Garren posted
I notice that whenever a satellite drops out
it causes the oscillator white trace and the DAC green trace to jump around.
I wonder why that happens when there are 6 other good satellites.
The main causes of this is a poor location setting, (do a 24 + hr survey)
or the TBolt is
Paul
The MV89 is a double oven unit, and assuming it is setup and working correctly,
it's sensitivity to thermo capacity, external temperature effects, sweep spot,
and all the other nutty stuff, is Way below the MV89's noise level which is
generally under 2e-12 when just setting on a bench in
No page. The effect is nothing very special. No relativity.
Mostly just the effect of the oscillator's G sensitivity caused by tilting
and acceleration as it swings.
What is generally measured with a 2 G static turn over test.
The thing about the test is that it gives a signal that is very
Thanks, Poul
If that was their point then, I missed it completely.
The way I read it, I think you are giving them WAY too much credit about
them understanding subtle things like that.
Yes we do agree that using low accuracy 1PPS signals can cause some
unforeseen problems.
They are using 10
Poul
I agree, 1PPS from many GPS engines, if sawtooth correction is not used, can
add all sorts of errors like hanging bridges.
Some can sound really bad, like non zero bias over short or very long time
periods and 12 ns of early or late wonder.
It's interesting to talk about these problems,
I second that, when done correctly, it works great. But there are all kinds of
ways to do it poorly.
First off,
What the TBolt is best for is to provide great long term frequency stability
that can be better than a Rb or Cs.
If you want a low phase noise signal without spurs,
Don't use the
Don
no internal connection needed.
Lots of ways to do it,
an isolated optical isolator connect to a couple of pins on the RS232
connector is one way.
The LH controller can also be used to just Heat for those that don't like
moving parts,
or dual with heat and cool as well as just drive a
.
ws
Thanks, Warren, for the refresh. So the L.H. fan control signal is
bang-bang, and not really a PID, as it's on the DTR data line.
Don
ws at Yahoo
Don
no internal connection needed.
Lots of ways to do it,
an isolated optical isolator connect to a couple of pins
(+12V) line.
ws
**
So the other signal is on pin 7, RTS?
Don
*
ws at Yahoo
Don
No, it is not bang-bang. Look at the plot results.
You don't get .001 deg type resolution and control with a bang-bang
controller.
It is a full Linear, universal, PID
Brooke
One simple way I'veused to eliminate the two problems you brought up is by
Greatly restricting the tuning effect of the Dac voltage.
Only big downside is you then may have to manually reset the nominal Osc
freq every once in a while if the Dac gets near a limit.
With a little thought an
This is mentioned ( that the 10811 is not always operated at it's exact
turn over temperature) in the HPJ article on the 10811.
(Required reading for anyone playing with 10811's).
Rick Karlquist N6RK
**
Yes it does and it also says that is to save testing time and make it field
As already stated, there are many different ways to design and or tune a
temperature controller so it does not overshoot.
The trade off being that it may then take a little longer to get to the
finial temperature.
BUT SO WHAT??? If one is concerned about a little oven overshoot then they
at karlquist.com wrote:
ws at Yahoo wrote:
As already stated, there are many different ways to design
and or tune a temperature controller so it does not overshoot.
The 10811 control loop is constrained by the large oven mass
and the limited size of the integrator capacitor. The
capacitor
A problem I've seen when using the hermetic sealed soldered version of the
10811 from a dual oven unit,
is when the case is sealed the osc makes a good barometer because of changes
in its case due to barometric changes.
A 1 inch difference (such as 30 to 29) caused something on the order of
Within minutes the frequency changed more than the spec
For humidity to get thru something like that it takes weeks or more it does
it at all.
That fast of reaction, Sure sounds like some other effect like blowing a
little air on the case or loading the osc output with water in the output
Doug wrote:
If you are constantly jerking the control voltage back-and-forth ...
Interesting, I can certainly see how that could be the case if one tried to
Track a GPS too fast,
Or used a noisy non Tbolt engine, Or a poor control loop.
But it is not in any way consistent with what I see
Magnus
One problem is that I do not have anything that is known better or even near
as good as the GPS to compare against when it comes to accuracy or stability
at greater than one day.
(If I did I'd be working on making it better instead of improving a cheap
LPRO Rb)
As you point out, a
Magnus
I probable was not very clear in my posting. (what else is new?)
There where TWO completely different subjects, goals and techniques in the
same Posting.
#1 was how to Log data for valid ADEV plots. That takes setting the filter
OFF for the reasons you state.
The ADEV tau axes provides
You would first have to answer which are better to use for short term, Cs or
Rb?
(the answer is: a good OCXO)
My guess is it does not mater, all are so much better than what is received
by a Tbolt.
And for long term where a Cs wins, they are disiplined/corrected in some
way so it don't mater.
John
It would be great to have a direct Tbolt driver on TimeLab.
Right now it is so much trouble and time to use it, it takes away of the
great real time capabilities of TimeLab.
According to Tom his really good Cs has an Flicker noise floor of almost 10
days using 4 ns rms for phase noise.
John
What was the RMS and PP phase noise for your 8e-14 test?
Something to keep in mind is that although the Z3801 has a better Osc than
the typical Tbolt.
Long term, really low noise is all about the quality of the GPS signal and
engine.
The Z3801's GPS engine is far inferior and not even
of 4 to 10 nanoseconds without SA (http://tycho.usno.navy.mil/gpstt.html).
That may not be apples-to-apples methodology, but it implies that
sub-nanosecond results may be difficult to obtain.
John
On Oct 7, 2011, at 4:16 PM, ws at Yahoo warrensjmail-...@yahoo.com
wrote:
John
What
Power factor correction power supplies has not been a BIG problem with my
OLD recycled equipment.
I tried to Cover that case in my end note,
With switchers, turn the variact to normal and use the other safety features
and a big enough light bulb to keep from blowing it all up if something is
.
I'd like to see what the Phase noise is of other Tbolts using this same
method, especially when using a good choke ring antenna that has a good
sky
view.
ws
ws at Yahoo wrote:
The noise data is my measured values which I do several different ways.
Some
of which are:
The GPS
, the Racal Instruments 2351
VXI TIC has 8pS single shot maximum resolution, the Wavecrest SIA3000
signal analyzer has 200femtoS hardware resolution at 3GHz.
On 10/13/11, ws at Yahoo warrensjmail-one at yahoo.com wrote:
I know very little about the HP58503A. Any chance it is using the old 6
channel Oncore
, the Wavecrest SIA3000 signal analyzer has 200 femtoS hardware resolution at 3GHz.** On 10/13/11, ws at Yahoo wrote: I know very little about the HP58503A. Any chance it
is using the old 6 channel Oncore GPS engine? If it is like the Oncore I tested long ago, that noise was about
You missed something somewhere
The Tbolt's RMS noise is 100 ps for the phase and 10 ps noise on the PPT
using unfiltered one second data.
These include the RMS sum of several noise sources.
The resolution is sub ps.
The noise is much greater than the resolution so averageing works fine
ws
is of other Tbolts using this same
method, especially when using a good choke ring antenna that has a good
sky view.
ws
*
ws at Yahoo wrote:
The noise data is my measured values which I do several different ways.
Some
of which are:
The GPS engine value
Simple way is to use LadyHeather.
From its output, you can tell if either or both are working correctly as
well as how well they are working.
That is assuming of course that there is at least one working GPS satellite
in view at all times.
If not it well tell you that also.
ws
The sensitivity of that EFC input is so low on my LPRO unit, that the PS and
DAC noises are not a problem at all.
Should add a 1K resistor in series with the Dac out before connecting it to
anything outside of the TBolt.
Attached is an expanded 4 day plot showing part of the same LPRO run
Chris posted:
So how to test it? anyone have any creative ideas?
That's easy, get a couple more of them.
The using a scope, trigger on one unit and watch the phase drift of the
others.
With most basic scopes you can detect sub ns phase changes of 10MHz signals
this way, which allows you to
ADEV and friends was invented and most useful to better characterized and
compared oscillators.
To make any meaningful comparison test, the results MUST be reproducible to
some level.
Errors bands are there to show what the reproducible level is, but
unfortunately the error bands do not
Right all those things need to be controlled if doing high end nut-testing.
Most time nuts already know enough not to shake their Osc or tweak its Power
supply etc when taking ADEV data.
What is often left as the major error source (that can most easily be
controlled) with a careful setup is
The other way to get around the inaction of the temperature effects and
drift effects to start and stop the displayed plot at the same temperature
and more important is do the ageing ageing rate over a an multiple of
complete temp cycles which is why that plot is exactly 7 days long. giving 7
John
If you have the raw phase data, can you post a plot of what the well
filtered freq offset looks like over that 10 day period?
I've have found a properly filtered high resolution freq vs. time plot
provides a lot more useful information than the couple of data numbers of a
ADEV plot for
It is easer for me to scale the nom freq setting than the data so
I scaled the 1E+7 osc freq by 1e+4, because my raw data is in parts per
1e-11 instead of in Hz.
Gives the same answer either way. I'm using an improved TPLL to take the raw
data, Ulrich's great Plotter program to do the plots.
geraldo
Is this normal, or do I have a defective unit?
It is normal for a defaul Tbolt, with any (or all) of the following:
MultiPath
a poor antenna,
a poor sky view,
a poor location survey
a poor elevation mask setting
a poor Sat Level setting
a poor TC setting
A poor Sat cable
ALL need to
Try again, I reset it. The setting were so far off, that may of caused your
problems.
ws
time-nuts] Help with KE5FX ThunderboltGeraldo Lino de Campos geraldo at
decampos.net
Sat Nov 27 20:42:34 UTC 2010
When running KE5FX thunderbolt, it doesn´t take the station
Others said:
There is a downside to this approach which should be understood, it will
also averaging out the white noise of the DUTs.
The time interval counter method severely undersamples the phase noise
spectrum leading to aliasing effects.
The measured ADEV depends on the associated filter
John
If it is off very far the first thing I'd suspect is the inner oven.
Assuming the freq is still stable and low noise, one option is to rewire it,
and make the freq adjustment accessible.
Removing the original inner wiring wrap also provides many other advantages,
and no down side
.
But if you want nut performance, best not to use the same supply for them.
I start with a 15V supply, so that there is no interaction between circuits.
ws
*
From: Richard (Rick) Subject: Re: [time-nuts] HP 10811
On 2/11/2016 2:56 PM, ws at Yahoo via time-nuts wrote:
>
Joe
The inner oven voltage needs to be stable! To better than 0.1V.
Unlike the single oven unit, the inner oven on the dual oven unit runs fine
at 15 Volts. It draws a couple hundred ma after warm-up.
One thing that improves the performance of a dual oven 10811 when being used
in a standalone
Same here for me in central California near the coast(SLO county).
My Tbolt lost all satellites all at the same time, for 100 min @ ~5:30 PM
PST.
Then just as suddenly all came back on line, with no input from me.
A truly unique experience for this Tbolt which runs pretty much
continuously.
LH
Tom
Impressive. Nice job.
How would one go about to prove beyond a doubt in that experiment that 18ns
of phase shift in 24 hrs was truly caused by freq offset due to Relativity
and not by some other combination of environment and handling issues that
effected phase &/or freq once the identical
on Wed, Jan 18, 2017 Chris wrote:
>But BEFORE you try and improve the Rb performance you need to have some way
>to MEASURE its performance. This is likely much harder.
Testing most RB's mid & long term performance can be done "on the cheap" by
using a Tbolt that's been set up to accept it
If you have a good antenna setup and a constant temperature environment:
The way to get the lowest noise over short time periods on a TBolt is to set
the TC setting as high as you can (typically 500 to 1000+), and set the
Damping factor as fast as you can (typically 0.7 to 1).
The reason is
A cold oven freq is off by hundred's by Hz, Much much greater than the range
of the Dac
The TBolt does not start tuning until it's oven has warmed up.
Setting anything in the Tbolt biased on cold start turn-on is counter
productive. It takes days or weeks for it settle down.
At initial turn-on
Bert
a) 1e-10 freq error, Sounds to me like you have a typical TBolt with near
factory default setting.
The most important thing to get good Tbolt frequency performance is the
antenna, with good sky view and correct location setting.
After that there are some 'basic' Tbolt setting and things
Corby
Just a 1 cent thought that may not apply or be accurate.
C-fields are current sensitive, so if they are wound with copper wire, any
small change in their temperature, even when temperature controlled, could
have a effect much greater than 1PPM on that current when driven from a
fixed
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