Sorry Everyone,
The answer is in the LH readme, and I completely overlooked it.
/k[?=#] - set temp control parameter '?'
Cheers,
david
Hi All,
I've setup a TBolt with a late model oscillator mounted externally to
the case, and moved the C version temp sensor from the main PCB to the
oscillator. With a little fan, LH is keeping the temperature within
about 0.02dC. Amazing, given I have about 10dC ambient variations.
How do I start LH with the PID parameters obtained during the autotune
(KA)?
Which bit of which source file should I look at to figure this out?
Thanks to Mark, John, Warren and others for LH!
davidh
On 17/01/2011 9:49 AM, WarrenS wrote:
Here is a Plot of the results, (The post would not accept both
pictures at the same time)
This is the 'KISS' enclosure and driver I use with Lady Heather's
temperature controller that holds the temperature change to under
0.01 deg.
I have the box just setting on top of a PC next to the a window.
'KISS' = Keep It Simple and SMALL ...
I don't know if this low resolution picture will post correctly.
If anyone wants a high resolution view of the H/W,
or an expanded plot showing the results over a 2 week period,
I can provide them, if someone will send me the name of a site to
post them at.
ws
***************
----- Original Message -----
From: "Mark Sims"
<holrum-pkbjnfxxiarbdgjk7y7tuq-xmd5yjdbdmrexy1tmh2...@public.gmane.org>
Sent: Saturday, January 15, 2011 12:53 PM
Subject: [time-nuts] Achievable temperature stability for
Thunderboltenvironment?
Using Lady Heather's temperature controller (fan+cardboard box+solid
state
relay+baffling and thermal mass to taste) I get around +/- 3
millidegree
temperature control when the AC/furnace is not running and +/- 20
millidegrees with them cycling. Long term temperature average is
down in the
tens of microdegrees. Under ideal conditions, I have seen over an
hour where
the temperature sensor did not move a single microdegree! The active
temperature control has a most definite positive effect on the device
performance.
I place the power supply in the thermal enclosure to minimize its
output
temperature coefficient. Yes, the thermal sensor is away from the
oscillator
module (and power supply) but in the semi-closed environment of the
box, the
thermal stability on one area is pretty much the same everywhere. I
have
chosen my box so that if the fan stops (for whatever reason) the
temperature
in the box still does not exceed 50C.
For the ultra best uber performance you need to maximize the quality
of all
the input and environmental variables (temperature, power, antenna,
surveyed
location, disciplining parameters, etc) Choose your antenna mask
angle and
signal level threshold to minimize satellite constellation
switching. With a
little nutty attention to the details you can get parts per trillion
performance out of the little beastie.
**********************
As long as the Tbolt's Osc is being disciplined, I have found:
Most Tbolt's with factory default settings (i.e TC = 100) will show
minimum
effects with standard room temperature changes. No special protection
needed.
A unit that is tuned a bit better (in a box and TC of 300 to 500), then
temperature changes of less than 1 deg / hr will be OK.
A better optimized setup with TC settings in the 500 to 1000 sec
range, a
max temperature rate of change of up to 0.1 deg C per hr will have
minimum
effect.
If you want to go all out time nuts, (with "Special" TC setting
above 1000)
then best to hold the sensor temperature to within 0.02 deg total
change,
which can be done using Lady Heather's Temperature controller.
How high you can go with the TC setting, depends on many things,
such as how
stable the Tbolt's Oscillator is. Each setup is different.
A TC setting of 1000 sec is generally the max you should go. With this
Tbolt, the best results can be obtained with a 'special' TC setting
to 2000
to 3000.
Attached is the last 2 weeks of a Lady Heather plot, showing a
temperature
tracking test I did to see how long it takes a Tbolt to learn a new
environment.
This unit has a Poor antenna, 1 sec ADEV of 1e-12, Aging of 4 e-12 /
day,
Temp coeff of 2.5e-10 / deg.
Have fun
ws
************************
>
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