Re: [time-nuts] Oscillators and Ovens

[Bob Camp]

Hi

I would say there are *very* few companies out there that will 
sell you high grade  precision OCXO crystals in single piece quantities.  
I think  you would get one much quicker and cheaper by pulling it out 
of an eBay OCXO. You can do good far removed phase noise with 
a lot of crystals. Once you look close in, the performance of the 
resonator matters. ADEV is the same issue, longer Tau’s are very
resonator dependent. 

Bob

> On Nov 12, 2017, at 10:14 AM, Attila Kinali  wrote:
> 
> Hi Jim,
> 
> On Wed, 1 Nov 2017 11:39:32 -0700
> jimlux  wrote:
> 
>> So, it would be nice to have a *cheap* lowish power packaged part that 
>> has the Q of an OCXO, but without the power consumption of the oven 
>> (typically measured in watts).
>> 
>> yeah, I'd be operating it *way* far from the optimum turnover temp, so 
>> the tempco might be huge (in oscillator terms), but I don't really care 
>> - in fact, that might give me a way to measure the temperature of the 
>> system.
> 
> Have you tried to build your own oscillator? There are a few companies
> that still sell single crystals. If you could piggy pack on some bigger
> customers production, you should be able to get the crystals relatively
> cheap. All you then have to do is to design an approriate, low noise
> oscillator. If you can relax your frequency specs, ie if you don't care
> if you are off by a few ppm, then you could scavenge the rejected crystals
> from said big customer.
> 
>   Attila Kinali
> 
> -- 
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering.  -- The Doctor
> ___
> 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.

___
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.

Re: [time-nuts] Oscillators and Ovens

[Attila Kinali]

Hi Jim,

On Wed, 1 Nov 2017 11:39:32 -0700
jimlux  wrote:

> So, it would be nice to have a *cheap* lowish power packaged part that 
> has the Q of an OCXO, but without the power consumption of the oven 
> (typically measured in watts).
> 
> yeah, I'd be operating it *way* far from the optimum turnover temp, so 
> the tempco might be huge (in oscillator terms), but I don't really care 
> - in fact, that might give me a way to measure the temperature of the 
> system.

Have you tried to build your own oscillator? There are a few companies
that still sell single crystals. If you could piggy pack on some bigger
customers production, you should be able to get the crystals relatively
cheap. All you then have to do is to design an approriate, low noise
oscillator. If you can relax your frequency specs, ie if you don't care
if you are off by a few ppm, then you could scavenge the rejected crystals
from said big customer.

Attila Kinali

-- 
You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to
fit the views, which can be uncomfortable if you happen to be one of the
facts that needs altering.  -- The Doctor
___
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.

Re: [time-nuts] Oscillators and Ovens

[jimlux]

On 11/1/17 1:38 PM, Hal Murray wrote:



In general, OCXOs have crystals with high Q -> low phase noise,  especially
compared to a TCXO, which *can't* have high Q, or the  temperature
compensation circuit can't do it's work.


I don't understand that.  Why can't I build a high Q TCXO?  I don't need to
change the compensation very fast.  Are good crystals high enough Q that it
would take too long?


Think of the oscillator as an amplifier and a high Q mechanical filter - 
it gets the Q from being mechanically stiff.


In order to move the frequency, you have to electrically push it, which 
is counter to the mechanical stiffness.  You just don't have the tuning 
range available.


We struggled on a project to build a high Q, but adjustable DRO, and 
that was the fundamental problem.





What's the time constant?  I'd guess it's Q/freq, maybe with factors of 2pi
or e or ???

That seems small relative to how fast temperature changes.  (but maybe fast
relative to FCC smearing or things like that)




___
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.

Re: [time-nuts] Oscillators and Ovens

[Bob kb8tq]

Hi

As mentioned in Rick’s post, it’s not really Q, it’s the motional capacitance 
that is the issue. 
Even if you resonate out C0, you still have to deal with Cm. The only practical 
high Q designs
for crystals are very low Cm resonators. Yes, if you could do a design that had 
Rm of 0.1 ohms
it could be high Q without a high Cm. That’s not the way it works out. 

Since the electrical equivalent circuit is related to the physics of the 
resonator, simply changing 
this or that is not trivial. You might well have to change the basic material 
to impact some of this.
Simply as a side note, SC’s are “worse” (lower) for Cm than AT’s of similar 
frequency and overtone. 

> On Nov 1, 2017, at 6:44 PM, Dana Whitlow  wrote:
> 
> Bob,
> 
> This discussion is getting really interesting.  In thinking about the
> crystal Q versus
> tuning range conundrum, two (presumably-overlapping) concerns come to mind:
> 
> 1. The motional parameters of a high-Q crystal are such that the external
> network
>needed to pull it very far would be wholly impractical.

Depending on you definition of impractical … this is TimeNuts …. In the real 
world, yes indeed
impractical. 

> 
> 2. Varactors themselves probably have pretty limited Q over much of their
> range.

They have a very finite Q. That turns into loss in the oscillator circuit. Loss 
goes up as the
pull increases. The varactor is a bigger part of the circuit as the pull 
increases.  The Q of a real oscillator 
is only partly from the crystal. Tossing more loss into the oscillator will 
impact the overall Q. 
You might go from crystal / 2 to crystal / 5 (very arbitrary numbers and only 
for illustration … ) 

> 
> Is my thinking on the right track at all?

Pretty much.

Bob

> 
> Dana  K8YUM
> 
> On Wed, Nov 1, 2017 at 5:13 PM, Bob kb8tq  wrote:
> 
>> Hi
>> 
>> A high Q crystal by design is very difficult to tune. Putting it in a
>> circuit that will
>> swing it far enough to compensate it degrades the Q. In addition, thermal
>> noise
>> will come into the compensation circuit (even if it is noise free) and
>> degrade things.
>> 
>> Bob
>> 
>>> On Nov 1, 2017, at 4:38 PM, Hal Murray  wrote:
>>> 
>>> 
 In general, OCXOs have crystals with high Q -> low phase noise,
>> especially
 compared to a TCXO, which *can't* have high Q, or the  temperature
 compensation circuit can't do it's work.
>>> 
>>> I don't understand that.  Why can't I build a high Q TCXO?  I don't need
>> to
>>> change the compensation very fast.  Are good crystals high enough Q that
>> it
>>> would take too long?
>>> 
>>> What's the time constant?  I'd guess it's Q/freq, maybe with factors of
>> 2pi
>>> or e or ???
>>> 
>>> That seems small relative to how fast temperature changes.  (but maybe
>> fast
>>> relative to FCC smearing or things like that)
>>> 
>>> 
>>> --
>>> These are my opinions.  I hate spam.
>>> 
>>> 
>>> 
>>> ___
>>> 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.
>> 
>> ___
>> 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.
>> 
> ___
> 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.

___
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.

Re: [time-nuts] Oscillators and Ovens

[Richard (Rick) Karlquist]

On 11/1/2017 3:44 PM, Dana Whitlow wrote:

Bob,

This discussion is getting really interesting.  In thinking about the
crystal Q versus
tuning range conundrum, two (presumably-overlapping) concerns come to mind:

1. The motional parameters of a high-Q crystal are such that the external
network
 needed to pull it very far would be wholly impractical.

2. Varactors themselves probably have pretty limited Q over much of their
range.

Is my thinking on the right track at all?

Dana  K8YUM




Sorry your thinking is NOT on the right track.

What determines the pullability of a crystal is the ratio of the
motional capacitance to the static capacitance, commonly denoted
as C1/C0.  The Q of the crystal has nothing to do with it.  The
only thing significant about the Q is that it limits the
how QUICKLY you can change the crystal frequency.

What determines the noise of a crystal is the intrinsic
flicker of frequency noise.  The Q has nothing to do with it.
If the Q is degraded somewhat by adding varactors to pull the
frequency, it doesn't affect the noise.  It is true that if
varactors are used, it is possible that the noise will be
degraded if the tuning voltage is not clean enough.  The
HP smart clocks were always limited by this problem because
no realizable voltage source was good enough, at least 20
years ago.

In the 5071, I modified the 10811 to increase its tuning range
by an order of magnitude.  This did not affect its noise
at all, AKAIK.  The zener diode reference in the 10811 is
actually quite good.  This modification was done to eliminate
the need to tweak the coarse tuning of the 10811 as it aged.

Having said this, with currently available technology, I recommend
using frequency synthesizers to do a "virtual pull"
on crystal oscillators, rather than trying to pull them
with varactors.

Rick N6RK
___
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.

Re: [time-nuts] Oscillators and Ovens

[Dana Whitlow]

Bob,

This discussion is getting really interesting.  In thinking about the
crystal Q versus
tuning range conundrum, two (presumably-overlapping) concerns come to mind:

1. The motional parameters of a high-Q crystal are such that the external
network
needed to pull it very far would be wholly impractical.

2. Varactors themselves probably have pretty limited Q over much of their
range.

Is my thinking on the right track at all?

Dana  K8YUM

On Wed, Nov 1, 2017 at 5:13 PM, Bob kb8tq  wrote:

> Hi
>
> A high Q crystal by design is very difficult to tune. Putting it in a
> circuit that will
> swing it far enough to compensate it degrades the Q. In addition, thermal
> noise
> will come into the compensation circuit (even if it is noise free) and
> degrade things.
>
> Bob
>
> > On Nov 1, 2017, at 4:38 PM, Hal Murray  wrote:
> >
> >
> >> In general, OCXOs have crystals with high Q -> low phase noise,
> especially
> >> compared to a TCXO, which *can't* have high Q, or the  temperature
> >> compensation circuit can't do it's work.
> >
> > I don't understand that.  Why can't I build a high Q TCXO?  I don't need
> to
> > change the compensation very fast.  Are good crystals high enough Q that
> it
> > would take too long?
> >
> > What's the time constant?  I'd guess it's Q/freq, maybe with factors of
> 2pi
> > or e or ???
> >
> > That seems small relative to how fast temperature changes.  (but maybe
> fast
> > relative to FCC smearing or things like that)
> >
> >
> > --
> > These are my opinions.  I hate spam.
> >
> >
> >
> > ___
> > 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.
>
> ___
> 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.
>
___
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.

Re: [time-nuts] Oscillators and Ovens

[Bob kb8tq]

Hi

A high Q crystal by design is very difficult to tune. Putting it in a circuit 
that will 
swing it far enough to compensate it degrades the Q. In addition, thermal noise
will come into the compensation circuit (even if it is noise free) and degrade 
things. 

Bob

> On Nov 1, 2017, at 4:38 PM, Hal Murray  wrote:
> 
> 
>> In general, OCXOs have crystals with high Q -> low phase noise,  especially
>> compared to a TCXO, which *can't* have high Q, or the  temperature
>> compensation circuit can't do it's work. 
> 
> I don't understand that.  Why can't I build a high Q TCXO?  I don't need to 
> change the compensation very fast.  Are good crystals high enough Q that it 
> would take too long?
> 
> What's the time constant?  I'd guess it's Q/freq, maybe with factors of 2pi 
> or e or ???
> 
> That seems small relative to how fast temperature changes.  (but maybe fast 
> relative to FCC smearing or things like that)
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> ___
> 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.

___
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.

Re: [time-nuts] Oscillators and Ovens

[Chris Caudle]

On Wed, November 1, 2017 3:38 pm, Hal Murray wrote:
>
>> In general, OCXOs have crystals with high Q -> low phase noise,
>> especially
>> compared to a TCXO, which *can't* have high Q, or the  temperature
>> compensation circuit can't do it's work.
>
> I don't understand that.  Why can't I build a high Q TCXO?

Compensation implies pulling the frequency away from the natural
resonance.  High Q implies that the frequency cannot be pulled very far
away from natural resonance.
The two items are directly contradictory.

-- 
Chris Caudle




 I don't need
> to
> change the compensation very fast.  Are good crystals high enough Q that
> it
> would take too long?
>
> What's the time constant?  I'd guess it's Q/freq, maybe with factors of
> 2pi
> or e or ???
>
> That seems small relative to how fast temperature changes.  (but maybe
> fast
> relative to FCC smearing or things like that)
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
> ___
> 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.
>


___
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.

Re: [time-nuts] Oscillators and Ovens

[Hal Murray]

> In general, OCXOs have crystals with high Q -> low phase noise,  especially
> compared to a TCXO, which *can't* have high Q, or the  temperature
> compensation circuit can't do it's work. 

I don't understand that.  Why can't I build a high Q TCXO?  I don't need to 
change the compensation very fast.  Are good crystals high enough Q that it 
would take too long?

What's the time constant?  I'd guess it's Q/freq, maybe with factors of 2pi 
or e or ???

That seems small relative to how fast temperature changes.  (but maybe fast 
relative to FCC smearing or things like that)


-- 
These are my opinions.  I hate spam.



___
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.

Re: [time-nuts] Oscillators and Ovens

[jimlux]

On 11/1/17 10:59 AM, Attila Kinali wrote:

Hi Jim,

On Wed, 1 Nov 2017 06:17:31 -0700
jimlux  wrote:


That's why I wish they'd sell OCXOs, cheap, without the oven. Or maybe
look for regular XO (no TC).  Those might have a more "pure" (read lower
order) freq vs temp characteristic.



It feels like I have asked this before, but I cannot remember and
cannot find the mailSo: What do you mean by "OCXO without oven?"




I often have requirements for "good phase noise" but no particular 
requirement for "good temperature stability" or Allan Deviation for tau 
> 200 seconds - we get frequency knowledge from other sources (e.g. 
just like a GPSDO, or it can be inferred from the measurement)
I often have a system where the environment is pretty benign - a typical 
on-orbit temperature variation might be a degree or two over 90 minutes 
(or longer), if that - we don't know what the temperature will be (in 
advance), but once it's up there, it's pretty stable.  Maybe the temp 
changes a bit due to relative orientation to the sun and similar 
effects, so there's a annual variation.  My current spacecraft is 
expected to change maybe 5-6 degrees over the year.


For instance, in a software defined radio, the input oscillator is often 
fed into some sort of NCO or DDS for tuning - knowledge of the frequency 
is what you really want, because the ultimate requirement is on the 
frequency accuracy at the input or output of the radio - the regulators 
care not a whit what kind of oscillator is inside (well, they DO ask on 
the license application, but it's really not relevant)


THere are also systems like Doppler radars - they need good pulse to 
pulse stability, and low phase noise to avoid reciprocal mixing 
degradation of the noise floor - but they care not what the exact 
frequency is.


In general, OCXOs have crystals with high Q -> low phase noise, 
especially compared to a TCXO, which *can't* have high Q, or the 
temperature compensation circuit can't do it's work.


So, it would be nice to have a *cheap* lowish power packaged part that 
has the Q of an OCXO, but without the power consumption of the oven 
(typically measured in watts).


yeah, I'd be operating it *way* far from the optimum turnover temp, so 
the tempco might be huge (in oscillator terms), but I don't really care 
- in fact, that might give me a way to measure the temperature of the 
system.


I have gotten quotes for OCXOs with the oven disabled-  but that's 
making it a custom part and as Bob has pointed out, the moment you 
deviate from the "catalog part", the cost (and often more importantly, 
the delivery time) goes up.


I think the ideal, of course, is to get an oscillator high performance 
crystal cut with the turnover temp around 20-30C - useless for a OCXO, 
but might be real useful for GPS/temp compensated oscillator where the 
oscillator drives a DDS (or or provides an output giving the estimated 
frequency).




___
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.

[time-nuts] Oscillators and Ovens (was: Designing an embedded precision GPS time)

[Attila Kinali]

Hi Jim,

On Wed, 1 Nov 2017 06:17:31 -0700
jimlux  wrote:

> That's why I wish they'd sell OCXOs, cheap, without the oven. Or maybe 
> look for regular XO (no TC).  Those might have a more "pure" (read lower 
> order) freq vs temp characteristic.


It feels like I have asked this before, but I cannot remember and
cannot find the mailSo: What do you mean by "OCXO without oven?"

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
___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

Observing a curve and being able to compensate it are often two different 
things. Hysteresis is one very obvious example. Another is simple sensor lag. A 
some what less obvious one is that the temperature performance is also 
influenced by the rate of change in temperature.

Here's another thing to consider:

If your crystal is running 3 ppm / C, and you are after 3.0 x 10^-11 stability 
at one second - You will need to either have a rate of change at ~ 1x10^-5 
C/sec (0.6 mC / min) or you will need to compensate for some pretty small 
changes. That of course makes a bunch of assumptions ….

Bob

On Aug 31, 2012, at 11:26 PM, Jim Lux jim...@earthlink.net wrote:

 On 8/31/12 7:16 PM, Bob Camp wrote:
 Hi
 
 Ok, that gets you back to the basics of really major delta F / delta T 
 slopes.
 
 Bob
 
 yeah.. but as long as you know what the curve is.. the NCO has a huge range 
 (after all, we already have to tune over 500 kHz...a few hundred Hz isn't a 
 big deal.
 
 
 A more complex problem is doing insitu calibration from, e.g., GPS signals or 
 from some externally received frequency reference. (since the radio in 
 question can also work as a GPS receiver, eventually).
 
 
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 9/1/12 8:32 AM, Bob Camp wrote:

Hi

Observing a curve and being able to compensate it are often two different 
things. Hysteresis is one very obvious example. Another is simple sensor lag. A 
some what less obvious one is that the temperature performance is also 
influenced by the rate of change in temperature.

Here's another thing to consider:

If your crystal is running 3 ppm / C, and you are after 3.0 x 10^-11 stability 
at one second - You will need to either have a rate of change at ~ 1x10^-5 
C/sec (0.6 mC / min) or you will need to compensate for some pretty small 
changes. That of course makes a bunch of assumptions ….




In this application,  the requirement for frequency accuracy has to do 
with initial acquisition.. that is, you want the signal (or receiver 
tuning) to be within some few hundred Hz of where it's expected to be 
(because the receiver is narrow band).



The ground station typically has a Doppler predict based on orbit 
knowledge, that predict has some uncertainty.  Added to the radio 
frequency uncertainty.  (SNUG - Space Network User Guide, has more info)


Once you've acquired, the receiver and ground station will track (i.e. 
the ground station puts in the estimated Doppler, so all you're really 
tracking is the variation in the local oscillator).  (for a LEO 
satellite at 2.3 GHz, the 7km/s orbital velocity already puts tens of 
kHz variation on it)


(and this completely neglects that a modern radio could use something 
like an FFT for acquisition)


Temperature changes are pretty slow.. I'm seeing 5-10 degree cyclical 
variation over 90-100 minutes.  Actually, the bigger change is during 
the warm up transient, going from off and cold to on and warm over 10 
minutes or so.


In other applications, where you're not going in and out of the sun 
every revolution (i.e. deep space, rather than LEO) and you were 
interested in Allan deviation type measurements for gravity science 
(where we're looking for 1E-13 over 100 sec sort of performance), what 
we'd probably do is warm up early.. Turn it on, compensate based on the 
measured temperature, and then hold the compensation fixed during the 
measurement, letting the ground worry about the apparent frequency 
change due to Doppler.  We'd have a high quality narrow band signal, 
just at an unknown (but reasonably stable) frequency.  What the science 
team is usually interested in is small relative changes in phase  
amplitude(occultations) or in small changes in frequency (Doppler, for 
gravity science).


(we regularly measure velocity to cm/sec precision for outer planet 
orbiters like Cassini, Juno, etc.)



___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

I suspect that a good IT cut would probably do better than an SC in either 
application. In the deep space situation, a copper slug in a dewar sounds like 
a reasonable addition to the design.

Bob

On Sep 1, 2012, at 11:53 AM, Jim Lux jim...@earthlink.net wrote:

 On 9/1/12 8:32 AM, Bob Camp wrote:
 Hi
 
 Observing a curve and being able to compensate it are often two different 
 things. Hysteresis is one very obvious example. Another is simple sensor 
 lag. A some what less obvious one is that the temperature performance is 
 also influenced by the rate of change in temperature.
 
 Here's another thing to consider:
 
 If your crystal is running 3 ppm / C, and you are after 3.0 x 10^-11 
 stability at one second - You will need to either have a rate of change at ~ 
 1x10^-5 C/sec (0.6 mC / min) or you will need to compensate for some pretty 
 small changes. That of course makes a bunch of assumptions ….
 
 
 
 In this application,  the requirement for frequency accuracy has to do with 
 initial acquisition.. that is, you want the signal (or receiver tuning) to be 
 within some few hundred Hz of where it's expected to be (because the receiver 
 is narrow band).
 
 
 The ground station typically has a Doppler predict based on orbit knowledge, 
 that predict has some uncertainty.  Added to the radio frequency uncertainty. 
  (SNUG - Space Network User Guide, has more info)
 
 Once you've acquired, the receiver and ground station will track (i.e. the 
 ground station puts in the estimated Doppler, so all you're really tracking 
 is the variation in the local oscillator).  (for a LEO satellite at 2.3 GHz, 
 the 7km/s orbital velocity already puts tens of kHz variation on it)
 
 (and this completely neglects that a modern radio could use something like an 
 FFT for acquisition)
 
 Temperature changes are pretty slow.. I'm seeing 5-10 degree cyclical 
 variation over 90-100 minutes.  Actually, the bigger change is during the 
 warm up transient, going from off and cold to on and warm over 10 minutes or 
 so.
 
 In other applications, where you're not going in and out of the sun every 
 revolution (i.e. deep space, rather than LEO) and you were interested in 
 Allan deviation type measurements for gravity science (where we're looking 
 for 1E-13 over 100 sec sort of performance), what we'd probably do is warm up 
 early.. Turn it on, compensate based on the measured temperature, and then 
 hold the compensation fixed during the measurement, letting the ground worry 
 about the apparent frequency change due to Doppler.  We'd have a high quality 
 narrow band signal, just at an unknown (but reasonably stable) frequency.  
 What the science team is usually interested in is small relative changes in 
 phase  amplitude(occultations) or in small changes in frequency (Doppler, 
 for gravity science).
 
 (we regularly measure velocity to cm/sec precision for outer planet orbiters 
 like Cassini, Juno, etc.)
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Magnus Danielson]

On 09/01/2012 05:53 PM, Jim Lux wrote:

On 9/1/12 8:32 AM, Bob Camp wrote:

Hi

Observing a curve and being able to compensate it are often two
different things. Hysteresis is one very obvious example. Another is
simple sensor lag. A some what less obvious one is that the
temperature performance is also influenced by the rate of change in
temperature.

Here's another thing to consider:

If your crystal is running 3 ppm / C, and you are after 3.0 x 10^-11
stability at one second - You will need to either have a rate of
change at ~ 1x10^-5 C/sec (0.6 mC / min) or you will need to
compensate for some pretty small changes. That of course makes a bunch
of assumptions ….




In this application, the requirement for frequency accuracy has to do
with initial acquisition.. that is, you want the signal (or receiver
tuning) to be within some few hundred Hz of where it's expected to be
(because the receiver is narrow band).


The ground station typically has a Doppler predict based on orbit
knowledge, that predict has some uncertainty. Added to the radio
frequency uncertainty. (SNUG - Space Network User Guide, has more info)

Once you've acquired, the receiver and ground station will track (i.e.
the ground station puts in the estimated Doppler, so all you're really
tracking is the variation in the local oscillator). (for a LEO satellite
at 2.3 GHz, the 7km/s orbital velocity already puts tens of kHz
variation on it)

(and this completely neglects that a modern radio could use something
like an FFT for acquisition)

Temperature changes are pretty slow.. I'm seeing 5-10 degree cyclical
variation over 90-100 minutes. Actually, the bigger change is during the
warm up transient, going from off and cold to on and warm over 10
minutes or so.

In other applications, where you're not going in and out of the sun
every revolution (i.e. deep space, rather than LEO) and you were
interested in Allan deviation type measurements for gravity science
(where we're looking for 1E-13 over 100 sec sort of performance), what
we'd probably do is warm up early.. Turn it on, compensate based on the
measured temperature, and then hold the compensation fixed during the
measurement, letting the ground worry about the apparent frequency
change due to Doppler. We'd have a high quality narrow band signal, just
at an unknown (but reasonably stable) frequency. What the science team
is usually interested in is small relative changes in phase 
amplitude(occultations) or in small changes in frequency (Doppler, for
gravity science).

(we regularly measure velocity to cm/sec precision for outer planet
orbiters like Cassini, Juno, etc.)


If you can make reasonable predictions of the heating and cooling 
profile, you could use that and hopefully gain a decade or so, and any 
slew in detectors and would mostly affect the remaining error.


You could also make use of uplink carrier and GPS to improve the model 
state of your crystal. That way the predicted and feed forward values 
could be kept fairly well adapted. Naturally, you would want a fall-back 
scenario to back out for wider offset search if you failed to maintain 
the model. You don't want to loose your bird due to temporary system 
failure. Another alternative would be to allow for the downlink 
frequency to be a hint for the uplink where the frequency is such that 
you can pull in the bird if need to.


Cheers,
Magnus

___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 9/1/12 11:00 AM, Bob Camp wrote:

Hi

I suspect that a good IT cut would probably do better than an SC in either 
application. In the deep space situation, a copper slug in a dewar sounds like 
a reasonable addition to the design.



If you're going to do dewars, then you're talking USOs for which the 
technology is quite well developed with ovens, etc.


But that's a kilo, several watts, and a liter.

What you want is something that is better than, say, 0.1 ppm, that is 
comparable in mass/power/volume/cost to an existing 1-5 ppm TCXO (about 
1x2x0.5 cm)



___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

True on the volume and weight. Not as much power as an OCXO since it's passive. 
At 1x 2 x 0.5 you could fix the power and weight by using an EMXO. You still 
would have more power than the TCXO, but no were near as much as the couple 
watts a USO uses.

Bob

Bob

On Sep 1, 2012, at 10:41 PM, Jim Lux jim...@earthlink.net wrote:

 On 9/1/12 11:00 AM, Bob Camp wrote:
 Hi
 
 I suspect that a good IT cut would probably do better than an SC in either 
 application. In the deep space situation, a copper slug in a dewar sounds 
 like a reasonable addition to the design.
 
 
 If you're going to do dewars, then you're talking USOs for which the 
 technology is quite well developed with ovens, etc.
 
 But that's a kilo, several watts, and a liter.
 
 What you want is something that is better than, say, 0.1 ppm, that is 
 comparable in mass/power/volume/cost to an existing 1-5 ppm TCXO (about 
 1x2x0.5 cm)
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Javier Herrero]

El 30/08/2012 20:53, saidj...@aol.com escribió:

There are some drawbacks to this type of SC-cut MCXO I would think,  and it
could possibly be replaced by a much higher performance Symmetricom CSAC,
probably at a lower cost and higher availability:
  
* Q-tech MCXO is ITAR controlled, CSAC is not

* MCXO has 20ppb over temp stability, CSAC has 1ppb spec, typical units can
  be much lower than that. Our GPSTCXO has 75ppb over temp, not much more
than the MCXO, but probably at 1/10th the cost.
* The G-sensitivity of CSAC is at least 50x better than the MCXO  (its so
low, its very hard to measure)
* Aging of MCXO is much higher (order of magnitude)
* Symmetricom is a big player, Q-tech is relatively small and unknown
* I remember that there are patents on the MCXO held by FEI?
* Power consumption is very similar, future CSAC units will have much lower
  power than the MCXO.
  
The MCXO does have lower phase noise, it's an SC-cut cyrstal after all. But

  with CSAC's now becoming available from multiple sources, why use an MCXO?
  
bye,

Said

As you say about G-sensitivity, let time pass until the CSAC is also 
ITAR controlled ;) It will no take too much.


Regards,

Javier

___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

An SC is going to have it's temperature curve centered up around 95C or so. If 
it's been cut as an OCXO crystal the turns will be up there as well. By the 
time it gets to room temp, the delta F / delta T is moving mighty fast. Think 
in terms of multiple ppm/C. A typical cell phone TCXO crystal is in the sub 0.1 
ppm/C range in the vicinity of room temp.
In addition, SC's are pretty hard to pull. For a normal TCXO (no DDS) something 
 40 ppm of range would be needed. By the time you get the wide tune stuff in 
the circuit, the phase noise isn't going to be anything special. 

Bob

On Aug 31, 2012, at 12:10 AM, Jim Lux jim...@earthlink.net wrote:

 On 8/30/12 9:04 PM, Bob Camp wrote:
 Hi
 
 A standard clock crystal is pretty much junk. as far as temperature 
 performance is concerned. Even a cheap TCXO is likely to be pretty good over 
 25 C +/- 10C.
 
 
 yes.. but, say, one had a decent SC cut with good phase noise properties, but 
 large (but repeatable) temperature characteristics.
 
 Can I get good accuracy AND good phase noise, for less hassle/power/size than 
 an OCXO?
 
 My radio has a TCXO and a clock oscillator, so the clock oscillator is my 
 test article for the temperature compensation scheme..
 
 
 
 Bob
 
 On Aug 30, 2012, at 11:35 PM, Jim Lux jim...@earthlink.net wrote:
 
 On 8/30/12 6:12 PM, Bob Camp wrote:
 Hi
 
 If the temperature is varying slowly *and* there are no gradients you may 
 get your order of magnitude over some range. You might be surprised at 
 your TCXO. A lot of them are pretty darn good in the vicinity of room 
 temp. You may already be an order of magnitude past your ppm or two for 
 fairly normal temperature changes.
 
 
 Temp does vary slowly (the radio weighs on the order of 6kg)..
 
 Need to hold spec (in theory) from -20 to +40C.  The oscillator runs about 
 10 degrees hotter inside.
 
 About 0.2 ppm from 5C to 40C.  +/- 1ppm worst case over the whole 
 temperature range.
 
 What I'm also interested in is whether I can compensate a non TCXO 66MHz 
 CPU clock oscillator (even cheaper, potentially better phase noise with a 
 higher Q crystal, etc.)
 
 ___
 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.
 
 
 ___
 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.
 
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/31/12 7:06 AM, Bob Camp wrote:

Hi

An SC is going to have it's temperature curve centered up around 95C
or so. If it's been cut as an OCXO crystal the turns will be up there
as well. By the time it gets to room temp, the delta F / delta T is
moving mighty fast. Think in terms of multiple ppm/C. A typical cell
phone TCXO crystal is in the sub 0.1 ppm/C range in the vicinity of
room temp. In addition, SC's are pretty hard to pull. For a normal
TCXO (no DDS) something  40 ppm of range would be needed. By the
time you get the wide tune stuff in the circuit, the phase noise
isn't going to be anything special.

Bob



We're not pulling the crystal.. we just let it sit.
What we do is change an NCO in the software radio implementation. 
Typically, you have a coarse tune with a PLL in steps of 500kHz-1MHz, 
and then you do the fine tune in software with a digital 
mixer/downconverter and an NCO (which also is part of the carrier 
tracking loop).




___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

Ok, that gets you back to the basics of really major delta F / delta T slopes.

Bob

On Aug 31, 2012, at 8:55 PM, Jim Lux jim...@earthlink.net wrote:

 On 8/31/12 7:06 AM, Bob Camp wrote:
 Hi
 
 An SC is going to have it's temperature curve centered up around 95C
 or so. If it's been cut as an OCXO crystal the turns will be up there
 as well. By the time it gets to room temp, the delta F / delta T is
 moving mighty fast. Think in terms of multiple ppm/C. A typical cell
 phone TCXO crystal is in the sub 0.1 ppm/C range in the vicinity of
 room temp. In addition, SC's are pretty hard to pull. For a normal
 TCXO (no DDS) something  40 ppm of range would be needed. By the
 time you get the wide tune stuff in the circuit, the phase noise
 isn't going to be anything special.
 
 Bob
 
 
 We're not pulling the crystal.. we just let it sit.
 What we do is change an NCO in the software radio implementation. Typically, 
 you have a coarse tune with a PLL in steps of 500kHz-1MHz, and then you do 
 the fine tune in software with a digital mixer/downconverter and an NCO 
 (which also is part of the carrier tracking loop).
 
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/31/12 7:16 PM, Bob Camp wrote:

Hi

Ok, that gets you back to the basics of really major delta F / delta T slopes.

Bob

yeah.. but as long as you know what the curve is.. the NCO has a huge 
range (after all, we already have to tune over 500 kHz...a few hundred 
Hz isn't a big deal.



A more complex problem is doing insitu calibration from, e.g., GPS 
signals or from some externally received frequency reference. (since the 
radio in question can also work as a GPS receiver, eventually).





___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

An OCXO crystal needs to be good only at one temperature. The crystal in an 
MCXO needs to do well over a wide range of temperatures. That complicates 
things quite a bit.

Bob

On Aug 30, 2012, at 12:22 AM, Hal Murray hmur...@megapathdsl.net wrote:

 
 rich...@karlquist.com said:
 No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal. This
 crystal could very easily cost more than an OCXO crystal. 
 
 What's special about it?
 
 I assume the cost-more aspect would be to allow an overall goodness factor 
 competitive with an OCXO in the low power corner of the marketplace.  It 
 might be cheaper overall to use a good crystal and a uP to correct for 
 temperature than provide the power to run the oven.
 
 
 
 The other area where a uP is useful is in an environment with high vibration. 
  It can correct for acceleration as well as temperature.  There were several 
 good URLs mention on this list in the past year or two.  The context was 
 radar on helicopters.  Helicopters are full of vibrations/accelerations.  The 
 numbers work out such that the frequency broadening due to vibration is 
 interesting if your radar is looking for slowly moving things like people.
 
 --
 
 Crazy question dept:
 
 What do low cost rubidium oscillators do when vibrating?  Is it dominated by 
 the cleanup crystal?
 
 
 
 -- 
 These are my opinions.  I hate spam.
 
 
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

The typical watch crystal has a parabolic temperature coefficient with it's 
peak near 90F. The slope (and difficulty of correction) goes up as you move 
away from the peak. A simple drop / add one cycle (or do nothing) in a second 
approach would be adequate to do all the steering needed. 

Bob

On Aug 30, 2012, at 12:35 AM, Hal Murray hmur...@megapathdsl.net wrote:

 
 Well, basically the temperature of a wrist watch is very constant at around
 90F.  That and a table lookup that gives an adjustment for number of cycles
 per tick vs temperature. 
 
 My introduction to this area was roughly a comment like that.
 
 The other half of the comment was that watches keep (much) less-good time if 
 you park them on the night stand while you are sleeping.
 
 
 -- 
 These are my opinions.  I hate spam.
 
 
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/29/12 8:45 PM, Richard (Rick) Karlquist wrote:


On 8/27/2012 11:45 PM, WB6BNQ wrote:



A microprocessor controlled XO is a non oven crystal oscillator system
that has
additional computational control providing a bit more than just mere
passive
temperature compensation.  The additional computational capability
deals with
having coefficients of that particular oscillator's behavior pre coded to
compensate for the nonlinear behavior over a given temperature rang


It doesn't use coefficients.  It has a look up table of frequency vs
temperature.



A microprocessor controlled XO system allows for using cheap crystals
with
minimum processing time and costs.  Because of limited storage space
there is no


No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal.
This crystal could very easily cost more than an OCXO crystal.



Isn't the crystal cut (and the circuit designed) in such a way that it 
supports both the fundamental and the third overtone simultaneously, and 
comparing the frequencies of the two (or, more accurately, fF- fthird/3) 
is how they measure the temperature, which is then used to look up the 
correction factor in a PROM.



___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/29/12 9:22 PM, Hal Murray wrote:


rich...@karlquist.com said:

No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal. This
crystal could very easily cost more than an OCXO crystal.


http://www.q-tech.com/mcxo.html



What's special about it?
Has to support the overtones properly. Not only does it have to be a 
good oscillator crystal, it also has to be a good thermometer




I assume the cost-more aspect would be to allow an overall goodness factor 
competitive with an OCXO in the low power corner of the marketplace.  It might 
be cheaper overall to use a good crystal and a uP to correct for temperature 
than provide the power to run the oven.



Power consumption, size, etc.  Also, faster startup time (no waiting for 
an oven to stabilize)





The other area where a uP is useful is in an environment with high vibration.  
It can correct for acceleration as well as temperature.  There were several 
good URLs mention on this list in the past year or two.  The context was radar 
on helicopters.  Helicopters are full of vibrations/accelerations.  The numbers 
work out such that the frequency broadening due to vibration is interesting if 
your radar is looking for slowly moving things like people.

--

Crazy question dept:

What do low cost rubidium oscillators do when vibrating?  Is it dominated by 
the cleanup crystal?






___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

The fundamental / third approach is one of several possible ways to go. You
can also run an SC on the B and C modes to get thermometer data. Early
implementations used a pair of independent blanks, one cut to be a good
thermometer. Some have even gone as far as to mount a thermistor on the
crystal.

No matter what you do, it adds cost.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Jim Lux
Sent: Thursday, August 30, 2012 8:55 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] oscillators

On 8/29/12 8:45 PM, Richard (Rick) Karlquist wrote:

 On 8/27/2012 11:45 PM, WB6BNQ wrote:


 A microprocessor controlled XO is a non oven crystal oscillator system
 that has
 additional computational control providing a bit more than just mere
 passive
 temperature compensation.  The additional computational capability
 deals with
 having coefficients of that particular oscillator's behavior pre coded to
 compensate for the nonlinear behavior over a given temperature rang

 It doesn't use coefficients.  It has a look up table of frequency vs
 temperature.


 A microprocessor controlled XO system allows for using cheap crystals
 with
 minimum processing time and costs.  Because of limited storage space
 there is no

 No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal.
 This crystal could very easily cost more than an OCXO crystal.


Isn't the crystal cut (and the circuit designed) in such a way that it 
supports both the fundamental and the third overtone simultaneously, and 
comparing the frequencies of the two (or, more accurately, fF- fthird/3) 
is how they measure the temperature, which is then used to look up the 
correction factor in a PROM.


___
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.



___
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.

Re: [time-nuts] oscillators

[Rick Karlquist]

Hal Murray wrote:

 rich...@karlquist.com said:
 No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal.
 This
 crystal could very easily cost more than an OCXO crystal.

 What's special about it?

First, it has to have no activity dips over the full
operating temperature range.  OCXO crystals only have to work
at the oven temperature.  Activity dips, according to John Vig,
are the reason whey they don't use mode B to sense temperature.

Second, it has to be cut correctly so that the beat note between
the fundamental times 3 and 3rd overtone modes is a useful
indicator of temperature.



 I assume the cost-more aspect would be to allow an overall goodness factor
 competitive with an OCXO in the low power corner of the marketplace.  It
 might be cheaper overall to use a good crystal and a uP to correct for
 temperature than provide the power to run the oven.

Again, the MCXO is not a poor man's OCXO.  It tends to be used
in applications such as manpack radios where battery constraints
rule out ovens, regardless of cost.



 

 The other area where a uP is useful is in an environment with high
 vibration.  It can correct for acceleration as well as temperature.  There

I've never heard of this being done.  Do you have a reference?


Rick Karlquist N6RK


___
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.

Re: [time-nuts] oscillators

[SAIDJACK]

There are some drawbacks to this type of SC-cut MCXO I would think,  and it 
could possibly be replaced by a much higher performance Symmetricom CSAC,  
probably at a lower cost and higher availability:
 
* Q-tech MCXO is ITAR controlled, CSAC is not
* MCXO has 20ppb over temp stability, CSAC has 1ppb spec, typical units can 
 be much lower than that. Our GPSTCXO has 75ppb over temp, not much more  
than the MCXO, but probably at 1/10th the cost.
* The G-sensitivity of CSAC is at least 50x better than the MCXO  (its so 
low, its very hard to measure)
* Aging of MCXO is much higher (order of magnitude)
* Symmetricom is a big player, Q-tech is relatively small and unknown
* I remember that there are patents on the MCXO held by FEI?
* Power consumption is very similar, future CSAC units will have much lower 
 power than the MCXO.
 
The MCXO does have lower phase noise, it's an SC-cut cyrstal after all. But 
 with CSAC's now becoming available from multiple sources, why use an MCXO?
 
bye,
Said
 
 
 
 
In a message dated 8/30/2012 10:35:56 Pacific Daylight Time,  
rich...@karlquist.com writes:

First,  it has to have no activity dips over the full
operating temperature  range.  OCXO crystals only have to work
at the oven temperature.   Activity dips, according to John Vig,
are the reason whey they don't use  mode B to sense temperature.

Second, it has to be cut correctly so that  the beat note between
the fundamental times 3 and 3rd overtone modes is a  useful
indicator of  temperature.



___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

The original patents on the MCXO are government property. One of the Ft.
Monmouth guys came up with the fundamental / third overtone idea back in the
80's. Several (at least three) companies were licensed by the government to
make the part.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of saidj...@aol.com
Sent: Thursday, August 30, 2012 2:54 PM
To: rich...@karlquist.com; time-nuts@febo.com
Subject: Re: [time-nuts] oscillators

There are some drawbacks to this type of SC-cut MCXO I would think,  and it 
could possibly be replaced by a much higher performance Symmetricom CSAC,  
probably at a lower cost and higher availability:
 
* Q-tech MCXO is ITAR controlled, CSAC is not
* MCXO has 20ppb over temp stability, CSAC has 1ppb spec, typical units can 
 be much lower than that. Our GPSTCXO has 75ppb over temp, not much more  
than the MCXO, but probably at 1/10th the cost.
* The G-sensitivity of CSAC is at least 50x better than the MCXO  (its so 
low, its very hard to measure)
* Aging of MCXO is much higher (order of magnitude)
* Symmetricom is a big player, Q-tech is relatively small and unknown
* I remember that there are patents on the MCXO held by FEI?
* Power consumption is very similar, future CSAC units will have much lower 
 power than the MCXO.
 
The MCXO does have lower phase noise, it's an SC-cut cyrstal after all. But 
 with CSAC's now becoming available from multiple sources, why use an MCXO?
 
bye,
Said
 
 
 
 
In a message dated 8/30/2012 10:35:56 Pacific Daylight Time,  
rich...@karlquist.com writes:

First,  it has to have no activity dips over the full
operating temperature  range.  OCXO crystals only have to work
at the oven temperature.   Activity dips, according to John Vig,
are the reason whey they don't use  mode B to sense temperature.

Second, it has to be cut correctly so that  the beat note between
the fundamental times 3 and 3rd overtone modes is a  useful
indicator of  temperature.



___
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.



___
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.

Re: [time-nuts] oscillators

[Magnus Danielson]

On 08/30/2012 06:33 PM, Bob Camp wrote:

Hi

The fundamental / third approach is one of several possible ways to go. You
can also run an SC on the B and C modes to get thermometer data. Early
implementations used a pair of independent blanks, one cut to be a good
thermometer. Some have even gone as far as to mount a thermistor on the
crystal.

No matter what you do, it adds cost.


The reason for doing it is to lower powerconsumption in critical 
applications.


Cheers,
Magnus

___
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.

Re: [time-nuts] oscillators

[Dennis Ferguson]

On 30 Aug, 2012, at 13:14 , Rick Karlquist wrote:
 The other area where a uP is useful is in an environment with high
 vibration.  It can correct for acceleration as well as temperature.  There
 
 I've never heard of this being done.  Do you have a reference?

I'm not sure how that would be done with a single crystal but I heard
a talk by David Allan about a (carefully oriented) array of 6 crystals
for which that was done.  A Kalman filter which understood the physics
of acceleration effects was applied to the output of the 6 crystals
to produce a composite clock and, as a side effect, inertial navigation
information.  This allowed the composite clock to be corrected for
g-effects as well as providing the same data that would be output by
a conventional, mechanical inertial navigation unit.

I think the target application was a drone aircraft, with the clock
output ending up at a GPS receiver while the inertial data was used
as a fallback if the GPS was jammed and as a sanity check to detect
GPS spoofing.  This seemed like a nice one-stone-several-birds solution.
I have a copy of the powerpoint somewhere, but I've not seen this
written down anywhere else.

Dennis Ferguson

___
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.

Re: [time-nuts] oscillators

[Azelio Boriani]

Interesting this third overtone/fundamental*3 idea but what makes the third
overtone not equal to the fundamental*3? Is the crystal operated in series
or parallel resonance?

On Thu, Aug 30, 2012 at 10:30 PM, Magnus Danielson 
mag...@rubidium.dyndns.org wrote:

 On 08/30/2012 06:33 PM, Bob Camp wrote:

 Hi

 The fundamental / third approach is one of several possible ways to go.
 You
 can also run an SC on the B and C modes to get thermometer data. Early
 implementations used a pair of independent blanks, one cut to be a good
 thermometer. Some have even gone as far as to mount a thermistor on the
 crystal.

 No matter what you do, it adds cost.


 The reason for doing it is to lower powerconsumption in critical
 applications.

 Cheers,
 Magnus


 ___
 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.

___
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.

Re: [time-nuts] oscillators

[Rick Karlquist]

Azelio Boriani wrote:
 Interesting this third overtone/fundamental*3 idea but what makes the
 third
 overtone not equal to the fundamental*3? Is the crystal operated in series
 or parallel resonance?


That is where the special SC cut crystal comes into play.
It's not so much that the 3rd OT is on a different frequency, but
rather that it has a different and known tempco relative to the
fundamental, so it can be used as a thermometer.  It would be
interesting to take a crystal out of a random 10811 and compare the
frequencies of the fundamental and 3rd OT vs temperature to see
if that crystal would accidentally make a good thermometer.

Rick Karlquist N6RK


___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

It turns out that the fundamental is not quite 1/3 of the third overtone. You 
can impact the degree of offset by changing the contour of the blank. The 
temperature coefficient is also different on the fundamental. The net result is 
that you can get a pretty good thermometer reading by mixing one with the other 
divided by 3.

Bob

On Aug 30, 2012, at 4:37 PM, Azelio Boriani azelio.bori...@screen.it wrote:

 Interesting this third overtone/fundamental*3 idea but what makes the third
 overtone not equal to the fundamental*3? Is the crystal operated in series
 or parallel resonance?
 
 On Thu, Aug 30, 2012 at 10:30 PM, Magnus Danielson 
 mag...@rubidium.dyndns.org wrote:
 
 On 08/30/2012 06:33 PM, Bob Camp wrote:
 
 Hi
 
 The fundamental / third approach is one of several possible ways to go.
 You
 can also run an SC on the B and C modes to get thermometer data. Early
 implementations used a pair of independent blanks, one cut to be a good
 thermometer. Some have even gone as far as to mount a thermistor on the
 crystal.
 
 No matter what you do, it adds cost.
 
 
 The reason for doing it is to lower powerconsumption in critical
 applications.
 
 Cheers,
 Magnus
 
 
 ___
 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.
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

You can do the same thing with an AT as with an SC. They both exhibit the 
fundamental / third offset and tempo delta.

Bob

On Aug 30, 2012, at 5:10 PM, Rick Karlquist rich...@karlquist.com wrote:

 Azelio Boriani wrote:
 Interesting this third overtone/fundamental*3 idea but what makes the
 third
 overtone not equal to the fundamental*3? Is the crystal operated in series
 or parallel resonance?
 
 
 That is where the special SC cut crystal comes into play.
 It's not so much that the 3rd OT is on a different frequency, but
 rather that it has a different and known tempco relative to the
 fundamental, so it can be used as a thermometer.  It would be
 interesting to take a crystal out of a random 10811 and compare the
 frequencies of the fundamental and 3rd OT vs temperature to see
 if that crystal would accidentally make a good thermometer.
 
 Rick Karlquist N6RK
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Magnus Danielson]

On 08/30/2012 11:10 PM, Rick Karlquist wrote:

Azelio Boriani wrote:

Interesting this third overtone/fundamental*3 idea but what makes the
third
overtone not equal to the fundamental*3? Is the crystal operated in series
or parallel resonance?



That is where the special SC cut crystal comes into play.
It's not so much that the 3rd OT is on a different frequency, but
rather that it has a different and known tempco relative to the
fundamental, so it can be used as a thermometer.  It would be
interesting to take a crystal out of a random 10811 and compare the
frequencies of the fundamental and 3rd OT vs temperature to see
if that crystal would accidentally make a good thermometer.


All the different modes have different temperature dependencies. Being 
able to maintain dual oscillation on both over the range seems like a 
reasonable challenge.


Cheers,
Magnus

___
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.

Re: [time-nuts] oscillators

[Hal Murray]

rich...@karlquist.com said:
 The other area where a uP is useful is in an environment
 with high vibration.  It can correct for acceleration as well
 as temperature.

 I've never heard of this being done.  Do you have a reference?

This is probably the paper I was thinking of.  Looks like I made up the uP 
part.  Sorry for the confusion.  It's a fun read even if it doesn't mention 
uP.

http://www.freqelec.com/oscillators/g-comp_qz_brfg_04-07.pdf

g- Compensated, Miniature,
  High Performance Quartz
  Crystal Oscillators

Frequency
Electronics Inc.
Hugo Fruehauf
h...@fei-zyfer.com
April 2007


From:
  http://www.febo.com/pipermail/time-nuts/2010-February/044414.html


-- 
These are my opinions.  I hate spam.




___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/30/12 9:33 AM, Bob Camp wrote:

Hi

The fundamental / third approach is one of several possible ways to go. You
can also run an SC on the B and C modes to get thermometer data. Early
implementations used a pair of independent blanks, one cut to be a good
thermometer. Some have even gone as far as to mount a thermistor on the
crystal.



I've used the sensor on oscillator can technique very recently on a 
software defined radio.  Over the next year, I'll get some data on how 
well it works in use.  The idea is to use a low power TCXO and a sensor, 
rather than an OCXO, to meet a fairly tight frequency requirement (a few 
hundred Hz out of 2 GHz)  The TCXO can get you do a few ppm or better. 
The sensor should let me get about an order of magnitude better, and I 
need to measure the temperature anyway, and it's easy to integrate with 
the software waveform code.




___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/30/12 12:37 PM, Bob Camp wrote:

Hi

The original patents on the MCXO are government property. One of the Ft.
Monmouth guys came up with the fundamental / third overtone idea back in the
80's. Several (at least three) companies were licensed by the government to
make the part.




Gotta be careful there..

A lot of times these days, the government doesn't own the patent, they 
get a government use license.  If it was a civil servant doing the 
work, then, yes, government owns it, and anyone can use it.  However, if 
it was a contractor at a government facility, or developed under a 
contract (particularly a university), then it might be much stickier. 
If you wanted to build something to sell to the government, then getting 
a license is easy.  But for the general public, perhaps not.


Working at JPL, which is part of Cal Tech, on NASA's nickle, we're made 
VERY aware of exactly who owns the fruits of our brains, and who gets to 
use it.  The Bayh Dole act has many unexpected consequences.



These days, a lot of the people working at government labs are not civil 
servants, but are Technical Support and Engineering Personnel.  This 
allows them to report a lower headcount of government employees.


___
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.

Re: [time-nuts] oscillators

[Don Latham]

Elecraft seems to be having some trouble with the KX3 stability for WSJT
on 6m. They also have a temp sensor on the bard, apparently and are also
trying this out. I don't know any more about it than that.
Don

Jim Lux
 On 8/30/12 9:33 AM, Bob Camp wrote:
 Hi

 The fundamental / third approach is one of several possible ways to
 go. You
 can also run an SC on the B and C modes to get thermometer data. Early
 implementations used a pair of independent blanks, one cut to be a
 good
 thermometer. Some have even gone as far as to mount a thermistor on
 the
 crystal.


 I've used the sensor on oscillator can technique very recently on a
 software defined radio.  Over the next year, I'll get some data on how
 well it works in use.  The idea is to use a low power TCXO and a sensor,
 rather than an OCXO, to meet a fairly tight frequency requirement (a few
 hundred Hz out of 2 GHz)  The TCXO can get you do a few ppm or better.
 The sensor should let me get about an order of magnitude better, and I
 need to measure the temperature anyway, and it's easy to integrate with
 the software waveform code.



 ___
 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.



-- 
Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind.
De Erroribus Medicorum, R. Bacon, 13th century.
If you don't know what it is, don't poke it.
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com



___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

The guy(s) who did the original work were indeed full time DOD employees.

Bob

On Aug 30, 2012, at 8:11 PM, Jim Lux jim...@earthlink.net wrote:

 On 8/30/12 12:37 PM, Bob Camp wrote:
 Hi
 
 The original patents on the MCXO are government property. One of the Ft.
 Monmouth guys came up with the fundamental / third overtone idea back in the
 80's. Several (at least three) companies were licensed by the government to
 make the part.
 
 
 
 Gotta be careful there..
 
 A lot of times these days, the government doesn't own the patent, they get a 
 government use license.  If it was a civil servant doing the work, then, 
 yes, government owns it, and anyone can use it.  However, if it was a 
 contractor at a government facility, or developed under a contract 
 (particularly a university), then it might be much stickier. If you wanted to 
 build something to sell to the government, then getting a license is easy.  
 But for the general public, perhaps not.
 
 Working at JPL, which is part of Cal Tech, on NASA's nickle, we're made VERY 
 aware of exactly who owns the fruits of our brains, and who gets to use it.  
 The Bayh Dole act has many unexpected consequences.
 
 
 These days, a lot of the people working at government labs are not civil 
 servants, but are Technical Support and Engineering Personnel.  This allows 
 them to report a lower headcount of government employees.
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

If the temperature is varying slowly *and* there are no gradients you may get 
your order of magnitude over some range. You might be surprised at your TCXO. A 
lot of them are pretty darn good in the vicinity of room temp. You may already 
be an order of magnitude past your ppm or two for fairly normal temperature 
changes.

Bob

On Aug 30, 2012, at 8:01 PM, Jim Lux jim...@earthlink.net wrote:

 On 8/30/12 9:33 AM, Bob Camp wrote:
 Hi
 
 The fundamental / third approach is one of several possible ways to go. You
 can also run an SC on the B and C modes to get thermometer data. Early
 implementations used a pair of independent blanks, one cut to be a good
 thermometer. Some have even gone as far as to mount a thermistor on the
 crystal.
 
 
 I've used the sensor on oscillator can technique very recently on a 
 software defined radio.  Over the next year, I'll get some data on how well 
 it works in use.  The idea is to use a low power TCXO and a sensor, rather 
 than an OCXO, to meet a fairly tight frequency requirement (a few hundred Hz 
 out of 2 GHz)  The TCXO can get you do a few ppm or better. The sensor should 
 let me get about an order of magnitude better, and I need to measure the 
 temperature anyway, and it's easy to integrate with the software waveform 
 code.
 
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Magnus Danielson]

On 08/31/2012 03:12 AM, Bob Camp wrote:

Hi

If the temperature is varying slowly *and* there are no gradients you may get 
your order of magnitude over some range. You might be surprised at your TCXO. A 
lot of them are pretty darn good in the vicinity of room temp. You may already 
be an order of magnitude past your ppm or two for fairly normal temperature 
changes.


I haven't seen that any of the TCXOs compensates for the temperature 
hysteresis. It would be cool if they did.


The ability to handle temperature gradients can be troublesome for both 
TCXOs and OCXOs.


TCXOs have become quite good these days.

Cheers,
Magnus

___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

Some TCXO's have less hysteresis than others…...

Bob

On Aug 30, 2012, at 9:29 PM, Magnus Danielson mag...@rubidium.dyndns.org 
wrote:

 On 08/31/2012 03:12 AM, Bob Camp wrote:
 Hi
 
 If the temperature is varying slowly *and* there are no gradients you may 
 get your order of magnitude over some range. You might be surprised at your 
 TCXO. A lot of them are pretty darn good in the vicinity of room temp. You 
 may already be an order of magnitude past your ppm or two for fairly normal 
 temperature changes.
 
 I haven't seen that any of the TCXOs compensates for the temperature 
 hysteresis. It would be cool if they did.
 
 The ability to handle temperature gradients can be troublesome for both TCXOs 
 and OCXOs.
 
 TCXOs have become quite good these days.
 
 Cheers,
 Magnus
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[jmfranke]

If a civil servant was the inventor, the government is assigned the rights 
and no one can use it for other than government applications without a 
license. At one time I helped license government patents to companies.


John

--
From: Jim Lux jim...@earthlink.net
Sent: Thursday, August 30, 2012 8:11 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] oscillators


On 8/30/12 12:37 PM, Bob Camp wrote:

Hi

The original patents on the MCXO are government property. One of the Ft.
Monmouth guys came up with the fundamental / third overtone idea back in 
the
80's. Several (at least three) companies were licensed by the government 
to

make the part.




Gotta be careful there..

A lot of times these days, the government doesn't own the patent, they get 
a government use license.  If it was a civil servant doing the work, 
then, yes, government owns it, and anyone can use it.  However, if it was 
a contractor at a government facility, or developed under a contract 
(particularly a university), then it might be much stickier. If you wanted 
to build something to sell to the government, then getting a license is 
easy.  But for the general public, perhaps not.


Working at JPL, which is part of Cal Tech, on NASA's nickle, we're made 
VERY aware of exactly who owns the fruits of our brains, and who gets to 
use it.  The Bayh Dole act has many unexpected consequences.



These days, a lot of the people working at government labs are not civil 
servants, but are Technical Support and Engineering Personnel.  This 
allows them to report a lower headcount of government employees.


___
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.




___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

I think they would do better to just put in a connector to drive it with a 
TBolt….

Bob

On Aug 30, 2012, at 8:47 PM, Don Latham d...@montana.com wrote:

 Elecraft seems to be having some trouble with the KX3 stability for WSJT
 on 6m. They also have a temp sensor on the bard, apparently and are also
 trying this out. I don't know any more about it than that.
 Don
 
 Jim Lux
 On 8/30/12 9:33 AM, Bob Camp wrote:
 Hi
 
 The fundamental / third approach is one of several possible ways to
 go. You
 can also run an SC on the B and C modes to get thermometer data. Early
 implementations used a pair of independent blanks, one cut to be a
 good
 thermometer. Some have even gone as far as to mount a thermistor on
 the
 crystal.
 
 
 I've used the sensor on oscillator can technique very recently on a
 software defined radio.  Over the next year, I'll get some data on how
 well it works in use.  The idea is to use a low power TCXO and a sensor,
 rather than an OCXO, to meet a fairly tight frequency requirement (a few
 hundred Hz out of 2 GHz)  The TCXO can get you do a few ppm or better.
 The sensor should let me get about an order of magnitude better, and I
 need to measure the temperature anyway, and it's easy to integrate with
 the software waveform code.
 
 
 
 ___
 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.
 
 
 
 -- 
 Neither the voice of authority nor the weight of reason and argument
 are as significant as experiment, for thence comes quiet to the mind.
 De Erroribus Medicorum, R. Bacon, 13th century.
 If you don't know what it is, don't poke it.
 Ghost in the Shell
 
 
 Dr. Don Latham AJ7LL
 Six Mile Systems LLP
 17850 Six Mile Road
 POB 134
 Huson, MT, 59846
 VOX 406-626-4304
 www.lightningforensics.com
 www.sixmilesystems.com
 
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

Indeed, at least three companies received licenses.

Bob

On Aug 30, 2012, at 10:14 PM, jmfranke jmfra...@cox.net wrote:

 If a civil servant was the inventor, the government is assigned the rights 
 and no one can use it for other than government applications without a 
 license. At one time I helped license government patents to companies.
 
 John
 
 --
 From: Jim Lux jim...@earthlink.net
 Sent: Thursday, August 30, 2012 8:11 PM
 To: time-nuts@febo.com
 Subject: Re: [time-nuts] oscillators
 
 On 8/30/12 12:37 PM, Bob Camp wrote:
 Hi
 
 The original patents on the MCXO are government property. One of the Ft.
 Monmouth guys came up with the fundamental / third overtone idea back in the
 80's. Several (at least three) companies were licensed by the government to
 make the part.
 
 
 
 Gotta be careful there..
 
 A lot of times these days, the government doesn't own the patent, they get a 
 government use license.  If it was a civil servant doing the work, then, 
 yes, government owns it, and anyone can use it.  However, if it was a 
 contractor at a government facility, or developed under a contract 
 (particularly a university), then it might be much stickier. If you wanted 
 to build something to sell to the government, then getting a license is 
 easy.  But for the general public, perhaps not.
 
 Working at JPL, which is part of Cal Tech, on NASA's nickle, we're made VERY 
 aware of exactly who owns the fruits of our brains, and who gets to use it.  
 The Bayh Dole act has many unexpected consequences.
 
 
 These days, a lot of the people working at government labs are not civil 
 servants, but are Technical Support and Engineering Personnel.  This 
 allows them to report a lower headcount of government employees.
 
 ___
 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.
 
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/30/12 6:12 PM, Bob Camp wrote:

Hi

If the temperature is varying slowly *and* there are no gradients you may get 
your order of magnitude over some range. You might be surprised at your TCXO. A 
lot of them are pretty darn good in the vicinity of room temp. You may already 
be an order of magnitude past your ppm or two for fairly normal temperature 
changes.



Temp does vary slowly (the radio weighs on the order of 6kg)..

Need to hold spec (in theory) from -20 to +40C.  The oscillator runs 
about 10 degrees hotter inside.


About 0.2 ppm from 5C to 40C.  +/- 1ppm worst case over the whole 
temperature range.


What I'm also interested in is whether I can compensate a non TCXO 66MHz 
CPU clock oscillator (even cheaper, potentially better phase noise with 
a higher Q crystal, etc.)


___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/30/12 6:29 PM, Magnus Danielson wrote:

On 08/31/2012 03:12 AM, Bob Camp wrote:

Hi

If the temperature is varying slowly *and* there are no gradients you
may get your order of magnitude over some range. You might be
surprised at your TCXO. A lot of them are pretty darn good in the
vicinity of room temp. You may already be an order of magnitude past
your ppm or two for fairly normal temperature changes.


I haven't seen that any of the TCXOs compensates for the temperature
hysteresis. It would be cool if they did.


That is the dominant error source for changes over the 5-40C.. about 0.2 
ppm difference when going up from -55 to +85 and going down over the 
same range.




The ability to handle temperature gradients can be troublesome for both
TCXOs and OCXOs.

TCXOs have become quite good these days.

Cheers,
Magnus

___
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.




___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

A standard clock crystal is pretty much junk. as far as temperature performance 
is concerned. Even a cheap TCXO is likely to be pretty good over 25 C +/- 10C.

Bob

On Aug 30, 2012, at 11:35 PM, Jim Lux jim...@earthlink.net wrote:

 On 8/30/12 6:12 PM, Bob Camp wrote:
 Hi
 
 If the temperature is varying slowly *and* there are no gradients you may 
 get your order of magnitude over some range. You might be surprised at your 
 TCXO. A lot of them are pretty darn good in the vicinity of room temp. You 
 may already be an order of magnitude past your ppm or two for fairly normal 
 temperature changes.
 
 
 Temp does vary slowly (the radio weighs on the order of 6kg)..
 
 Need to hold spec (in theory) from -20 to +40C.  The oscillator runs about 10 
 degrees hotter inside.
 
 About 0.2 ppm from 5C to 40C.  +/- 1ppm worst case over the whole temperature 
 range.
 
 What I'm also interested in is whether I can compensate a non TCXO 66MHz CPU 
 clock oscillator (even cheaper, potentially better phase noise with a higher 
 Q crystal, etc.)
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/30/12 9:04 PM, Bob Camp wrote:

Hi

A standard clock crystal is pretty much junk. as far as temperature performance 
is concerned. Even a cheap TCXO is likely to be pretty good over 25 C +/- 10C.



yes.. but, say, one had a decent SC cut with good phase noise 
properties, but large (but repeatable) temperature characteristics.


Can I get good accuracy AND good phase noise, for less hassle/power/size 
than an OCXO?


My radio has a TCXO and a clock oscillator, so the clock oscillator is 
my test article for the temperature compensation scheme..





Bob

On Aug 30, 2012, at 11:35 PM, Jim Lux jim...@earthlink.net wrote:


On 8/30/12 6:12 PM, Bob Camp wrote:

Hi

If the temperature is varying slowly *and* there are no gradients you may get 
your order of magnitude over some range. You might be surprised at your TCXO. A 
lot of them are pretty darn good in the vicinity of room temp. You may already 
be an order of magnitude past your ppm or two for fairly normal temperature 
changes.



Temp does vary slowly (the radio weighs on the order of 6kg)..

Need to hold spec (in theory) from -20 to +40C.  The oscillator runs about 10 
degrees hotter inside.

About 0.2 ppm from 5C to 40C.  +/- 1ppm worst case over the whole temperature 
range.

What I'm also interested in is whether I can compensate a non TCXO 66MHz CPU 
clock oscillator (even cheaper, potentially better phase noise with a higher Q 
crystal, etc.)

___
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.



___
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.




___
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.

Re: [time-nuts] oscillators

[Don Latham]

Bob: Great minds run in the same track :-)
Don

Bob Camp
 Hi

 I think they would do better to just put in a connector to drive it with
 a TBolt….

 Bob

 On Aug 30, 2012, at 8:47 PM, Don Latham d...@montana.com wrote:

 Elecraft seems to be having some trouble with the KX3 stability for
 WSJT
 on 6m. They also have a temp sensor on the bard, apparently and are
 also
 trying this out. I don't know any more about it than that.
 Don

 Jim Lux
 On 8/30/12 9:33 AM, Bob Camp wrote:
 Hi

 The fundamental / third approach is one of several possible ways to
 go. You
 can also run an SC on the B and C modes to get thermometer data.
 Early
 implementations used a pair of independent blanks, one cut to be a
 good
 thermometer. Some have even gone as far as to mount a thermistor on
 the
 crystal.


 I've used the sensor on oscillator can technique very recently on a
 software defined radio.  Over the next year, I'll get some data on
 how
 well it works in use.  The idea is to use a low power TCXO and a
 sensor,
 rather than an OCXO, to meet a fairly tight frequency requirement (a
 few
 hundred Hz out of 2 GHz)  The TCXO can get you do a few ppm or
 better.
 The sensor should let me get about an order of magnitude better, and
 I
 need to measure the temperature anyway, and it's easy to integrate
 with
 the software waveform code.



 ___
 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.



 --
 Neither the voice of authority nor the weight of reason and argument
 are as significant as experiment, for thence comes quiet to the mind.
 De Erroribus Medicorum, R. Bacon, 13th century.
 If you don't know what it is, don't poke it.
 Ghost in the Shell


 Dr. Don Latham AJ7LL
 Six Mile Systems LLP
 17850 Six Mile Road
 POB 134
 Huson, MT, 59846
 VOX 406-626-4304
 www.lightningforensics.com
 www.sixmilesystems.com



 ___
 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.


 ___
 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.




-- 
Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind.
De Erroribus Medicorum, R. Bacon, 13th century.
If you don't know what it is, don't poke it.
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com



___
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.

Re: [time-nuts] oscillators

[Richard (Rick) Karlquist]

On 8/27/2012 11:45 PM, WB6BNQ wrote:



A microprocessor controlled XO is a non oven crystal oscillator system that has
additional computational control providing a bit more than just mere passive
temperature compensation.  The additional computational capability deals with
having coefficients of that particular oscillator's behavior pre coded to
compensate for the nonlinear behavior over a given temperature rang


It doesn't use coefficients.  It has a look up table of frequency vs
temperature.



A microprocessor controlled XO system allows for using cheap crystals with
minimum processing time and costs.  Because of limited storage space there is no


No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal.
This crystal could very easily cost more than an OCXO crystal.


way for the system to have enough data to even try to compete with the quality 
of
a decent OCXO.  Beyond its initial calibration setup, it has no way of keeping 
it
tied to a known reference, like the Thunderbolt is doing.

BillWB6BNQ


An MCXO is a very good, but expensive TCXO.  Only temperature, not aging 
is corrected.


It has nothing to do with smart clocks.

Rick Karlquist N6RK

___
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.

Re: [time-nuts] oscillators

[Neville Michie]

Does anyone know about what technology is used in Swiss watches to get much 
better performance from 
their xtals than you might expect?
I assumed that they had look up lists to insert extra counts to compensate for 
ambient variations,
but I have never heard any details.
cheers,
Neville Michie






On 30/08/2012, at 1:45 PM, Richard (Rick) Karlquist wrote:

 
 On 8/27/2012 11:45 PM, WB6BNQ wrote:
 
 
 A microprocessor controlled XO is a non oven crystal oscillator system that 
 has
 additional computational control providing a bit more than just mere passive
 temperature compensation.  The additional computational capability deals with
 having coefficients of that particular oscillator's behavior pre coded to
 compensate for the nonlinear behavior over a given temperature rang
 
 It doesn't use coefficients.  It has a look up table of frequency vs
 temperature.
 
 
 A microprocessor controlled XO system allows for using cheap crystals with
 minimum processing time and costs.  Because of limited storage space there 
 is no
 
 No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal.
 This crystal could very easily cost more than an OCXO crystal.
 
 way for the system to have enough data to even try to compete with the 
 quality of
 a decent OCXO.  Beyond its initial calibration setup, it has no way of 
 keeping it
 tied to a known reference, like the Thunderbolt is doing.
 
 BillWB6BNQ
 
 An MCXO is a very good, but expensive TCXO.  Only temperature, not aging is 
 corrected.
 
 It has nothing to do with smart clocks.
 
 Rick Karlquist N6RK
 
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[mike cook]

nippedLe 30/08/2012 06:12, Neville Michie a écrit :

Does anyone know about what technology is used in Swiss watches to get much 
better performance from
their xtals than you might expect?
I assumed that they had look up lists to insert extra counts to compensate for 
ambient variations,
but I have never heard any details.
cheers,
Neville Michie


check out 
http://forums.watchuseek.com/f9/thermocompensation-methods-movements-2087.html

snipped

--
Les chiens aboient, et la caravane passe.


___
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.

Re: [time-nuts] oscillators

[Chuck Harris]

Well, basically the temperature of a wrist watch is very
constant at around 90F.  That and a table lookup that gives
an adjustment for number of cycles per tick vs temperature.

All quartz watches since about 1990 are microprocessor based,
and have a table lookup.  They can only be regulated using
a special computer interface provided by the manufacturer.

-Chuck Harris

Neville Michie wrote:

Does anyone know about what technology is used in Swiss watches to get much 
better performance from
their xtals than you might expect?
I assumed that they had look up lists to insert extra counts to compensate for 
ambient variations,
but I have never heard any details.
cheers,
Neville Michie






On 30/08/2012, at 1:45 PM, Richard (Rick) Karlquist wrote:



On 8/27/2012 11:45 PM, WB6BNQ wrote:



A microprocessor controlled XO is a non oven crystal oscillator system that has
additional computational control providing a bit more than just mere passive
temperature compensation.  The additional computational capability deals with
having coefficients of that particular oscillator's behavior pre coded to
compensate for the nonlinear behavior over a given temperature rang


It doesn't use coefficients.  It has a look up table of frequency vs
temperature.



A microprocessor controlled XO system allows for using cheap crystals with
minimum processing time and costs.  Because of limited storage space there is no


No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal.
This crystal could very easily cost more than an OCXO crystal.


way for the system to have enough data to even try to compete with the quality 
of
a decent OCXO.  Beyond its initial calibration setup, it has no way of keeping 
it
tied to a known reference, like the Thunderbolt is doing.

BillWB6BNQ


An MCXO is a very good, but expensive TCXO.  Only temperature, not aging is 
corrected.

It has nothing to do with smart clocks.

Rick Karlquist N6RK

___
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.



___
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.



___
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.

Re: [time-nuts] oscillators

[Hal Murray]

rich...@karlquist.com said:
 No it doesn't use a cheap crystal.  It uses a *special* SC cut crystal. This
 crystal could very easily cost more than an OCXO crystal. 

What's special about it?

I assume the cost-more aspect would be to allow an overall goodness factor 
competitive with an OCXO in the low power corner of the marketplace.  It might 
be cheaper overall to use a good crystal and a uP to correct for temperature 
than provide the power to run the oven.



The other area where a uP is useful is in an environment with high vibration.  
It can correct for acceleration as well as temperature.  There were several 
good URLs mention on this list in the past year or two.  The context was radar 
on helicopters.  Helicopters are full of vibrations/accelerations.  The numbers 
work out such that the frequency broadening due to vibration is interesting if 
your radar is looking for slowly moving things like people.
  
--

Crazy question dept:

What do low cost rubidium oscillators do when vibrating?  Is it dominated by 
the cleanup crystal?



-- 
These are my opinions.  I hate spam.




___
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.

Re: [time-nuts] oscillators

[Hal Murray]

 Well, basically the temperature of a wrist watch is very constant at around
 90F.  That and a table lookup that gives an adjustment for number of cycles
 per tick vs temperature. 

My introduction to this area was roughly a comment like that.

The other half of the comment was that watches keep (much) less-good time if 
you park them on the night stand while you are sleeping.


-- 
These are my opinions.  I hate spam.




___
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.

Re: [time-nuts] oscillators

[WB6BNQ]

Chris,

That is a big no !  What the Thunderbolt is doing is adjusting the OCXO to keep
it aligned with a known reference from the GPS system.  The fact that a
microprocessor is involved is from a totally different perspective.

A microprocessor controlled XO is a non oven crystal oscillator system that has
additional computational control providing a bit more than just mere passive
temperature compensation.  The additional computational capability deals with
having coefficients of that particular oscillator's behavior pre coded to
compensate for the nonlinear behavior over a given temperature range.

A microprocessor controlled XO system allows for using cheap crystals with
minimum processing time and costs.  Because of limited storage space there is no
way for the system to have enough data to even try to compete with the quality 
of
a decent OCXO.  Beyond its initial calibration setup, it has no way of keeping 
it
tied to a known reference, like the Thunderbolt is doing.

BillWB6BNQ


Chris Albertson wrote:

 On Mon, Aug 27, 2012 at 7:33 PM, Jim Lux jim...@earthlink.net wrote:

  On 8/27/12 4:15 PM, Rick Karlquist wrote:
 
  Several decades ago, the concept of the smart clock arose
  at what was then HP.  The idea was as discussed here to
  characterize past aging, predict future aging, and
  then correct the aging.
 
 
 We know what a OCXO is and a TCXO is.  I was at a presentation at work a
 whike back and they called what you describe a MPCXO  or MicroProcessor
 Compensated XO.They said the characteristics were between the OCXO and
 TCXO

 Doesn't the thunderbolt do this.  I think it watches the aging rate of the
 OCXO and adjusts during hold over.

 --

 Chris Albertson
 Redondo Beach, California
 ___
 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.


___
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.

Re: [time-nuts] oscillators

[Jim Lux]

On 8/27/12 10:45 PM, Chris Albertson wrote:

On Mon, Aug 27, 2012 at 7:33 PM, Jim Lux jim...@earthlink.net wrote:


On 8/27/12 4:15 PM, Rick Karlquist wrote:


Several decades ago, the concept of the smart clock arose
at what was then HP.  The idea was as discussed here to
characterize past aging, predict future aging, and
then correct the aging.




We know what a OCXO is and a TCXO is.  I was at a presentation at work a
whike back and they called what you describe a MPCXO  or MicroProcessor
Compensated XO.They said the characteristics were between the OCXO and
TCXO

Doesn't the thunderbolt do this.  I think it watches the aging rate of the
OCXO and adjusts during hold over.




Not really.  The MCXO has a one time calibration for frequency vs 
temperature that's programmed into it (and some use *very* clever ways 
to measure the temperature).  The disciplining algorithms in a GPSDO are 
a bit smarter; some explicitly develop a model for the f vs T and apply 
it, in others it's essentially embedded in a higher order filter which 
takes the measured T, along with other parameters, into the filter.


I don't know if the GPSDOs try to do a time series fit/model (at least 
for low order terms) to deal with things like diurnal variation.  They 
could.


I should note that the MCXO approach, popularized as a better TCXO in 
a small low power package, is also used in some software defined radios, 
except that there's no separate microcontroller.  The frequency vs 
temperature characteristic is just embedded in the other algorithms in 
the radio's host processor.


___
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.

Re: [time-nuts] oscillators

[Chris Albertson]

On Mon, Aug 27, 2012 at 11:45 PM, WB6BNQ wb6...@cox.net wrote:

 Chris,

 That is a big no !  What the Thunderbolt is doing is adjusting the OCXO to
 keep
 it aligned with a known reference from the GPS system.  The fact that a
 microprocessor is involved is from a totally different perspective.


Yes but but the t-bolt remembers the corrections is was applying and
continues to apply them whenthe GPS signal goes away.   I'm pretty sure one
of the things it remembers is the aging rate.

I know the real uP controlled XOs use programmed data for aging rate and
temp compensation the t-bolt gts it's own data by comparing with GPS.


Chris Albertson
Redondo Beach, California
___
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.

Re: [time-nuts] oscillators

[Chris Albertson]

On Tue, Aug 28, 2012 at 6:17 AM, Jim Lux jim...@earthlink.net wrote:

  The MCXO has a one time calibration for frequency vs temperature that's
 programmed into it (and some use *very* clever ways to measure the
 temperature).  The disciplining algorithms in a GPSDO are a bit smarter;


Yes, correct.  But I was talking about during hold-over.   t-bolt in
holdover is no longer a GPSDO.It falls back on using a temperature and
aging model.

Chris Albertson
Redondo Beach, California
___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

I don't know that there is any data showing the TBolt adjusting for aging
during holdover. In other words: showing the holdover DAC voltage changing
at a completely constant temperature. 

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Albertson
Sent: Tuesday, August 28, 2012 12:19 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] oscillators

On Tue, Aug 28, 2012 at 6:17 AM, Jim Lux jim...@earthlink.net wrote:

  The MCXO has a one time calibration for frequency vs temperature that's
 programmed into it (and some use *very* clever ways to measure the
 temperature).  The disciplining algorithms in a GPSDO are a bit smarter;


Yes, correct.  But I was talking about during hold-over.   t-bolt in
holdover is no longer a GPSDO.It falls back on using a temperature and
aging model.

Chris Albertson
Redondo Beach, California
___
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.



___
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.

[time-nuts] oscillators

[Arthur Dent]

I don't know that there is any data showing the TBolt adjusting for aging
during holdover. In other words: showing the holdover DAC voltage changing
at a completely constant temperature. 

Bob

I haven't seen any data either but here is information from section 5.1.2 
of the 2003 Thunderbolt manual:

Kalman filtering is a technique that improves the performance of a GPS 
disciplined clock when GPS drops out. This state is called holdover. 
During holdover the clock relies solely on the oscillator. Oscillator 
performance is subject to two basic effects. First, changes in environmental 
temperature can cause the oscillator to speed up [or] slow down. Second, the
oscillator has a natural tendency to drift over time. This is called aging. 
Both temperature and aging can be mathematically predicted. However, the 
characteristics vary from crystal to crystal. The Kalman filtering monitors the 
unique oscillator performance over time and temperature and records this 
behavior. Then when the clock goes into holdover this filtering corrects for 
these effects producing a more accurate clock. The longer a clock has
to ’train’ the better the Kalman filtering performance will be. 24 hours is 
considered the minimum necessary for good performance

-Arthur
___
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.

Re: [time-nuts] oscillators

[Bob Camp]

Hi

... then if you take a look at the status printout on a TBolt Kalman
filter always shows up as disabled. Thus the who knows what they are
doing.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Arthur Dent
Sent: Tuesday, August 28, 2012 1:02 PM
To: time-nuts@febo.com
Subject: [time-nuts] oscillators

I don't know that there is any data showing the TBolt adjusting for aging
during holdover. In other words: showing the holdover DAC voltage changing
at a completely constant temperature. 

Bob

I haven't seen any data either but here is information from section 5.1.2 
of the 2003 Thunderbolt manual:

Kalman filtering is a technique that improves the performance of a GPS 
disciplined clock when GPS drops out. This state is called holdover. 
During holdover the clock relies solely on the oscillator. Oscillator 
performance is subject to two basic effects. First, changes in environmental

temperature can cause the oscillator to speed up [or] slow down. Second, the
oscillator has a natural tendency to drift over time. This is called aging. 
Both temperature and aging can be mathematically predicted. However, the 
characteristics vary from crystal to crystal. The Kalman filtering monitors
the 
unique oscillator performance over time and temperature and records this 
behavior. Then when the clock goes into holdover this filtering corrects for

these effects producing a more accurate clock. The longer a clock has
to 'train' the better the Kalman filtering performance will be. 24 hours is 
considered the minimum necessary for good performance

-Arthur
___
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.



___
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.

[time-nuts] oscillators

[Jim Lux]

On 8/27/12 4:15 PM, Rick Karlquist wrote:

Several decades ago, the concept of the smart clock arose
at what was then HP.  The idea was as discussed here to
characterize past aging, predict future aging, and
then correct the aging.  The goal wasn't to turn a quartz
oscillator into an atomic clock replacement, but simply
to get the oscillator through a 1 hour or so holdover time
during GPS outages.  It sort of worked for that very limited
purpose, but in general, past performance of HP crystals wasn't
a very good predictor of future results.  Crystals would age
in one direction for a while and possibly slow down as time
when on, but then then might start aging in the other direction.
There were also frequency jumps that were substantial and totally
random.  The reason why the HP crystals were unpredictable was
that all the deterministic processes such as mass preferentially
depositing on the crystal, so as to make the frequency age
lower, had been eliminated by years of manufacturing improvements.
The remaining processes were of the nature of quartz stress
relaxation that were very random.

Rick Karlquist



We see similar things in USOs  (and other components as well) for 
spaceflight..


Things that people worried about 60 or more years ago just don't occur 
anymore.  People used to obsessively try to match diodes in HV strings, 
for instance, because the process variability was high enough to make a 
difference.  These days, you get a reel of diodes and they're all pretty 
much the same, and even reel to reel from month to month they don't 
change much.That's what all that 6-sigma stuff is all about, after all.


All the low hanging, and even middle hanging, fruit has been picked..

(one big exception.. ICs which are not designed for radiation tolerance 
seem to have large variability in radiation tolerance..it's just not 
something that's controlled for in the process)



___
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.

Re: [time-nuts] oscillators

[Chris Albertson]

On Mon, Aug 27, 2012 at 7:33 PM, Jim Lux jim...@earthlink.net wrote:

 On 8/27/12 4:15 PM, Rick Karlquist wrote:

 Several decades ago, the concept of the smart clock arose
 at what was then HP.  The idea was as discussed here to
 characterize past aging, predict future aging, and
 then correct the aging.


We know what a OCXO is and a TCXO is.  I was at a presentation at work a
whike back and they called what you describe a MPCXO  or MicroProcessor
Compensated XO.They said the characteristics were between the OCXO and
TCXO

Doesn't the thunderbolt do this.  I think it watches the aging rate of the
OCXO and adjusts during hold over.

-- 

Chris Albertson
Redondo Beach, California
___
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.

Re: [time-nuts] Oscillators on eBay

[corby d dawson]

Hi,

I listed some frequency standard related items on eBay and will be
listing some more in the next week or so.

search items by seller corbymite

Cheers!

Corby Dawson

Get credit card help today.  Safe, fast, and easy.  Click Now.
http://thirdpartyoffers.juno.com/TGL2141/fc/Ioyw6i3m2DVEnCitPqF2XZrte7CfOtBRWnkHUz5bpTMlZ9Gh8ofDPr/

___
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.