Re: [time-nuts] WWVB format change in 2012

[paul swed]

As Tom mentioned I am familiar with the chips. But the bottom line is there
are no chips either old style or new around anymore from what I have seen.
If you can find the consumer atomic clocks that are pretty rare these days
you can get the AM clock receiver from those. The new chips (Literally the
die, not even an soic) was supposed to show up in clocks around the new
year. They never did or at least its totally not apparent. The intent was
not for consumer but embedded in things like stop lights.
But this thread shifted from the original request I believe for something
that could be used in Singapore.
Regards
Paul
WB8TSL

On Tue, Mar 1, 2016 at 7:39 AM, Bob Camp  wrote:

> Hi
>
> > On Mar 1, 2016, at 2:44 AM, Sanjeev Gupta  wrote:
> >
> > On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta  wrote:
> >
> >> Are there commercially (or widely-used) receivers for professional use
> >> which listen to the WWVB signal?
> >
> >
> > Folks, I am trying to trace down xtendwave.  They seem to have released a
> > Everset IC, and then renamed themselves to Everset in 2013 or 2014.
> >
> > Is there *any* commercial gear available for WWVB at all, today?  Price
> is
> > not an issue, just a public product page will do.
>
> GPS has become so cheap and it’s so accurate under normal conditions that
> you rarely see anything else considered for this stuff. That’s not to say
> that a
> monoculture is a good idea (it isn’t).
>
> Bob
>
>
> >
> >
> > --
> > Sanjeev Gupta
> > +65 98551208 http://www.linkedin.com/in/ghane
> > ___
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Re: [time-nuts] WWVB format change in 2012

[Bob Camp]

Hi

> On Mar 1, 2016, at 2:44 AM, Sanjeev Gupta  wrote:
> 
> On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta  wrote:
> 
>> Are there commercially (or widely-used) receivers for professional use
>> which listen to the WWVB signal?
> 
> 
> Folks, I am trying to trace down xtendwave.  They seem to have released a
> Everset IC, and then renamed themselves to Everset in 2013 or 2014.
> 
> Is there *any* commercial gear available for WWVB at all, today?  Price is
> not an issue, just a public product page will do.

GPS has become so cheap and it’s so accurate under normal conditions that
you rarely see anything else considered for this stuff. That’s not to say that a
monoculture is a good idea (it isn’t). 

Bob


> 
> 
> -- 
> Sanjeev Gupta
> +65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] WWVB format change in 2012

[Hal Murray]

gha...@gmail.com said:
> Is there *any* commercial gear available for WWVB at all, today?  Price is
> not an issue, just a public product page will do. 

I don't know of any gear that is currently available in the US.

A few years ago, you used to be able to get a small board and ferrite 
antenna.  I think it was under $20.  I just poked around and they are no 
longer available.
  https://www.sparkfun.com/products/retired/10060
They have a link to the data sheet if you are curious.  It's an old chip that 
only decodes the AM part of the signal so it doesn't get the advantages of 
the new modulation.

This might be a lead if you are in the UK:
  http://www.tuxcat.com/benjy/ham/WWVB/

If you are desperate, consider buying a battery powered clock and taking it 
apart to find the antenna and WWVB chip.  The chip will probably be under a 
blob of epoxy.  You will have to hack the board.  ...

-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] WWVB format change in 2012

[Tom Van Baak]

Sanjeev Gupta wrote:
> Folks, I am trying to trace down xtendwave.  They seem to have released a
> Everset IC, and then renamed themselves to Everset in 2013 or 2014.

Contact Paul Swed or me off-list about this.

> Is there *any* commercial gear available for WWVB at all, today?  Price is
> not an issue, just a public product page will do.

Time by radio -- WWVB (and DCF-77, MSF, JJY) -- is still in use. But most of 
the high-end commercial timing companies have long since switched to GPS. Now 
that most everyone on the planet has a mobile phone or WiFi or internet, the 
need for 1-bit-per-second time over LF or SW radio is not as great as it was 20 
years ago.

But you asked for product pages. Try these:

https://www.meinbergglobal.com/english/products/usb-wwvb-clock.htm

https://www.lacrossetechnology.com/clocks/atomic-digital/wall/
https://www.lacrossetechnology.com/clocks/atomic-analog/

http://www.casio.com/products/Watches/wave_ceptor/

http://www.jp-watch.com/product/44

http://www.ebay.com/itm/181283274562

/tvb
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Re: [time-nuts] WWVB format change in 2012

[Majdi S. Abbas]

On Tue, Mar 01, 2016 at 03:44:01PM +0800, Sanjeev Gupta wrote:
> Folks, I am trying to trace down xtendwave.  They seem to have released a
> Everset IC, and then renamed themselves to Everset in 2013 or 2014.

It's not an IC, exactly, it's a bare product intended for 
integration into something else.

> Is there *any* commercial gear available for WWVB at all, today?  Price is
> not an issue, just a public product page will do.

There's plenty of older gear out there that did not phase lock,
and works just fine.  Existing chipsets and receivers work fine for 
those.  Even phase locking receivers can be modified.

They changed the simple carrier to a phase keyed one, but they
did not change the amplitude coding.

I know Meinberg had WWVB modules available for some of their
products, you might see what they are up to.

--msa
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Re: [time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta  wrote:

> Are there commercially (or widely-used) receivers for professional use
> which listen to the WWVB signal?


Folks, I am trying to trace down xtendwave.  They seem to have released a
Everset IC, and then renamed themselves to Everset in 2013 or 2014.

Is there *any* commercial gear available for WWVB at all, today?  Price is
not an issue, just a public product page will do.


-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] WWVB format change in 2012

[jimlux]

On 2/29/16 5:31 AM, Tim Shoppa wrote:

I have observed always less than 1 millisecond offset and skew with the
ntpd wwv audio refclock over more than the past decade.

Setting up the audio refclocks involves calculating and configuring
propagation delay and delays in the receiver and audio chain. As Sanjeev
has mentioned, setting up audio drivers for lowlatency by platform specific
ioctl's is necessary and that may imply code portability issue.

While propagation delay over a several thousand mile path is circa 10ms,
the ionospheric changes are way less than a percent of that. I don't think
it was you Hal, but someone else here was implying uncertainties in
propagation delay on the hundreds of milliseconds, and that is off by 3
orders of magnitude.

(Yes I have heard and observed long path, as well as ionospheric changes in
short path)




the entire transit time around the earth is 150 milliseconds, so you're 
right "hundreds of milliseconds" must be a typo: "hundreds of 
microseconds" sounds believable.




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Re: [time-nuts] WWVB format change in 2012

[Paul]

On Mon, Feb 29, 2016 at 6:35 AM, Hal Murray  wrote:

> The audio stuff seems particularly ugly.
>
> Are there any good non-GPS options these days?  In this context, "good" is
> a
> bit hard to pin down.  My straw man is either something in production or
> something like a TBolt or Z38xx that is available surplus at hobbyist
> prices.
>

On Mon, Feb 29, 2016 at 6:39 AM, Hal Murray  wrote:
tic-...@bodosom.net said:
>> If you can get audio they work.  The documented accuracy for WWV is
within 1
>> millisecond of the time pulse.

>Where is that documented and/or can anybody verify that they get results in
>that range?

First off this is a bit time-nuts relevant because RF timing propagation is
germane but the basic pulse extraction is low accuracy and hence not so
much time-nut relevant.  That also informs the forest for the trees issue
here: the original intent (as in Dr. Mills PDP-11 assembler coded
demodulator) is a periodic (i.e. daily) clock update.  So despite the
predicted 1ms accuracy a .1s system error was probably considered
acceptable.  The WWV refclock shares this operational sense with the ACTS
driver.  You phone home maybe once a day and, in the case of the ACTS
driver, NTPD won't use it unless you're orphaned.

Regarding non-GPS.  Do you consider a CDMA receiver non-GPS?  How about a
disciplined oscillator in hold-over?  In consideration of the recent GPS
glitch is GLONASS non-GPS or are you speaking more broadly (ie. GPS as a
synonym for GNSS).

And lastly despite the politics it would seem the folks on the
ntp-questions and ntp-hackers are a better resource.  Unless they're all
here.
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Re: [time-nuts] WWVB format change in 2012

[jimlux]

On 2/29/16 3:39 AM, Hal Murray wrote:


tic-...@bodosom.net said:

If you can get audio they work.  The documented accuracy for WWV is within 1
millisecond of the time pulse.


Where is that documented and/or can anybody verify that they get results in
that range?

What is the (ballpark) of the day/night shift?



http://www.cliftonlaboratories.com/wwv_short_term_jitter.htm
 has a number of off the air measurements, and a reference to a  1959 
HP journal article about the timing uncertainty


http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1959-11.pdf

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Re: [time-nuts] WWVB format change in 2012

[jimlux]

On 2/29/16 3:39 AM, Hal Murray wrote:


tic-...@bodosom.net said:

If you can get audio they work.  The documented accuracy for WWV is within 1
millisecond of the time pulse.


Where is that documented and/or can anybody verify that they get results in
that range?

What is the (ballpark) of the day/night shift?


https://www.febo.com/pages/hf_stability/ shows the "about 1 Hz" 
variation one sees in various places.


That's the apparent variation in frequency which is really the phase 
shift changing during sunrise/sunset.


Looking at the 10 MHz data, it looks like there's a 0.1 Hz change 
lasting about 2 hours.  I think that's a change of 720 cycles, or 72 
microseconds at 10 MHz.

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Re: [time-nuts] WWVB format change in 2012

[Tim Shoppa]

I have observed always less than 1 millisecond offset and skew with the
ntpd wwv audio refclock over more than the past decade.

Setting up the audio refclocks involves calculating and configuring
propagation delay and delays in the receiver and audio chain. As Sanjeev
has mentioned, setting up audio drivers for lowlatency by platform specific
ioctl's is necessary and that may imply code portability issue.

While propagation delay over a several thousand mile path is circa 10ms,
the ionospheric changes are way less than a percent of that. I don't think
it was you Hal, but someone else here was implying uncertainties in
propagation delay on the hundreds of milliseconds, and that is off by 3
orders of magnitude.

(Yes I have heard and observed long path, as well as ionospheric changes in
short path)


Tim N3QE


On Monday, February 29, 2016, Hal Murray  wrote:

>
> tic-...@bodosom.net  said:
> > If you can get audio they work.  The documented accuracy for WWV is
> within 1
> > millisecond of the time pulse.
>
> Where is that documented and/or can anybody verify that they get results in
> that range?
>
> What is the (ballpark) of the day/night shift?
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] WWVB format change in 2012

[Martin Burnicki]

Bob Camp wrote:
> Hi
> 
> WWVB and WWV (like any radio uncorrected radio system) has fairly predictable 
> shifts
> associated with the day / night ionosphere. One *could* fix that issue with a 
> table
> based on station location. I do not know of any library of code that does 
> that already. 
> 
> The next “layer” of trouble comes from how the low cost receivers are 
> implemented. The
> common issue is local noise. The common solution is a narrowband crystal 
> filter in front
> of the receiver. The bandwidth of that filter (and to some extent it’s 
> temperature dependance) place
> a “best case” limit on performance in the 10’s to 100’s of ms range depending 
> on the 
> exact details. There are higher performance receivers (but not a lot of them) 
> that do get into
> the single digit ms range. At that point the propagation issue mentioned 
> above needs some
> work. 
> 
> Further complicating things is the distance factor. A user in Denver with 
> ground wave “view” 
> of the transmitter will do *much* better than the numbers above. A user in 
> Miami or Bangor ME 
> may be very lucky to get close to the numbers above on an intermittent basis. 

I'm basically familiar with the ground wave / sky wave problem. Quite
some time ago I had found a PDF on the 'net with some explanations,
measurements, and a U.S. map showing e.g. which regions were mostly
affected by temporary cancellation due to interference of the sky and
groundwave with the same amplitude.

If I remember correctly this was an old publication from NIST or so.
Eventually it's hard to find by search machines since it wasn't a
generated PDF with text, but just a scan of an old printed article.

Unfortunately I hadn't saved a copy, and now I'm unable to find it.
Anybody has a hint what this could have been?


Thanks,

Martin

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Re: [time-nuts] WWVB format change in 2012

[Hal Murray]

m...@latt.net said:
>   What are you trying to do?  Kill the refclocks entirely, or just pare 
> them
> down to essentials? 

The idea is to drop the ones that aren't being used and/or we can't test.  If 
we dropped one in error, we can recover it.

The audio stuff seems particularly ugly.  I don't know if that's just because 
I/we don't understand that area and/or if POSIX didn't get it right and/or if 
OSes don't implement POSIX audio.


Are there any good non-GPS options these days?  In this context, "good" is a 
bit hard to pin down.  My straw man is either something in production or 
something like a TBolt or Z38xx that is available surplus at hobbyist prices.


A reasonable candidate for a low cost WWV receiver would be one of the USB 
receiver modules.  I think they are targeted at TV but they cover a wide 
input frequency range.  I think the SDR projects are using them.  If anybody 
has experience with them in a non-Windows environment please poke me off 
list.  A friend gave me one, but I got distracted before I got it working.


-- 
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Re: [time-nuts] WWVB format change in 2012

[Hal Murray]

tic-...@bodosom.net said:
> If you can get audio they work.  The documented accuracy for WWV is within 1
> millisecond of the time pulse. 

Where is that documented and/or can anybody verify that they get results in 
that range?

What is the (ballpark) of the day/night shift?


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta  wrote:

> I am reviewing and expanding and for the NTPSec project <
> http://www.ntpsec.org >, a fork of NTP.
>

Apologies, this should have been:

I am reviewing and expanding and documentation for the NTPSec project <
http://www.ntpsec.org >, a fork of NTP.

-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] WWVB format change in 2012

[Bob Camp]

Hi

WWVB and WWV (like any radio uncorrected radio system) has fairly predictable 
shifts
associated with the day / night ionosphere. One *could* fix that issue with a 
table
based on station location. I do not know of any library of code that does that 
already. 

The next “layer” of trouble comes from how the low cost receivers are 
implemented. The
common issue is local noise. The common solution is a narrowband crystal filter 
in front
of the receiver. The bandwidth of that filter (and to some extent it’s 
temperature dependance) place
a “best case” limit on performance in the 10’s to 100’s of ms range depending 
on the 
exact details. There are higher performance receivers (but not a lot of them) 
that do get into
the single digit ms range. At that point the propagation issue mentioned above 
needs some
work. 

Further complicating things is the distance factor. A user in Denver with 
ground wave “view” 
of the transmitter will do *much* better than the numbers above. A user in 
Miami or Bangor ME 
may be very lucky to get close to the numbers above on an intermittent basis. 

For time transfer, you have “carrier phase ambiguity” due to the day night 
propagation shifts. Simply
put the time delay to the transmitter caused the received signal to vary by 
more than one cycle. That 
makes it a less than ideal source of time. For precision use, a WWVB system 
often does a 
carrier measure at a single time per day. The phase data is averaged over may 
days to make
a precision estimate. This works ok for a frequency based (think GPSDO) type 
system). For autonomous 
timing it’s not a practical solution. 

Bob


> On Feb 28, 2016, at 11:15 AM, Sanjeev Gupta  wrote:
> 
> On Sun, Feb 28, 2016 at 10:57 PM, Bob Camp  wrote:
> 
>> The new WWVB format is troublesome for older gear that looks at carrier
>> phase as a source of precision timing. The NTP driver does not do this.
>> 
>> The new WWVB format is fine for any gear that recovers time from the
>> AM modulation on the carrier. This is what the NTP driver *does* do.
>> 
> 
> This is a very clear phrasing, thanks.
> 
> My understanding is that existing commercially-available equipment that
> recovers time from the AM carrier provides an accuracy on the order of a
> milli-second.  Anything better required tracking phase.
> 
> So, what would the (NTP with current WWVB equipment) accuracy and jitter be?
> 
> I appreciate that we seem to be moving towards a GPS-monoculture, but how
> close is the (NTP with WWVB AM) to the 50 microseconds number?
> 
> -- 
> Sanjeev Gupta
> +65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] WWVB format change in 2012

[Paul]

On Sun, Feb 28, 2016 at 2:09 AM, Sanjeev Gupta  wrote:

>
> Among NTPSec's goals are a smaller, auditable, code-base; hence support for
> receivers last available in the early-1990s is being removed.
>

I'm a bit confused by your question and the responses.

There are (I believe) three audio drivers supporting WWV, CHU and IRIG.
These drivers are receiver agnostic.  If you can get audio they work.  The
documented accuracy for WWV is within 1 millisecond of the time pulse.

There are multiple drivers supporting WWV/CHU/DCF.  These are for specific
families of RF receivers which produce a digital stream of some sort (e.g.
ISA bus communication).

Presumably the latter are what you're looking at as obsolete (e.g.
Truetime, Traconix, Chronolog, Ultralink etc. [and my apologies if any of
these are not obsolete]).

Perhaps you could clarify your intent.
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Re: [time-nuts] WWVB format change in 2012

[jimlux]

On 2/28/16 7:07 AM, Sanjeev Gupta wrote:

On Sun, Feb 28, 2016 at 9:45 PM, Tim Shoppa  wrote:


Support for WWV in ntpd using the wwv_audio refclock is very good and
delivers jitters substantially less than a millisecond. I have been using
this for over a decade.



Thank you.  In particular, WWV, as compared to WWVB.


What you're looking at (unless you're very close to WWV or WWVH) is the 
uncertainty in the skywave path through the ionosphere.





Is there an on-web reference that I can document, so that the NTPSec
developers can decide on if and how to support WWV.



A reference to what WWV radiates as a signal?
http://www.nist.gov/pml/div688/grp40/wwv.cfm

http://tf.nist.gov/general/pdf/1383.pdf



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Re: [time-nuts] WWVB format change in 2012

[James Flynn]

Sanjeev Gupta  writes:


> that as a result of the change, precision equipment may not be able to
> recover a usable signal from the new modulation scheme, rendering it
> useless for the sub-100 microsec disciplining.

In fact, the new scheme may actually help with accurate ON-TIME 
determination.  Currently, I have a proof-of-concept research system 
running that routinely keeps time to well within the rather broad 100 uS 
range when compared to GPS. This system does not yet use the phase 
information, but uses other techniques to extract the ON-TIME information 
from the signal (which still has to be corrected for propagation delays.) 
Future work will include using the phase information and I am confident 
this will only improve the results.

> A supplementary question: If you have your own homebrew for these 
signals,
> do you use them as a refclock for NTP?

While the proof-of-concept system is not being used for a refclock for 
NTP, it is able to keep time as described above and FREQUENCY to the under 
1 E-10 range. I am still working to improve that and hope to verify it in 
a way directly traceable to NIST.

James Flynn
California State University Northridge




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Re: [time-nuts] WWVB format change in 2012

[Majdi S. Abbas]

On Sun, Feb 28, 2016 at 03:09:32PM +0800, Sanjeev Gupta wrote:
> I am reviewing and expanding and for the NTPSec project <
> http://www.ntpsec.org >, a fork of NTP.
> 
> Among NTPSec's goals are a smaller, auditable, code-base; hence support for
> receivers last available in the early-1990s is being removed.

I'm not sure I would make that assumption.  Given recent attacks
on NTP (that will ultimately require a new protocol to fix), the ability 
of more upstream references is better than fewer.

Stripping things out that would provide more sources of trusted
time appears to be at odds with making NTP "more secure."

> I have been on this list for some years (thank you), but as I am in
> Singapore, I did not pay attention to the WWVB format change.  I understand
> that as a result of the change, precision equipment may not be able to
> recover a usable signal from the new modulation scheme, rendering it
> useless for the sub-100 microsec disciplining.

So the common, cheaper receivers that just looked at the AM 
envelope are unaffected.  Higher grade, phase tracking receivers were
affected, but can be modified to restore the carrier, and thus are
still operable.

> However, I am not clear if WWV and WWVH are still usable by commercially
> available equipment, or of such equipment is also obsolete now.

WWV and WWVH have worked pretty much the same way they do now
for decades; I have running WWV and WWVH refclocks, even the TrueTime
TL_3 (in REFCLOCK_TRUE.)

Where this gets sticky is there is support for older receivers
(say, OMEGA and the like), in the same refclocks (continuing to use
TRUE as an example here.)

So, you could safely remove the bits pertaining to OMEGA, but
I'd retain the WWV, WWVB, TCU, and XL-DC support.)  Since the XL-DC
is a GPS, I suppose you could implement support for it in gpsd.

Other, older refclocks are in a similar state, where one
vendor used more or less the same serial protocol regardless of 
what the actual reference was.

What are you trying to do?  Kill the refclocks entirely, or
just pare them down to essentials?

Cheers,

--msa 
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Re: [time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

On Sun, Feb 28, 2016 at 10:57 PM, Bob Camp  wrote:

> The new WWVB format is troublesome for older gear that looks at carrier
> phase as a source of precision timing. The NTP driver does not do this.
>
> The new WWVB format is fine for any gear that recovers time from the
> AM modulation on the carrier. This is what the NTP driver *does* do.
>

This is a very clear phrasing, thanks.

My understanding is that existing commercially-available equipment that
recovers time from the AM carrier provides an accuracy on the order of a
milli-second.  Anything better required tracking phase.

So, what would the (NTP with current WWVB equipment) accuracy and jitter be?

I appreciate that we seem to be moving towards a GPS-monoculture, but how
close is the (NTP with WWVB AM) to the 50 microseconds number?

-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

On Sun, Feb 28, 2016 at 9:45 PM, Tim Shoppa  wrote:

> Support for WWV in ntpd using the wwv_audio refclock is very good and
> delivers jitters substantially less than a millisecond. I have been using
> this for over a decade.
>

Thank you.  In particular, WWV, as compared to WWVB.

Is there an on-web reference that I can document, so that the NTPSec
developers can decide on if and how to support WWV.

-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] WWVB format change in 2012

[Bob Camp]

Hi


Ok, I think we have a bit of a terminology issue here. 

The new WWVB format is troublesome for older gear that looks at carrier 
phase as a source of precision timing. The NTP driver does not do this.

The new WWVB format is fine for any gear that recovers time from the 
AM modulation on the carrier. This is what the NTP driver *does* do. 

Simply put - WWVB and NTP work just as well today as they did 20 years
ago. 

As a “future project”, adding a driver to NTP to work with the bitstream from 
the new phase modulation would be a nice thing. At the moment the number
of receivers capable of handling this modulation is pretty small. I would 
wait until there is at least one commercial product on the market before
a driver is written.

Bob

> On Feb 28, 2016, at 2:09 AM, Sanjeev Gupta  wrote:
> 
> Hi,
> 
> I am reviewing and expanding and for the NTPSec project <
> http://www.ntpsec.org >, a fork of NTP.
> 
> Among NTPSec's goals are a smaller, auditable, code-base; hence support for
> receivers last available in the early-1990s is being removed.
> 
> I have been on this list for some years (thank you), but as I am in
> Singapore, I did not pay attention to the WWVB format change.  I understand
> that as a result of the change, precision equipment may not be able to
> recover a usable signal from the new modulation scheme, rendering it
> useless for the sub-100 microsec disciplining.
> 
> However, I am not clear if WWV and WWVH are still usable by commercially
> available equipment, or of such equipment is also obsolete now.
> 
> I have read Wikipedia, the NIST pages, etc, and am still confused.  Could
> someone summarise current state:
> 
> 
>   1. Are there commercially (or widely-used) receivers for professional
>   use which listen to the WWVB signal?
>   2. Are there commercially (or widely-used) receivers for professional
>   use which listen to the WWV(H) signal?
> 
> A supplementary question: If you have your own homebrew for these signals,
> do you use them as a refclock for NTP?
> 
> Thank you
> 
> 
> -- 
> Sanjeev Gupta
> +65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] WWVB format change in 2012

[Tim Shoppa]

Having a diversity of refclocks is important for any real NTP
implementation. There is a strong tendency towards a GPS monoculture and
the implementers must work against it.

Support for WWV in ntpd using the wwv_audio refclock is very good and
delivers jitters substantially less than a millisecond. I have been using
this for over a decade.

ntpd also supports CHU.

Here is a recent article showing how to use the BPSK format of WWVB:
http://www.arrl.org/files/file/QEX_Next_Issue/2015/Nov-Dec_2015/Magliacane.pdf

Tim N3QE

On Sun, Feb 28, 2016 at 2:09 AM, Sanjeev Gupta  wrote:

> Hi,
>
> I am reviewing and expanding and for the NTPSec project <
> http://www.ntpsec.org >, a fork of NTP.
>
> Among NTPSec's goals are a smaller, auditable, code-base; hence support for
> receivers last available in the early-1990s is being removed.
>
> I have been on this list for some years (thank you), but as I am in
> Singapore, I did not pay attention to the WWVB format change.  I understand
> that as a result of the change, precision equipment may not be able to
> recover a usable signal from the new modulation scheme, rendering it
> useless for the sub-100 microsec disciplining.
>
> However, I am not clear if WWV and WWVH are still usable by commercially
> available equipment, or of such equipment is also obsolete now.
>
> I have read Wikipedia, the NIST pages, etc, and am still confused.  Could
> someone summarise current state:
>
>
>1. Are there commercially (or widely-used) receivers for professional
>use which listen to the WWVB signal?
>2. Are there commercially (or widely-used) receivers for professional
>use which listen to the WWV(H) signal?
>
> A supplementary question: If you have your own homebrew for these signals,
> do you use them as a refclock for NTP?
>
> Thank you
>
>
> --
> Sanjeev Gupta
> +65 98551208 http://www.linkedin.com/in/ghane
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> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
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[time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

Hi,

I am reviewing and expanding and for the NTPSec project <
http://www.ntpsec.org >, a fork of NTP.

Among NTPSec's goals are a smaller, auditable, code-base; hence support for
receivers last available in the early-1990s is being removed.

I have been on this list for some years (thank you), but as I am in
Singapore, I did not pay attention to the WWVB format change.  I understand
that as a result of the change, precision equipment may not be able to
recover a usable signal from the new modulation scheme, rendering it
useless for the sub-100 microsec disciplining.

However, I am not clear if WWV and WWVH are still usable by commercially
available equipment, or of such equipment is also obsolete now.

I have read Wikipedia, the NIST pages, etc, and am still confused.  Could
someone summarise current state:


   1. Are there commercially (or widely-used) receivers for professional
   use which listen to the WWVB signal?
   2. Are there commercially (or widely-used) receivers for professional
   use which listen to the WWV(H) signal?

A supplementary question: If you have your own homebrew for these signals,
do you use them as a refclock for NTP?

Thank you


-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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