Re: [time-nuts] TV Signals as a frequency reference

[Ruslan Nabioullin]

On Sat, Mar 31, 2018 at 9:38 AM, Bob kb8tq <kb...@n1k.org> wrote:
> You probably would do better to build a gizmo to pull timing off you local 
> cell towers.
> The hardware to do it is relatively well documented. As long as you are 
> careful about
> which system you use, the timing should be GPS based ….

Commercially-made cellular reference receivers obviously do exist (IT
folks tend to love them due to there being no need for outdoor antenna
requirements).

-Ruslan

-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] Introduction, new list member, Ms Tisha Hayes, AA4HA

[Ruslan Nabioullin]

On Wed, Mar 28, 2018 at 9:49 PM, Tisha Hayes <tisha.ha...@gmail.com> wrote:

> Perry and I would make our pilgrimages to the Huntsville Ham Fest and
> usually I ended up buying equipment from him. One of the items he sent my
> way was an HP 3586B that I am finally beginning to put to use.
>

Hmm that measuring receiver model (diffs can be found in:
http://www.militaryradio.com/manuals/HP/hp3586-a-b-c.pdf ) was apparently
intended for testing and troubleshooting purposes for those ancient
FDM-based POTS trunk systems, not as a general-purpose HF measuring
receiver (the HP 3586C)---I'm not sure how well they would function as HF
receivers for WWV and CHU following impedance adaptation (b/c it doesn't
have a 50 ohm unbalanced interface).

In my case, I supply my time transfer volunteers with the following setup:

vertical antenna -> TVSS -> preamplifier -> military rackmount preselector
-> military/intelligence rackmount parametric demodulator or HP 3586C ->
Xeon NTP server via soundcard

with GNU/Linux daemon software which commands the preselector and
demodulator via GPIB.

Still, WWV/CHU-derived public NTP nodes are virtually nonexistent, and
therefore there's a strong need for them, regardless of the sophistication
of the receiver, due to the pitfalls of GNSS.

-Ruslan

-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] WWVB Antenna revisited/Spectracom 8182

[Ruslan Nabioullin]

On Thu, Mar 22, 2018 at 6:25 AM, D. Resor <organli...@pacbell.net> wrote:

> I've been reading and researching what I will need to connect a Spectracom
> 8182 Netclock/2 for use here at home as a WWV(B) clock.
>

from Spectracom's official website:

``
8182 NetClock/2
WWVB referenced master clock. Will no longer operate as intended due to the
changes in the WWVB signal in 2012. Successor product is the SecureSync
time and frequency reference system [not true, at least in our enlightened
context---the SecureSync system is merely GNSS; the only terrestrial signal
that it's capable of is eLoran, but even that requires a separate receiver
unit].
''

The best approach would be to set up at least one HF AM receiver tuned to
WWV or CHU (preferably using a jamming-resistant antenna configuration),
connecting it to your NTP server, the daemon of which would use the NTP
WWV/CHU decoder modules.

-Ruslan

-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

[Ruslan Nabioullin]

On Thu, Feb 22, 2018 at 5:48 PM, djl <d...@montana.com> wrote:
> Fine. The Chinese have no concept of, or ignore, intellectual property
> rights.

Which is not necessarily perverse---there exist people (most notably
those of the so-called Pirate Party movements worldwide) who deem the
legal theories of the copyright and the patent to be absurd.  That is
all that I will say, for I do not wish to excessively deviate from the
topic of discourse.

-Ruslan

-- 
Ruslan Nabioullin
Wittgenstein Laboratories
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(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] Receiving the MSF time signal on cheap radio modules

[Ruslan Nabioullin]

On Tue, Feb 6, 2018 at 2:37 PM, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote:
> If you look in http://phk.freebsd.dk/phkrel/NTPns.20080902.tgz
> you will find a file called dcf77_blame.c with my code,
> here is a couple of the simpler tests:
>
> /* LSB of minutes must be different from previous minute */
> j = ip->shiftprev[(offset + 21) % 60];
> if (j * ip->shiftreg[(offset + 21) % 60] > 0)
> FAIL((why, " 0"));
>
> /*
>  * If the LSB of minutes was '1' in previous minute
>  * the next higher bit must have changed, if it was
>  * a '0' it must not.
>  */
> if (j *
> ip->shiftreg[(offset + 22) % 60] *
> ip->shiftprev[(offset + 22) % 60] > 0)
> FAIL((why, " 1"));
> ...
> I did a parallel prototype for MSF, but I didn't need it
> so I never completed it, not sure I have it around any
> more.
>
> I should really write an article about that code...

How difficult would it be to complete these modules and integrate them
with the rest of NTP, as NTP decoder modules?  So instead of an AM HF
receiver, the setup for these signals would be:

LF receiver set to CW demodulation set to appropriate parameters ->
NTP timekeeping system sound card

One of my organization's projects consists of robust public time
transfer via NTP over the Internet, based on a combination of various
on-site standards (rackmount OCXO, rubidium, and/or cesium standards)
and external signals (incl. WWV and CHU, using preamplifier ->
preselector -> analog parametric demodulator -> sound card, controlled
by ionospheric prediction daemon software on GNU/Linux via GPIB), the
nodes being geographically dispersed throughout the US and Canada.
It's probable that I will end up relocating to Western Europe
(coincidentally, the Republic of Ireland!) in the moderate future, and
therefore it would be nice if these LF or HF signals were to be
supported, for use as fallbacks to the standard GNSS sources (each
site typically will have one military and one industrial civilian
rackmount GPS receiver).

-Ruslan

-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] New ISO8601 ?

[Ruslan Nabioullin]

So this new revision enables essentially for the encoding of ``ca.''?
Obviously the current revision allows for varying degrees of fixed
chronological granularity levels.

-Ruslan

On Thu, Nov 23, 2017 at 9:01 AM, Dana Whitlow <k8yumdoo...@gmail.com> wrote:
> I believe the phrase "circa 1967" fits the bill pretty well, although
> it may fall a little bit short of "...but it’s all a bit of a blur”.
>
> Dana
>
> On Thu, Nov 23, 2017 at 7:18 AM, Poul-Henning Kamp <p...@phk.freebsd.dk>
> wrote:
>
>> 
>> In message <4bec82c4-583e-4632-8589-d898cc2bd...@n1k.org>, Bob kb8tq
>> writes:
>>
>> >I had never realized there was a format for expressing “I think it was
>> 1967 but it’s
>> >all a bit of a blur”.
>>
>> I think that is one of the major reasons for the revision.
>>
>>
>> --
>> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
>> p...@freebsd.org | TCP/IP since RFC 956
>> FreeBSD committer   | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by incompetence.
>> ___
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-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] Sulzer 2.5 For Sale

[Ruslan Nabioullin]

That system clearly is a rudimentary (simply based on amplitude)
failover controller---e.g., a shoestring setup could have an EOL
cesium standard (relatively-accurate but -unreliable) that's not on
UPS and a UPS-backed OCXO (like this unit) (relatively-inaccurate but
-reliable) connected to ``REF IN'' and ``STBY IN'', resp.  Honestly
this standard appears to be ancient and the high-level build quality
appears to be questionable.

-Ruslan

On Sat, Oct 21, 2017 at 10:05 PM, Richard Mogford <rch...@earthlink.net> wrote:
> Hello
>
> I am selling a Sulzer 2.5 frequency standard.It is rack mounted with a
> separate power supply and no battery.It also has an “Amplitude Fault
> System.”(I have not been able to find out what this does.) There is a PDF
> manual that I will send the buyer with the equipment.  The switch setting #4
> shows zero milliamps.
>
> I am not an expert in these devices by any means, but have been running the
> Sulzer for several days using John Miles’ excellent TimeLab software.I have
> pasted in below an Allen Deviation plot for three days of data collection.
>
> I will be selling the Sulzer on auction on eBay starting on Monday, October
> 23.The starting bid will be $200.Shipping may be around $50.
>
>
> Please contact me if you have any questions.
>
>
> Richard
> AE6XO
> rch...@earthlink.net
>
>
>
>
>
>
>
>
>
>
>
>
>
>
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-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] HP5090A Off Air Standard Receiver

[Ruslan Nabioullin]

On 06/18/2017 04:17 PM, GandalfG8--- via time-nuts wrote:> I have a 
5090B which I'm hoping to get up and running when it finally

reaches the top of the to do list and my view is that it would be much better to
  leave the original electronics undisturbed and to drive it with a  200 KHz
signal divided down from a from a GPSDO or a rubidium  module, although
having one of the latter already running at 800KHz  does leave me a bit
biased:-)


What in the world would the point of that be!?  It appears to be a 
long-obsolete product, so have you searched for more modern time code 
receivers from timing instrumentation (Meinberg, Brandywine, et al.) and 
surplus vendors?  It'll probably be pretty expensive, for it's probably 
much less popular than WWVB and DCF77.  Have you tried the latter?  It 
might be receivable from Britain, and I've seen some surplus DCF77 
receivers (e.g., an old ISA card).


-Ruslan

--
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Wittgenstein Laboratories
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(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] Exciting news for the western US eloran to be on the air!!

[Ruslan Nabioullin]

Excellent!!  Do you know why the testing periods terminate, and
whether Wildwood will return back on air?

-Ruslan

-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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[time-nuts] current status of eLORAN globally

[Ruslan Nabioullin]

Hi, what's the current status of eLORAN globally?  It's difficult to
find the latest information on this on the WWW.  As I understand it,
there currently exist only two active eLORAN projects, Ursanav/US
gov't in the US, and Babcock Comms/UK gov't in the UK (and possibly
South Korea as well?).  I know that the former has operated only one
site in the near past (Wildwood), though the testing period (according
to its website) has expired and I'm not seeing any information on a
continuation.  As for the latter, as the recent thread has informed
us, at least one site is active (albeit experiencing some technical
issues), Anthorn.  In particular, more detailed information, analysis,
and predictions on these efforts are sought.

Thanks in advance,
Ruslan

-- 
Ruslan Nabioullin
Wittgenstein Laboratories
rnabioul...@gmail.com
(508) 523-8535
50 Louise Dr.
Hollis, NH 03049
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Re: [time-nuts] Problems with CHU

[Ruslan Nabioullin]

Bob Camp wrote:
> Once upon a time it was done with a mechanical marvel of a device.

And before those electromechanical contraptions, there was this :):
https://en.wikipedia.org/wiki/Speaking_clock#/media/File:1937TimeVoice.jpg

-Ruslan

On Thu, Feb 16, 2017 at 1:18 PM, Bob Camp  wrote:

> Hi
>
> Not quite sure what happened to the original message before it got here …
>
> The voice / time announcements on WWV and CHU date back quite a ways. I
> wonder just
> how old the gear they currently are using is? Once upon a time it was done
> with a
> mechanical marvel of a device.
>
> Bob
>
>
> > On Feb 16, 2017, at 12:52 PM, jmfra...@cox.net wrote:
> >
> > I meant to type 7.850 MHz, re-engaged brain.
> >
> > John WA4WDL
> >
> >  jmfra...@cox.net wrote:
> >>
> >> I do not know if anyone has noticed, but since sometime before 17:00
> UTC, the voice announcements on the 7.8350 kHz signal have been messed up.
> Some times they are missing, other times they are incorrect. I have not
> checked the other frequencies. I was working in my workshop and switched to
> CHU to stay aware of the time and noticed the discrepancies.
> >>
> >> John  WA4WDL
> >
> > ___
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Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Ruslan Nabioullin]

On 02/15/2017 01:17 PM, Chris Albertson wrote:

Why set up a dedicated NTP server if you only have two computers
that will use it?Your server will be accurate to a few
microseconds but your two computers will only by good to a few
milliseconds because ethernet is not nearly as good as PPS.


Well Ethernet can be *extremely* accurate if PTP is used (a whitepaper 
specifies <= 100 ns accuracy if the LAN is optimized for it).


Well, the assumption here is that one would render this service 
available to the public, registering the server(s) with the NTP website 
and/or the NTP Pool Project; n.b. this is still possible for connections 
lacking a static IP address, by means of an IPv6 tunnel, available at no 
cost from at least one vendor.  Otherwise yes, by some perspectives it 
can be considered quite pointless and wasteful to operate dedicated 
servers, standards, receivers, etc. with no means of time transfer to 
customers.


> NTP is almost zero load on the CPU and the best thing is the NTP
> accuracy is not effected by CPU load  SO you can run other service
> without degrading the NTP server.

Well n.b. TVB's hardware PPS timestamping post.  Also WWV and CHU 
decoding by NTP's modules can be problematic, as well as the obvious 
case of the server being overloaded.  Finally note that based on others' 
experimentation, the motherboard's XO temperature is nontrivially-highly 
correlated with CPU load, so for better motherboard XO-based holdover 
performance, once must create an ersatz oven utilizing the CPU(s), by 
running them at full utilization (obviously with proper scheduling 
priority), so typically volunteer distributed computing project(s) such 
as BOINC (SETI@home, etc.), Folding@Home, etc.  Of course then power 
consumption becomes problematic.


-Ruslan
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[time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Ruslan Nabioullin]

Hi, generally speaking, what are the performance differences between the 
following: 1. direct RS-232 (i.e., what I believe is a standard PCI card 
offering RS-232---essentially UARTs interfaced more-or-less directly to 
the PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI cards (which might 
also have an IRIG input or even an onboard GNSS receiver).


Thanks in advance,
Ruslan
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Re: [time-nuts] eLoran is up and operating. Looking good

[Ruslan Nabioullin]

On 02/06/2017 09:06 PM, Bob Camp wrote:

On Feb 6, 2017, at 7:38 PM, Ruslan Nabioullin
<rnabioul...@gmail.com> wrote:

So any ideas on how likely it will be that eLORAN becomes deployed
with at least partial US coverage within the next 5--10 years?


No, this is not the world as I would like it to be. It is the world
we live in now and are likely to live in for the foreseeable future.


Yes, from the perspective of myself and my fellow transhumanists, the 
world is quite primitive in all aspects.  I yearn for the day when 
singularity will take over and our primitive species is relegated to 
wildlife status.  But I digress, as usual.



If we are looking at it purely as a timing reference the outlook is
not real good. Best guess about 1 in 1,000. I’m probably estimating
that on the generous side. If there is some other magic use for the
thing (or a couple dozen other uses) that might change the equation.
Right now those other uses are not very obvious.

Why the lousy outlook:

1) The way a system like this gets funded is for it to have  a lot of
users. It might also get funded if some crazy black project needs it.
That’s not happening with Loran. Loran died in the first place due to
a lack of users. 2) For a system like this to have a lot of users,
you need to pass regulations requiring it’s use. That may seem odd,
but that’s the way it works. Loran co-existed with GPS for a long
time. GPS was *less* reliable back then than it is today.  Using
Loran for timing was a very rare thing outside a handful of labs. 3)
To regulate it into major systems, it needs to have at least a
country wide coverage and more likely a bit more than that. Without
that there isn’t enough of a timing market to address. You need to
retrofit it into every cell tower in the country (for instance). 4)
Loran getting into buildings from a single site (even fairly close) …
not so much if they are full of switching power supplies, you have a
problem. You need to have *many* Loran transmitters. Cell timing is
moving out of the “edge” and into the central hubs. That means
buildings full of switchers. 5) Tying multiple time sources into a
system costs big money. If you only have two clocks, how do you
decide which one is wrong? Not an easy question to answer. That money
has to come from somebody. Nobody wants to pay. The cell carriers
have never been excited about investment that does not immediately
result in more customers. 6) There are multiple competing “for pay”
backup timing systems. Adding another one to the mix is pretty hard
to justify. Even more so if you can “steal” timing off of one and not
pay for it. That would be the case with an eLoran that works with all
our old gear. 7) Like it or not, justified or not, cost effective
(not), the world is hung up on space based systems. There is no
excitement in 1950’s technology. 8) Loran for exact timing has some
major issues with propagation delay. If your goal is the same as the
system specs ( < 100 ns) that’s going to be a really tough nut to
crack. Do they *need* < 100 ns? It’s in the spec …


Makes sense---I was doubtful that it would be successful in non-niche 
commercial areas, considering the different priorities and philosophy 
(or lack thereof) in mind by the manufacturers and userbase.



Right now we have multiple broadcast time sources running 24/7 at
various frequencies with various coverage zones. As far as I know
*none* of them are tied into major systems. That’s just the way it
is, and it’s nothing new. Even in military systems, multiple time
sources into a system is a very rare thing. In commercial systems …


Yes, WWV/WWVH, WWVB, and CHU, within North America.  Very sad to hear 
that---fusing standards and external sources of diverse characteristics 
(MTBF, Allan deviation, propagation mode, sociopolitical considerations, 
etc.) is the central approach of my project.


WWVB altered the signal format in '12, rendering phase locked-loop-based 
receivers into metal paperweights (i.e., the remaining lab units used as 
a fallback), and apparently there is no replacement nor retrofit, like a 
Costas Loop (the only receiver I have found is a Meinberg USB unit, 
which very well might not even work with the new format; I have in fact 
submitted multiple quote requests, to no avail).  At the very least 
millions of domestic and personal radio clocks use it (along with a 
couple other analogs in some other parts of the world, like DCF77), not 
that this approach is remotely optimal.


As for WWV/WWVH and CHU, it's quite a sad situation---I have only 
counted 1--2 registered NTP servers that actually use at least one 
channel, despite the fact that: 1. NTP has decoding modules built-in for 
all these signals; 2. the equipment setup is typically simpler and 
cheaper compared to dealing with mounting a GPS antenna on the roof and 
interfacing with PPS, esp. if one uses a Chinese $6.50 incl. shipping HF 
receiver off eBay; 3. it's a decent, and essentially only (not co

Re: [time-nuts] eLoran is up and operating. Looking good

[Ruslan Nabioullin]

So any ideas on how likely it will be that eLORAN becomes deployed with 
at least partial US coverage within the next 5--10 years?  There exists 
a solid company working on its R (UrsaNav), apparently increased 
awareness in government, and UrsaNav entered into a partnership with 
Spectracom for integrating its UN-152B (modern SDR-based eLORAN, 
Loran-C, and Chayka frequency and time transfer receiver) for GNSS 
fallback, which has been tested for commercial applications (e.g., 
NYSE), so apparently there is some commercial demand (I have been told 
by an engineer at Google that they are aware of this for Spanner and 
their other R projects requiring time metrology, but have not decided 
yet).


-Ruslan
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Re: [time-nuts] information about the Austron Synchronous Filter 2090A

[Ruslan Nabioullin]

On 02/05/2017 02:58 AM, Poul-Henning Kamp wrote:

I belive [sic] the idea is that if you have two Loran-C receivers
tracking two different GRIs, the 2090A can blank out the strongest
stations [sic] pulses for the weaker chains [sic] receiver.


So it functions sort of as a preselector, one whose universe of
discourse is LORAN-C, for improved reception performance of the receiver
tracking the weaker GRI?

-Ruslan
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[time-nuts] information about the Austron Synchronous Filter 2090A

[Ruslan Nabioullin]

Hi, any ideas on what the Austron Synchronous Filter 2090A is for?  I 
couldn't find it in the '88 catalog.  I recall seeing some hits for it 
in old unclassified DoD R publications in the past, wherein it was 
used as part of an experimental LORAN reception setup.


-Ruslan
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Ruslan Nabioullin]

On 02/03/2017 10:02 AM, paul swed wrote:

Ruslan
NH will be easy to pick it up. The core frequency is 3 Cesiums in a
cluster. As for time transfer it can but its really a pain in the
backend and that information is indeed in the data channel. So make
us jealous with your CS and RBs. :-) I am down in Franklin Ma so we
are actually close compared to others.


I'm actually jealous of your LORAN time/frequency metrology capability 
:).  Apparently UrsaNav (headquartered locally in North Billerica, MA!) 
are the ones performing these particular aforementioned R efforts; I 
have visited their corporate website and have read about their projects 
and product portfolio, and have developed a liking for this company 
(despite being anarchosocialist).  The reason is that philosophically 
I'm a strong advocate of resilient technology and social policies, and 
consequently that is the entire purpose of my nonprofit time/frequency 
metrology and transfer project.  As an example, the redundant 
timekeeping and NTP transfer minicomputers will be provided with 7--10 
WWV and CHU channels received with redundant auto-failover HF antennae, 
just in case some channels fail (and that is in addition to redundant 
GPS and of course the set of redundant UPS-, solar-, and 
generator-backed standards, which hopefully will grow to there being a 
fused ensemble of two modern Cs standards at any one time, rather than 
the current scheme of the VXI-based controller simply running one at a 
time in an auto-failover configuration).


-Ruslan
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Ruslan Nabioullin]

On 02/03/2017 09:53 AM, Bob Camp wrote:

With reasonable gear, you can pick up the European Loran chains in
the US on a regular basis. You can also pick up the Russian system
that runs on the same frequency. The gotcha there is that you are
looking at “skywave” rather than “ground wave” signals to some
degree. That degrades their value for timing or for navigation. (Yes,
it is all a lot more complicated that than very simple / quick
summary).


Oh wow, I did not know that LORAN reception is adequate over such long 
distances.  So Chayka is essentially compatible with Loran-C frequency 
transfer receivers?  And is it still online?  If so, it could be used as 
a fallback in the unfortunate case that eLORAN R projects in the US fail.


-Ruslan
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Ruslan Nabioullin]

On 02/02/2017 09:47 PM, paul swed wrote:

Ruslan,
Seems to be backward compatible. Yes.
All of my stuff works austrons and SRS 700.
Whats your location? The transmitter is in NJ and I am near Boston. So
somewhat close for me. My antenna is the standard boat preamp and whip
antenna. 6 foot off the ground.
Regards
Paul
WB8TSL


Very exciting news!  I and my modest metrology lab is located in 
southern NH.  But time transfer won't work, right?  I'm not interested 
in LORAN-based frequency transfer due to my having a number of modern Cs 
standards, Rb standards, a disciplined OCXO standard, and currently one 
low-end (+/- 150 ns) GPS time and frequency receiver (the XL-AK).


-Ruslan
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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Ruslan Nabioullin]

On 02/02/2017 01:59 PM, paul swed wrote:

Well this is nice almost a 2 month long test.
So if you thought about seeing if you could receive eLoran on your Loran C
receiver this is a good opportunity. With respect to the data channel
pretty sure none of the receivers we have know or care about it.


So eLORAN, both the present experimental form and the expected future 
standard, is completely forward-compatible?


-Ruslan
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Re: [time-nuts] Distribution amplifier (again!) - now mostly ok but has gain peaking

[Ruslan Nabioullin]

On 01/28/2017 06:58 AM, Anders Wallin wrote:

Hi all,
I've been tinkering with another distribution amplifier design and made
some measurements earlier this week.


Have you looked at the design of the HP/Agilent/Keysight E1750A (sine 
timebase of various standard frequencies) and E1752A (PPS) VXI plugins? 
They were designed and engineered in the 90s and were obsoleted by at 
least Keysight, but I recently purchased them due to their low cost and 
size savings (my lab is already filled with stacks of equipment).  Their 
theory of operation is described in the manual available on Keysight's 
website.


-Ruslan
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Re: [time-nuts] purpose of time of day display units

[Ruslan Nabioullin]

On 01/22/2017 07:26 PM, Hal Murray wrote:

Many years ago, I designed network gear.  That was back when a controller was
a board full of small and medium sized chips rather than a single big chip.
I always put a few LEDs on the board wired up where the microcode could get
at them.  Most of the time they were just eye candy.  But occasionally I
would borrow one and hack the microcode so a LED would be interesting on a
scope.


Ah, just like those status LEDs on PCBs, subsystems, and modules in 
properly-engineered equipment (both old and modern minicomputers, 
aerospace equipment, VME and VXI systems, some other servers [some of 
HP's small servers, at least, even feature a neat diagram on the front 
panel, with status LEDs indicating the status of key subsystems or 
components thereof], etc.)  Apple's hardware obviously is an offender in 
this regard---I remember once having to service an iMac (or some other 
modern Apple PC), and I seriously could not figure out how to turn it 
on, and when I had to temporarily shut off the power distribution 
system, I could not figure out what the PC's power state was (to ensure 
a graceful shutdown of the system).


-Ruslan
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[time-nuts] purpose of time of day display units

[Ruslan Nabioullin]

Hi, looking at pictures of various time metrology equipment setups for 
best practices and inspiration, I have commonly seen time of day display 
unit(s) installed in racks containing processing or time transfer 
equipment, e.g., 
http://www.xyht.com/wp-content/uploads/2015/05/Powers_Master_Clock.jpg. 
All that these units do is merely display the time of day and sometimes 
the date, typically by means of seven segment LED displays, of the time 
code inputted to them (typically IRIG-B, I'm guessing).  Any ideas why 
such a unit is necessary when one can simply look at the time displayed 
by timing receivers and time code generators (and even some standards), 
and the interface of some fusor, defined in this context as a system 
which performs timing data fusion (by implementing a paper clock or a 
more primitive algorithm) and timekeeping, either by means of a direct 
shell, or via something like NTP?


Thanks in advance,
Ruslan
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Re: [time-nuts] Line Voltage [Was: Anyone (ideally in the UK) ...]

[Ruslan Nabioullin]

On 01/01/2017 12:07 AM, Chris Albertson wrote:

Just a comment for anyone who wants to log line voltage v. time.   If
you have an APC "Smart UPS" battery backup unit these will log voltage
and frequency to a file.  The unit connects to a computer via USB (and
an AC power cable).


As a more professional alternative, I suggest installing a power quality 
analyzer, particularly the Dranetz 658, which can be had for a modest 
amount off eBay.  If I remember correctly it is from the late 80s era, 
but nevertheless is very feature-filled---modular (mainframe with cards 
for: 4 channels for v, V, i, I, and f [incl. harmonic distortion 
analysis to the 50th. harmonic]; environmental monitoring [T, RH, 
radiated RF, conducted RF]; etc.), physically robust (but not 
rackmountable, I believe), is networkable with another such unit and of 
course interfaceable with a server via RS-232, and has a human interface 
right on the unit (incl. an entire miniature keyboard, floppy drive for 
memory expansion, and even a built-in thermal printer!)  When I was 
doing research, I could not find any other power quality analyzer that 
is physically robust, not to mention cheap, and those IT environmental 
monitors were underwhelming (no modularity, no RF probing, etc.), so I 
opted for this model for monitoring home metrology and METI lab and 
datacenter conditions, incl. the solar generation subsystem.


-Ruslan
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Re: [time-nuts] Nutty time-nuttery with WWVB

[Ruslan Nabioullin]

On 11/10/2016 05:46 PM, Tom Van Baak wrote:

To be honest, this is very impractical and backward-thinking.
I would suggest instead upgrading to the Internet-of-things paradigm, replacing
these time-of-day displays with full computers running NTP and connected
to your LAN (Android smartwatches; repurposed old smartphones, tablets,
laptops, etc.; and smartclocks


Hi Ruslan,

Please tell me this comment is humor or maybe just trolling.
Or are you actually serious?


I am absolutely serious.

-Ruslan
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Re: [time-nuts] Nutty time-nuttery with WWVB

[Ruslan Nabioullin]

On 11/10/2016 05:10 PM, Artek Manuals wrote:

I think you have missed the point this is not so much about keeping time
down to the nano-second


I was suggesting NTP, not PTP.


The WWVB clocks being discussed here come in a plethora of decorator
styles and display varieties ( though most are old analog dials) some up
to 3' in diameter.. They are battery powered so one does not have to
connect them to external power source.  They serve a dual purpose 
for the lady friends who keep us fat and happy they are pleasing to the
their sense of form and feng shui (If momma aint happy ..aint nobody
happy)


Then find a more rationally-minded wife or partner.

 .  For the engineer in us we know that the time is accurate to

the second and we don't have get out the step ladder to crawl up there
and reset the clock twice a year when daylight savings changes over.
When I was a road warrior I had a wrist watch that kept WWVB time and I
always knew down to the second how much time I had before I missed the
next flight or train out of Dodge. ( I haven't worn a watch by the way
since I retired in 2008 !)

Nowadays I suppose you could build/buy one that talks to your WLAN but I
suspect the battery life is not quite as good as the current WWVB
version which can run off a watch battery for 5 years.


Well you would have to bother with the rather-pointless project of 
building a WWVB simulator, taking care not to cause interference. 
Stationary clocks do not have to be battery-powered.  Yes, battery life 
would obviously be a problem for typical smartwatches, but assuming a 
rational mind, virtually everyone will opt for a smartwatch over a 
WWVB-synchronized dumbwatch, despite the battery life penalty incurred.



On the other hand
I know I can sleep better at night knowing my WWVB clock has not joined
the dark side and is mindlessly helping the terrorists bring down the
power grid 8^(


What a brilliant idea---lets refuse to embrace computerization and the 
transition to Internet-of-things (which should've happened in the 80s) 
out of fear of the expansion of botnets; furthermore, lets roll back 
computerization, and maybe even eliminate all computers?  Why have 
progress when we can have regress?  Of course, we shall disregard the 
fact that there are a wide array of all sorts of security 
countermeasures (correctness proofs, sourcecode auditing, multifactor 
authentication, ASLR, DoD-style MACs, firewalls, IDSs, honeypots, 
tarpits, etc.) and the fact that all properly-designed high-security 
and/or critical systems are either completely air-gapped (SIPRNet, 
JWICS, NSANet, stock exchange internal networks, etc.), or are 
unidirectionally interfaced with the Internet (many SCADA sites, etc.)


-Ruslan
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Re: [time-nuts] Nutty time-nuttery with WWVB

[Ruslan Nabioullin]

On 11/10/2016 07:18 AM, Peter Reilley wrote:

I have a few of those "atomic" clocks that receive WWVB to set the time.
However since I live on the east coast they may only pick up the signal
once or twice per year.

Could I implement my own personal WWVB transmitter that would
be powerful enough to be picked up by the clocks in my house?
The signal at 60 KHz might be able to be produced directly by some
sound cards.   With that and a ferrite rod antenna I might get
reliable time elsewhere in my house outside of my lab.

Has anyone tried this?

Pete.


To be honest, this is very impractical and backward-thinking.  I would 
suggest instead upgrading to the Internet-of-things paradigm, replacing 
these time-of-day displays with full computers running NTP and connected 
to your LAN (Android smartwatches; repurposed old smartphones, tablets, 
laptops, etc.; and smartclocks [I'm certain that some Silicon Valley 
``genius'' has already come out with such an ``invention'' and the 
Chinese are churning out cheap knockoffs]), which will query your home 
metrology lab's NTP server(s), and instead using WWVB as an additional 
timing signal for diversifying your timing source portfolio (with a good 
antenna, of course), if you haven't done so already (though such 
products appear to be extremely sparse nowadays, for civilian-minded 
users have superficially reasoned that GPS is all that is necessary).


-Ruslan
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Re: [time-nuts] This may be my new favorite old oscillator

[Ruslan Nabioullin]

On 11/08/2016 12:16 AM, Skip Withrow wrote:

Hello Time-Nuts,

I recently acquired an HP 5065A rubidium oscillator (with 10811 10MHz
OCXO). I think I pretty much have it running now and have been letting it
cook for the last couple of weeks.  I offset the C-field + and - and
measured the frequency to calculate the C-field sensitivity. My unit came
out to 1.96x10E-12 per dial unit, which agrees with the manual stated
2x10E-12. So, calculated the on frequency C-field value and dialed it in.

Attached is a Lady Heather plot of the frequency over the last 3 days.  The
purple line is the 1pps plot with the vertical scale being 20ns per
division.  So, the unit is off about 125ns over the last 72 hours (running
about 4.92x10E-13 slow).  So my C-field setting is off about 1/4 of a
division, but I think I'm going to leave well enough alone.

The yellow line is the NTBW50AA temperature sensor, and you can clearly see
when the furnace cycles.  I was away for the weekend, and you can also
clearly see when I came home this evening and turned up the heat.  At the
very end of the plot is the spike when I turned on the lights in the shop.

I love using a Thunderbolt/NTBW50AA for making frequency measurements this
way.  I remove the OCXO, and insert the 10MHz from the DUT.  Then disable
disciplining so the DAC voltage doesn't try to chase the open loop
oscillator.  Of course the short-term performance looks worse than it
actually is because of measuring against GPS, but the long-term
measurements are very good.

I want to log this unit at regular intervals to see what the aging looks
like.  Also need to do some measurements against the cesium to see what the
short-term performance might be.  But, I think this oscillator will be a
good reference in many cases in lieu of using the cesium.

Regards,
Skip Withrow



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I hope you will forgive me for reducing the SNR of this forum a bit, but 
is that a pro-Trump message embedded in that Lady Heather plot? 
Furthermore, it might also be promoting electoral fraud, though 
``...vote often!'' is ambiguous (maybe that's plausible deniability?)


-Ruslan
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Re: [time-nuts] Thinking outside the box a super reference

[Ruslan Nabioullin]

On 11/03/2016 06:10 PM, Attila Kinali wrote:

On Thu, 3 Nov 2016 16:37:06 -0400
Ruslan Nabioullin <rnabioul...@gmail.com> wrote:


What about instead establishing an open-source hardware project for a
frequency standard fusor?  I was researching COTS solutions for this for
my rubidium ensemble and could only find this one product, which
obviously should be exorbitant in cost:


You don't need a hardware project for this, as long as a paper clock
is enough for you. Just buy a couple of kiwi-sdr (or anything similar),
provide all of them with a common clock source and you get a comparison
of all your atomic clocks with minimum effort and can build from that
a paper clock easily. The paper clock can than be used for the measurement
you do, using one of the atomic clocks (preferably the one with the lowest
phase noise) as reference.


If it's so relatively straightforward, then why not establish such a 
project instead of reinventing the wheel by attempting to perform atomic 
standard R and fabrication on a shoestring?  It should be much more 
practical, even considering the fact that one will obtain diminishing 
returns on the ensemble's n, and furthermore should be extremely 
successful---apparently only a single Russian company holds a global 
monopoly on this product, apart from custom-fabricated setups in 
national metrology labs, and numerous people would benefit (why purchase 
an exorbitantly-expensive and short-lifespan cesium standard when one 
can fuse a redundant ensemble of rubidium standards?  Or for 
lower-budget and/or higher-MTBF setups, the same for a rubidium standard 
and OCXO standards, resp.)


Another project, much simpler in comparison but even more useful, would 
be a rack-mount standard for an OCXO or rubidium physics package, which 
should consist of just a chassis, power supply, thermal structure, and a 
monitoring subsystem with interfaces (LEDs, an LCD display, and 
RS-232/USB/GPIB/Ethernet).  The used market is flooded with cheap 
physics packages, yet actual standards are uncommon and expensive.


-Ruslan
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Re: [time-nuts] Thinking outside the box a super reference

[Ruslan Nabioullin]

On 11/03/2016 04:07 PM, Bert Kehren via time-nuts wrote:


Over the past there has been talk about building from  scratch high
performance references. I think consensus was that it is out of  reach.


What about instead establishing an open-source hardware project for a 
frequency standard fusor?  I was researching COTS solutions for this for 
my rubidium ensemble and could only find this one product, which 
obviously should be exorbitant in cost: 
http://vremya-ch.com/english/product/indexe817.html?Razdel=11=54


-Ruslan
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Re: [time-nuts] WWV receivers?

[Ruslan Nabioullin]

On 10/26/2016 02:54 AM, Hal Murray wrote:


tsho...@gmail.com said:

I'm all for a diversity of systems - putting all our eggs in the GPS basket
seems unwise (and I maintain WWV receivers hooked to NTP at home!)


What is available in the way of WWV receivers?  Anybody got a summary handy?


Yes, diversity is generally good, as it is in a sociological context. 
Despite being such a ubiquitous and critical system in all domains, 
military and civilian, US and foreign, and therefore being a recipient 
of extensive funding and R, it is a high-profile target to adversaries 
by means of anti-satellite weapons, cyberattacks, ground segment 
attacks, and jamming; additionally, the constellation is subject to the 
natural threats that all satellites face, and the system is controlled 
by a homogeneous structure of human entities, which reserve the right to 
deny coverage to a subset (typically hotspots in times of conflict).  It 
was a goal of my time metrology project, so I did do research in this 
area, expecting to use CHU (which also adds political diversity, for 
then it would be US [GPS] and Canada [CHU]) and maybe also WWV, but I 
abandoned the idea in favor of allocating the bulk of the budget to 
procurement of equipment and supporting equipment for my own house 
standard by means of a rubidium ensemble.


Yes, standalone WWV receivers of course do exist; if one wishes to go 
this route, the only practical means is by purchasing one of those 
ancient (late 70s era probably) Systron Donner time code generator units 
off eBay, which you'll notice has a BNC port on the back for an HF 
antenna (or just the audio feed---who knows?  Documentation is scarce). 
However, unless you need WWV-derived PPS, this approach is *greatly* 
suboptimal; the best approach would be to find your desired HF 
receiver(s) and connect them via sound card(s) to the NTP server(s), 
using the WWV module (and/or CHU).  Besides the unknowns resulting from 
documentation scarcity, this approach brings flexibility and the 
benefits of the ``less is more'' philosophy, for you gain: the freedom 
to decide what models of equipment to incorporate; flexibility in 
channels (you can also do CHU, and even within WWV you can do 2.5, 5, 
10, 15, and/or 20 MHz); and avoidance of obsolescence---remember, you're 
relying on some human entity's signal, who in this case of a 
seemingly-unpopular (at least nowadays) signal is under little 
obligation to preserve the characteristics and even presence of such a 
signal---look at what happened with the WWVB signal change, which 
effectively rendered what were once nice standard frequency WWVB 
receivers into paperweights.


For the radio, the best overall approach might be using $32 or so 
RTL-SDRs which feature a case.  However, the reception quality of these 
units is not so great, the DSP might overwhelm low-power and embedded 
servers, and there might be latency issues; I'm not familiar enough with 
SDRs to state for sure.  Another cheap approach is to simply use $12 or 
so, incl. shipping, handheld HF receivers, though from past experience 
the reception quality of them is absolutely awful and they are portable, 
consumer-grade devices, meaning that there's no antenna BNC port, there 
might be no power input apart from the terminals in the battery 
compartment, and there are no means of elegantly rack-mounting them.  A 
more costly approach is to use a general-purpose HF receiver (like 
typical Icom or Yaesu units that typical amateur radio operators use) or 
a professional HF receiver; unfortunately one is very limited in the 
latter, which consists of, in ascending order of price: HP 3586C (a 
measuring receiver actually), Ten-Tec (from the research I have done, is 
generally similar to Watkins Johnson [WJ], but lacks high-reliability 
specifications), and WJ.


For the sound card, it has been reported that those cheap Chinese USB 
sound cards, costing <$2 each incl. shipping, are adequate; I actually 
ordered a quantity-discounted lot of 5 or so of the popular variant 
which contains status LEDs before changing plans, so that's the best 
approach if you wish to use multiple sources or servers.


Note that for high-reliability setups, one must factor in potential 
service degradation caused by civil unrest or remote equipment failure, 
such as reduced station power output due to electricity shortages, loss 
of some channels, or jamming by adversaries.


-Ruslan
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Re: [time-nuts] Roughtime

[Ruslan Nabioullin]

On 10/05/2016 01:17 AM, Chris Albertson wrote:

All that said, there is money to be made  by spoofing time.   If I can fool
a stock broker into accepting trades minutes late I could be rich.


Minutes?  I thought the proper unit for that is nanoseconds :).

-Ruslan
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Re: [time-nuts] COTS cesium standard physics package life

[Ruslan Nabioullin]

On 09/29/2016 11:45 AM, Scott McGrath wrote:

It depends on the beam tube   There is a fixed amount of Cs in any
given beam tube this pool of Cs is consumed during operation.Once
the Cs is depleted the tube will no longer function.It's possible
with intermittent use for the tube to run for decades as long as
vacuum maintenance is performed.   Most Cs tubes have a published
expected lifetime before replacement is required  while maintaining
published specifications.   It's possible to extend tube life
somewhat by increasing oven temp and electrode voltages but the
signal becomes noisier as a result


Aha, that's what I was thinking---the manual was misleading and made no 
sense in this regard.  Thanks!


-Ruslan
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Re: [time-nuts] COTS cesium standard physics package life

[Ruslan Nabioullin]

On 09/29/2016 02:02 PM, Bob Camp wrote:

The “operating” case will ultimately kill various parts in the
standard that would not die sitting on the shelf.


Oh, really?  I thought that cesium depletion is essentially the only 
real killer.


-Ruslan
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Re: [time-nuts] COTS cesium standard physics package life

[Ruslan Nabioullin]

On 09/29/2016 01:50 PM, John Ackermann N8UR wrote:

2.  Tube vacuum and other physical aspects that may deteriorate over
time, whether or not the tube is operating.  The routine ion pumping
helps keep the vacuum up in storage, but is not as effective as the
continuous pumping that occurs during operation.

This is guesswork, but I suspect the warranty period was based on (1),
which is why it is shorter on the high-performance tubes, which deplete
cesium more rapidly.  There may also have been an assumption that not
many customers were buying Cs standards and putting them in storage.


But I'm interested in a different case---having the unit be continuously 
in operation (so continuous pumping, not two or three times per the 
period), but having the cesium physics package be in rare, intermittent 
operation.


-Ruslan
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Re: [time-nuts] COTS cesium standard physics package life

[Ruslan Nabioullin]

On 09/29/2016 01:03 PM, Bob Camp wrote:

2) How long on average is the tube likely to be useful.


So you are implying that the package life is depleted at a roughly equal 
rate regardless of whether the package is fully operating, has just the 
pump operating, or is completely shut off?


-Ruslan
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[time-nuts] COTS cesium standard physics package life

[Ruslan Nabioullin]

Hi, I'm unable to fully grasp the lifetime specifications of typical 
COTS cesium standard physics packages, for both old and new designs. 
For example, the documentation of an older HP standard specifies a shelf 
life of two years if the ion pump is operated two or three times per 
year, yet at the same time the ``beam tube warranty'' period is three 
years.  Does this mean that if the physics package is fully operating 
(i.e., LOOP OPEN, OPER, or LTC), then it's guaranteed to last at least 
three years, but if it's completely shut down, except for vacuum 
maintenance sessions (using the mode CS OFF) two or three times per 
year, it will last only two years?  Also, what will the expected 
lifetime of the package be if the standard is kept as a reserve, 
specifically, continuously-powered with the mode set to CS OFF (so 
continuous vacuum maintenance), and activated or deactivated to or from, 
resp., OPER, as needed, excl. the time spent fully operating (i.e., in 
this case, the time spent in the OPER mode doesn't count)?


Thanks in advance,
Ruslan
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[time-nuts] Austron 2010B (disciplined OCXO) square wave conversion

[Ruslan Nabioullin]

Hi, I recently bought an Austron 2010B, a disciplined OCXO standard with 
adjustable disciplining parameters, for use as a clean-up oscillator and 
a decent fallback to my Ball MRT-H, a rubidium standard.  I figured that 
the quartz standard's 1 Mhz and 5 MHz outputs are fine---the former is 
exactly what my Truetime 814-149, a time code generator, needs for 
eventually providing PPS output to my SPARC-based NTP server, and the 
latter can be doubled, amplified, and distributed, all with a single 
distribution amplifier unit, for use as a timebase for transmitters and 
lab instruments.  Only later did I realize that for some bizarre reason, 
all of the outputs are square wave, not sinusoidal!  Great.


Any ideas on the likely reason that the unit was engineered with only 
square wave outputs?  Obviously this will render division to PPS 
trivial, but all of the applicable equipment that I've encountered use a 
sinusoidal reference, not a square one, so it doesn't seem prudent to 
exclude sine.  And naturally, what is the most prudent course of action 
in this situation?  I'd rather use something prebuilt than building my 
own converter, but all the distribution amplifiers I've looked at lack 
such a conversion feature, and I'm unsure whether plain square to sine 
converters are suitable for such time/frequency metrology applications.


Thanks in advance,
Ruslan
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[time-nuts] standard fusion for accuracy and redundancy

[Ruslan Nabioullin]

Hi, I'm in the process of setting up a public stratum 1 NTP server which 
will have at least one standard as a fallback to GPS (and possibly WWV 
and CHU), in addition to its primary purpose as a timebase for a 
microwave active SETI transmitter.  So far I have an aging = 1E-11 
rubidium standard (which has expired calibration documentation), and I'm 
interested in adding more standards in the future, specifically 
high-quality OCXO(s) and additional rubidium standard(s) (I'm 
uninterested in cesium standards due to their definite and short 
lifespan, and masers are, in almost all certainty, insanely expensive).


Based on attempts of understanding the NTP documentation and answers 
from NTP fora, NTP doesn't perform PPS fusion for accuracy, but rather 
merely for redundancy (correct me if I'm wrong).  Therefore, this 
complicates things to an extreme degree, for it means that the RF 
outputs (typically 100 kHz, 1 MHz, 5 Mhz, and/or 10 MHz), or PPS outputs 
have to be combined using some sort of a weighted fusion method (or 
simply unweighted, if the aging figures are similar across all the 
standards).  The only commercial piece of equipment to perform this, 
manufactured by some Russian corporation, is obscure and just by the 
look of it prohibitively-expensive.  So that leaves custom fabrication; 
the best information I could find regarding this is the paper ``A 
Digital Technique for Combining Frequency Standards'', by Lynn Hawkey, 
published in '69, which outlines nonnovel approaches and a novel 
approach to fusion.  The method that's attractive to myself is the old 
RF mixing one, wherein double-balanced mixer(s) are used to sum RF 
signals from standards of similar aging figures, the resulting output(s) 
filtered, and the output finally sent to a frequency divider to generate 
the desired final RF signal (like 1 MHz for typical time code 
generators).  Any ideas?


Thanks in advance,
Ruslan
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[time-nuts] Lucent RFTG-M-XO

[Ruslan Nabioullin]

Has anyone been successful in using a Lucent RFTG-M-XO with NTP? This module
is attractive to me because it has the ability to be connected to a Rb
standard. Unfortunately, documentation is obscure; based on the limited
documentation available, it seems as though the module does not output a
timecode but only a PPS signal and a status code (J6 in
http://www.n4iqt.com/lucentgps/small_notes_rftg-m-xo.jpg ).

-- 
Ruslan Nabioullin
rnabioul...@gmail.com
rnabi...@student.umass.edu
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