Re: [time-nuts] Fwd: Re: law and regulation applying to time.. was Re: OOPS on my wwv legal post

[David J Taylor via time-nuts]

From: shouldbe q931
[]
On Fri, Aug 31, 2018 at 10:31 AM Dr. Götz Romahn  wrote:


For German regulations see here:
https://www.ptb.de/cms/en/ptb/fachabteilungen/abt4/fb-44/ag-442/dissemination-of-legal-time.html
Götz


CET is derived from UTC

https://www.ptb.de/cms/en/ptb/fachabteilungen/abt4/fb-44/ag-441/realisation-of-legal-time-in-germany.html
==

Which contains the interesting statement:

 "The Physikalisch-Technische Bundesanstalt PTB is entrusted by the Time 
Act to realise and disseminate legal time to the public. The most popular 
means is the transmission of standard frequency and time signals by the 
transmitter DCF77 (Working Group 4.42)."


DCF77 being the 77.5 kHz transmitter.

Cheers,
David
--
SatSignal Software - Quality software for you
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 



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Re: [time-nuts] NIST

[Magnus Danielson]

Hi Hal,

On 08/31/2018 08:17 PM, Hal Murray wrote:
> 
> att...@kinali.ch said:
>> I have somewhere a paper (which i cannot find currently, sorry) that used a
>> dish trained at one of the EGNOS satellites and used it as the only source
>> for timing. IIRC the results were promising, but not spectacular. The problem
>> being that all the ionospheric and tropospheric ...
> 
> There is another problem in that area.  How accurately is the location of the 
> satellite known?  published?
> 
> Geo-sync satellites actually wander around their nominal positions.  How much 
> does that effect timing?  I've seen figure-8 pictures of the pattern, but I 
> don't remember any data on elevation changes.

The figure of 8 is just one of the artifacts of the elliptic orbit, and
it does cause distance changes and hence affect timing. Correct
ephimeris data is needed for good compensation. We do that for GPS
satellites too, which is part of the systems capability that the
receiver can do these compensations unaided with anything but the
signals from space segment.

Cheers,
Magnus

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Re: [time-nuts] NIST

[Magnus Danielson]

On 08/31/2018 03:36 PM, Bob kb8tq wrote:
> Hi
> 
>  “Backbone timing” gets done by boxes buried deep in systems. Those systems 
> take years
> to design. The boxes that go in them similarly take years to get onto the 
> market. Once designed
> deployment is far from instantaneous. Operators are always pressed by cost 
> constraints. Adding
> anything beyond the minimums … not going to happen.
> 
> The result is that there are no systems out there that use WWVB or WWV other 
> than wrist watches
> and wall clock like devices. Utilities (cell phones, internet, finance ) run 
> with something else. Converting
> them to a secondary “something” is a many years sort of thing, even if it is 
> technically feasible. 
> 
> You can pull a bunch of spare GPS sat’s out of storage and get them in orbit 
> *way* quicker than you can 
> rebuild every cell tower in the country. In fact, newer designs run their 
> timing in a way that a GPS failure 
> is not that big a deal. How long it’ll take before that sort of design is 
> common in the US…. years and years …
> 
> If you are going to come up with a time source at the ~ 10 ns level, that’s 
> not going to happen from WWVB
> or WWV. They never were good enough to get to that level and it’s not on the 
> transmit end. You would need
> a very different system. It’s been a long time since any of these services 
> (internet, finance, cell )  were in the 
> millisecond or even the microsecond range. The modern stuff in all theses 
> areas  is  < 100 ns. 

The actual requirements is usually on the 1-10 us level, but they are
happy when they have the extra precision.

> How long would it take to change all this? Well first some random Senior 
> Member of the IEEE would 
> have to start writing papers about the various issues. Various organizations 
> in various countries would 
> need to hold meeting after meeting after meeting talking things over. 
> Somebody eventually would have
> to come up with funds to actually try a few things. Maybe they work in the 
> real world / maybe they don’t
> work. 
> 
> Once you prove you have a system that can do “good enough", you would need 
> laws / regulations passed to
> make the “new thing” part of the required designs. You also need funding 
> bills to deploy the “source” end 
> of things and time to get that up and running. Once it’s running, you then 
> give manufacturers some amount of time 
> to get it in the field ….. and extensions when that doesn’t happen. Twenty 
> years? Thirty years? Maybe longer? 
> This stuff does not go very fast. 

It's been done for 10+ years now. Some 15+ countries have nation wide
networks that makes them GPS independent for some applications.
It has been a fun system to design and deploy.

Getting more precision isn't all that hard, it just takes more effort in
the details and hence money and time. If people need 100 ns or 10 ns
system time, it can be done.

> Best bet on what the “new thing” would be? Something like IEEE-1588 over 
> fiber. It cuts out a bunch of this and 
> that in terms of experiments and testing the basic system. We know most of 
> *how* to do it already. It’s just a matter 
> of a  billions of dollars in tax money to get the gaps filled in and then a 
> few tens of billions in tax money to get
> the backbone gear in place. Once that’s done you ramp up to the really 
> expensive part of the deal ….Is it paid
> for by your tax return in April or by a higher price on every cell call / 
> transaction you make? … who knows … it’s 
> a tax that you are paying either way. 

IEEE 1588 isn't working out at all for WAN, it's stuck in LAN
environment, which is the dirty little secret of the industry. There is
trials for dedicated wavelengths with using 1588 or it's extension White
Rabbit that works great, but in any form of production environment it's
a mess.

Network based precision timing takes a number of hurdles to handle. I've
done my fair bit of them.

Cheers,
Magnus

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Re: [time-nuts] NIST

[Magnus Danielson]

Hi,

On 08/31/2018 12:18 AM, Poul-Henning Kamp wrote:
> 
> In message <96e995c4-5ca2-af02-9738-0a6d87a9f...@pacific.net>, Brooke Clarke 
> writes:
> 
>> But it's extremely hard to make a jammer for WWVB (60 kHz) [...]
> 
> You can do it city-scale with a 18-wheeler sized loop-antenna
> and a good size diesel-generator.
> 
> However pedestrians will very likely note metalic items vibrating
> as they pass the "mystery white truck".
> 
> Sweden were much more serious about it:
> 
>   http://www.antus.org/RT02.html
> 
> Tl;drs:
> 
> They erected 9 200m tall Loran-C class antennas each driven by
> a Loran-C transmitter with an advanced degree which could jam
> Loran-C or Chayka.
> 
> They even mounted decoy parabolas on the towers them to hide their
> true purpose.
> 
> The fact that all the transmitters were on the east coast does drop
> a hint that swedens much touted neutrality had a bit of a slant.
> 

The "On" switch of the network where in the air defenece bunker. It was
only marked with "På" (Swedish for On) with no further markings. It was
designed for when the soviet bombers comes, at least they should loose
their Chayka guidance.

I knew one of the folks that where boss over the system, was to his
funeral recently. He also worked hard to get the classified material and
make a public report out of it. Time to refresh your swedish, as I doubt
any translations exist in public.

Cheers,
Magnus

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Re: [time-nuts] NIST

[Magnus Danielson]

On 08/30/2018 11:20 PM, Brooke Clarke wrote:
> Hi Bob:
> 
> I would disagree in that ease of jamming/spoofing is strongly related to
> wavelength.  That's because antenna efficiency goes down as the size of
> the antenna gets smaller than 1/4 wave.
> So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4
> wavelength is a few inches, something that  you can hold in your hand.
> It's harder to make a WWV jammer (.5, 5, 10, 15, 20 MHz) since a 1/4
> wavelength in in the range of  500 to 12 feet, something that can be
> mounted on a vehicle for the higher frequencies.
> But it's extremely hard to make a jammer for WWVB (60 kHz) where a
> 1/4wavelength is over 4,000 feet.  This means an antenna that can be
> vehicle mounted will be very inefficient. Note this also means that it's
> extremely hard to make a Loran-C jammer.  Note that the WWVB and LORAN-C
> transmitters run very high power and the antennas are massive.

Locally you can transmit with a much smaller antenna. It's been shown
and works.

Sweden used to have a network of 212 m towers to jam and spoof
Loran-C/Chayka. It was a top secret network.

> This also means that if someone makes a WWVB simulator for their house
> the signal at the next door neighbor's house is probably going to be too
> small to effect their clocks.

Magnetic loop works, non-resonant suffice. Magnetic lopp is used for
hearing aid, and it doesn't take much. Enough for the house. Not getting
you very far though.

> PS. Some decades ago I maintained a beacon transmitter "LAH" on 175 kHz
> where the rules for unlicensed operation limited the input power to 1
> Watt and total antenna length to 50 feet.  Under these conditions the
> effective radiated power might be 2 milliwatts, orders of magnitude less
> if a portable system.
> http://www.auroralchorus.com/pli/1750meter_antennas.pdf
> 

The 137 kHz band for radio amateurs is limited, but with radiated power,
and getting up to that power is a great success and considering the band
and that one use CW it should be fun.

Cheers,
Magnus

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