Mark Posted
I laid out a through-hole version of Warren's board in Eagle
and had OSHPARK fab up three of them.
I sent one to Warren and am using the other two.
The one mod I made was to use a single darlington TO-220 instead
of the two transistor stage that Warren used.
They seem to work quite
Claude
what is the simplest method to measure sub second ADEV?
The answer depends on many unstated things.
Among them is your definition of simple, the Frequency of the DUT, the noise
floor, your budget and your available time..
After budget and frequency, the next most important thing is the
Stu
Thanks for the great information feedback.
No, No, the ~3e-12 is Not an error in the H/W. That would of course cause a
constant phase drift error to accumulate.
The Tbolt has no trouble holding 1e-12 control or even better than 1e-13 when
using the extended time constant mode with an
Stewart
The part that I do not understand is how the TBolt is able to calculate
such high resolution frequency offset answers on its Osc ppt output
so fast. The frequency offset answers seem to have way too high of
absolute accuracy compared to what is possible using the phase data.
Example:
Another unique thing about the TBolt engine is how fast it can calculate a
Freq change in its 10MHz osc.
Over short times periods, it can be 100 times better than a standard 1PPS
GPS engine.
It would be interesting to compare it to a high end dual freq GPS.
With the Tbolt in manual hold over
I second Poul-Henning Kamp's comments concerning D-terms,
(mostly) as done in the TBolt and likely other GPSDOs.
A 'D-term' helps fast loops like a TPLL where you
want a high bandwidth with the P gain as high as possible.
For slow noisy loops like a cleanup osc or a GPSDO,
what helps is a
Authur wrote:
Take a look at the plot where I adjust a rubidium standard and see what you
think.
I think it is a great idea, and shows that LadyHeather and a modified TBolt
can make a great high end, stand alone Time-Nut tester without the need of a
reference osc or offset osc, or any other
Some of the reasons that ADEV values change over time may be
caused by one of these two things that I have seen cause poor plots.
Either of which can cause changes in the ADEV values across
a wide range of taus, and the effect can change over long run ins.
Hopefully Magnus will comment if ADEV
Bob Camp posted (Wed Oct 22 20:38:47 EDT 2014)
Re: [time-nuts] Phase, One edge or two?
ADEV most certainly does change with time, even for short tau's.
Can you elaborate?
Such as when, why, what kind of change, how much change,
at how short of tau's, over how long of time,
and using what
Poul said;
If you tell me it is a sine and give me the time of two zero crossings
I can tell you everything there has or ever will be to know ...
just to add a bit more nut picking on comment #3.
When talking about sub picosecond per second time nut type accuracy, there
is no such thing as
Lots of interesting responses,
but I did not see any posted that answered the original question:
Is the CERN method described in the paper the best way to make a state of
the art femtosecond DDMDT?
www.ee.ucl.ac.uk/lcs/previous/LCS2011/LCS1136.pdf
Restating
Assuming it is kept Digital, and not
The recent discussions about the simple digital mixer got me thinking about
the performance vs. complexity trade offs when measuring accurate, high
resolution, phase drift differences between two oscillators.
It would seem to me, that using both the positive and negative slope edges
of the
:50 , WarrenS warrensjmail-...@yahoo.com wrote:
With the values of K1, K2 K3 constant,
and the initial state of I#1, I#2 and Last_Input all zero
assuming there is no rounding, clipping or overflow in the math
and that if I've made any obvious dumb typo errors that they are
corrected,
If we
a controller at all and that for this reason the question
whether they produce the same output is close to being irrelevant.
Best regards
Ulrich
-Ursprungliche Nachricht-
Von: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] Im Auftrag von WarrenS
Gesendet: Mittwoch, 16. April
Agree, not so clear. I did not expect this to be so hard to explain. See if
this helps any.
The code snippets are from a S/W simulator program that loops thru one of
these code versions, producing a new Output each time a new Input value is
made available.
In most programs an index i is not
A question to the math time-nuts
With the values of K1, K2 K3 constant,
and the initial state of I#1, I#2 and Last_Input all zero
assuming there is no rounding, clipping or overflow in the math
and that if I've made any obvious dumb typo errors that they are corrected,
Given this PID type of
***
Warren,
On 13/04/14 19:24, WarrenS wrote:
Magnus wrote
You are over-focusing ...
At least on that we totally agree.
The same can be said of you in over-focusing on what comes before the
Phase error term Vdp. The PI code we've been discussing does not care.
Can we just focus to see if you can find
that says in part;
the fundamental theorem of calculus can be loosely expressed in words as:
the integral of a derivative of a function is that original function, ...
ws
***
Warren,
On 13/04/14 07:44, WarrenS wrote:
Magnus wrote
It may appear so, but the derivate
function, ...
ws
***
Warren,
On 13/04/14 07:44, WarrenS wrote:
Magnus wrote
It may appear so, but the derivate, scale-factor F and integrate does not
make the scale-factor F equalent to P, since you are forgetting that the
derivate removes the DC term
We don't
Magnus
Interesting, Am I missing something or is there an error in your code or
logic.
Looks to me like the code is a PI controller with a added D term (Vdf)
of input,
and the D is then Integrated with a scale factor of F at Vi = Vi +
F*Vdf ...
An integrated derivative is exactly equal
term effect, Not quite the same effect short term.
Vi = Vi + (I * Vdp) ; Initial Vi value = F*First_Vdp_reading)
Vf = Vi + (P+F) * Vdp
ws
Magnus Danielson wrote
Warren,
On 12/04/14 21:09, WarrenS wrote:
Magnus
Interesting, Am I missing something
Magnus
I think all three below provide the exact same results.
If true, That may not be doing what you wanted.
ws
Vi = Vi + (I * Vdp) ; Initial Vi value = - F * First_Vdp_reading)
Vf = Vi + (P+F) * Vdp
? same as:
Vi = Vi + (I * Vdp)
Vf = Vi + (P+F) * Vdp - Offset;(where
, WarrenS wrote:
Magnus
Interesting, Am I missing something or is there an error in your code or
logic.
Looks to me like the code is a PI controller with a added D term
(Vdf) of input,
and the D is then Integrated with a scale factor of F at Vi = Vi +
F*Vdf ...
An integrated derivative is exactly
Ulrich
Thanks for posting the reference.
Very interesting and useful. The clues they give sounds like enough
information to do the Smartclock loop control things that they talk about.
ws
***
Hi Brooke,
HP had some way around SA that improved the timekeeping.
HP
The single oven HP10811's heater supply is spec 20 to 30V, (=18V is mostly
OK, 19V is better)
The Inner oven voltage spec on the Dual Oven 10811s that I have is 12 to
30Volts, (All work good down to ~11V)
Internally my dual oven units use a 5V ref in their heater controller
instead of a 10V
John
In answer to your original questions,
No problem if you have a good setup including a good sky view, antenna, and
TBolt setup.
It is important to do each run at the different locations at the same time
of the day and average the results for as long as you can.
Best is to do a 24 Hr
Stephan
Did you also notice that the AC coupling is done **after** the sine wave has
already been clipped by the previous stage (according to the schematic
note)?
This generally is not a good way to remove DC offset from a low level
'noisy' signal.
I doubt that Bruce was recommending doing
One thing to be aware of on the MV89 is that it is a 5 MHz osc that uses a
freq doubler.
On the ones I've tested, without further filtering, every other cycle's
period is different by ~ 1 ns or so.
For a time nut that likes to see 1ps jitter, it is a whole lot of cycle to
cycle edge jitter
Said Jackson posted:
Crystal jumps are the biggest menace facing users of crystals/oscillators
today.
Are you including both phase jumps and frequency jumps together?
Is one more or likely to happen than the other?
Is it mostly a jump that effects just the phase or freq, or is there
I agree with John that it is a super waste of effort and money or at the
very least can be for many.
But for the extreme time-nut, so what?
Being an extreme TBolt nut, and having done this many times before,
I have to point out where a large amount of time and effort can help
Do protect
OT for the current heading, so I renamed it Oscillator stability
as Tom says, it's a complicated subject.
And to complicate things even further, here are a few of advanced subtleties
that I've observed from the TBolt when using LadyHeather.
1) The TBolt uses the received GPS signal as the
Dave
With your GPS Antenna sitting underneath all those multipath reflectors (the
other antenna's above it),
That is far from optimal from a time-nut standpoint if you are trying to get
the best performance possible.
Should strive for no metal or reflective surfaces above the GPS antenna in
Charles
sorry for the delayed answer, see below for why.
I did my own thing for the outer oven controller.
Mark C. S. was kind enough to redraw the schematic of what I made and post
it on his site.
http://www.vk2hmc.net/blog/?p=526
Do you know that often *your* postings do not show up on the
David asked:
Where does this non-linearity get corrected?
What test modulation patterns could I use to verify and calibrate the
[TPLL] gadget?
What other tests would you recommend?
Of course you could try and do some form of post data processing (before
filtering), but the KISS answer for
)
**
From: WarrenS
Tom
My posting and plot was only meant to show the difference in tempco
between an undisciplined single and dual oven 10811 osc which in this
case is clearly = 60 to 1.
Your comments bring up a different subject which is who needs it and how
good does a controlled GPSDO
for the outer oven off case?
/tvb
- Original Message -
From: WarrenS
Sent: Friday, July 12, 2013 6:04 PM
Subject: Re: [time-nuts] 10811 outer oven controller.
Bob said {the 10811 will run fine without the outer oven}
What I've seen is that a dual oven 10811 will run
Bob said {the 10811 will run fine without the outer oven}
What I've seen is that a dual oven 10811 will run even **finer** and have up
to 100 times less sensitivity to normal room temperature changes with a
simple outer oven controller and a few mods.
In 2010 I compared the performance of a
All the data is in an adev plot... The cross overs will happen... you have
to measure them.
True, but then what do you do?
It is not quite as simple or easy as it may sound.
Although it is a good place to start,
for best results in a GPSDO you can not just compare the ADEV crossover
points of
Common View, so my experiment turned into a
dual Tbolt DMTD.
For some post I did, see Time Nuts back in Oct of 2011 from WarrenS and
ws at Yahoo
Common View Tbolt-Tic, DMTD using TBolts and Measuring ADEV using
TBolt-Tic tester
(*) The TBolt Engine is capable of 1e-11 at 3 seconds.
and 1e-12
-
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]
On Behalf Of WarrenS
Sent: Tuesday, February 26, 2013 10:53 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Lady Heather numbers
Can anyone comment on the picture.
I don't know
That should be that v360, Not dxxx to set the View Display time
use space or ? for Tbolt help screens
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
Can anyone comment on the picture.
I don't know if what I have would be considered good as far as accuracy and
stability is concerned.
The screen dump is way too short to give much detail.
What can be said from what is there:
From a Ham standpoint it is all working fine and is much better
/A%20Small%20DMTD%20System.pdf
Adrian
***
Tom Van Baak schrieb:
Hi Bob,
The TPLL method is described by NIST:
http://tf.nist.gov/phase/Properties/one.htm
A few years ago it was re-developed by WarrenS, a dedicated and frequent
contributor to this list.
See also John Miles
Tom
For simple, cheap, low performance and fast to build with junk box parts,
hard to beat:
What I made long ago for myself (before time-nut days).
I still use it today for low end stuff, and it is all done with standard
74HC DIP parts.
The main IC is a 74HCT4046 Phase lock loop with
Guys,
So much speculation on how the Tbolt uses it's temperature sensor data.
Having spending hundreds of man hrs and thousands of Tbolt running hrs,
testing all kinds of things to find ways to improve my Tbolt's performance.
This is what I've found happens on My Non E TBolt with version#3
Another thing that could of effected the results when measuring the effect
of a low resolution sensor chip during holdover,
is that it is real hard for the Klaman filter to learn anything useful from
it, without some careful manipulation of the variables.
Mostly all it would normally record
tvb posted
Were you able to test how quickly, or how well, the filter learned the tempco
of the OCXO?
Only at a couple of very general data points.
Using a very Bad unit, the Kalman filter had an effect, although not very good
in under 1/2 day.
After a week or so on a good unit, it helped
To: WarrenS warrensjmail-...@yahoo.com
Cc: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Thursday, November 15, 2012 6:57 PM
Subject: Re: [time-nuts] getting a grip on 10811 drift (trying to read my
instruments)
You all were right, my targeting of the 50 ohm
Chris
HP 10811 can't drift that much that fast unless something is near broken, or
being connected wrong like gnds or PS voltage.
Check the operation of the oven. It must be close and sort of working
otherwise it would not be on freq as close as it is, but maybe it is
drifting.
The other
Chris
QI can measure the control voltage change over time and convert that into a
frequency drift?
Yes, no problem as long as the discipline loop is working OK.
It is very easy to plot the oscillator's long term drift per day, by just
plotting the filtered analog EFC control voltage.
, WarrenS wrote:
Chris
QI can measure the control voltage change over time and convert that into
a frequency drift?
Yes, no problem as long as the discipline loop is working OK.
It is very easy to plot the oscillator's long term drift per day, by just
plotting the filtered analog EFC control
Sounds like another source of this confusion is that there is more than one
version of the HP10811 inner heater circuit.
Where as most 10811's start loosing performance at around 15 volts on their
inner oven.
I have one 10811, that was taken out of a dual oven version, that maintains
full
The basic problem is that one can not meet Allan's requirement
of the integral of the instantaneous frequencies over tau0 time
and Nyquist-Shannon sampling theorem requirement if taking just
one raw phase sample per displayed ADEV tau0.
The two requirements are then mutually exclusive.
This is
Have you used Lady Heather to automatically set the Default settings?
To allow the Tbolt to work with weak signals from any antenna that I've
tried, even when indoors,
I start by setting the TBolt's AMU level from the default of 4 down to 0.
This can be done with the Tbolt S/W or LH.
My
And here it goes again for about the umpteenth time, how to detect the
presents of a short low rep rate pulse.
This can be done with ANY analog scope by using the normal trigger mode
and setting the trigger correctly.
An analog scope can detect the presents of any short pulse no matter how low
That works when there is a trigger LED,
OR Just need to slow down the sweep rate to say 10ms / div or slower and
then there will be a nice clear, easy to see, can't miss, white line, across
ANY scope with each pulse when the scope is triggered by a short low rep
input pulse.
Only for the Nuts,
ZCD have been discussed at great length this time and before, and bandwidth
can be a major issue, but still much is being left out.
With a little care, one can easily get to 1ns type accuracy, with the
various suggestions,
but that only gives 1e-9 / sec of accuracy, not even
Two part question:
I'd like to test the effect of small signal level changes on the phase output
of a high resolution linear phase detector at ADEV values below 1e-16 and tau
1000 sec.
I'm looking for suggestions on how I can manually vary the signal amplitude of
one of it's 10 MHz sine wave
It is interesting that the leap seconds correction is always a positive
number.
But less so now than 40 years ago according to:
http://en.wikipedia.org/wiki/Leap_second
So does that mean the earth is speeding up? Maybe the cause is all the DARK
ENERGY out there speeding everything up :)
Magnus wrote:
It's sad that they have not described the control algorithm in greater
detail.
I have to ask WHY??
The paper is So low tech, It is hardly worth reading, let alone wondering
how it is done, IF the goal is to learn something a bit advanced.
Maybe I'm just missing the satire here.
Wolfgang asked
Does anybody know a possibility to get a resolution 1 mHz ? (in 1 second)
The goal is look for frequency deviations caused by external influences ...
A silly question to ask time nuts. :)
How good do you really want it to be?
1 mHz out of 10 MHz in one second is only 1 part in
Recording high speed and/or long general purpose raw Osc data, the file can
become very large.
I'm looking for a simple, fast and easy (and cheap) way to transfer large
compressed data files of up to say a 100 MB between time-nuts.
I know there are all kinds places one can store large files
Bob
Worked great for my long zip file, and a large. jpg
Thanks very easy to use, this will be very helpful to me.
still a little problem, It would NOT take my short .gif file unless I
falsely renamed it with a .jpg extension
ws
Bob Smither smither at c-c-i.com
Bob Smither
Bob
The gif files upload OK now but the ones with funny non standard names
will not download for me.
can you tell me which character it does not like?
ws
*
[time-nuts] How best to exchange Large files?
WarrenS wrote:
Bob
Worked great for my long zip file, and a large. jpg
John said in part;
ignore the last two (ADEV) plot points as there isn't enough data for
them to be very meaningful.
you need a lot more than 10 days data to draw any real conclusions;
IMHO, ADEV is not the right tool or even a very useful tool for evaluation
the long term performance of
In additional to the standard ADEV answers,
Two important additional performance numbers to consider when testing
and evaluating a RB Osc, are its TempCo, (as in freq change per degC)
and its Ageing rate, (as in drift rate per day).
Anyone with a spare TBolt can measure them.
One simple method
To get the most from ADEV numbers one needs to be able to get
repeatable and reproducible results.
To get that at short taus the tester needs sub ps resolution.
To get it at long taus, all uncontrolled variable influences that effect the
results (such as temperature) need to be removed and
John
I have Not seen any reliable consistent way to predict what the Tbolt will
use for it's altitude, It seems to just do it's own thing.
It is certainly NOT the same as the Oncore's answers.
To get close and see if the different is 30 meters etc, take the Tbolt out
of fixed location and
Indeed,
ADEV is for random freq variation not easily measured by other means.
Temperature fluctuations do not cause random freq changes and the
temperature's effect should be removed if one wants accurate long term ADEV
numbers.
Even daily diurnal cycles due to temperature can have major
bottle, or a better design that's less environment sensitive.
(difference between TRL6 and lower, for those into such things)
**
From: WarrenS warrensjmail-...@yahoo.com
Indeed,
ADEV is for random freq variation not easily measured by other means.
Temperature fluctuations
Chris asked:
LH reports the signal at 40dB, +-2dB. Is that good enough?
Good enough for what? The TBolt can be setup to work with that, but it could
certainly be much better.
With a good Tbolt antenna setup you should see about 50 db for overhead
birds and in the high 40's for the lower
to Chris
What I've seen is that holding 0.1 C AT the SENSOR is pretty easy,
(Lady Heather will hold the TBolt's sensor to 0.01 deg using just a fan),
AND if you blow a lot of air around, then keeping the air gradients inside a
closed 'oven box' below 0.1 deg is also NO problem.
to Bert
Have
Yes almost as long as you include ONE more Resistor, R2 added below.
The dual cap thing does not get rid of leakage entirely, but close enough in
most cases.
That configuration is most useful for slow open loop filters when you want
low leakage errors.
It may be a bit of an overkill for a
this thread has wandered a bit.
The thread was originally for Simple...
Bottom line is that electrolytic caps can be made to work fine for a
SIMPLE analog controller built for home NUT use,
Not recommended for space or critical life support applications, or any
production thing.
Besides
Hal posted:
For those who aren't familiar with this trick, it's easy to make a low pass
filter in software:
X = X*(1-k) + k*new orX = X - k*X + k*new
OR
Gives exact same results using only one multiply,
New_X = Last_X + k * (New_data - Last_X)
OR
For powers of square root of two
Here is another analog control example based on the quick and dirty example
below.
It is a simple and Very poor GPSDO Rb design as far as noise jitter goes
because of the nonlinear and high Phase detector gain, and high 1e-8 noise
jitter on the PPS,
but still no problem to do with cheap
Chris
Here is a GPSDO I built that better fits Your definition of Simple. I used
this as my freq standard before getting a TBolt.
1) Feed the PPS output of an oncore GPS timing engine which has 1 Hz or
better yet 100 Hz output to the clk of a D FlipFlop (74HC74)
2) Feed the FF's D from a
, WarrenS warrensjmail-one at
yahoo.comwrote:
Chris
Here is a GPSDO I built that better fits Your definition of Simple. I
used this as my freq standard before getting a TBolt.
1) Feed the PPS output of an oncore GPS timing engine which has 1 Hz or
better yet 100 Hz output to the clk of a D FlipFlop
Fred
What you may of seen was how to use a TBolt to discipline a LPRO Rb.
There are several time nut posting on how to do that in a very simple and
high performance way.
http://www.febo.com/pipermail/time-nuts/2011-May/056526.html
IF? the RS232 command changes the freq and does not reset the phase,
then the way to get there is to use dither or PWM between two frequency
values.
Example: to change the phase 1ps, change the freq by 7e-13 for 1.4 seconds
and then put it back.
If you want finer resolution than 1 ps then
Sounds like an interest project, Do you have any performance plots?
It would be interesting to see how it compares with the TPLL2 which uses a
$5.00 USB sound card to greatly improve the performance of the old all
analog $10 TPLL.
Using mostly junk box parts, and a 3e-13 selected HP10811
MB asked (off line):
I have wanted to find out how to marry one of my Tbolts to one of my LPRO
Rb oscillators for a long time.
Some say doing this is a waste of time.
All depends what you plan to do with it.
Changing the Tbolt's internal Osc to an external LPRO Rb Osc will increase
the
I have a more basic time-nut question. Why is it a problem at all?
How can the time uncertainty between two known and fixed locations be that
large?
If they know they have a 70ns uncertainty in time, that would suggest that
their time measurement is known to be varying at one or both places.
Tbolt-Tic is what I call a Tbolt when it is NOT used as a GPSDO controller
but instead used as a high resolution time interval counter. (really a time
difference logger).
How do you make a single TBolt-Tic much better?
Simple, By making a dual TBolt-Tic.
From an offshoot of my Common view
Thanks Guys, Gives me lots to consider and go over.
Not going to be quite as easy as I hoped. Then if it was easy it would not
be Nut-fun.
Lots to learn, which I do best with experiments.
Sounds like using times much longer than 1 Hr is the way others do it, But
then they have different
. By comparison, the ADEV of a Tbolt
in the TPLL mode looks a lot like a bare GPS receiver. Would that work
better for what you want to do?
... snip
Ed
***
On 10/18/2011 12:32 PM, WarrenS wrote:
I'm doing some experiments in hopes of using the TBolt-Tic in a common
view configuration
Maybe this is too simple
LadyHeather is always checking the Tbolt's Internal Osc value against the
GPS.
By watching it's plot outputs you can tell if the Tbolt is on freq.
(compared to the GPS)
If no plot outputs, then something is broken, at that point is does not
matter what, can assume it
I'm doing some experiments in hopes of using the TBolt-Tic in a common view
configuration to lower the short term noise.
That is, instead of comparing a local externally connected Tbolt Osc to the
GPS, I want to compare it remotely to one of say Tom's supper H-masers or Cs
references.
The
So where do I get a cheap, used Russian GPSDO?
I have not seen any on EBay
Can I trade them my Tbolt? :)
per:
http://tycho.usno.navy.mil/ptti/1998/Vol%2030_18.pdf
Although not as well known as the GPS, the Russian global satellite
navigation system GLONASS possesses comparable capabilities
Anyone know what the propagation delay temperature coefficient is for RG6U coax
and how much it varies between different brands of cable?
In my efforts to improve the Tbolt's performance to make it into a better Cs
substitute,
test suggest that the temperature coefficient of the antenna lead-in
On Oct 16, 2011, at 1:32 PM, WarrenS wrote:
Anyone know what the propagation delay temperature coefficient is for RG6U
coax and how much it varies between different brands of cable?
In my efforts to improve the Tbolt's performance to make it into a better
Cs substitute,
test
the expected results column.
I think it's the same URL but 067.pdf as the file name.
John
On Oct 16, 2011, at 2:21 PM, WarrenS wrote:
Thanks John
Any chance using 75 ohm cable (as suggested in the Tbolt manual) like
RG6U, when used in a 50 Ohm system could be orders of magnitude
Rix
If you are using LadyHeather, Post or send me a screen shot using W S
Cr
Maybe just that the min or max Dac values are not set to - + 5V, or
something else easily fixed.
ws
[time-nuts] Thunderbolt error?
Rix Seacord eseacord at verizon.net
Hi gang
I'm getting an
again.
Attached is the screen shot
Thanks much
Rix
***
On 10/16/2011 3:47 PM, WarrenS wrote:
Rix
If you are using LadyHeather, Post or send me a screen shot using
W S Cr
Maybe just that the min or max Dac values are not set to - + 5V, or
something else easily fixed.
ws
Tom
Thanks for the Tbolt vs. H-maser data log,
That's great data showing how good GPS can be out to 200,000 sec with SA
off.
Your data showing a little under 5e-14 at 1 day, makes a very good reference
point to remember.
Any guess when your plot would flattens out or turn around?
It is also
I'll try again.
My last post was completely garbled somewhere along the line.
Using the 1 sec ADEV noise floor from the plot at
http://www.febo.com/pipermail/time-nuts/attachments/20111007/48d1ab68/attachment-0001.gif
This shows the RMS sum of the short term GPS signal's noise Plus the Tbolt
Thanks Tom very interesting.
I like your guess on how they get such a low noise for the PPT data.
I would like to know why they would go to the trouble, because I don't see
anywhere that information is used except for the PPT output.
Alos the Tbolt's PPT freq data, long term is usually offset
Good ideas, That's more to put on my to do list, But not near the top.
I've got two external Tbolts (one is a loaner) plus an internal one.
Right now I'm limited because of some long term testing I doing.
Something to be careful about when doing what you suggest is that the two
Tbolts will not
John wrote:
I'm curious where you got the noise data for the TBolt GPS engine
Besides the measured ADEV plot I posted at
http://www.febo.com/pipermail/time-nuts/attachments/20111007/48d1ab68/attachment-0001.gif
Attached is another way I've measured Phase noise of the Tbolt, to optimizing
Peter Gottlieb nerd at verizon.net wrote:
99% of the time I just plug things in and see what happens.
I do fix a lot of stuff, though,
Hmmm,
I have to wonder if there is more than a casual cause and effect
relationship between those two statements.
I've seen a strong relationship between
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