[time-nuts] time nuts overflow / gentle reminder

[Tom Van Baak]

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/tvb
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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?

[Dan Rae]

Way back in 1960 something Braun in Germany made a little alarm clock 
using a 4.194304 MHz crystal which could reach this level of accuracy.  
I had one and it certainly met the Harrison level of timekeeping when I 
used it for navigation.  I think that the crystal cut used had a 
temperature coefficient at room temperatures that had minimal variation 
at around this frequency.   Way better than the 32+ kHz crystals used now.


The clock died in the end but I still have the crystal somewhere :^)

Dan


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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?

[Bob kb8tq]

HI

> On Apr 11, 2018, at 5:38 PM, Richard (Rick) Karlquist  
> wrote:
> 
> The aging spec on the 10811 is 5 parts in 10^10 per day.
> After 60 days, it could be off 30 ppb.  So what we
> have here is a non-ovenized AT cut that is better
> than an ovenized SC cut.  I'm sure.

As a practical point - they didn’t leave the factory until they hit that spec, 
Manufacturing
being what it is, having OCXO’s hang around was not a popular thing. The 
5x10^-10
per day at 5 or 10 days might well drop by quite a bit a month or two later. 
Back in the
day, this was a “who knows / who cares / meets spec” sort of thing. 

I’m not sure that everybody buys the “log rule” for aging. I think there are a 
lot of reasonable
objections to it. That aside, if there *is* a rule that applies to 80% of your 
crystals …. that’s 
doing very well. By watch standards that is “perfection”.  Measure something 
over a 10 day
period and plug that into the firmware. Yes, the watch sits in test for 10 days 
… .and you 
charge for that. 


> 
> I am reminded of the old Accutron ads.  The headlines
> guaranteed so many seconds a day or whatever it was.
> The fine print says they don't actually guarantee that.
> The only remedy under that guarantee is that they
> agree to adjust the watch to be in spec at the
> watch repair shop and hand it back to you.  Thus,
> they didn't have to worry about aging.  Just come
> into the shop as often as necessary :-)

I wonder how many watch shops are set up to re-shoot the memory in a watch CPU? 
Most of them seem to have a hard time swapping a battery and keeping things dry 
enough 
that the watch doesn’t fog up in the cold ….

Bob


> 
> Rick N6RK
> 
> On 4/11/2018 9:26 AM, 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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Re: [time-nuts] Cheap jitter measurements

[Hal Murray]

kb...@n1k.org said:
> Except that’s not the way most timers run. The silicon needed to get a
> programable  divider to work at 2.4 GHz is expensive. If you dig into the
> hardware descriptions,  the clock tree feeds something much slower to the
> “top end” of the typical timer in a CPU or MCU. The exception is the high
> perf timers in some of the Intel chips.  There the issue is getting them to
> relate to anything “outside” the chip.

I think I got started in this area back in the early DEC Alpha days.  They 
had a register that counted raw clock cycles.  Simple.  I got stuck thinking 
that was the obvious/clean way to do things.

Many thanks for giving me a poke to go learn more about this area.

That was back before battery operation was as interesting as it is today.  I 
suspect power is more likely the critical factor.  Half the power goes into 
the low order bit, so counting by 4 every 4th cycle rather than 1 every cycle 
saves 3/4 of the power.


> That may be what the kernel does, but it implements the result as a drop /
> add to a counter.  

If the source of time is a register counting CPU clock ticks, and the CPU 
clock (2 or 3 GHz) is faster than the resolution of the clock (1 ns) it will 
be hard to see any drop/add.  However, if the time register is significantly 
slower, then the drop/add is easy to spot.  But all that is lost in the noise 
of cache misses and such.

Here is a histogram from an Intel Atom running at 1.6 GHz.

First pass, using rpcc.
cycles  Hits
24 86932
36904825
48  8011
60   122
72 1
   14411
...
So it looks like the cycle counter gets bumped by 12.  That's a strange 
number.  I suspect it's tangled up with changing the clock speed to save 
power.  There are conflicting interests in this area.  If you want to keep 
time, you need a register than ticks at a constant rate as you change speed.  
If you are doing performance analysis, you want a register than counts cycles 
at whatever speed the CPU is running.  Or maybe I'm confused.

Second pass, using clock_gettime.
  nSec  Hits
   698 2
   768 5
   769 2
   838 3
   908 2
   977 1
   978 3
  1047237102
  1048383246
  1117204072
  1118172490
  1187   275
  1188   135
  1257   263
  125847
  1326 7
  1327   216
...
The clock seems to be ticking in 70ns steps.  That doesn't match 12 clock 
cycles so I assume they are using something else.

>From another system:
Second pass, using clock_gettime.
  nSec  Hits
19 45693
20347538
21591129
22 15284
2363
2434
2532
...
Note that this is 50 times faster than the previous example.

I haven't figured out the kernel and library software for reading the clock.  
There is a special path for some functions like reading the clock that avoids 
the overhead of getting in/out of the kernel.  I assume there is some shared 
memory.
  https://en.wikipedia.org/wiki/VDSO

Again, thanks Bob.

TICC arrived today.


-- 
These are my opinions.  I hate spam.



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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?

[Hal Murray]

kb...@n1k.org said:
> 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.  

There is a wonderful message in the archives someplace that describes how to 
adjust a watch.  The recipe is roughly:
  Adjust watch to run correctly in the shop.
  Give it to customer.  Tell him to come back after a week of normal use.
  Measure offset.
  Adjust watch to compensate for that offset.

That probably doesn't work very well if your watch spends the night on the 
stand and your room temperature changes a lot from summer to winter.


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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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Don’t worry about how powerful the machines are. Worry about who the machines 
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?

[Richard (Rick) Karlquist]

The aging spec on the 10811 is 5 parts in 10^10 per day.
After 60 days, it could be off 30 ppb.  So what we
have here is a non-ovenized AT cut that is better
than an ovenized SC cut.  I'm sure.

I am reminded of the old Accutron ads.  The headlines
guaranteed so many seconds a day or whatever it was.
The fine print says they don't actually guarantee that.
The only remedy under that guarantee is that they
agree to adjust the watch to be in spec at the
watch repair shop and hand it back to you.  Thus,
they didn't have to worry about aging.  Just come
into the shop as often as necessary :-)

Rick N6RK

On 4/11/2018 9:26 AM, 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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Re: [time-nuts] suggestions on getting 24 Mhz ?

[Tom Van Baak]

Pete,

Is your goal to make SDR frequency measurements? One solution: grab any 24 MHz 
oscillator you find but use a counter with known accurate timebase 
(Rb,Cs,GPSDO) to continuously record its actual frequency. Don't adjust the 
frequency; just record it. Then, apply those readings as corrections to your 
SDR measurements. This software (or pencil & paper) correction method should 
give equivalent results as an atomic- or GPS-disciplined 24 MHz timebase.

/tvb

- Original Message - 
From: "Pete Lancashire" 
To: "Discussion of precise time and frequency measurement" 
Sent: Wednesday, April 11, 2018 3:00 AM
Subject: [time-nuts] suggestions on getting 24 Mhz ?


> Needed for SDR project as external clock source.
> 
> -pete
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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?

[Bob kb8tq]

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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Re: [time-nuts] suggestions on getting 24 Mhz ?

[Mark Goldberg]

On Wed, Apr 11, 2018 at 11:15 AM, Bob kb8tq  wrote:

> Hi
>
> > On Apr 11, 2018, at 12:11 PM, Graham / KE9H 
> wrote:
> >
> > Phase noise is (usually) more important than absolute frequency accuracy.
>
> It’s probably well worth looking into exactly what you are after in terms
> of phase noise,
> spurs, and stability *before* deciding on a solution. In some cases things
> like DDS spurs
> are a non-issue. In other cases phase noise at certain offsets is a really
> big deal, but at
> other offsets … it’s a non-issue.
>
>
I am using the single output Bodnar GPSDO driving a frequency locked Wenzel
low phase noise oscillator and using that for my SDR ADC clock. I am using
it to take phase noise measurements and it certainly is as good as the
references I have available, and matches pretty well with measurements on a
$90k phase noise meter.

The Wenzel eliminates far out spurs from the GPSDO. Note that different
register values may result in the same frequency output of the GPSDO, but
spurs can be very different. For some frequencies and with the right
register values, I expect the GPSDO alone may be good enough for an SDR
clock, but I have not tried.

This is the best I can measure with this setup. I think the ADC noise
limits the far out phase noise.

Offset   Phase Noise
(Hz)   (dBc/Hz)
10 -96.9
20   -103.0
50   -106.9
100 -109.7
200 -117.7
500 -128.4
1,000  -136.4
2,000  -140.1
5,000  -143.1
10,000-144.9
20,000-145.6
50,000-145.7
100,000  -146.2
1,000,000   -146.6

Regards,

Mark
W7MLG
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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?

[Poul-Henning Kamp]

In message <02d201d3d1b1$d7318640$859492c0$@joshreply.com>, tn...@joshreply.com 
writes:

>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. 

For an application where neither phase noise nor jitter matters,
it is certainly feasible to measure the tempco of the X-tal at the
factory and let a micro-power computer use temperature measurements
to model the "perfect" frequency and phase.

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

[tnuts]

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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[time-nuts] Citizen Concept watch: Ultraprecise Eco-Drive movement Calibre 0100

[Brooke Clarke]

Hi:

Claims +/- 1 second per year and is autonomous.  Uses an AT cut crystal at 8,388,608 Hz (2^23 ) and has a custom 
temperature compensation for each watch.  Solar powered, and the hands stop if the watch is in the dark to save power.

http://www.citizenwatch-global.com/100th/product/calibre0100/index.html

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

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Re: [time-nuts] suggestions on getting 24 Mhz ?

[Bob kb8tq]

Hi


> On Apr 11, 2018, at 12:11 PM, Graham / KE9H  wrote:
> 
> Phase noise is (usually) more important than absolute frequency accuracy.

It’s probably well worth looking into exactly what you are after in terms of 
phase noise, 
spurs, and stability *before* deciding on a solution. In some cases things like 
DDS spurs
are a non-issue. In other cases phase noise at certain offsets is a really big 
deal, but at
other offsets … it’s a non-issue. 

Bob


> 
> I suggest some kind of low phase noise master oscillator (OCXO) feeding a
> DDS without an internal multiplier.
> 
> If internal multiplier in DDS, that, rather than the frequency reference
> source will set the phase noise floor of the sampling.
> 
> --- Graham
> 
> ==
> 
> On Wed, Apr 11, 2018 at 11:00 AM, Jerry Hancock  wrote:
> 
>> For and RSP?  I used an HP 3325 locked to my Cs beam and took the signal
>> from the back.  I think I paid no more than $100 for the 3325a and one I
>> got for free.
>> 
>> Regards,
>> 
>> Jerry
>> 
>> 
>>> On Apr 11, 2018, at 4:49 AM, jster...@att.net wrote:
>>> 
>>> Leo Bodnar GPSDO - adjustable Low-jitter GPS-locked precision frequency
>> reference 400 Hz to 810 MHz .  He has a new one, single output for 99
>> british pounds.
>>> 
>>> Jerry NY2KW
>>> 
>>> -Original Message-
>>> From: time-nuts  On Behalf Of Pete
>> Lancashire
>>> Sent: Wednesday, April 11, 2018 6:00 AM
>>> To: Discussion of precise time and frequency measurement <
>> time-nuts@febo.com>
>>> Subject: [time-nuts] suggestions on getting 24 Mhz ?
>>> 
>>> Needed for SDR project as external clock source.
>>> 
>>> -pete
>>> ___
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Re: [time-nuts] Cheap jitter measurements

[Achim Gratz]

Gary E. Miller writes:
> It tests the time to do two back to back clock_gettime().  Output
> looks like this:
>
> # ./clock_test 
> samples 101, delay 1000 ns
> min 67 ns, max 302 ns, mean 176 ns, median 197 ns, StdDev 52 ns
>
> You run it a few times and you will see the granularity in the
> measurements is 10's of ns, or more, depending on your CPU.

…and it has to be 52ns since the timer that's used by the kernel on the
newer rasPi runs off the 19.2MHz clock.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

SD adaptations for Waldorf Q V3.00R3 and Q+ V3.54R2:
http://Synth.Stromeko.net/Downloads.html#WaldorfSDada
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[time-nuts] WWVB information

[Doug Millar via time-nuts]

Hi, My Spectracom 8161 comparator and 8171A clock are chugging right along in 
sync with the proper time. I have only looked at the digital LED output and it 
is within one second of my other WWVB  clocks.  Seems like magic. It came in 
synch about two weeks ago and stayed there. I haven't changed anything in my 
lab or moved the units. Antenna is still the same.  Pictures available. 
Doug K6JEY
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Re: [time-nuts] suggestions on getting 24 Mhz ?

[Graham / KE9H]

Phase noise is (usually) more important than absolute frequency accuracy.

I suggest some kind of low phase noise master oscillator (OCXO) feeding a
DDS without an internal multiplier.

If internal multiplier in DDS, that, rather than the frequency reference
source will set the phase noise floor of the sampling.

--- Graham

==

On Wed, Apr 11, 2018 at 11:00 AM, Jerry Hancock  wrote:

> For and RSP?  I used an HP 3325 locked to my Cs beam and took the signal
> from the back.  I think I paid no more than $100 for the 3325a and one I
> got for free.
>
> Regards,
>
> Jerry
>
>
> > On Apr 11, 2018, at 4:49 AM, jster...@att.net wrote:
> >
> > Leo Bodnar GPSDO - adjustable Low-jitter GPS-locked precision frequency
> reference 400 Hz to 810 MHz .  He has a new one, single output for 99
> british pounds.
> >
> > Jerry NY2KW
> >
> > -Original Message-
> > From: time-nuts  On Behalf Of Pete
> Lancashire
> > Sent: Wednesday, April 11, 2018 6:00 AM
> > To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
> > Subject: [time-nuts] suggestions on getting 24 Mhz ?
> >
> > Needed for SDR project as external clock source.
> >
> > -pete
> > ___
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >
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Re: [time-nuts] suggestions on getting 24 Mhz ?

[Pete Lancashire]

Yea, was also thinking of grabbing one of my 3325B's and hiding it under
the desk :-)

Going to see on Ebay if there are any 24 MHz VXCO's

-pete

On Wed, Apr 11, 2018 at 9:00 AM, Jerry Hancock  wrote:

> For and RSP?  I used an HP 3325 locked to my Cs beam and took the signal
> from the back.  I think I paid no more than $100 for the 3325a and one I
> got for free.
>
> Regards,
>
> Jerry
>
>
> > On Apr 11, 2018, at 4:49 AM, jster...@att.net wrote:
> >
> > Leo Bodnar GPSDO - adjustable Low-jitter GPS-locked precision frequency
> reference 400 Hz to 810 MHz .  He has a new one, single output for 99
> british pounds.
> >
> > Jerry NY2KW
> >
> > -Original Message-
> > From: time-nuts  On Behalf Of Pete
> Lancashire
> > Sent: Wednesday, April 11, 2018 6:00 AM
> > To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
> > Subject: [time-nuts] suggestions on getting 24 Mhz ?
> >
> > Needed for SDR project as external clock source.
> >
> > -pete
> > ___
> > 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.
> >
> >
> > ---
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> > https://www.avast.com/antivirus
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Re: [time-nuts] suggestions on getting 24 Mhz ?

[Jerry Hancock]

For and RSP?  I used an HP 3325 locked to my Cs beam and took the signal from 
the back.  I think I paid no more than $100 for the 3325a and one I got for 
free.

Regards,

Jerry


> On Apr 11, 2018, at 4:49 AM, jster...@att.net wrote:
> 
> Leo Bodnar GPSDO - adjustable Low-jitter GPS-locked precision frequency 
> reference 400 Hz to 810 MHz .  He has a new one, single output for 99 british 
> pounds.
> 
> Jerry NY2KW
> 
> -Original Message-
> From: time-nuts  On Behalf Of Pete Lancashire
> Sent: Wednesday, April 11, 2018 6:00 AM
> To: Discussion of precise time and frequency measurement 
> Subject: [time-nuts] suggestions on getting 24 Mhz ?
> 
> Needed for SDR project as external clock source.
> 
> -pete
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Re: [time-nuts] Dual GPSDO - any advantage?

[ewkehren via time-nuts]

We use Excell nice to make plots and when needed add calculations File is to 
large for time nuts contact me direct and I will send you an exampleBert Kehren


Sent from my Galaxy Tab® A
 Original message From: CORNACCHIA via time-nuts 
 Date: 4/10/18  2:35 PM  (GMT-05:00) To: ewkehren via 
time-nuts  Subject: Re: [time-nuts] Dual GPSDO - any 
advantage? 
 Bert may I ask how you created the charts (what software are you using).Thank 
You
    On Tuesday, April 10, 2018, 9:04:58 a.m. EDT, ewkehren via time-nuts 
 wrote:  
 
 Looking at the pictures it is the same unit I bought. It is not dual oven bit 
trimble works with LH right now shows tracking 10 satelites.Attached  is data 
that made  me buy a second one for Jürg for $ 129  and one more for me for 
$9.50.What you see is highly filtered data to see long time changes to better 
understand if analog filtering os possible. Planning on using Wenzel 600 sec. 
Filter maybe up to 2000 seconds. Board is ready for order.Top plot is my data 
against my Cs 5061B bottom is original Tbolt against his FTS  Cs. We use 53132 
counters.I think  the new one lends it self better for filtering looking at 
both  with my Tracor, Trimble uses a  much shorter time constant and no short 
1E-10 changes you see on our standard units.Will keep you posted         Bert 
Kehren

Sent from my Galaxy Tab® A
 Original message From: Tim Shoppa  Date: 
4/10/18  6:46 AM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: Re: [time-nuts] Dual GPSDO - any 
advantage? 
Most of the Chinese cheapo units have been frequency, not phase locked.

It would be great if you could put the GPSDO outputs into a 2 Channel scope and 
eyeball them for a while to see if they appear in phase (say plus-minus 20ns) 
over a few hours.

Tim N3QE

> On Apr 10, 2018, at 1:43 AM, donald collie  wrote:
> 
> I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
> error!] They are stated as being new, and use a Trimball dual oven OCXO. I
> plan to run these in parallel [2 antennas, 2 feedlines, and 2 GPSDO`s] It`s
> been said that a man with two watches is never happy - unless, of course,
> they agree with each other ;-). Being identical the outputs should be
> coherent, unless one becomes faulty [one advantage of having two - any
> discrepancy and you know something must be wrong]], but is there some
> crafty way I can squeeze a little more "accuracy" out of two than if I only
> used one?
> TIA for your commentsDonald
> Brett Collie ZL4GX
> 
> PS : I have no connection to the eBay seller. The US$9-50 seems to include
> a basic puck antenna, long downlead, and 4 interseries adaptors
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Re: [time-nuts] Dual GPSDO - any advantage?

[Heinz Breuer]

The seller added 100 pieces. At this moment 110 are sold.
Auction #273145006434

Well it sounds too good to be true but I ordered 4 pieces just in case that it 
is real.

With PayPal there is little risk.
vy 73 Heinz DH2FA, KM5VT

Von meinem iPhone gesendet

> Am 10.04.2018 um 23:25 schrieb Richard Solomon :
> 
> In the past I have had excellent experiences with e-Bay when it comes to
> 
> bad sellers. If the parts never arrive, there is no question, I got a refund.
> 
> If the parts were not as described, still no problems.
> 
> 
> e-Bay seems to have been more on the side of the Buyer lately. A far cry
> 
> from their early days when the Seller's word was Gospel.
> 
> 
> 73, Dick, W1KSZ
> 
> 
> Sent from Outlook
> 
> From: time-nuts  on behalf of Dr. David Kirkby 
> 
> Sent: Tuesday, April 10, 2018 12:24:41 PM
> To: Discussion of precise time and frequency measurement
> Cc: gandal...@aol.com
> Subject: Re: [time-nuts] Dual GPSDO - any advantage?
> 
>> On 10 April 2018 at 17:11, Clint Jay  wrote:
>> 
>> Sad to say I think I was right, the listings have been pulled already and
>> the seller now has zero items for sale.
> 
> The listing has not been pulled. Yes the seller has 0 to sell, but because
> he has sold out of the 100. I still have the purchase in my purchase
> history, and no messages from eBay about fraud.
> 
>> 
>> Get those paypal refund cases logged.
> 
> One would need to wait until they don't arrive. Luckily they were not much.
> 
> Then it is better to complain to eBay first. If you don't get any
> satisfaction from eBay, then you can go to PayPal. But by going directly to
> PayPal, you will have lost the chance to get a refund via eBay. So the
> sensible order to try to get refunds is
> 
> 1) eBay
> 2) PayPal
> 3) Chargeback on credit card.
> 
> Never advance to stage PayPal unless you have exhaused attempts at eBay.
> Never make a chargeback unless you have exhaused atttempts at both eBay and
> PayPal.
> 
> Sometimes it can be a bit of an uphill struggle to get refunds from eBay
> for dodgy sellers, but in this case it should be fairly easy if the goods
> don't arrive. On the off-chance they do, we have scored well.
> 
> 
> Clint. M0UAW IO83
> 
> 
> Dave G8WRB.
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Re: [time-nuts] Cheap jitter measurements

[Bob kb8tq]

Hi

> On Apr 11, 2018, at 4:58 AM, Hal Murray  wrote:
> 
> 
> g...@rellim.com said:
>> It tests the time to do two back to back clock_gettime().
> 
> That's the time it takes to read the clock.  That's not what I mean by 
> granularity but I think I see how you might use that word.  The comment at 
> the top of the code says "latency".
> 
> When I hear "granularity", I think of the tick size of the clock.  It's easy 
> to measure a big tick size, read the clock, spin reading until it changes, 
> subtract.

In the case of putting out a pulse, the clock to the timer you are using (or 
the i/o clock on the pin) most certainly creates granularity. 


> 
> Things get interesting if the tick size is less than the time it takes to 
> read the clock.  In that case, you may be able see the tick size with a 
> histograms of the times to read the clock.
> 
> With calibration, I can correct for the duration of time it takes to read the 
> clock.  I'm not sure how to do the calibration.  In some cases it cancels 
> out.  Cache misses may be more significant.
> 
> 
> PS: Try running that code on an ARM.  

Take a look at the clock specs on the various sub systems. If a pin is 
involved, you may have a 50 MHz clock spec. If your code is 
coming from flash then it’s got it’s own clock that might be < 30 MHz. 

Lots of nasty little gotcha’s. 

One point is that these also impact how a piece of software “self evaluates” in 
the same environment. To the degree that some
of this is very hard to detect, it might get missed. That gets us back to the 
desire for an external measurement.

Bob


> And consider reading the clock 3 times and collecting 2 sets of data.  The 
> idea is that the first read takes all the cache misses so the time for the 
> second read should be faster and cleaner.
> 
> I see a tick size of 1 microsecond on a Pi 1, and 52 ns on a Pi 2 and Pi 3.
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] TCVCXO Adjustment

[Bob kb8tq]

Hi

On a TCXO a proper 12 bit DAC should do fine. The “don’t use for DC” DAC’s
that are built in to a MCU …. who knows. At DC they probably aren’t 12 bits 
anyway. 

If the TCXO is rated to age < 1 ppm per year and has a 10 ppm EFC (yes you 
*could* wonder about that combo) the DAC would need to drift 10% per year to 
match the rating on the oscillator. That’s a pretty horrid DAC. 

If the TCXO is rated for 0.1 ppm in the first year, that’s a mighty tight TCXO. 
The
DAC now needs to do 1% per year. Even the MCU parts *should* get to that level.

The same basic logic applies to temperature. If your TCXO claims 0.1 ppm from 
-30 to +70, best to check it. Even so, the DAC is still at the 1% point and 
likely 
does an adequate job. 

Bottom line - TCXO’s aren’t OCXO’s. They are a bit easier to deal with unless 
you
happen to have one of the exotic ones. If you do have an exotic TCXO you likely
paid more for it than an OCXO and thus know why you did so ….

We are not talking about disciplining the oscillator. We’re just taking about 
putting
it on frequency after it has been built into a system. In the case of 
disciplining, a lot
of things come into play. In the case of one time set to frequency, once you 
get past 
the likely drift over a few weeks …. why bother? 

Bob

> On Apr 11, 2018, at 5:09 AM, Hal Murray  wrote:
> 
> 
> wayne.hol...@gmail.com said:
>> Since the TCVCXO includes a voltage control input, my plan is to also add a
>> 12-Bit Digital-to-Analog Converter ...
> 
> What's the temperature stability of the D/A?
> 
> How does that compare with a 10 turn pot?  I remember a comment about pots 
> aging.  It was somewhat recently.  I don't remember the details.  I think it 
> was something like the wiper wore a small groove which made it hard to make 
> tiny adjustments.  I don't know how long it takes for the groove to form.
> 
> A possible option is to just measure the osc and do the adjustment in 
> software.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] suggestions on getting 24 Mhz ?

[Jimmy D. Burrell]

Hi Pete,

Speaking from limited experience, I wonder if a garden variety OCXO at say 10 
MHz + some CMOS logic to act as a frequency multiplier might not fit the build? 
 Then again, perhaps 24MHz is a little fast for the logic chips.. not sure.

Hope this helps spark some discussion.

Jim…
N5SPE

> On Apr 11, 2018, at 5:00 AM, Pete Lancashire  wrote:
> 
> Needed for SDR project as external clock source.
> 
> -pete
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Re: [time-nuts] suggestions on getting 24 Mhz ?

[jimlux]

On 4/11/18 3:00 AM, Pete Lancashire wrote:

Needed for SDR project as external clock source.

-pete


I assume you mean derived from a high quality 10 MHz.

some sort of discrete divide multiply?   divide by 5 multiply by 12?
A PLL with VCXO with good far out noise?  (sort of like "clean up loops" 
used for distributing 10 or 100 MHz )

A DDS (with internal multiplier)


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Re: [time-nuts] suggestions on getting 24 Mhz ?

[jsternmd]

Leo Bodnar GPSDO - adjustable Low-jitter GPS-locked precision frequency 
reference 400 Hz to 810 MHz .  He has a new one, single output for 99 british 
pounds.

Jerry NY2KW

-Original Message-
From: time-nuts  On Behalf Of Pete Lancashire
Sent: Wednesday, April 11, 2018 6:00 AM
To: Discussion of precise time and frequency measurement 
Subject: [time-nuts] suggestions on getting 24 Mhz ?

Needed for SDR project as external clock source.

-pete
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[time-nuts] suggestions on getting 24 Mhz ?

[Pete Lancashire]

Needed for SDR project as external clock source.

-pete
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Re: [time-nuts] TCVCXO Adjustment

[Hal Murray]

wayne.hol...@gmail.com said:
> Since the TCVCXO includes a voltage control input, my plan is to also add a
> 12-Bit Digital-to-Analog Converter ...

What's the temperature stability of the D/A?

How does that compare with a 10 turn pot?  I remember a comment about pots 
aging.  It was somewhat recently.  I don't remember the details.  I think it 
was something like the wiper wore a small groove which made it hard to make 
tiny adjustments.  I don't know how long it takes for the groove to form.

A possible option is to just measure the osc and do the adjustment in 
software.


-- 
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Re: [time-nuts] Cheap jitter measurements

[Hal Murray]

g...@rellim.com said:
> It tests the time to do two back to back clock_gettime().

That's the time it takes to read the clock.  That's not what I mean by 
granularity but I think I see how you might use that word.  The comment at 
the top of the code says "latency".

When I hear "granularity", I think of the tick size of the clock.  It's easy to 
measure a big tick size, read the clock, spin reading until it changes, 
subtract.

Things get interesting if the tick size is less than the time it takes to read 
the clock.  In that case, you may be able see the tick size with a histograms 
of the times to read the clock.

With calibration, I can correct for the duration of time it takes to read the 
clock.  I'm not sure how to do the calibration.  In some cases it cancels out.  
Cache misses may be more significant.


PS: Try running that code on an ARM.  And consider reading the clock 3 times 
and collecting 2 sets of data.  The idea is that the first read takes all the 
cache misses so the time for the second read should be faster and cleaner.

I see a tick size of 1 microsecond on a Pi 1, and 52 ns on a Pi 2 and Pi 3.

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Re: [time-nuts] TCVCXO Adjustment

[ed breya]

If it's just to set for the initial setup or aging, just do it the 
old-fashioned way, with a trimmer pot to run the Vt - simple, easy to 
program, and it remembers the setting.

Ed
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