Re: [time-nuts] And another Thunderbolt question

[Mike Cook]

> Le 8 août 2017 à 17:53, Vlad  a écrit :
> 
> 
> Hello Netizens,
> 
> After the power outage, my TB start to shows some strange behavior.

   Was it a normal power outage , or lightning strike ? Mine just went through 
a normal power outage without issue. 

> 
> As I start LH, the screen shows like this (You could see the date stamp as 
> Dec 1997_
> 
> https://www.patoka.ca/OCXO/TBT0.png

   This is normal now that the GPS week rollover has occurred for these devices.
  Strange that there are no sat stats as the antenna status looks ok, there is 
an almanac  and it would appear that the date and time are being retrieved for 
some sat . 

> 
> 
> Then, few seconds after, the date will be corrected
> 
> https://www.patoka.ca/OCXO/TBT1.png

   This is normal . The wizard has corrected the bad data. 

> 
> And after another few seconds, I have a almost dark screen like this
> 
> https://www.patoka.ca/OCXO/TBT3.png

 I haven’t seen this

> 
> I tried to use ThunderBolt Monitor software to reset my TB to factory 
> settings. It didn't helps. This monitor always shows me correct time, but 
> date back from 1997. And its always no sats.

Tboltmon has no date fix. Again strange that no sat data is available, like the 
receiver is not reporting sv data to the application. 

> 
> What else could be done to resurrect the device ? Thanks !
> 
> 
> -- 
> WBW,
> 
> V.P.
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George Bernard Shaw

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Re: [time-nuts] ***SPAM*** Tsunami detection via GPS

[Mike Cook]

Hi you guys over the pond.

Don’t be shy. 
Did anyone measure their oscillators stability over the eclipse totality? 
Please share.
How about GPS?
Did you record the crickets?
Did the birds fly south?
Did your excess milage increase global warning.
Did the lights go out?
Did anyone in your immediate entourage turn into a witch?

I can understand if you weren’t making any scientific observations. When it 
last happened here, I limited mine to observing the phenomenon through a glass 
of Côte du Rhone.
Magic.

Regards.

> Le 20 août 2017 à 14:05, Jim Palfreyman  a écrit :
> 
> Some here may find this of interest.
> 
> http://www2.unb.ca/gge/Resources/gpsworld.february08.pdf
> 
> 
> Jim Palfreyman
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Re: [time-nuts] GNSS Disciplined Clock

[Mike Cook]

> Le 27 mai 2017 à 21:26, Ebrahim Roghanizad  a écrit :
> 
> Dear Chris
> 
> As far as I know, atmospheric effect can not be compensated by looking at
> satellites from all over the sky and averaging, since it does not have a
> random nature, rather it introduces bias to the solution. For example, if
> atmospheric effect is not removed, one can not get a relative position
> accuracy of sub-meter in long distances even by employing the method of
> RTK. All I said here is about position. Now, I would like to know about the
> output of time in this condition. What is the utmost reachable accuracy for
> a timing output from a GNSS receiver? I do not mean the precision that
> reflects the noise behavior. I think that the best result is obtained when
> the receiver supports dual frequency in order be able to deal with
> ionospheric delay. Am I right? In that case, is there any GNSS receiver
> with this ability?
> 

 I don’t know of any and over time have been looking for one . I guess there is 
no market for a pure GNSS solution. Current L1 only timing receivers can offer 
down to +/-6ns accuracy with quantization error data allowing correction of 
their PPS output down to the stability of the GPS signal. Using that data and 
available cheap delay line chips the 1PPS accuracy deliverable can be reduced 
to around +/-2-3ns .
It appears to be cheaper to use just the L1 derived time to lock better 
oscillators for better precision than that. 


> Thanks a lot
> 
> On Thu, May 25, 2017 at 10:01 PM, Chris Albertson > wrote:
> 
>> The long term stability of GPS is very good.  Some one here will point
>> out exactly how one measures it.   But roughly when speaking of
>> accuracy you always need to specify a time interval. For example
>> if the 1PPS is "off" by 15ns that is not bad and yes there are much
>> better systems if you need to measure time intervals on the order of
>> one second.   But if the signal is "off" by 15 ns over 100,000 seconds
>> that is well, 100,000 time better.
>> 
>> This is a basic reference and for some specialized end use case you
>> might couple it with other equipment.  Many of the concerns you had,
>> such as effects of the atmosphere get averaged out because the unit is
>> looking at satellites from all over the sky.  (averaging over space)
>> And you do git better results with better antenna locations that are
>> away from multi-path and have a 360 degree view of the horizon.  But
>> notice the unit has an temperature stabilized crystal oscillator that
>> is stable over many seconds. an is much more stable in the short term
>> then is a GPS receiver.  Trimble uses this crystal to average over
>> time
>> 
>> You also have to ask where is the tine data going to be used.  Are you
>> synchronizing a computer's internal clock or trying to measure the
>> frequency of a microwave transmitter
>> 
>> SO it falls back to the old thing about there being no "better" only
>> better for a specific use case.
>> 
>> Some of use were lucky enough to buy Trimble Thunderbolts, a previous
>> version of this unit when they were on eBay for $100 each.   For those
>> without 5 digits budget they ar pretty much the Gold Standard.  I have
>> mine installed with a good filtered DC power supply and an outdoor
>> antenna on mast well above the roofs of surrounding buildings. I
>> get long term stability of about one part in 10E13.   Yes 13 digits
>> over long periods.   (I think?)  It is really hard to know because my
>> measurement system is a little circular referenced
>> 
>> On Thu, May 25, 2017 at 6:27 AM, Ebrahim Roghanizad
>>  wrote:
>>> Dear members
>>> 
>>> I am a new amateur member in your group. Maybe my question has been
>> asked.
>>> Recently I found Trimble Mini-T GG, whose data sheet is attached, as a
>> good
>>> GNSS disciplined time reference. I would like to know if there exists a
>>> more accurate one, since it does not employ dual frequencies to
>> compensate
>>> ionospheric delay, though it handles both GPS and GLONASS. Besides, could
>>> anyone guide me about the presented accuracy in the datasheet? There, it
>> is
>>> stated that "When operating in Over Determined Timing Mode, the accuracy
>> of
>>> pulse per second (PPS) is within 15 nanoseconds of GNSS/UTC." Does it
>> mean
>>> that it includes both bias and the noise? In other words, is it true to
>> say
>>> that "The time-synchronization error between two of them with a long
>>> distance is less than 2*15 ns"?
>>> 
>>> Best Regards
>>> 
>>> ___
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>> mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> 
>> 
>> --
>> 
>> Chris Albertson
>> Redondo Beach, California
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Re: [time-nuts] Next Aug 21 eclipse and time flow

[Mike Cook]

To my mind there may be some effect due to small variations in gravity. The 
Chinese paper is very interesting and does propose classical explanations for 
the observed gravimeter anomalies. Even so , the variations that were detected 
by them should be detectable with a sufficiently stable clock. However as the 
reported anomalies are only 6-7 micro-gal which, using a quick interpolation of 
the units wikipedia article data, is roughly equivalent to an altitude 
variation of 2-3cm.  That would probably be undetectable with anything less 
than an ion clock.  


> Le 29 mai 2017 à 09:49, Michael Wouters  a écrit :
> 
> The effect you're looking for depends on a comparison of two different
> kinds of atomic clocks eg Cs vs H-maser so the maser comparison presumably
> will be a null measurement.
> 
> But I see the path of totality passes a bit north of NIST Boulder and I'm
> pretty sure they will notice if there is an effect ! ( I'm highly sceptical
> there is one. Searches for exotic physics over the last three decades have
> consistently turned up nothing. I did it myself at the beginning of my
> career with the "fifth force", a composition-dependent, short range
> gravity-like force. The positive results all turned out to have very subtle
> classical physics explanations)
> 
> Cheers
> Michael
> 
> On Mon, 29 May 2017 at 9:35 am, Jim Palfreyman  wrote:
> 
>> Personally I go with the Nature article. The other papers look like they
>> are anomaly hunting because they have a known event.
>> 
>> Having said that, we have two H masers at our observatory in Hobart and we
>> have a system set up to measure their phase difference down to about 0.03
>> ns. I will report back any anomaly.
>> 
>> Did We, of course, are not in the path of the eclipse, however
>> gravitationally
>> there is still an alignment. Just through the Earth.
>> 
>> 
>> Jim Palfreyman
>> 
>> 
>> On 29 May 2017 at 08:17, iovane--- via time-nuts 
>> wrote:
>> 
>>> On august 21 2017 a solar eclipse will sweep USA from coast to coast. A
>>> lifetime opportunity to do coordinated experiments to check this or that.
>>> One of the questions that doesn't have a final answer yet is whether or
>> not
>>> solar eclipses could affect the flow of time. They exist conflicting
>>> reports: Negative: http://www.nature.com/nature/journal/v402/n6763/full/
>>> 402749a0.html Positive: http://home.t01.itscom.net/
>>> allais/blackprior/zhou/zhou-1.pdf  http://home.t01.itscom.net/
>>> allais/blackprior/zhou/zhou-2.pdfPersonally I believe that the positive
>>> results were due to spurious responses of the atomic clocks to something
>>> else than gravity, or the clocks failed for some reason (e.g. jumping
>>> crystals then steered), or lower quality clocks had been sold to China.
>>> Anyway the recorded data do show an anomaly.As far as I know, no atomic
>>> clock tests are planned anywhere for that circumstance, but sincerely I
>>> don't believe this is the truth.Maybe the US time-nuts community, using
>> its
>>> plenty
>>> of atomic clocks, could give the final answer doing tests during the
>>> above mentioned eclipse.US time-nuts, what about the idea of doing
>>> yourselves a large scale coordinated test? Or do you actually believe
>> that
>>> this question is already definitively closed?(Even discovering that
>> atomic
>>> clocks might respond to someting else than gravity would be of great
>>> interest).Antonio I8IOV
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>>> 
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Re: [time-nuts] GPS splitter

[Mike Cook]

> Le 17 juin 2017 à 02:26, Tim Lister  a écrit :
> 
> On Fri, Jun 16, 2017 at 4:40 PM, Gregory Beat  wrote:
>> I have reached the point that I need a 4-port splitter for my GPS antenna 
>> (outdoor 5 volt).  Any recommendations of models (HP/Symmertricom/Microsemi) 
>> to acquire OR to avoid??
> 

I use Mini-Circuits ZN4PD1-50-S+  with added DC blocking  as they are not 
specifically GPS splitters.  Cheap and effective.



>> greg
>> ---
> 
> Cheers,
> Tim
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Re: [time-nuts] ***SPAM*** Re: GPS discipline oscillator vs phase lock

[Mike Cook]

> Le 17 juin 2017 à 07:55, Lifespeed via time-nuts  a écrit 
> :
> 
> Not too surprising to read locking two crystal oscillators together without 
> using a physical cable is difficult to impossible.  Essentially what I am 
> looking for is the phase alignment accuracy (and phase noise) one would get 
> PLL’ing one oscillator to the other using a cable, but over a longer 
> distance.  Some modest phase noise degradation might be acceptable, but not 
> an order of magnitude.  Clearly not a trivial problem. Yes, the jitter (phase 
> noise) typically accomplished from a PLL phase comparing at 100MHz is better 
> than what one could get “locking” to GPS.  It was just a thought, apparently 
> not a realistic one.  Thanks for disabusing me of that notion.
> 
> 
> 
> Sorry I can’t go into a lot of detail about the overall system block diagram, 
> but this one aspect of the design does just reduce to phase-locking two 
> oscillators over a distance.
> 

Why not just have ONE frequency generator locked to GPS if you want, and just 
distribute the output with equal length cables. It would mean a cable roll to 
store at one end, but you would be assured of phase coherency at both. No? 

> 
> 
> Bob, I think I understand your post processing method refers to the reality 
> that all broadcast signals from which phase information could be extracted 
> are modulated, introducing complications that would not be present with a 
> simple carrier.
> 
> 
> 
> Lifespeed
> 
> 
> 
> Hi
> 
> 
> 
> 
> 
> On Jun 16, 2017, at 7:24 PM, life speed  wrote:
> 
> 
> 
> That sounds like phase-locking the oscillators to a local radio transmitter.  
> Not sure there is any difference post-processing vs. real time.
> 
> 
> 
> The advantage is that you capture a much wider bandwidth signal than you can 
> lock to. That lets you extract better “instantaneous phase” information. With 
> the narrow band loop normally used for locking, loop dynamics get into the 
> picture. That on top of the RF propagation issues is a bit of a mess. It also 
> is quite possible to capture multiple radio (or TV or …) transmissions and 
> post process against all of them.
> 
> 
> 
> The bottom line is still that “many degrees” at 100 MHz is far more practical 
> than “tenth of a degree”. There are very few options if your application 
> really does need roughly a tenth of a degree. 
> 
> 
> 
> Bob
> 
> 
> 
> 
> 
> 
> 
> 
> 
> - Lifespeed
> 
> 
> 
>  _  
> 
> Hi
> 
> 
> 
> A far more common approach is to let the two oscillators free run and to 
> record something like a local broadcast station. 
> 
> You then post process all of the data to give you the phase accuracy. One of 
> several gotcha’s is the stability of any 
> 
> radio link at the level you are looking for.
> 
> 
> 
> Bob
> 
> 
> 
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Re: [time-nuts] ***SPAM*** Re: GPS splitter

[Mike Cook]

> Le 17 juin 2017 à 01:40, Gregory Beat  a écrit :
> 
> I have reached the point that I need a 4-port splitter for my GPS antenna 
> (outdoor 5 volt).  Any recommendations of models (HP/Symmertricom/Microsemi) 
> to acquire OR to avoid??
> 
> greg
> —

I use Mini-Circuits ZN4PD1-50-S+  with added DC blocking  as they are not 
specifically GPS splitters.  Cheap and effective.

>> I've decided I need more clocks :)
>> 
>> Dave
> 
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George Bernard Shaw

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Re: [time-nuts] What's the magic recipe for setting the date on KS-24361

[Mike Cook]

> Le 21 sept. 2017 à 06:30, Hal Murray  a écrit :
> 
> 
> I removed the antenna, power cycled, set the date, status looked good.
> Then I reconnected the antenna.
> After a while, if found some satellites and time jumped back to 1998.
> 
> Did I miss a step?
> 
> I used ":GPS:INIT:DATE 2016,09,05 »

I suspect that using 2016 instead of 2017 caused it to be over ridden as the 
week number could be pre-rollover or outside error limits. 

> It was leftover from the last time I set the date on some HP box.
> I just cut/pasted from my notes.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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George Bernard Shaw

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Re: [time-nuts] ***SPAM*** PRS10 PRBB Shematics

[Mike Cook]

> Le 7 oct. 2017 à 19:58, Mark Sims  a écrit :
> 
> SRS sells the connector.   You might want to make sure you have a tube of 
> ass-lube handy when you check the price...  It's around three times the 
> distribution price.  SRS really should have used a standard D-sub and a 
> couple of SMA connectors.
> 
> I considered laying out a PRBB clone, but didn't want to mess with sourcing 
> that damn connector.  I wound uo buying the PRBB and the heatsink (and a tube 
> 'o lube).   Spent more for those than the PRS-10.   The heatsink they ship 
> now does not seem to be nearly as good as the older one.  Also be aware that 
> the SRS ordering page is not HTTPS and your credit card info is sent in plain 
> text...  you might want to order over the phone.
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Re: [time-nuts] current crop of GPS receivers for Rpi/Beaglebone for NTP server/etc

[Mike Cook]

> Le 16 oct. 2017 à 15:45, jimlux  a écrit :
> 
> I have beagles, but others have pis.
> 
> There seem to be dozens of GPS receivers out there in a variety of form 
> factors.
> 
> What's the current "best" inexpensive choice for run of the mill 
> time-setting/1pps  that's a "catalog » item

Best I don’t know, but I have used Adafruit’s Ultimate GPS Hat for Raspberry PI 
 since May 2014 with no issues and good perf.
I have seen no PNP GPS capes for the BBB other than those configured for 
tracking apps so I have been using the mini modules with various Ublox chips. 
All wire and sticky tape. 

> 
> Plenty of online "how-to" from 2013 and 2014, but we here on the list know 
> that the "cheap GPS" receiver business is a very moving target - 4 years is a 
> long time.
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Re: [time-nuts] How do I compare GPS antennas?

[Mike Cook]

> Le 6 sept. 2017 à 04:23, Hal Murray  a écrit :
> 
> Was
>  Subject: Re: [time-nuts] GPS Antenna Feed Line Decision
> 
> kb...@n1k.org said:
>> There is pretty much no experiment you could run that would show a
>> difference  between the two. With a normal GPS, the “front end” of the radio
>> is in the antenna. The filtering and RF amplification there determine a lot
>> of things. The cable is just a  chunk of wire in the middle of the system.  
> 
> Does that depend on the antenna (and location) being "good" and both coaxes 
> being good-enough so that the receiver always has a good signal?  
> Alternatively, if the signal is good, you can't tell the difference in a few 
> db of attenuation.
> 
> But suppose the antenna location isn't good.  How can I tell if it is 
> good-enough?  Or how can I compare location A with location B?

  Good location depends on a couple of things.
   How much sky your antenna can see clearly.
   Are there any near/far objects that can create reflections.
  The first is easy with an eyeball.
  The second you can determine by monitoring the satellite map to see if it is 
reporting signals from satellites that should not be visible.  
  The receivers I have tried are good at ignoring reflections when there is 
ALSO line of site visibility but they can get confused when there is only a 
reflected signal.
  In my case, I have learned to do to site surveys and any experimental 
measurements in the periods when there are no reflections. 

> 
> The best I have been able to come up requires two identical receivers.  You 
> can verify that they are identical, or at least close enough, by running them 
> from a single antenna with a splitter.  I haven't gotten past that.

 I doubt that you need to measure the two locations simultaneously. Using the 
same receiver at both in succession for comparison should be good enough.

> 
> Assuming you had a not-good antenna, is there any numerical scale that would 
> be useful to describe its goodness?

 The signal quality reported by the graphic utilities in comparison with a « 
good » one.
 I tried a few and picked those which got the highest quality. 
For SVs that have LOS I get 36-47 whatever the scale is measured in (Motorola 
use C/No «  carrier to noise density » , while U-blox use Db (SNR)).
These seem to be typical values from some doc I saw on the web. It seems to be 
good enough. 

> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] GPS Antenna Feed Line Decision

[Mike Cook]

> Le 5 sept. 2017 à 16:17, Bob kb8tq  a écrit :
> 
> Hi
> 
> 
> 
>> On Sep 5, 2017, at 6:06 AM, Hal Murray  wrote:
>> 
>> 
>> Clay Autery  said:
>>> I will use something better than RG-59 or RG-6 (even if it is only "better"
>>> in my opinion).
>> 
>> Crazy thought department.  Can you also run a parallel run of RG-6 and run 
>> some tests to see if you can measure the difference?
> 
> There is pretty much no experiment you could run that would show a difference 
> between the two. With a normal GPS, the “front end” of the radio is in the 
> antenna. The
> filtering and RF amplification there determine a lot of things. The cable is 
> just a 
> chunk of wire in the middle of the system. 

Agreed.
I tried to see if there was any difference in the signal quality reported by 
Motorola UT+ and U-Blox Neo 6M (not timing grade but has a good 1PPS) over 30m 
of 2 different cable types.
I only had RG58(75 Ohm) and RG174(50 Ohm) . I used the signal quality graphics 
of the respective manufacturers utilities winoncore12 and u-center. There was 
very little visible difference in the levels and reported resolved positions 
were as in the same ball park ( I never get exact replication after surveys ). 
Neither was there any significant difference in the 1PPS signal. I only have a 
2 channel scope so had to measure each seperateley against a standard (PRS10). 
The receivers 1PPS quantization swamps the difference in the cable delay (which 
I was able to differentiate when measured separately). 
It make sense as the GPS signals are very weak and the receivers are good at 
getting data out, so just throwing in a bit of extra attenuation and noise 
doesn’t phase them at all. 

I was thinking of doing a test with just a twisted pair…. 


> 
> Bob
> 
> 
>> 
>> 
>> -- 
>> These are my opinions.  I hate spam.
>> 
>> 
>> 
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Re: [time-nuts] Very large X9.2 solar flare.

[Mike Cook]

When I saw the OP I did a quick check of my GPS receivers status. One of them, 
a Jackson Labs M2M replacement (actually a U-blox M8T) had just reset and gone 
to a 111ms offset.
Was that due to the CME?
Was it one of Murphy’s laws « Looking for problems actually creates them » ?
Or a result of Heisenberg’s principle in the macroscopic domain « You can’t 
measure something without disturbing it » ? 


> Le 7 sept. 2017 à 09:08, Andy  a écrit :
> 
>> 
>> The flare has been and gone!...is this another case of journalists
>> mixing up a flare with a CME ?
>> 
> 
> There was some of both.  SDO saw a flare, STEREO saw a CME.
> 
> Andy
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Re: [time-nuts] ***SPAM*** Looking For Z3801A Software

[Mike Cook]

> Le 29 août 2017 à 19:05, Richard Solomon  a écrit :
> 
> I came across an HP Z3801A that I had not unpacked, been sitting
> 
> in the box for 11 years !!
> 
> 
> Plugged it in and in about 30 minutes it showed a GPS Lock !!
> 
> 
> Now, the software I have so far found was designed in the Pre-
> 
> Cambrian era and will not work on my 64 bit WIN10 system.

I think that you will find that this fits the bill.

http://www.ke5fx.com/heather/readme.htm

> 
> 
> Is there any software (preferably free) out there that will work
> 
> with WIN10 ??
> 
> 
> Thanks, Dick, W1KSZ
> 
> 
> Sent from Outlook
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Re: [time-nuts] PRS10 PRBB Shematics

[Mike Cook]

Hi Jacques,
  I’ve bought three of these PRBB for my PRS10s and got none of the information 
that you are interested in supplied by SRS.
As you are asking for the Cannon connector used, I presume you don’t have one 
and maybe want to make one up? 
I have removed one and confirm that the Cannon connector is that described in 
the Operation and Service manual.
Unfortunately the parts are not in that manuals parts list. 

The connectors on mine are marked DAM-11WSM-A197   

You can get both that and the coax connector insert,DM53740-5008,  from Digikey 
for instance. Note the 2nd M is not in the Digikey reference.

Conceptually it looks pretty simple, with 10MHZ and 1PPS IN being just passed 
through and the data signals being inverted with a 74HC14D.
So there is no full RS232 conversion, limiting cable length probably. 
The 1LOCK/1PPS OUT signal through Cannon pin 1 appears to be double inverted 
before being fead to the BNC, to enable a LOCK lead to be lit as well as having 
the positive going  but narrow pulse.  

Mike

> Le 6 oct. 2017 à 23:19, Jacques Tiete  a écrit :
> 
> Fellow timenuts,
> 
> I’d like to find some more info about the SRS “PRBB” breakout board for the 
> PRS10, schematic diagram, parts list (eg. the cannon pcb connector used) and 
> all relevant info.
> An internet/timenuts research did not turn up anything relevant.
> 
> 
> thanks & 73’s,
> 
> Jacques
> 
> 
> Jacques Tiete
> jacq...@tiete.org
> GSM: 32(0)499 99 83 78
> 
> 
> 
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George Bernard Shaw

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Re: [time-nuts] PRS10 PRBB Shematics

[Mike Cook]

I couldn’t find the entire connector anywhere. 
The unpopulated D-Sub Digikey id is DAM-11W1SM-A197 (sorry, I had dropped the 1)
I couldn’t find a european distributer. Mouser has no stock. 

> Le 7 oct. 2017 à 16:06, Jerry <jster...@att.net> a écrit :
> 
> Mike
> 
> I searched Digikey for the canon connector but could not find it... they do 
> have the coax insert part number you listed.  Are you aware of any other 
> source for the entire connector? 
> 
> Jerry, NY2KW
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Cook
> Sent: Saturday, October 07, 2017 9:16 AM
> To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
> Subject: Re: [time-nuts] PRS10 PRBB Shematics
> 
> Hi Jacques,
>  I’ve bought three of these PRBB for my PRS10s and got none of the 
> information that you are interested in supplied by SRS.
> As you are asking for the Cannon connector used, I presume you don’t have one 
> and maybe want to make one up? 
> I have removed one and confirm that the Cannon connector is that described in 
> the Operation and Service manual.
> Unfortunately the parts are not in that manuals parts list. 
> 
> The connectors on mine are marked DAM-11WSM-A197   
> 
> You can get both that and the coax connector insert,DM53740-5008,  from 
> Digikey for instance. Note the 2nd M is not in the Digikey reference.
> 
> Conceptually it looks pretty simple, with 10MHZ and 1PPS IN being just passed 
> through and the data signals being inverted with a 74HC14D.
> So there is no full RS232 conversion, limiting cable length probably. 
> The 1LOCK/1PPS OUT signal through Cannon pin 1 appears to be double inverted 
> before being fead to the BNC, to enable a LOCK lead to be lit as well as 
> having the positive going  but narrow pulse.  
> 
> Mike
> 
>> Le 6 oct. 2017 à 23:19, Jacques Tiete <jacq...@tiete.org> a écrit :
>> 
>> Fellow timenuts,
>> 
>> I’d like to find some more info about the SRS “PRBB” breakout board for the 
>> PRS10, schematic diagram, parts list (eg. the cannon pcb connector used) and 
>> all relevant info.
>> An internet/timenuts research did not turn up anything relevant.
>> 
>> 
>> thanks & 73’s,
>> 
>> Jacques
>> 
>> 
>> Jacques Tiete
>> jacq...@tiete.org
>> GSM: 32(0)499 99 83 78
>> 
>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to 
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> "The power of accurate observation is commonly called cynicism by those who 
> have not got it. » George Bernard Shaw
> 
> ___
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> 
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Re: [time-nuts] NTP linked PC clock is slightly ahead of Lady Heather GPS time

[Mike Cook]

I have Win7-64 and my LH and system time are the same (with a very short delta 
of < 0.2s probably due to their respective window update time).
I use the Meinberg disturb of NTP. My client’s offset from the paris 
observatory is less than a millisec.

Maybe you should check your NTP status and see what offset you get from a known 
good source with ntpdate -b -d .




> Le 11 oct. 2017 à 13:29, Chris Wilson  a écrit :
> 
> 
> 
>  11/10/2017 12:24
> 
> Probably   a   simple  answer,  but I am curious as to why my PC clock
> which  is set by NTP on Windows 7 64 bit OS is ahead of Lady Heather's
> time,  locked  to  a  Trimble  Thunderbolt  by  about  half  a  second
> (guesstimate..)  I  caught  a screen shot of the discrepancy just now,
> it's at http://www.gatesgarth.com/time.jpg
> 
> I use NTP for low signal WSPR transmissions and a second out isn't the
> end  of  the  world,  if  indeed  something  IS out. More academic than
> problematic, thanks
> 
> -- 
>   Best Regards,
>   Chris Wilson.
> mailto: ch...@chriswilson.tv
> 
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Re: [time-nuts] inexpensive, black box, GPS or NTP based TTL time capture?

[Mike Cook]

On the home brew side there are GPS receivers (Ublox Lea 6T and Lea M8T) that 
will time tag incoming signals to sub usec resolution . You of course need a 
PC/micro to configure and read the data.
Also, if you are prepared to have a Beaglebone Black in your box you can use 
one or both of the two Programmable Real-time Units, modules in the SOC that 
are completely independant of the CPU running linux, to also get sub usec 
resolution. Programming required. 


> Le 18 oct. 2017 à 17:26, Attila Kinali  a écrit :
> 
> On Wed, 18 Oct 2017 08:47:58 -0600
> Rob Seaman  wrote:
> 
>> I’m at the annual planetary sciences meeting (in Provo this year) and 
>> several 
>> groups have expressed interest in duplicating our setup (details of FO 
>> converters, Schmitt triggers, etc, omitted) in a “cheap black box” to quote
>> one fellow. Lots of people contribute productively to NEO observations, 
>> including amateurs and small teams with little funding. Improving their 
>> timekeeping would help keep rocks from falling on you and your family.
> 
> What is this black box supposed to do? Just provide a PPS? IRIG-B?
> Or does it need to have time-stamping capabilities? If so, how many
> channels?
> 
> What are your time precision/accuracy requirements?
> 
> What how cheap is "cheap"? What is the volume?
> 
>   Attila Kinali
> -- 
> It is upon moral qualities that a society is ultimately founded. All 
> the prosperity and technological sophistication in the world is of no 
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Newbie to Time Nuts; Seeking wisdom, re Hydrogen MASER applications

[Mike Cook]

> Le 13 nov. 2017 à 01:29, Hal Murray  a écrit :
> 
> 
> apollo...@gmail.com said:
>> prior to my senior project most geodetic surveyors  used a Wooden boxed,
>> marine chronometer, to get sub second UT1 time, or  back then, GMT
> 
> How did you get the data out of the wooden box?
> 
  I have a couple of marine chronometers that have electrical contacts closing 
once a second. This signal is relayed by wires to terminals on the outside of 
the box.
  One came from a Tashkent astronomical observatory and is Sidereal time rated, 
the other is a nautical instrument which would probably have been connected to 
slave clocks.   
  

"The power of accurate observation is commonly called cynicism by those who 
have not got it. »
George Bernard Shaw

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Re: [time-nuts] Deaf Z3801

[Mike Cook]

> Le 15 nov. 2017 à 04:43, Bob Bownes  a écrit :
> 
> 
> I put my 3801 back in service the day before yesterday, or tried to. It’s 
> been on the shelf for about a year (off). 
> 
> I powered it up, and while it sees a few sats, it will not acquire any. 
> Changing to a known good antenna (off the NTP server) makes no difference. 
> 
> Anyone seen the behavior before? The location data is good, but the time/date 
> are way out. 

  Probably GPS week rollover. I think the fix is to power it up with the 
antenna disconnected, set te date and time manually and then reconnect the 
antenna.

> 
> Thanks!
> Bob
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Re: [time-nuts] H-maser drift

[Mike Cook]

Thanks for that input John. 

> Le 21 nov. 2017 à 21:26, John Ponsonby  a écrit :
> .
> 7. The RF discharge generates UV. This shines up the beam path and 
> illuminates the bulb coating in the region where the incoming atoms first 
> make contact with the bulb coating. This UV undoubtledly damages the FEP120 
> coating. The deterioration of the coating may be one of the causes of long 
> term drift.

Your excellent contribution addresses an issue of long term drift but Dana 
Whitlow’s question in a previous post which I repeat here related to a short 
term issue.

«  On the day of eye passage over the site ( of the eye of a hurricane) the 
frequency suddenly decreased by a few parts in 10^14, held about constant for 
roughly a week,then
resumed almost its original value and drift rate thereafter. « 

Maybe you could shine some light on that reported temporary frequency offset. 


> Cheers
> John P
> 
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Re: [time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

[Mike Cook]

> Le 15 déc. 2017 à 14:06, Attila Kinali  a écrit :
> 
> On Fri, 8 Dec 2017 09:40:29 -0800
> Tom McDermott  wrote:
> 
>> Researchers at Oxford U. have fabricated an atomic reference based on
>> a single nitrogen molecule inside a 60-atom carbon sphere ("Fullerene").
>> The cage of carbon isolates the nitrogen from external electric fields,
>> and they've developed a method to also isolate it from external magnetic
>> fields.
> 
> The original paper in question is [1]. As with the nitrogen vacancy
> clocks, which also trap nitrogen within a Carbon lattice, these have the
> drawback of quite high temperature coefficients, Harding et al measured 
> 89ppm/K.

I wonder if Cs-133 can be inserted into C-60 fullerene? If it could, then a 
primary reference on a chip might be possible.

> 
>   Attila Kinali
> 
> 
> [1] "Spin Resonance Clock Transition of the Endohedral Fullerene 15N@C60",
> by Harding, Zhou, Zhou, Myers, Ardavan, Briggs, Porfyrakis, Laird, 2017
> https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.140801
> -- 
> It is upon moral qualities that a society is ultimately founded. All 
> the prosperity and technological sophistication in the world is of no 
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Newbie to Time Nuts; Seeking wisdom, re Hydrogen MASER applications

[Mike Cook]

> Le 13 nov. 2017 à 12:12, Hal Murray  a écrit :
> 
> 
> michael.c...@sfr.fr said:
 prior to my senior project most geodetic surveyors  used a Wooden boxed,
 marine chronometer, to get sub second UT1 time, or  back then, GMT
> 
>>> How did you get the data out of the wooden box?
> 
>>  I have a couple of marine chronometers that have electrical contacts
>> closing once a second. This signal is relayed by wires to terminals on the
>> outside of the box. 
> 
> That gets you seconds if you count them.  How do you get sub seconds?  Just 
> count time since the PPS using a normal crystal and it will be good enough?

 In a sense.. When I was in the merchant navy in the 60s there were no crystal 
watches, so when taking sights we « transferred time » to a good 1/5sec 
stepping deck watch previously synchronized to the chronometer which of course 
was kept in the shelter of the Bridge. As this was done just prior to sights 
the offset would be known to less than or equal to that increment.  Marine 
chronometers may not be particularly accurate, but they can be extremely stable 
at about +/- 0.2sec or better per day variation. The daily drift being known 
from the clocks last rating, getting accurate offset timing from GMT was 
possible. The clocks themselves were re-rated every year. I’m in France and I 
don’t think that any borders in Europe were defined by astronomical 
observation, but in the US I believe that at least some of the state borders 
were thus fixed. As a second’s error in time will be about a nautical mile in 
US latitudes, I wonder if anyone has measured with GPS, how good the original
  surveys were.?


> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] ***SPAM*** Re: Why discipline Rubidium oscillator?

[Mike Cook]

> Le 20 nov. 2017 à 20:53, Dana Whitlow  a écrit :
> 
> 
> 
> In my pre-retirement job I rode herd on an active Hydrogen maser system,and 
> even
> that has a clear drift tendency.  Generally a couple or three times per
> year I had to make a frequency adjustment in the neighborhood of 3E-14.  And 
> still being
> privy to its performance, I was amused to note that its drift tendency was
> interrupted by the hurricane Maria.  On the day of eye passage over the site 
> the frequencysuddenly
> decreased by a few parts in 10^14, held about constant for roughly a week,then
> resumed almost its original value and drift rate thereafter.  If anybody 
> inthis group
> can explain* that* behavior (that is, held for a week before resuming old
> habits), I’d love to learn about it.

  You don’t mention the make of the instrument, but I suspect the same basic 
technology is used by all.
To quote from the Oscilloquartz page on their CH1-76A product:
«  The quantum device is used as a frequency discriminator in an automatic 
frequency tuning system of a crystal oscillator. » 
They don’t however quote stability relative to air pressure. However…..
It is known that atmospheric pressure changes can induce OCXO frequency changes 
due to deformation of the crystal envelope causing stray capacitance changes.
As the eye of a hurricane has greatly reduced air pressure than normal, by as 
much as 15%, it could be related.


> 
> Dana
> 
> 
> On Mon, Nov 20, 2017 at 1:40 PM, Bob kb8tq  wrote:
> 
>> Hi
>> 
>> There is no direct relation for an Rb to 10 MYz. Cs beam tubes are what
>> have a direct relation.
>> Even then, the qualifier is “under standard conditions”. They are
>> sensitive to magnetic field. Rb’s
>> also are sensitive to magnetic field. Both can be tuned by varying the
>> field. In the case of an Rb
>> that also takes care of a multitude of other issues.
>> 
>> In the case of Rb, there is a distribution of cells coming out of the
>> manufacturing process. Some
>> are pretty close to the “right” frequency. Others are way off (as in 100’s
>> of KHz or more). All of them
>> are capable of meeting the required specs. DDS techniques allow those
>> cells to be used in a
>> production part. That increases the yield and thus drops the production
>> cost.
>> 
>> Since you now magically have a DDS in the Rb, you can do all sorts of
>> interesting things. If you
>> suddenly need a 9.99900 MHz standard …. here it is … If you need to do
>> temperature compensation
>> via a lookup table … it just takes a bit of testing and some code to make
>> it happen. Indeed, the DDS
>> does also give you some issues. Without some sort of cleanup oscillator,
>> you will have spurs and
>> phase noise on the output.
>> 
>> Lots of fun ….
>> 
>> Bob
>> 
>> 
>>> On Nov 20, 2017, at 1:34 PM, Jerry Hancock  wrote:
>>> 
>>> I know this is going to sound dumb as I know many GPSDOs had rubidium
>> oscillators in them.  I can see why, in that during holdover, they would
>> tend to be more stable vs others, but given that there is a direct
>> mathematical relationship between the rubidium frequency and potentially
>> the 10Mhz desired output frequency, why do they have to be disciplined or
>> better yet, what advantage does it bring?  Also, I can see how you
>> discipline a DOCXO with the external voltage, how do you discipline a
>> rubidium?  Pulse stretching?
>>> 
>>> I guess I don’t understand how the technology works, but it seems like
>> an RF signal is swept that would be used to detect a dip at a pretty well
>> defined frequency.  This dip can be used to discipline the oscillator to
>> something like 9Ghz or a factor of what, 900+ times better than 10Mhz.  So
>> wouldn’t that be able to get your desired 10Mhz to 10,000,000.001 or pretty
>> much my level of measurement?  Or does is the dip not quite that precise?
>> If you can point me to a write-up on this I’ll go away.
>>> 
>>> Thanks to Gilbert for providing me with at least one rubidium oscillator
>> that is working out of 5 though 2 others seems to stay locked for a few
>> hours during my testing.
>>> 
>>> Jerry
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Re: [time-nuts] ***SPAM*** Re: Designing an embedded precision GPS time server

[Mike Cook]

> Le 29 oct. 2017 à 11:29, Leo Bodnar  a écrit :
> 
> 
> If you are making an open source thing you might want to use Laureline NTP 
> http://partiallystapled.com/pages/laureline-gps-ntp-server.html as a starting 
> point or as a performance yardstick.  I have never seen one so can't comment 
> on how well it works but if done properly it should be reasonably solid and 
> agile.  I think the guy who designed it also sells them commercially but from 
> what I can see the design is also available for others to use.

I bought one of these  three  years ago. It is very reliable and the perf is 
very good. I attach a couple of shots from this morning. 



It does not unfortunately propagate the leap second status. But as I use the 
NIST files that is not a problem.


> 
> Leo
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Re: [time-nuts] Designing an embedded precision GPS time server

[Mike Cook]

> Le 29 oct. 2017 à 11:29, Leo Bodnar  a écrit :
> 
> If you are making an open source thing you might want to use Laureline NTP 
> http://partiallystapled.com/pages/laureline-gps-ntp-server.html as a starting 
> point or as a performance yardstick.  I have never seen one so can't comment 
> on how well it works but if done properly it should be reasonably solid and 
> agile.  I think the guy who designed it also sells them commercially but from 
> what I can see the design is also available for others to use.
> 

Try again.Sorry if some of you got a SPAM header.. My client has issues.

I bought one of these  three  years ago. It is very reliable and the perf is 
very good. I attach a couple of shots from this morning. 


Unfortunately it does not propagate leap seconds.

> Leo
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Re: [time-nuts] On the IETF leap-seconds.list SHA1

[Mike Cook]

> Le 21 déc. 2017 à 07:01, Anders Wallin  a écrit :
> 
>> 
>>> For the Paris Observatory and USNO files my program agrees with the SHA1s
>>> in the files.
>>> For the IETF file there seems to be one byte, a "0" at the start of the
>>> third group of 8 hex characters missing.
>> 
>>   This is not a bug but a « feature ». From the ntpd leap hash checking
>> code:
>> 
>> * The NIST code creating the hash writes them out as 5 hex integers
>> * without leading zeros.
>> 
>>   Still, it a little unorthodox and complicates the code.
>> 
> 
> Ha! Thanks for explaining this.
> Indeed I find writing out the SHA-1 in groups of 8 characters without
> leading zeroes quite surprising and undocumented.
> The comments in leap-seconds.list about the SHA-1 refer to a /sha or
> /pub/sha folder - is that generic information on the SHA-1 or is there any
> inidication of the 8-char/leading-zeroes convention there?
> I quickly looked at FIPS-180 but didn't find anything about leading zeros
> there.

My guess is that during testing the NIST guy who created the program to print 
the list never hit the case where the integer created a less than 8 character 
hex output.
Probably used %8x instead of %08x in his format statement, or something analog 
if it was not C.  A case of «  economy of thought » .

> 
> I am still unable to access the NIST ftp-site linked earlier in this thread.
> 
> Anders
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Re: [time-nuts] On the IETF leap-seconds.list SHA1

[Mike Cook]

> Le 20 déc. 2017 à 12:51, Anders Wallin  a écrit :
> 
> Hi all,
> So I'm doing the typical Wednesday thing you might do, that is writing a
> small script for checking the SHA1 checksum in leap-seconds.list files.
> I came up with [1] which produces output [2].
> 
> For the Paris Observatory and USNO files my program agrees with the SHA1s
> in the files.
> For the IETF file there seems to be one byte, a "0" at the start of the
> third group of 8 hex characters missing.
> 
> This is somewhat funny/alarming, since the IETF leap-seconds.list is the
> first thing that shows up (at least for me) on google when looking for
> leap-seocnds.list.

   This is not a bug but a « feature ». From the ntpd leap hash checking code:

 * The NIST code creating the hash writes them out as 5 hex integers
 * without leading zeros. 

   Still, it a little unorthodox and complicates the code.
  
> 
> Please do add to and improve on my code on github - if this is your sort of
> thing ;)
> 
> happy holidays!
> Anders
> 
> [1]
> https://github.com/aewallin/leap-seconds.list_sha1_check/blob/master/leap_sha.py
> [2]
> https://github.com/aewallin/leap-seconds.list_sha1_check/blob/master/output.txt
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Re: [time-nuts] Ultra low power RTC

[Mike Cook]

> Le 7 mars 2018 à 11:10, Attila Kinali  a écrit :
> 
> On Tue, 6 Mar 2018 21:57:32 -0500
> Bob kb8tq  wrote:
> 
>> Assuming you are going to run it off a battery. What’s the self discharge
>> rate on a reasonable battery? 
> 
> With supply currents below 100nA you can assume that you are likely
> to be limited by the self-discharge using coin sized LiMnO2 cells
> (e.g. a CR2032 is specced in the order of 100-300nA self-discharge).
> For the smaller cells, you have to check which one is larger, but
> they are of the same order of magnitude.

This is interesting. When you talk of self discharge, is there any way of 
harnessing that. Is that what the chip manufactures are doing?

> 
> 
>   Attila Kinali
> -- 
> It is upon moral qualities that a society is ultimately founded. All 
> the prosperity and technological sophistication in the world is of no 
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] PRS10 Information and help needed

[Mike Cook]

Hi Arnold,
  It looks like your oscillator is locked to the rubidium and it is configured 
to lock to an incoming PPS sig, but the TT value is null, so maybe you have 
forgotten to connect the GPS? Or maybe to the wrong connector? Check the PPS in 
to see if you have a good signal. 
I don’t know about the ranges of the ad5,ad9 values. Yours are a little  lower 
than the one I have been looking at?
regards,
Mike


> Le 28 févr. 2018 à 22:14, Arnold Tibus  a écrit :
> 
> Hello Michael and Tom, thanks for the quick reaction!
> 
> Of course I did already think that the rubidium cell doesn't work any more, 
> but then I was astonished after more than 1 hour running how precise the 
> output frequency is and I could not see a drift beyond the natural noise/ 
> fluctuations which I can see as well with Tr. Thundelbolt. I did not yet look 
> deeper e.g. observing the longtime behaviour nor did I open the box (yet), 
> anyway I don't know much about the electronic internals.
> I have running the RbMon and looked to the data list which I have annexed. It 
> doesn't explain much for me therefore I am asking for help and support to 
> find possible solutions, there are so much excellent experts out here.
> I am worried that in fact the Rb capsule went over the Jordan ... perhaps it 
> can be revitalized but I have no experience with it.
> I doupt a bit the lamp heater control value etc., ad5 to ad9.
> What is the range ... ? How shall one understand these and other values?
> But finally, how can one improve the situation?
> 
> I am open for all good hints, instructions and ideas! (I am sure that there 
> are other timenuts also interested ;-)  )
> 
> many thanks in advance
> 
> Arnold
> 
> Am 28.02.2018 um 21:02 schrieb Michael Wouters:
>> Hello Arnold,
>> A frequency offset of a part in 10E-11 still sounds healthy to me. I wonder
>> whether there is some kind of electronic problem?
>> I have run 40 or so PRs10s and the lamp is the usual bit that dies.
>> If you hook up a computer to the RS232 port, there are lots of diagnostics
>> available.
>> Cheers
>> Michael
>> On Thu, 1 Mar 2018 at 5:47 am, Arnold Tibus  wrote:
>>> Hello fellow timenuts,
>>> 
>>> for my old PRS10 I need some information and help with technical
>>> informations.
>>> I have this item bought quite some years ago and I have manufactured an
>>> interface cable with the special connector last year. Did work fine.
>>> Taken out of storage I do get anymore the lock and PPS signal out.
>>> The 10 MHz output does look very good, the unloaded sine voltage is 2.8
>>> Vpp and the frequency is very precise and stable very close to the
>>> trimble thunderbolt GPS-out signal at abt. 10E-11.
>>> In the annex you can see the data output with more delailed info.
>>> Can somebody tell me more, is the life at the end and what and how can
>>> be done to revitalize this nice time machine? How much time more is
>>> expectable?
>>> 
>>> kind regards,
>>> 
>>> Arnold
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Re: [time-nuts] NEO-7 GPS default 1pps width?

[Mike Cook]

I have 6M and 8M and they are both 100ms 1PPS signals. Interpolate.

> Le 8 avr. 2018 à 15:51, jimlux  a écrit :
> 
> I've got some NEO-7Ms here, and without an oscilloscope handy - what's the 
> factory default 1pps pulse width?
> 
> The manual says pulseLenRatio is zero and pulseLenRatioLock is 100,000 (us)
> flags-lockedOtherSet is 1, so I think that means "only generate 100ms pulses 
> when locked"
> 
> 
> Does that align with anyone else's experience?
> 
> Tnx
> Jim
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are giving  power to.

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Re: [time-nuts] Any guesses as to how Citizen is claiming ±1 second/year with using this AT-cut 8.4MHz XTAL?

[Mike Cook]

I have a Citizen A660 movement which was spec’d at +/- 5 secs per year. I 
monitored it from when I bought it in December 2010 until its battery failed on 
03/11/2012. 
It was in spec when both on and off the wrist (off the wrist it was in a drawer 
at a constant temperature and the accuracy was a stability was lower) . 
The error in the first 18 months gave a yearly rate of +1,2 secs. Not bad. So 
maybe the new movement is just getting the advantage of higher frequency so 
that their cycle hops are finer grained.



> Le 11 avr. 2018 à 22:24, Bob kb8tq  a écrit :
> 
> Hi
> 
> Guess at the aging
> 
> Cut the crystal so it’s fairly flat at 25 to 35C
> 
> Do a basic / simple temperature compensation (TCXO)
> 
> …. and count on the errors to average out. 
> 
> The success of all that will depend a lot on how close your wrist is to the 
> environment they used for their guesswork. Did they count on you taking
> the watch off at night or not? What temperature is the room at? …..
> 
> Before you say it can’t be done, the whole “average out” thing is how time 
> pieces have been done for hundreds of years. The device may swing this 
> way and that …. done properly it eventually averages out. How well it works
> for you … that depends. 
> 
> Bob
> 
>> On Apr 11, 2018, at 12:26 PM, tn...@joshreply.com wrote:
>> 
>> That comes out to about 30ppb, and this is a pocket watch so they don’t seem
>> to depend on the temp stabilization of being attached to a human wrist. 
>> 
>> 
>> 
>> https://www.ablogtowatch.com/wp-content/uploads/2018/03/Citizen-Cal-0100-Eco
>> -Drive-Movement-04.jpg
>> 
>> 
>> 
>> I’ve been reading about the new watch that contains this crystal for about a
>> month, but just saw some more detail today
>> 
>> 
>> ---
>> 
>> AT-CUT QUARTZ CRYSTAL OSCILLATOR
>> 
>> While AT-cut quartz crystals have indeed been in production and use since as
>> early as 1934, the technology is more common in larger applications and not
>> necessarily wristwatches. To address the needs of individuals seeking only
>> the most accurate performance in a wristwatch, Citizen sought to apply and
>> optimize this available technology in a way that could serve watch consumers
>> on a more direct and personal level. When working to reach the accuracy of
>> the Cal.0100, Citizen opted for an AT-cut quartz oscillator instead of a
>> more traditional tuning fork shape (XY cut). Perhaps most notably, AT-cut
>> variations allow for greater temperature tolerances, specifically in the
>> range of -40°C to +125°C. Additionally, this configuration allows for
>> reduced deviations caused by wearer orientation, which can cause significant
>> changes in accuracy that aren't negligible when attempting this kind of
>> performance. As a result, wearers will not have to worry about errors caused
>> by spatial orientation and positioning becomes less of a concern. The same
>> can be said about durability, which Citizen also improved upon in
>> conjunction with the AT-cut oscillator. After all, shock experienced in
>> day-to-day situations could easily prove detrimental even for quartz
>> movements. And when the goal is an annual accuracy of ±1 second, that just
>> isn't acceptable.
>> 
>> 
>> 
>> https://www.ablogtowatch.com/citizen-cal-0100-eco-drive-watch-movement/
>> 
>> ---
>> 
>> 
>> 
>> Is this possible with an MXCO running across this wide temp range? How are
>> they compensating for aging at this level of precision?
>> 
>> 
>> 
>> Thanks!
>> 
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