In message <5583e434-4c72-4a4f-a60b-75a4204ef...@n1k.org>, Bob kb8tq writes:
> Backing up a bit …. the objective is not to minimize overshoot or
> keep the loop from oscillating. The issue here is optimizing the noise
> output of the combination of GPS + OCXO when combined via
> the cont
Hi
Backing up a bit …. the objective is not to minimize overshoot or
keep the loop from oscillating. The issue here is optimizing the noise
output of the combination of GPS + OCXO when combined via
the control loop. It’s a very different objective ….
Bob
> On Mar 7, 2020, at 8:01 PM, Bill Hawki
Try https://en.wikipedia.org/wiki/PID_controller
If that doesn't help, what we used to do for industrial process controllers was
to set Reset time to the largest value and Derivative to zero (to disable them)
and then increasethe gain until the loop oscillated when you made a step change
to the
Hi
That does not help you optimize the noise in a GPSDO. It’s targeted
at a completely different aspect of the control process.
Bob
> On Mar 7, 2020, at 6:04 PM, Hal Murray wrote:
>
>
> kb...@n1k.org said:
>> As far as I know there is no “closed form” solution to tuning a GPSDO. It is
>> ver
kb...@n1k.org said:
> As far as I know there is no âclosed formâ solution to tuning a GPSDO. It
> is
> very much a measure / tweak / measure / tweak sort of thing.
I've seen a recipe for tuning a PID controller. That was ages ago. I wonder
where.
The key idea was that you needed to be
This might be of interest to Time-Nuts. The reference to Russian
Loran is interesting.
https://rntfnd.org/2020/02/03/how-the-west-is-losing-the-navigation-and-timing-war-navigation-news/
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Michael bringing old Cesiums back to life is interesting business.
I have one thing to check. The c field settings. If the tubes been changed
that absolutely matters. Usually a resistor on the regulator baord of the
oven controller. I had a different tube in a unit and the straps were not
changed t
Learned gentlemen,
Thanks for all the replies!
Some additional info.
I'm 79 yo and never had any programming classes or experience in programming.
My specialty was the field of maintaining medical equipment. My tech education
in the USAF was ground radio (with tubes no less).
I wasn't aware th
Dear time-nuts,
I've had the chance to work on a 5061A over the last couple of days. I
guess it's a fairly old unit with "singing" oven controller and 105 5
MHz crystal oven assembly. Last digits from serial number are "0964" -
not sure if that indicates the date of mfg. It definitely has been
tam
Hi,
I am sure it is theoretically possible to find an optimal control loop
design if you have accurate models of the OCXO and for the behaviour of the
1PPS pulse.
TvB has written a GPSDO simulator which allows to code different PLL and
control algorithms. I have implemented something similar in Mat
Hi
As far as I know there is no “closed form” solution to tuning a GPSDO.
It is very much a measure / tweak / measure / tweak sort of thing.
That said, there are a lot of basic design constraints that are pretty
well known. Your DAC needs to have a pretty small LSB. Updates
are normally done onc
Hi,
How do you optimally tune the control loop time constant ?
(Mine gets quite unstable when the update rate is slow - and the amplitude of
the change step low - enough not to degrade the OCXO performance )
Is there a method described somewhere (like the Ziegler–Nichols method for PID)
?
Thx,
I cleaned up the graphs. There are a couple of big gaps in 2016. It's pretty
clean since then.
Each graph has 14 months - an extra before and after the nominal range.
There are a couple of big swings in late 2019: 70 and 80 seconds in a couple
of days.
http://users.megapathdsl.net/~hmurray/t
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