[time-nuts] Just When You Thought It Was Safe ....

[Bob Camp]

Hi

For all of you who dropped off the list back around Christmas and decided to 
re-join now that the KS box yack has died down …..

The usual auction site now has the pair selling for $100 and the “no GPS 
inside” part of the pair selling for $25 or two for $50.

Mighty fair prices considering that they are new old stock rather than salvage 
units. 

(Yes I suppose that if we all hold off, they could go lower still. They also 
could head over for scrap metal reclamation)

Bob

(no connection to seller)
___
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] Square to sine wave symmetrical conversion

[Bob Camp]

Hi
> On Jul 27, 2015, at 1:28 PM, Charles Steinmetz  wrote:
> 
> Bob wrote:
> 
>> In tis case the question is "do you *need* low harmonics in the oscillator
>> stage to get low phase noise?"
> 
> Note that there are actually two questions.  One is WRT the phase noise of 
> the oscillator itself, and the other WRT the phase noise of a system that 
> integrates the oscillator.  In particular, even harmonics in the oscillator 
> proper generate additional phase noise in the system when the signal is 
> AC-coupled and/or DC-restored, and when it is fed to a zero-cross detector or 
> other circuit that is sensitive to the symmetry of the waveform.
> 
> NIST published a paper on this.[1]  There is other research describing and 
> quantifying the phenomenon, as well.
> 
> Best regards,
> 
> Charles
> 
> 
> [1]  "The Effect of Harmonic Distortion on Phase errors in Frequency 
> Distribution and Synthesis," Walls and Ascarrunz  
> 
> 

An interesting (similar) experiment: 

Rather than measuring “timing error” as they did in the paper, do the same 
experiment (variations in mixer level) and measure the phase noise instead. The 
basic 
configuration of a DBM as a phase detector is pretty well documented. Set up 
the signals in quadrature and fire up the audio spectrum analyzer. Calibrate 
the beat
note in the usual fashion for each power setting and take a look at the 
indicated phase noise at some convenient offset like 1K or 10 KHz. 

If mixer saturation / harmonics are an issue, you should see the measured phase 
noise go up as the levels get closer to each other (mixer in saturation). 
Indeed what you 
see is that (if anything) the phase noise improves as the sensitivity of the 
system gets better with the higher level of drive. There are a whole raft of 
papers on this going
back several decades. It’s the normal approach to measuring very low levels of 
phase noise with the older DBM based instruments. 

Bob

> 
> 
> ___
> 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] Square to sine wave symmetrical conversion

[Bob Camp]

Hi


> On Jul 27, 2015, at 1:28 PM, Charles Steinmetz  wrote:
> 
> Bob wrote:
> 
>> In tis case the question is "do you *need* low harmonics in the oscillator
>> stage to get low phase noise?"
> 
> Note that there are actually two questions.  One is WRT the phase noise of 
> the oscillator itself, and the other WRT the phase noise of a system that 
> integrates the oscillator.  In particular, even harmonics in the oscillator 
> proper generate additional phase noise in the system when the signal is 
> AC-coupled and/or DC-restored, and when it is fed to a zero-cross detector or 
> other circuit that is sensitive to the symmetry of the waveform.
> 
> NIST published a paper on this.[1]  There is other research describing and 
> quantifying the phenomenon, as well.

Ok, *but* that’s really an issue with a *destination* circuit rather than the 
*feed* circuit. What they are talking about are 
zero cross errors rather than phase noise. Put another way:

Phase noise is L(f)
What they are talking about are time errors. 

Bob

> 
> Best regards,
> 
> Charles
> 
> 
> [1]  "The Effect of Harmonic Distortion on Phase errors in Frequency 
> Distribution and Synthesis," Walls and Ascarrunz  
> 
> 
> 
> 
> ___
> 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] Square to sine wave symmetrical conversion (part 2)

[Bob Camp]

Hi


> On Jul 27, 2015, at 11:52 AM, jerry shirᴀr  wrote:
> 
> Here's the rub Bob. I have been trying to find a way or have you explain
> how a high harmonic oscillator stage

You are confusing the current through the crystal with the current in the 
oscillator transistor. 
So:

Connect a 2N918 with the collector to +12V through a 50 ohm resistor. AC couple 
that resistor to your spectrum analyzer.
Connect the base of the transistor with a 10K to +12 and a 10K to ground
Connect a 1K ohm resistor from the emitter of the transistor to ground
Hook a 100 pf cap from base to emitter
Hook a 100 pf cap from emitter to base
Hook a 10.0 MHz fundamental crystal with a resistance of < 10 ohms  to the base 
of the transistor.
Hook a 32 pf cap from the other side of the crystal to ground

I *hope* that’s specific enough for you.

That circuit *will* oscillate. 

Look at the current on the 50 ohm resistor. It’s got plenty of harmonics.

With me so far or is this still to theoretical? 

Now, this *does* get a bit exciting, but it’s the way this circuit has been 
analyzed since the 1930’s (when it used a tube):

You shift the ground to the emitter for the purposes of seeing what’s going on. 
You now have an “input side” and an “output side” to
the active stage. This lets you break the loop for analysis.

In this format, the current in the collector is more clearly flowing through 
the 1K resistor and one of the 100 pf caps. 
The current that passes through the crystal flows through the other 100 pf cap 
(and the base) to ground. 

The current in the oscillator stage is every bit as nonlinear as you saw 
before. 

Since this is an oscillator, the current flows in a loop. There is no 
independent current in any one leg. They all are related. 
If you want to see this, hook up an oscilloscope to the collector resistor and 
apply power to the oscillator. The output does not
go instantly to a full output. It slowly builds up to the full value. The 
current circulates around the loop *many* times as the 
stage oscillates. 

Now:

Break the circuit (AC) at any of the connection points. It stops oscillating. 
(A DC break also does the same thing, but that’s cheating). 
Without everything hooked in a loop, you do not have oscillation. 

Next: 

Charles posted a long list of interesting transistors a few messages back. Try 
them one at a time and look at phase noise at 20 KHz offset. 
You will find that some are better than others. Take a look at the harmonics in 
the collector. They don’t correlate with the phase noise… 

So, unless you are looking at the crystal as being the oscillator (which it is 
not), there’s not much way to say that there are no harmonics
running around in this circuit. 

Is that simple enough?

> is even possible and zip. You don't
> know and I certainly don't know. So there's that.

*IF* your desire is for an explanation, offensive comments probably are not a 
good idea….

Bob

> 
> Jerry
> On Jul 27, 2015 9:33 AM, "Bob Camp"  wrote:
> 
>> Hi
>> 
>> Here’s the basic point:
>> 
>> What is *required* for low phase noise?
>> 
>> If you can build *one* oscillator that violates a “law” then that “law” is
>> not
>> valid. In tis case the question is “do you *need* low harmonics in the
>> oscillator
>> stage to get low phase noise?”
>> 
>> Here on the list, we get obsessed about all sorts of stuff. That’s fine.
>> It’s fun.
>> We learn things taking stuff past “the limit”. The gotcha is that can make
>> it
>> hard to keep track of “what is necessary ”.
>> 
>>> On Jul 27, 2015, at 12:47 AM, jerry shirᴀr  wrote:
>>> 
>>> Thanks Tim.  I love reading these papers.  However my copy states "In
>> fact,
>>> were it not for this slight non-linearity, it would be virtually
>>> impossible to build a simple lamp-stabilized RC oscillator with good
>>> envelope stability over a wide frequency range." rather than "In fact,
>> were
>>> it not for [amplifier] nonlinearity, it would be impossible to build a
>>> simple oscillator with good envelope stability."  The meaning changes a
>>> little bit.
>>> 
>>> Thanks Bob,
>>> 
>>> Even looking at Tim's article, they are talking about a low degree of
>>> distortion with an RC oscillator.  I am assuming that the Q of the RC
>> would
>>> be quite low with respect to the overtone crystals you speak, and yet the
>>> RC oscillator described here has low distortion from the oscillator
>> stage.
>> 
>> The objective of an RC lab oscillator design *is* low harmonic distortion.
>> They
>> have awful phase noise.
>> 
>>> 
>>> Putting a filter in the feedback path with the high Q crystal seems like
>>> you would be de-Q-ing the crystal and losing the high Q characteristics
>> of
>>> the crystal.
>> 
>> The oscillator must be a closed loop to operate. There will *always* be
>> things
>> “in series” with the crystal.
>> 
>>> Any changes of filter components over time seems like it
>>> would necessarily add drift to the oscillator.
>> 
>> Since you *must* tune the oscillator on frequency and you *mu

Re: [time-nuts] Square to sine wave symmetrical conversion

[Charles Steinmetz]

Jerry wrote:


I have been trying to find a way [to] explain how a
high harmonic oscillator stage is even possible and zip.


Simple.  Use a circuit with way more gain than necessary, and bias it 
so that it goes into saturation at the one end of its voltage 
excursion long before the current gain drops off at the other 
end.  So, its average gain over a whole cycle comprises a pretty 
linear region bounded on the one end by a region of near-zero gain 
due to hard clipping.  Since the gain element loads the resonator 
heavily during the period of saturation, the circuit Q is much less 
than it should be -- so even if you take the output from a relatively 
high-Q node, there isn't enough Q to filter out the high harmonic content.


Lots of commercial oscillator products have been built exactly that 
way, usually with a Tee or Pi output filter with moderate Q (an 
output network of some sort is necessary anyway to match a 50 ohm 
load -- using a Tee or Pi with some Q cuts the harmonics to a dull roar).


Best regards,

Charles



___
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] ground plane for cheap helix antennas?

[Alan Ambrose]

Hi Attila, Bob et al



>>> Generally speaking, you do want satellites as low on the horizon as 
>>> possible, because they give you the most accurate x/y position solution.

>>> The idea is to get a location where you can see at least 2/3 of those 
>>> tracks when they are above about 20 degrees to the horizon.

>>> Hint: the holdover estimator does not handle warmup as well as it should

Thanks for the interesting responses. Especially interesting re importance of 
accurate location / using low elevation sats / sky view / warm-up. Getting the 
optimum accuracy partly sounds like a multi-dimensional optimisation problem to 
me - I might just write the code for that :)

I am enjoying the discussion atm on the list immensely :)

Alan


___
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] Square to sine wave symmetrical conversion

[Charles Steinmetz]

Bob wrote:


In tis case the question is "do you *need* low harmonics in the oscillator
stage to get low phase noise?"


Note that there are actually two questions.  One is WRT the phase 
noise of the oscillator itself, and the other WRT the phase noise of 
a system that integrates the oscillator.  In particular, even 
harmonics in the oscillator proper generate additional phase noise in 
the system when the signal is AC-coupled and/or DC-restored, and when 
it is fed to a zero-cross detector or other circuit that is sensitive 
to the symmetry of the waveform.


NIST published a paper on this.[1]  There is other research 
describing and quantifying the phenomenon, as well.


Best regards,

Charles


[1]  "The Effect of Harmonic Distortion on Phase errors in Frequency 
Distribution and Synthesis," Walls and 
Ascarrunz  




___
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] Square to sine wave symmetrical conversion (part 2)

[jerry shirᴀr]

Here's the rub Bob. I have been trying to find a way or have you explain
how a high harmonic oscillator stage is even possible and zip. You don't
know and I certainly don't know. So there's that.

Jerry
On Jul 27, 2015 9:33 AM, "Bob Camp"  wrote:

> Hi
>
> Here’s the basic point:
>
> What is *required* for low phase noise?
>
> If you can build *one* oscillator that violates a “law” then that “law” is
> not
> valid. In tis case the question is “do you *need* low harmonics in the
> oscillator
> stage to get low phase noise?”
>
> Here on the list, we get obsessed about all sorts of stuff. That’s fine.
> It’s fun.
> We learn things taking stuff past “the limit”. The gotcha is that can make
> it
> hard to keep track of “what is necessary ”.
>
> > On Jul 27, 2015, at 12:47 AM, jerry shirᴀr  wrote:
> >
> > Thanks Tim.  I love reading these papers.  However my copy states "In
> fact,
> > were it not for this slight non-linearity, it would be virtually
> > impossible to build a simple lamp-stabilized RC oscillator with good
> > envelope stability over a wide frequency range." rather than "In fact,
> were
> > it not for [amplifier] nonlinearity, it would be impossible to build a
> > simple oscillator with good envelope stability."  The meaning changes a
> > little bit.
> >
> > Thanks Bob,
> >
> > Even looking at Tim's article, they are talking about a low degree of
> > distortion with an RC oscillator.  I am assuming that the Q of the RC
> would
> > be quite low with respect to the overtone crystals you speak, and yet the
> > RC oscillator described here has low distortion from the oscillator
> stage.
>
> The objective of an RC lab oscillator design *is* low harmonic distortion.
> They
> have awful phase noise.
>
> >
> > Putting a filter in the feedback path with the high Q crystal seems like
> > you would be de-Q-ing the crystal and losing the high Q characteristics
> of
> > the crystal.
>
> The oscillator must be a closed loop to operate. There will *always* be
> things
> “in series” with the crystal.
>
> > Any changes of filter components over time seems like it
> > would necessarily add drift to the oscillator.
>
> Since you *must* tune the oscillator on frequency and you *must* select
> the overtone, you will have caps and inductors in the loop.
>
> > What do you think?  Of
> > course I am not saying that you can't put filters in the crystal circuit
> > but rather that is something I would never recommend doing that in a
> > precision oscillator design.
>
> Except you have to do it. Since you have to do it, every example out there
> of a low phase noise oscillator has at least some caps in series with the
> crystal. The vast majority have both coils and caps.
>
> >
> > I realize what the impedance plot looks like of AT-cut and SC-cut
> crystals
> > but my question was specifically about harmonics.  That is the topic of
> > this thread.  Are you thinking that crystals are rich in harmonics?  I am
> > not really seeing an idea of where you are saying the harmonic components
> > come from in these high precision oscillators in the oscillator circuit.
>
> The limiting action in the oscillator device creates harmonics.
>
> >
> > What are the "impedance properties" of the crystal?
>
> There are literally thousands of papers on this. The simple answer is that
> they have *many* resonant modes.
>
> >  Why use a crystal
> > rather than slapping a cap and a coil in there to get your desired
> > frequency?
>
> 1) Because it’s Q is higher
> 2) Because it’s more stable
>
> >
> > When you "pick off" the collector current, wouldn't that include the
> > amplified base to emitter junction noise inherent in simple transistor
> > oscillator circuits?
>
> Again, it’s a loop. The current goes around in circles. There is no magic
> “clean here” current. If you are looking at an OCXO that doubles the
> crystal
> before the output is created, it’s a really good bet they pulled the signal
> off the collector of the oscillator. The net result is still a low phase
> noise
> oscillator.
>
> >  Would that be the same as the crystal current?
>
> You can’t have an oscillator with just a crystal. You also need other
> “stuff”….
>
> Bob
>
> >
> > Thanks.
> >
> > Jerry
> > ___
> > 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] Square to sine wave symmetrical conversion (part 2)

[Bob Camp]

Hi

Here’s the basic point:

What is *required* for low phase noise? 

If you can build *one* oscillator that violates a “law” then that “law” is not
valid. In tis case the question is “do you *need* low harmonics in the 
oscillator
stage to get low phase noise?”

Here on the list, we get obsessed about all sorts of stuff. That’s fine. It’s 
fun.
We learn things taking stuff past “the limit”. The gotcha is that can make it
hard to keep track of “what is necessary ”.

> On Jul 27, 2015, at 12:47 AM, jerry shirᴀr  wrote:
> 
> Thanks Tim.  I love reading these papers.  However my copy states "In fact,
> were it not for this slight non-linearity, it would be virtually
> impossible to build a simple lamp-stabilized RC oscillator with good
> envelope stability over a wide frequency range." rather than "In fact, were
> it not for [amplifier] nonlinearity, it would be impossible to build a
> simple oscillator with good envelope stability."  The meaning changes a
> little bit.
> 
> Thanks Bob,
> 
> Even looking at Tim's article, they are talking about a low degree of
> distortion with an RC oscillator.  I am assuming that the Q of the RC would
> be quite low with respect to the overtone crystals you speak, and yet the
> RC oscillator described here has low distortion from the oscillator stage.

The objective of an RC lab oscillator design *is* low harmonic distortion. They
have awful phase noise. 

> 
> Putting a filter in the feedback path with the high Q crystal seems like
> you would be de-Q-ing the crystal and losing the high Q characteristics of
> the crystal.  

The oscillator must be a closed loop to operate. There will *always* be things
“in series” with the crystal. 

> Any changes of filter components over time seems like it
> would necessarily add drift to the oscillator.  

Since you *must* tune the oscillator on frequency and you *must* select
the overtone, you will have caps and inductors in the loop. 

> What do you think?  Of
> course I am not saying that you can't put filters in the crystal circuit
> but rather that is something I would never recommend doing that in a
> precision oscillator design.

Except you have to do it. Since you have to do it, every example out there
of a low phase noise oscillator has at least some caps in series with the 
crystal. The vast majority have both coils and caps. 

> 
> I realize what the impedance plot looks like of AT-cut and SC-cut crystals
> but my question was specifically about harmonics.  That is the topic of
> this thread.  Are you thinking that crystals are rich in harmonics?  I am
> not really seeing an idea of where you are saying the harmonic components
> come from in these high precision oscillators in the oscillator circuit.

The limiting action in the oscillator device creates harmonics. 

> 
> What are the "impedance properties" of the crystal?

There are literally thousands of papers on this. The simple answer is that
they have *many* resonant modes. 

>  Why use a crystal
> rather than slapping a cap and a coil in there to get your desired
> frequency?

1) Because it’s Q is higher
2) Because it’s more stable

> 
> When you "pick off" the collector current, wouldn't that include the
> amplified base to emitter junction noise inherent in simple transistor
> oscillator circuits?

Again, it’s a loop. The current goes around in circles. There is no magic
“clean here” current. If you are looking at an OCXO that doubles the crystal
before the output is created, it’s a really good bet they pulled the signal
off the collector of the oscillator. The net result is still a low phase noise
oscillator. 

>  Would that be the same as the crystal current?

You can’t have an oscillator with just a crystal. You also need other “stuff”….

Bob

> 
> Thanks.
> 
> Jerry
> ___
> 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] 60Hz line data

[Bob Camp]

Hi

The utility of the watch crystal is greatly enhanced in a wrist watch by
the calibration process on the watch. When they use one in an AC powered
clock (say a clock / radio / alarm) , it’s as a backup device. Power goes out
and the crystal keeps time. They don’t do much (any at all) calibration in this
application. The resultant time error is “ok” for an hour or so. It would be 
really objectionable over a week or a month.

Bob

> On Jul 27, 2015, at 12:31 AM, Bill Byrom  wrote:
> 
> In the early 1970's both LED and LSI integrated circuit technology
> advanced to the point that digital wristwatches were introduced. These
> used 32,768 Hz crystals. Use of this technology was made in digital desk
> clocks (such as alarm radio clocks), but I think that for many years it
> was much less expensive to use the AC line as a frequency standard.
> Early Mostek clock IC's used the 50/60 Hz powerline as the reference and
> didn't include provisions for a crystal.
> 
> The first digital clock I owned was a flip card clock radio in around
> 1970. An AC line powered synchronous motor slowly flipped minute and
> hour cards. A few years later I had a Radio Shack LED wristwatch.
> 
> I see that 32,768 Hz crystals can now be purchased for US $0.15 each in
> lots of 100.
> 
> --
> Bill Byrom N5BB
> 
> 
> 
> On Sun, Jul 26, 2015, at 07:08 PM, Dave Martindale wrote:
>> It's not just synchronous-motor clocks that use line frequency as a time
>> reference.  I have a Heathkit alarm clock that counts cycles of line
>> frequency as its timebase.  I think that was common in the early
>> generations of NMOS clock chips.  The clock does have a backup oscillator
>> (powered by a 9 V battery) for use when line voltage disappears, but its
>> accuracy is horrible.  I think it's an RC oscillator, and in a power
>> failure of a few hours it will accumulate minutes of time error.
>> 
>> So a bunch of people with analog and digital clocks from that era are
>> likely to notice the drift, particularly at 20 minutes/year.
>> 
>> When did 32 kHz crystals get cheap enough that line-powered clocks
>> started
>> using them as a time reference instead of counting line cycles?
>> 
>> - Dave
>> 
>> On Sun, Jul 26, 2015 at 2:25 PM, Bill Byrom  wrote:
>> 
>>> 
>>> 60Hz Stability on Power Grid Going Away?
>>> 
>>> http://www.radiomagonline.com/deep-dig/0005/60hz-stability-on-power-grid-going-away/33527
>>> 
>>> NERC Frequency Response Standard Background Document
>>> 
>>> http://www.nerc.com/comm/oc/rs%20landing%20page%20dl/related%20files/bal-003-1_background_document_clean_20121130.pdf
>>> 
>>> It  appears from various comments that with no manual time correction,
>>> the accumulated time error in the East Interconnection will typically
>>> gain 20+ minutes/year. The West will gain 8 minutes/year and ERCOT
>>> (Texas area) will gain 2 minutes/year.
>>> 
>>> http://www.ercot.com/content/meetings/rms/keydocs/2011/0518/03_manual_time_error_correction_elimination_field_trial.doc
>>> 
>>> So don't trust an AC synchronous motor clock in North America.
>>> 
>>> --
>>> Bill Byrom N5BB
>>> 
>>> 
>> _
>> 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] Picked up the Austral 2200A tonight

[Jason Ball]

Just picked it up, it has an internal rubidium which piqued my interest as
worst case I could cannibalize the unit.  It's also been sitting on a shelf
for > 10 years so the oscillator should hopefully have some life left in it.

What does surprise me is the firmware is dated 25th August 1998, I was of
the opinion these units weren't Y2K compliant and would have assumed an
update in 1998 would have been tested...   gps rollover not withstanding.

Is there anyway to get the 10MHz output running off the rubidium without a
satellite lock ?   I can't seem to trigger it just yet.

My plan is to use a DDS to generate a 1.Ghz LO and to feed this into a
suitable mixer to down convert to the 75.42Mhz input signal for the gps
reference as a start to see if I can get the thing working, allowing for
the 1024 week offset of course.  Just waiting on parts at the moment.

Cheers
J.


-- 
--
Teach your kids Science, or somebody else will :/

ja...@ball.net
vk2...@google.com 
callsign: vk2vjb
___
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] Austron 2010B useful in Australia/Sydney at all ?

[Mike Cook]

Trying again in case the SPAM header frightened you. My ISP is flagging some 
nut mail. Don’t know why.


> Le 27 juil. 2015 à 09:44, Mike Cook  a écrit :
> 
> Back in the 2011, the same Q was asked here and there was a response from Rob 
> Kimberley who had worked at Austron 
>  to say 
> that they had been successfully used for the app that you are thinking of. 
> From what I gather, the 2010B has a very good oscillator , the same as in a 
> 1250A ( see   ) so using it 
> disciplined by a more longer term stable, but noisier ref such as loran, Rb, 
> you could get the best of both worlds.  
> 
> 
>> Le 27 juil. 2015 à 04:20, Jason Ball  a écrit :
>> 
>> I've decided to pick up this unit as it is in really nice condition and
>> inexpensive.
>> 
>> I'll see if I can pickup the e-loran signals on my ham kit over that
>> weekend to see if there is any point, failing that another member of time
>> buts may be interested.
>> 
>> J
>> 
>> 
>> On Mon, Jul 27, 2015 at 9:27 AM, Jason Ball  wrote:
>> 
>>> 
>>> I can pick one up in excellent condition for a reasonably low price...
>>> but only if it could be useful.
>>> 
>>> J.
>>> 
>>> 
>>> --
>>> --
>>> Teach your kids Science, or somebody else will :/
>>> 
>>> ja...@ball.net
>>> vk2...@google.com 
>>> callsign: vk2vjb
>>> 
>>> 
>> 
>> 
>> -- 
>> --
>> Teach your kids Science, or somebody else will :/
>> 
>> ja...@ball.net
>> vk2...@google.com 
>> callsign: vk2vjb
>> ___
>> 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.
> 
> "Ceux qui sont prêts à abandonner une liberté essentielle pour obtenir une 
> petite et provisoire sécurité, ne méritent ni liberté ni sécurité."
> Benjimin Franklin
> 

"Ceux qui sont prêts à abandonner une liberté essentielle pour obtenir une 
petite et provisoire sécurité, ne méritent ni liberté ni sécurité."
Benjimin Franklin
___
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] Square to sine wave symmetrical conversion (part 2)

[jerry shirᴀr]

Thanks Tim.  I love reading these papers.  However my copy states "In fact,
were it not for this slight non-linearity, it would be virtually
impossible to build a simple lamp-stabilized RC oscillator with good
envelope stability over a wide frequency range." rather than "In fact, were
it not for [amplifier] nonlinearity, it would be impossible to build a
simple oscillator with good envelope stability."  The meaning changes a
little bit.

Thanks Bob,

Even looking at Tim's article, they are talking about a low degree of
distortion with an RC oscillator.  I am assuming that the Q of the RC would
be quite low with respect to the overtone crystals you speak, and yet the
RC oscillator described here has low distortion from the oscillator stage.

Putting a filter in the feedback path with the high Q crystal seems like
you would be de-Q-ing the crystal and losing the high Q characteristics of
the crystal.  Any changes of filter components over time seems like it
would necessarily add drift to the oscillator.  What do you think?  Of
course I am not saying that you can't put filters in the crystal circuit
but rather that is something I would never recommend doing that in a
precision oscillator design.

I realize what the impedance plot looks like of AT-cut and SC-cut crystals
but my question was specifically about harmonics.  That is the topic of
this thread.  Are you thinking that crystals are rich in harmonics?  I am
not really seeing an idea of where you are saying the harmonic components
come from in these high precision oscillators in the oscillator circuit.

What are the "impedance properties" of the crystal?  Why use a crystal
rather than slapping a cap and a coil in there to get your desired
frequency?

When you "pick off" the collector current, wouldn't that include the
amplified base to emitter junction noise inherent in simple transistor
oscillator circuits?  Would that be the same as the crystal current?

Thanks.

Jerry
___
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] 60Hz line data

[Bill Hawkins]

 
Gotta get some answers from my relative in a PA gas fired plant. A year
ago he told me that the plan to deregulate the number of cycles in a day
had been abandoned. The referenced documents are older than that.

OTOH, there's no other explanation for Hal Murray's observation of the
West Coast grid variation.

Seems to me that all of the rotating synchronous machinery connected to
a grid is constrained by all of that heavy rotating machinery to change
speed quite slowly, like starting to change the direction of a ship
heading to a port about 5 miles out.

There are at least three grids in the US that are independent of each
other in frequency. That reduces the strains on a grid from distant
changes. Power is transferred using high voltage DC transmission lines.
Really large solid state inverters convert between AC and DC. Each
inverter can make any frequency it wants to, subject to the constraints
of all that synchronous machinery.

Frankly, I'm puzzled by the graphs that relate to the time offset. All
that's available to the observer is the line frequency. Relative time
may be inferred with a cycle counter. How is that counter set to UTC?
How can you tell the difference between time error from some reference
point, and cycles gained or lost in the counting equipment - due to
noise and/or computer interrupt servicing routines?

When I asked for data from parts of the country east of the Rockies (on
7/10), I got one reply from a person who is not a member of the list but
reads archive sites. He sent his long term graph for Texas and the link
to a real-time statistics page that gave him the data for the graph.

The statistics are at (strip the stuff after com/ to get the home page
and further details):

http://www.ercot.com/content/cdr/html/real_time_system_conditions.html

His chart (with permission) is at:

http://home.earthlink.net/~schultdw/power/all.png

In this case, the time reference was given by the power company. No
cycles were counted.

Regards,
Bill Hawkins

___
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] 60Hz line data

[Bill Byrom]

In the early 1970's both LED and LSI integrated circuit technology
advanced to the point that digital wristwatches were introduced. These
used 32,768 Hz crystals. Use of this technology was made in digital desk
clocks (such as alarm radio clocks), but I think that for many years it
was much less expensive to use the AC line as a frequency standard.
Early Mostek clock IC's used the 50/60 Hz powerline as the reference and
didn't include provisions for a crystal.

The first digital clock I owned was a flip card clock radio in around
1970. An AC line powered synchronous motor slowly flipped minute and
hour cards. A few years later I had a Radio Shack LED wristwatch.

I see that 32,768 Hz crystals can now be purchased for US $0.15 each in
lots of 100.

--
Bill Byrom N5BB
 
 
 
On Sun, Jul 26, 2015, at 07:08 PM, Dave Martindale wrote:
> It's not just synchronous-motor clocks that use line frequency as a time
> reference.  I have a Heathkit alarm clock that counts cycles of line
> frequency as its timebase.  I think that was common in the early
> generations of NMOS clock chips.  The clock does have a backup oscillator
> (powered by a 9 V battery) for use when line voltage disappears, but its
> accuracy is horrible.  I think it's an RC oscillator, and in a power
> failure of a few hours it will accumulate minutes of time error.
>  
> So a bunch of people with analog and digital clocks from that era are
> likely to notice the drift, particularly at 20 minutes/year.
>  
> When did 32 kHz crystals get cheap enough that line-powered clocks
> started
> using them as a time reference instead of counting line cycles?
>  
> - Dave
>  
> On Sun, Jul 26, 2015 at 2:25 PM, Bill Byrom  wrote:
>  
>>  
>> 60Hz Stability on Power Grid Going Away?
>>  
>> http://www.radiomagonline.com/deep-dig/0005/60hz-stability-on-power-grid-going-away/33527
>>  
>> NERC Frequency Response Standard Background Document
>>  
>> http://www.nerc.com/comm/oc/rs%20landing%20page%20dl/related%20files/bal-003-1_background_document_clean_20121130.pdf
>>  
>> It  appears from various comments that with no manual time correction,
>> the accumulated time error in the East Interconnection will typically
>> gain 20+ minutes/year. The West will gain 8 minutes/year and ERCOT
>> (Texas area) will gain 2 minutes/year.
>>  
>> http://www.ercot.com/content/meetings/rms/keydocs/2011/0518/03_manual_time_error_correction_elimination_field_trial.doc
>>  
>> So don't trust an AC synchronous motor clock in North America.
>>  
>> --
>> Bill Byrom N5BB
>>  
>>  
> _
> 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.