tvb wrote:
do either of you have actual tempco numbers?
I checked my notes and found that I did not record any free-running
tempco values. My observations were based on the scale factors I had
to use to get the temperature and DAC graphs in Lady Heather to
overlay each other. I initially
Hi
LH can get a bit confused about OCXO tempo. It's not really the software's
fault, as you point out - the data just isn't there.
Bob
On Dec 14, 2012, at 5:36 AM, Charles P. Steinmetz
charles_steinm...@lavabit.com wrote:
tvb wrote:
do either of you have actual tempco numbers?
I
...@lavabit.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Friday, December 14, 2012 2:36 AM
Subject: Re: [time-nuts] Thunderbolt oven / non-stable operating temperature
tvb wrote:
do either of you have actual tempco numbers?
I checked my notes and found
On 12/11/2012 10:33 PM, Charles P. Steinmetz wrote:
All three have Trimble 37265 OCXOs
(( sorry to single out that one line ))
Just a curiosity. Is there any way to check that via software? Did you
just physically look under the cover, or how did you figure out which
type of oscillator your
Hi
The OCXO is a dumb version. It does not talk to the TBolt. There's no way to
check it in software. There are a few examples out there that have late model
stickers on the outside and earlier parts on the inside. There's pretty much no
way to know what you have without opening up the box.
Sarah wrote:
All three have Trimble 37265 OCXOs
Just a curiosity. Is there any way to check that via software? Did you
just physically look under the cover, or how did you figure out which
type of oscillator your thunderbolt has?
You need to open it up. There is a sticker on the OXCO can:
tvb wrote:
the tempco can be inferred from temp and quadratic PPS offset
residuals (EFC gain is not a factor in this case)
It would be interesting (to me, at least) to know the spread of EFC
gains from a reasonable population of Tbolts.
Best regards,
Charles
Hi
The real answer to that is going to be a that depends kind of thing. The
population of units in the basement are all within 20% of each other as
measured by LH's auto tune process.
Bob
On Dec 14, 2012, at 2:51 PM, Charles P. Steinmetz
charles_steinm...@lavabit.com wrote:
tvb wrote:
Warrenm
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
-nuts] Thunderbolt oven / non-stable operating temperature
Although ignorant of why, I have a pretty good of idea of what is happening.
There is a 1:1 correlation between the TBolt temperature output reading and the
rest of the TBolt reported values. In particular the estimate of the TBolt
] Thunderbolt oven / non-stable operating temperature
Although the Trimble oscillator has superb phase noise performance, it has
TERRIBLE temperature sensitivity. It appears to be a single oven
oscillator, not a double oven. The PWM'ed fan temperature control
implemented in Lady Heather effectively
Hi
I suspect that to use the temperature chip data, it needs to be running on GPS
for several days while ramping temperature. After that, put it in holdover,
observe the time drift over the next four hours with a similar ramp. Since they
work with the later chip, the ramp would have to be
Bill wrote:
Well, perhaps you are not looking close enough. That is you need to
be observing
at a finer level of comparison. The changes, observed here and at another
location, are in parts in 10-10 to 10-11 range, sometimes
larger. At one of the
locations there was a direct correlation
If it is used for tempco it should affect the temp by stabilizing offset with
temp changes correct? Maybe a more correct approach would be to disconnect it
and test. Has been awhile since I read that testing stuff.
Doc
Sent from mobile
On Dec 11, 2012, at 6:39 AM, Charles P. Steinmetz
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bill Dailey
Sent: Tuesday, December 11, 2012 10:45 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thunderbolt oven / non-stable operating temperature
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
Warren wrote:
During normal operation my Tbolt uses the temperature and ADC data
to in its Kalman filter that then can predict a simple linear
temperature constant, and simple linear ageing rate.
* * *
But the **Only** time the Kalman filter is used is during
Holdover. It does this
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
Hi Warren,
Starting from a factory reset, it has something it will use in under 1/2 day.
And that would explain my and Charles' null results. Nice.
If the temperature has not been thru a few cycles and /or the Ageing is still
at a high initial cold start rate and still changing,
the
Although the Trimble oscillator has superb phase noise performance, it has
TERRIBLE temperature sensitivity. It appears to be a single oven oscillator,
not a double oven. The PWM'ed fan temperature control implemented in Lady
Heather effectively makes the unit a double oven. Also, by
Mark wrote:
Although the Trimble oscillator has superb phase noise
performance, it has TERRIBLE temperature sensitivity.
It appears that most do but some don't. Between the results I have
seen posted on the list (Lady Heather screen shots) and my own data,
they seem to fall into two
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
Although the Trimble oscillator has superb phase noise
performance, it has TERRIBLE temperature sensitivity.
It appears that most do but some don't. Between the results I have
seen posted on the list (Lady Heather screen shots) and my own data,
they seem to fall into two groups. I have
Hello Tom,
the GPS noise dominates for typical double oven OCXO's where the tempcos
are very small (say below 5E-012 per degree C).
On single oven units, the tempcos are typically 50 to 200 times larger, and
thus the required EFC change over temperature is also that much larger.
If I am
Ended up with a gently used trimble thunderbolt a few months ago, and
been trying to figure out the best settings to use (time constant,
damping, etc.) for best performance.
I got distracted though. There is something which I find rather
annoying, and I'm spending more time messing with this
Hi
The oven in the OCXO keeps the crystal at a constant temperature. It is normal
for the TBolt it's self to idle 10 to 20C above ambient. The temperature sensor
is located near the 9 pin D connector. It shows a temperature somewhere in
between the ambient and the OCXO case temperature. Some
measurement
time-nuts@febo.com
Sent: Monday, December 10, 2012 5:15 PM
Subject: [time-nuts] Thunderbolt oven / non-stable operating temperature
Ended up with a gently used trimble thunderbolt a few months ago, and
been trying to figure out the best settings to use (time constant,
damping, etc
Sarah,
The reported temperature is not the oven temp, but rather the temp of the
circuit board just behind the DB-9 serial connector. As far as I know, the
actual oven temp is not available outside the OCXO.
Regards,
geo
On Mon, Dec 10, 2012 at 5:15 PM, Sarah White kuze...@gmail.com wrote:
I feel like shouldn't need to fuss with ambient conditions this heavily
for an OCXO, and find myself researching construction / design for a DIY
outer-oven to wrap the thunderbolt in.
Anyone have experience with non-stable temperature on a trimble thunderbolt?
The temperature you see is not from
On 12/10/2012 5:22 PM, Bob Camp wrote:
Hi
The oven in the OCXO keeps the crystal at a constant temperature. It is
normal for the TBolt it's self to idle 10 to 20C above ambient. The
temperature sensor is located near the 9 pin D connector. It shows a
temperature somewhere in between the
I believe that the high temperature alarm you see is triggered at 50 degrees
C. If that is what you're seeing without artificially raising the temperature
of the Thunderbolt by insulating it so it can't radiate the heat, what I said
about replacing the chip is correct but if it is staying
On 12/10/2012 6:10 PM, Arthur Dent wrote:
I believe that the high temperature alarm you see is triggered at 50 degrees
C. If that is what you're seeing without artificially raising the
temperature
of the Thunderbolt by insulating it so it can't radiate the heat, what I said
about
Sarah,
That temperature sensor does have an effect on the final outcome as it is part
of
the internal equation. So buffering the ambient temperature is important.
You do not need to go crazy, but having it contained in a box with some small
amount
of heat applied and maintained by some
Hi Charles,
Well, perhaps you are not looking close enough. That is you need to be
observing
at a finer level of comparison. The changes, observed here and at another
location, are in parts in 10-10 to 10-11 range, sometimes larger. At one of the
locations there was a direct correlation to
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